[PATCH v5 0/14] Uprobes v5

[PATCH v5 0/14] Uprobes v5

[Srikar Dronamraju]

intro.patch

From: Srikar Dronamraju <srikar@linux.vnet.ibm.com>

Uprobes Patches

Changelog from v4:
  - Rebased to tip tree. (2.6.35-rc3-tip)

Changelog from v3:
  - Reverted to background page replacement as suggested by Peter Zijlstra.
  - Dso in 'perf probe' can be either be a short name or a absolute path.
  - Addressed comments from Masami, Frederic, Steven on traceevents and perf

Changelog from v2:
  - Addressed comments from Oleg, including removal of interrupt context
    handlers, reverting background page replacement in favour of
    access_process_vm().

  - Provides perf interface for uprobes.

Changelog from v1:
 - Added trace_event interface for uprobes.
 - Addressed comments from Andrew Morton and Randy Dunlap.

For previous posting: please refer: http://lkml.org/lkml/2010/3/20/107
and http://lkml.org/lkml/2010/5/18/307

This patchset implements Uprobes which enables you to dynamically break
into any routine in a user space application and collect information
non-disruptively.

This patchset is a rework based on suggestions from discussions on lkml
in January and March this year (http://lkml.org/lkml/2010/1/11/92,
http://lkml.org/lkml/2010/1/27/19, http://lkml.org/lkml/2010/3/20/107
and http://lkml.org/lkml/2010/3/31/199 ). This implementation of
uprobes doesnt depend on utrace.

When a uprobe is registered, Uprobes makes a copy of the probed
instruction, replaces the first byte(s) of the probed instruction with a
breakpoint instruction. (Uprobes uses background page replacement
mechanism and ensures that the breakpoint affects only that process.)

When a CPU hits the breakpoint instruction, Uprobes gets notified of
trap and finds the associated uprobe. It then executes the associated
handler. Uprobes single-steps its copy of the probed instruction and
resumes execution of the probed process at the instruction following the
probepoint. Instruction copies to be single-stepped are stored in a
per-process "execution out of line (XOL) area". Currently XOL area is
allocated as one page vma.

Advantages of uprobes over conventional debugging include:

1. Non-disruptive.
Unlike current ptrace based mechanisms, uprobes tracing wouldnt
involve signals, stopping threads and context switching between the
tracer and tracee.

2. Much better handling of multithreaded programs because of XOL.
Current ptrace based mechanisms use single stepping inline, i.e they
copy back the original instruction on hitting a breakpoint.  In such
mechanisms tracers have to stop all the threads on a breakpoint hit or
tracers will not be able to handle all hits to the location of
interest. Uprobes uses execution out of line, where the instruction to
be traced is analysed at the time of breakpoint insertion and a copy
of instruction is stored at a different location.  On breakpoint hit,
uprobes jumps to that copied location and singlesteps the same
instruction and does the necessary fixups post singlestepping.

3. Multiple tracers for an application.
Multiple uprobes based tracer could work in unison to trace an
application. There could one tracer that could be interested in
generic events for a particular set of process. While there could be
another tracer that is just interested in one specific event of a
particular process thats part of the previous set of process.

4. Corelating events from kernels and userspace.
Uprobes could be used with other tools like kprobes, tracepoints or as
part of higher level tools like perf to give a consolidated set of
events from kernel and userspace.  In future we could look at a single
backtrace showing application, library and kernel calls.

Here is the list of TODO Items.

- Allowing probes across fork.
- Allowing probes per-executable/per dso.
- Allow multiple probes to share a probepoint.
- Return probes.
- Support for other architectures.
- Uprobes booster.
- Merge uprobes and kprobes trace_event.
- replace macro with bits in inat table.

The current patchset is based on 2.6.35-rc3-tip.

Please do provide your valuable comments.

Thanks in advance.
Srikar

Srikar Dronamraju (10):
 1.  X86 instruction analysis: Move Macro W to insn.h
 2.  mm: Move replace_page() to mm/memory.c
 3.  user_bkpt: User Space Breakpoint Assistance Layer
 4.  user_bkpt: X86 details for User space breakpoint assistance
 5.  user_bkpt: Slot allocation for Execution out of line
 6.  uprobes: Uprobes Implementation
 7.  uprobes: X86 details for Uprobes
 8.  samples: Uprobes samples
 9.  uprobes: Uprobes Documentation patch
 10. trace: Share common code for uprobes/kprobes traceevents
 11. trace: uprobes trace_event interface
 12. perf: Dont adjust symbols if lookup is by name.
 13. perf: Re-add make_absolute_path().
 14. perf: perf interface for uprobes.

 Documentation/uprobes.txt          |  236 +++++++++
 arch/Kconfig                       |   31 ++
 arch/x86/Kconfig                   |    2 +
 arch/x86/include/asm/insn.h        |    7 +
 arch/x86/include/asm/thread_info.h |    2 +
 arch/x86/include/asm/user_bkpt.h   |   43 ++
 arch/x86/kernel/Makefile           |    3 +
 arch/x86/kernel/kprobes.c          |    7 -
 arch/x86/kernel/signal.c           |   17 +
 arch/x86/kernel/uprobes.c          |   77 +++
 arch/x86/kernel/user_bkpt.c        |  572 ++++++++++++++++++++++
 fs/exec.c                          |    4 +
 include/linux/mm.h                 |    4 +
 include/linux/mm_types.h           |    4 +
 include/linux/sched.h              |    3 +
 include/linux/uprobes.h            |  169 +++++++
 include/linux/user_bkpt.h          |  305 ++++++++++++
 include/linux/user_bkpt_xol.h      |   40 ++
 kernel/Makefile                    |    3 +
 kernel/fork.c                      |   21 +
 kernel/trace/Kconfig               |   13 +
 kernel/trace/Makefile              |    1 +
 kernel/trace/trace.h               |    5 +
 kernel/trace/trace_kprobe.c        |  141 +------
 kernel/trace/trace_probe.h         |  159 +++++++
 kernel/trace/trace_uprobe.c        |  921 ++++++++++++++++++++++++++++++++++++
 kernel/uprobes.c                   |  681 ++++++++++++++++++++++++++
 kernel/user_bkpt.c                 |  589 +++++++++++++++++++++++
 kernel/user_bkpt_xol.c             |  302 ++++++++++++
 mm/ksm.c                           |  112 -----
 mm/memory.c                        |  120 +++++
 samples/Kconfig                    |    7 +
 samples/Makefile                   |    2 +-
 samples/uprobes/Makefile           |   17 +
 samples/uprobes/uprobe_example.c   |   83 ++++
 tools/perf/builtin-probe.c         |   13 +-
 tools/perf/builtin-top.c           |   20 -
 tools/perf/util/abspath.c          |   81 ++++
 tools/perf/util/cache.h            |    1 +
 tools/perf/util/event.c            |   20 +
 tools/perf/util/event.h            |    1 +
 tools/perf/util/probe-event.c      |  466 +++++++++++++------
 tools/perf/util/probe-event.h      |   37 +-
 tools/perf/util/probe-finder.c     |   20 +-
 tools/perf/util/probe-finder.h     |    6 +-
 tools/perf/util/symbol.c           |    6 +-
 46 files changed, 4917 insertions(+), 457 deletions(-)
---

 0 files changed, 0 insertions(+), 0 deletions(-)

[PATCH v5 1/14] X86 instruction analysis: Move Macro W to insn.h

[Srikar Dronamraju]

move_W_to_insn.patch

From: Srikar Dronamraju <srikar@linux.vnet.ibm.com>

Move Macro W to asm/insn.h

Macro W used to know if the instructions are valid for
user-space/kernel space.  This macro is used by kprobes and
user_bkpt. (i.e user space breakpoint assistance layer.) So moving it
to a common header file asm/insn.h.

TODO: replace macro W with bits in inat table. (suggested by Masami Hiramatsu)

Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
---

 arch/x86/include/asm/insn.h |    7 +++++++
 arch/x86/kernel/kprobes.c   |    7 -------
 2 files changed, 7 insertions(+), 7 deletions(-)


diff --git a/arch/x86/include/asm/insn.h b/arch/x86/include/asm/insn.h
index 88c765e..2ceb3d0 100644
--- a/arch/x86/include/asm/insn.h
+++ b/arch/x86/include/asm/insn.h
@@ -23,6 +23,13 @@
 /* insn_attr_t is defined in inat.h */
 #include <asm/inat.h>
 
+#define W(row, b0, b1, b2, b3, b4, b5, b6, b7, b8, b9, ba, bb, bc, bd, be, bf)\
+	(((b0##UL << 0x0)|(b1##UL << 0x1)|(b2##UL << 0x2)|(b3##UL << 0x3) |   \
+	  (b4##UL << 0x4)|(b5##UL << 0x5)|(b6##UL << 0x6)|(b7##UL << 0x7) |   \
+	  (b8##UL << 0x8)|(b9##UL << 0x9)|(ba##UL << 0xa)|(bb##UL << 0xb) |   \
+	  (bc##UL << 0xc)|(bd##UL << 0xd)|(be##UL << 0xe)|(bf##UL << 0xf))    \
+	 << (row % 32))
+
 struct insn_field {
 	union {
 		insn_value_t value;
diff --git a/arch/x86/kernel/kprobes.c b/arch/x86/kernel/kprobes.c
index 345a4b1..9ab62e2 100644
--- a/arch/x86/kernel/kprobes.c
+++ b/arch/x86/kernel/kprobes.c
@@ -66,12 +66,6 @@ DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
 
 #define stack_addr(regs) ((unsigned long *)kernel_stack_pointer(regs))
 
-#define W(row, b0, b1, b2, b3, b4, b5, b6, b7, b8, b9, ba, bb, bc, bd, be, bf)\
-	(((b0##UL << 0x0)|(b1##UL << 0x1)|(b2##UL << 0x2)|(b3##UL << 0x3) |   \
-	  (b4##UL << 0x4)|(b5##UL << 0x5)|(b6##UL << 0x6)|(b7##UL << 0x7) |   \
-	  (b8##UL << 0x8)|(b9##UL << 0x9)|(ba##UL << 0xa)|(bb##UL << 0xb) |   \
-	  (bc##UL << 0xc)|(bd##UL << 0xd)|(be##UL << 0xe)|(bf##UL << 0xf))    \
-	 << (row % 32))
 	/*
 	 * Undefined/reserved opcodes, conditional jump, Opcode Extension
 	 * Groups, and some special opcodes can not boost.
@@ -98,7 +92,6 @@ static const u32 twobyte_is_boostable[256 / 32] = {
 	/*      -----------------------------------------------         */
 	/*      0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f          */
 };
-#undef W
 
 struct kretprobe_blackpoint kretprobe_blacklist[] = {
 	{"__switch_to", }, /* This function switches only current task, but

[PATCH v5 2/14] mm: Move replace_page to mm/memory.c

[Srikar Dronamraju]

move_replace_page.patch

From: Srikar Dronamraju <srikar@linux.vnet.ibm.com>

Move replace_page() and write_protect_page() to mm/memory.c

User bkpt will use background page replacement approach to insert/delete
breakpoints. Background page replacement approach will be based on
replace_page and write_protect_page.
Now replace_page() loses its static attribute.

Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
---

 include/linux/mm.h |    4 ++
 mm/ksm.c           |  112 -------------------------------------------------
 mm/memory.c        |  120 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 124 insertions(+), 112 deletions(-)


diff --git a/include/linux/mm.h b/include/linux/mm.h
index b969efb..206008e 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -858,6 +858,10 @@ void account_page_dirtied(struct page *page, struct address_space *mapping);
 int set_page_dirty(struct page *page);
 int set_page_dirty_lock(struct page *page);
 int clear_page_dirty_for_io(struct page *page);
+int replace_page(struct vm_area_struct *vma, struct page *page,
+					struct page *kpage, pte_t orig_pte);
+int write_protect_page(struct vm_area_struct *vma, struct page *page,
+						      pte_t *orig_pte);
 
 extern unsigned long move_page_tables(struct vm_area_struct *vma,
 		unsigned long old_addr, struct vm_area_struct *new_vma,
diff --git a/mm/ksm.c b/mm/ksm.c
index 6c3e99b..ce432e1 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -713,118 +713,6 @@ static inline int pages_identical(struct page *page1, struct page *page2)
 	return !memcmp_pages(page1, page2);
 }
 
-static int write_protect_page(struct vm_area_struct *vma, struct page *page,
-			      pte_t *orig_pte)
-{
-	struct mm_struct *mm = vma->vm_mm;
-	unsigned long addr;
-	pte_t *ptep;
-	spinlock_t *ptl;
-	int swapped;
-	int err = -EFAULT;
-
-	addr = page_address_in_vma(page, vma);
-	if (addr == -EFAULT)
-		goto out;
-
-	ptep = page_check_address(page, mm, addr, &ptl, 0);
-	if (!ptep)
-		goto out;
-
-	if (pte_write(*ptep)) {
-		pte_t entry;
-
-		swapped = PageSwapCache(page);
-		flush_cache_page(vma, addr, page_to_pfn(page));
-		/*
-		 * Ok this is tricky, when get_user_pages_fast() run it doesnt
-		 * take any lock, therefore the check that we are going to make
-		 * with the pagecount against the mapcount is racey and
-		 * O_DIRECT can happen right after the check.
-		 * So we clear the pte and flush the tlb before the check
-		 * this assure us that no O_DIRECT can happen after the check
-		 * or in the middle of the check.
-		 */
-		entry = ptep_clear_flush(vma, addr, ptep);
-		/*
-		 * Check that no O_DIRECT or similar I/O is in progress on the
-		 * page
-		 */
-		if (page_mapcount(page) + 1 + swapped != page_count(page)) {
-			set_pte_at(mm, addr, ptep, entry);
-			goto out_unlock;
-		}
-		entry = pte_wrprotect(entry);
-		set_pte_at_notify(mm, addr, ptep, entry);
-	}
-	*orig_pte = *ptep;
-	err = 0;
-
-out_unlock:
-	pte_unmap_unlock(ptep, ptl);
-out:
-	return err;
-}
-
-/**
- * replace_page - replace page in vma by new ksm page
- * @vma:      vma that holds the pte pointing to page
- * @page:     the page we are replacing by kpage
- * @kpage:    the ksm page we replace page by
- * @orig_pte: the original value of the pte
- *
- * Returns 0 on success, -EFAULT on failure.
- */
-static int replace_page(struct vm_area_struct *vma, struct page *page,
-			struct page *kpage, pte_t orig_pte)
-{
-	struct mm_struct *mm = vma->vm_mm;
-	pgd_t *pgd;
-	pud_t *pud;
-	pmd_t *pmd;
-	pte_t *ptep;
-	spinlock_t *ptl;
-	unsigned long addr;
-	int err = -EFAULT;
-
-	addr = page_address_in_vma(page, vma);
-	if (addr == -EFAULT)
-		goto out;
-
-	pgd = pgd_offset(mm, addr);
-	if (!pgd_present(*pgd))
-		goto out;
-
-	pud = pud_offset(pgd, addr);
-	if (!pud_present(*pud))
-		goto out;
-
-	pmd = pmd_offset(pud, addr);
-	if (!pmd_present(*pmd))
-		goto out;
-
-	ptep = pte_offset_map_lock(mm, pmd, addr, &ptl);
-	if (!pte_same(*ptep, orig_pte)) {
-		pte_unmap_unlock(ptep, ptl);
-		goto out;
-	}
-
-	get_page(kpage);
-	page_add_anon_rmap(kpage, vma, addr);
-
-	flush_cache_page(vma, addr, pte_pfn(*ptep));
-	ptep_clear_flush(vma, addr, ptep);
-	set_pte_at_notify(mm, addr, ptep, mk_pte(kpage, vma->vm_page_prot));
-
-	page_remove_rmap(page);
-	put_page(page);
-
-	pte_unmap_unlock(ptep, ptl);
-	err = 0;
-out:
-	return err;
-}
-
 /*
  * try_to_merge_one_page - take two pages and merge them into one
  * @vma: the vma that holds the pte pointing to page
diff --git a/mm/memory.c b/mm/memory.c
index 119b7cc..3fb2b9d 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2582,6 +2582,126 @@ void unmap_mapping_range(struct address_space *mapping,
 }
 EXPORT_SYMBOL(unmap_mapping_range);
 
+/**
+ * replace_page - replace page in vma by new ksm page
+ * @vma:      vma that holds the pte pointing to page
+ * @page:     the page we are replacing by kpage
+ * @kpage:    the ksm page we replace page by
+ * @orig_pte: the original value of the pte
+ *
+ * Returns 0 on success, -EFAULT on failure.
+ */
+int replace_page(struct vm_area_struct *vma, struct page *page,
+			struct page *kpage, pte_t orig_pte)
+{
+	struct mm_struct *mm = vma->vm_mm;
+	pgd_t *pgd;
+	pud_t *pud;
+	pmd_t *pmd;
+	pte_t *ptep;
+	spinlock_t *ptl;
+	unsigned long addr;
+	int err = -EFAULT;
+
+	addr = page_address_in_vma(page, vma);
+	if (addr == -EFAULT)
+		goto out;
+
+	pgd = pgd_offset(mm, addr);
+	if (!pgd_present(*pgd))
+		goto out;
+
+	pud = pud_offset(pgd, addr);
+	if (!pud_present(*pud))
+		goto out;
+
+	pmd = pmd_offset(pud, addr);
+	if (!pmd_present(*pmd))
+		goto out;
+
+	ptep = pte_offset_map_lock(mm, pmd, addr, &ptl);
+	if (!pte_same(*ptep, orig_pte)) {
+		pte_unmap_unlock(ptep, ptl);
+		goto out;
+	}
+
+	get_page(kpage);
+	page_add_anon_rmap(kpage, vma, addr);
+
+	flush_cache_page(vma, addr, pte_pfn(*ptep));
+	ptep_clear_flush(vma, addr, ptep);
+	set_pte_at_notify(mm, addr, ptep, mk_pte(kpage, vma->vm_page_prot));
+
+	page_remove_rmap(page);
+	put_page(page);
+
+	pte_unmap_unlock(ptep, ptl);
+	err = 0;
+out:
+	return err;
+}
+
+/**
+ * write_protect_page - mark the page readonly
+ * @vma:      vma that holds the page we want to mark
+ * @page:     page that needs to be marked readonly
+ * @orig_pte: pte for the protected page.
+ *
+ * Returns 0 on success, -EFAULT on failure.
+ */
+int write_protect_page(struct vm_area_struct *vma, struct page *page,
+						      pte_t *orig_pte)
+{
+	struct mm_struct *mm = vma->vm_mm;
+	unsigned long addr;
+	pte_t *ptep;
+	spinlock_t *ptl;
+	int swapped;
+	int err = -EFAULT;
+
+	addr = page_address_in_vma(page, vma);
+	if (addr == -EFAULT)
+		goto out;
+
+	ptep = page_check_address(page, mm, addr, &ptl, 0);
+	if (!ptep)
+		goto out;
+
+	if (pte_write(*ptep)) {
+		pte_t entry;
+
+		swapped = PageSwapCache(page);
+		flush_cache_page(vma, addr, page_to_pfn(page));
+		/*
+		 * Ok this is tricky, when get_user_pages_fast() run it doesnt
+		 * take any lock, therefore the check that we are going to make
+		 * with the pagecount against the mapcount is racey and
+		 * O_DIRECT can happen right after the check.
+		 * So we clear the pte and flush the tlb before the check
+		 * this assure us that no O_DIRECT can happen after the check
+		 * or in the middle of the check.
+		 */
+		entry = ptep_clear_flush(vma, addr, ptep);
+		/*
+		 * Check that no O_DIRECT or similar I/O is in progress on the
+		 * page
+		 */
+		if (page_mapcount(page) + 1 + swapped != page_count(page)) {
+			set_pte_at(mm, addr, ptep, entry);
+			goto out_unlock;
+		}
+		entry = pte_wrprotect(entry);
+		set_pte_at_notify(mm, addr, ptep, entry);
+	}
+	*orig_pte = *ptep;
+	err = 0;
+
+out_unlock:
+	pte_unmap_unlock(ptep, ptl);
+out:
+	return err;
+}
+
 int vmtruncate_range(struct inode *inode, loff_t offset, loff_t end)
 {
 	struct address_space *mapping = inode->i_mapping;

[PATCH v5 3/14] User Space Breakpoint Assistance Layer

[Srikar Dronamraju]

user_bkpt_core.patch

From: Srikar Dronamraju <srikar@linux.vnet.ibm.com>

User Space Breakpoint Assistance Layer (USER_BKPT)
Changelog from V3: (reimplement background page replacement)
	* Replemented background page replacement based on inputs
	  from Peter Zijlstra.

Changelog from v2: (addressing comments from Oleg)
	* Use access_process_vm instead of replace_page based
	  background page replacement.

Changelog from v1:
	* Use k(un)map_atomic instead of k(un)map.
	* Remove BUG_ON.
	* Few parameter changes to be more consistent with sparse.
	* Added kernel-doc comments whereever necessary.
	* Introduce a check to detect if post_xol can sleep.

Currently there is no mechanism in kernel to insert/remove breakpoints.

This patch implements user space breakpoint assistance layer provides
kernel subsystems with architecture independent interface to establish
breakpoints in user applications. This patch provides core
implementation of user_bkpt and also wrappers for architecture dependent
methods.

USER_BKPT currently supports both single stepping inline and execution
out of line strategies. Two different probepoints in the same process
can have two different strategies. It handles pre-processing and
post-processing of singlestep after a breakpoint hit.

Single stepping inline strategy is the traditional method where original
instructions replace the breakpointed instructions on a breakpoint hit.
This method works well with single threaded applications. However its
racy with multithreaded applications.

Execution out of line strategy single steps on a copy of the
instruction. This method works well for both single-threaded and
multithreaded applications.

There could be other strategies like emulating an instruction. However
they are currently not implemented.

Insertion and removal of breakpoints is by "Background page
replacement". i.e make a copy of the page, modify its the contents, set
the pagetable and flush the tlbs. This page uses enhanced replace_page
to cow the page. Modified page is only reflected for the interested
process. Others sharing the page will still see the old copy.

You need to follow this up with the USER_BKPT patch for your
architecture.

Uprobes uses this facility to insert/remove breakpoint.

TODO: Merge user_bkpt layer with uprobes.

Signed-off-by: Jim Keniston <jkenisto@us.ibm.com>
Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
---

 arch/Kconfig              |   14 +
 include/linux/user_bkpt.h |  305 +++++++++++++++++++++++
 kernel/Makefile           |    1 
 kernel/user_bkpt.c        |  589 +++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 909 insertions(+), 0 deletions(-)
 create mode 100644 include/linux/user_bkpt.h
 create mode 100644 kernel/user_bkpt.c


diff --git a/arch/Kconfig b/arch/Kconfig
index 4877a8c..4018d49 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -47,6 +47,17 @@ config OPTPROBES
 	depends on !PREEMPT
 	select KALLSYMS_ALL
 
+config USER_BKPT
+	bool "User-space breakpoint assistance (EXPERIMENTAL)"
+	depends on MODULES
+	depends on HAVE_USER_BKPT
+	depends on MMU
+	help
+	  User_bkpt (User-space breakpoint assistance layer) enables
+	  kernel subsystems to establish breakpoints in user applications.
+	  This service is used by components such as uprobes.
+	  If in doubt, say "N".
+
 config HAVE_EFFICIENT_UNALIGNED_ACCESS
 	bool
 	help
@@ -80,6 +91,9 @@ config USER_RETURN_NOTIFIER
 	  Provide a kernel-internal notification when a cpu is about to
 	  switch to user mode.
 
+config HAVE_USER_BKPT
+	def_bool n
+
 config HAVE_IOREMAP_PROT
 	bool
 
diff --git a/include/linux/user_bkpt.h b/include/linux/user_bkpt.h
new file mode 100644
index 0000000..4773541
--- /dev/null
+++ b/include/linux/user_bkpt.h
@@ -0,0 +1,305 @@
+#ifndef _LINUX_USER_BKPT_H
+#define _LINUX_USER_BKPT_H
+/*
+ * User-space BreakPoint support (user_bkpt)
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ *
+ * Copyright (C) IBM Corporation, 2008-2010
+ * Authors:
+ *	Srikar Dronamraju
+ *	Jim Keniston
+ */
+
+#include <asm/user_bkpt.h>
+struct task_struct;
+struct pt_regs;
+
+/**
+ * Strategy hints:
+ *
+ * %USER_BKPT_HNT_INLINE: Specifies that the instruction must
+ * be single-stepped inline.  Can be set by the caller of
+ * @arch->analyze_insn() -- e.g., if caller is out of XOL slots --
+ * or by @arch->analyze_insn() if there's no viable XOL strategy
+ * for that instruction.  Set in arch->strategies if the architecture
+ * doesn't implement XOL.
+ *
+ * %USER_BKPT_HNT_PERMSL: Specifies that the instruction slot whose
+ * address is @user_bkpt->xol_vaddr is assigned to @user_bkpt for the life of
+ * the process.  Can be used by @arch->analyze_insn() to simplify
+ * XOL in some cases.  Ignored in @arch->strategies.
+ *
+ * %USER_BKPT_HNT_TSKINFO: Set in @arch->strategies if the architecture's
+ * XOL handling requires the preservation of special
+ * task-specific info between the calls to @arch->pre_xol()
+ * and @arch->post_xol().  (E.g., XOL of x86_64 rip-relative
+ * instructions uses a scratch register, whose value is saved
+ * by pre_xol() and restored by post_xol().)  The caller
+ * of @arch->analyze_insn() should set %USER_BKPT_HNT_TSKINFO in
+ * @user_bkpt->strategy if it's set in @arch->strategies and the caller
+ * can maintain a @user_bkpt_task_arch_info object for each probed task.
+ * @arch->analyze_insn() should leave this flag set in @user_bkpt->strategy
+ * if it needs to use the per-task @user_bkpt_task_arch_info object.
+ */
+#define USER_BKPT_HNT_INLINE	0x1  /* Single-step this insn inline. */
+#define USER_BKPT_HNT_TSKINFO 0x2  /* XOL requires user_bkpt_task_arch_info */
+#define USER_BKPT_HNT_PERMSL	0x4  /* XOL slot assignment is permanent */
+
+#define USER_BKPT_HNT_MASK	0x7
+
+/**
+ * struct user_bkpt - user-space breakpoint/probepoint
+ *
+ * @vaddr:	virtual address of probepoint
+ * @xol_vaddr:	virtual address of XOL slot assigned to this probepoint
+ * @opcode:	copy of opcode at @vaddr
+ * @insn:	typically a copy of the instruction at @vaddr.  More
+ *	precisely, this is the instruction (stream) that will be
+ *	executed in place of the original instruction.
+ * @strategy:	hints about how this instruction will be executed
+ * @fixups:	set of fixups to be executed by @arch->post_xol()
+ * @arch_info:	architecture-specific info about this probepoint
+ */
+struct user_bkpt {
+	unsigned long vaddr;
+	unsigned long xol_vaddr;
+	user_bkpt_opcode_t opcode;
+	u8 insn[USER_BKPT_XOL_SLOT_BYTES];
+	u16 strategy;
+	u16 fixups;
+	struct bkpt_arch_info arch_info;
+};
+
+/* Post-execution fixups.  Some architectures may define others. */
+
+/* No fixup needed */
+#define USER_BKPT_FIX_NONE	0x0
+/* Adjust IP back to vicinity of actual insn */
+#define USER_BKPT_FIX_IP	0x1
+/* Adjust the return address of a call insn */
+#define USER_BKPT_FIX_CALL	0x2
+/* Might sleep while doing Fixup */
+#define USER_BKPT_FIX_SLEEPY	0x4
+
+#ifndef USER_BKPT_FIX_DEFAULT
+#define USER_BKPT_FIX_DEFAULT USER_BKPT_FIX_IP
+#endif
+
+#ifdef CONFIG_USER_BKPT
+extern int user_bkpt_init(u16 *strategies);
+extern int user_bkpt_insert_bkpt(struct task_struct *tsk,
+					struct user_bkpt *user_bkpt);
+extern unsigned long user_bkpt_get_bkpt_addr(struct pt_regs *regs);
+extern int user_bkpt_pre_sstep(struct task_struct *tsk,
+				struct user_bkpt *user_bkpt,
+				struct user_bkpt_task_arch_info *tskinfo,
+				struct pt_regs *regs);
+extern int user_bkpt_post_sstep(struct task_struct *tsk,
+			struct user_bkpt *user_bkpt,
+			struct user_bkpt_task_arch_info *tskinfo,
+			struct pt_regs *regs);
+extern int user_bkpt_cancel_xol(struct task_struct *tsk,
+			struct user_bkpt *user_bkpt);
+extern int user_bkpt_remove_bkpt(struct task_struct *tsk,
+			struct user_bkpt *user_bkpt);
+extern int user_bkpt_validate_insn_addr(struct task_struct *tsk,
+					unsigned long vaddr);
+extern void user_bkpt_set_ip(struct pt_regs *regs, unsigned long vaddr);
+extern bool user_bkpt_resume_can_sleep(struct user_bkpt *user_bkpt);
+#else	/* CONFIG_USER_BKPT */
+static inline int user_bkpt_init(u16 *strategies)
+{
+	return -ENOSYS;
+}
+static inline int user_bkpt_insert_bkpt(struct task_struct *tsk,
+						struct user_bkpt *user_bkpt)
+{
+	return -ENOSYS;
+}
+static inline unsigned long user_bkpt_get_bkpt_addr(struct pt_regs *regs)
+{
+	return -ENOSYS;
+}
+static inline int user_bkpt_pre_sstep(struct task_struct *tsk,
+	struct user_bkpt *user_bkpt, struct user_bkpt_task_arch_info *tskinfo,
+	struct pt_regs *regs)
+{
+	return -ENOSYS;
+}
+static inline int user_bkpt_post_sstep(struct task_struct *tsk,
+	struct user_bkpt *user_bkpt, struct user_bkpt_task_arch_info *tskinfo,
+	struct pt_regs *regs)
+{
+	return -ENOSYS;
+}
+static inline int user_bkpt_cancel_xol(struct task_struct *tsk,
+	struct user_bkpt *user_bkpt)
+{
+	return -ENOSYS;
+}
+static inline int user_bkpt_remove_bkpt(struct task_struct *tsk,
+	struct user_bkpt *user_bkpt)
+{
+	return -ENOSYS;
+}
+static inline int user_bkpt_validate_insn_addr(struct task_struct *tsk,
+	unsigned long vaddr)
+{
+	return -ENOSYS;
+}
+static inline void user_bkpt_set_ip(struct pt_regs *regs, unsigned long vaddr)
+{
+}
+static inline bool user_bkpt_resume_can_sleep(struct user_bkpt *user_bkpt)
+{
+	return false;
+}
+#endif	/* CONFIG_USER_BKPT */
+
+/**
+ * struct user_bkpt_arch_info - architecture-specific parameters and
+ * functions
+ *
+ * Most architectures can use the default versions of @read_opcode(),
+ * @set_bkpt(), @set_orig_insn(), and @is_bkpt_insn(); ia64 is an
+ * exception.  All functions (including @validate_address()) can assume
+ * that the caller has verified that the probepoint's virtual address
+ * resides in an executable VM area.
+ *
+ * @bkpt_insn:
+ *	The architecture's breakpoint instruction.  This is used by
+ *	the default versions of @set_bkpt(), @set_orig_insn(), and
+ *	@is_bkpt_insn().
+ * @ip_advancement_by_bkpt_insn:
+ *	The number of bytes the instruction pointer is advanced by
+ *	this architecture's breakpoint instruction.  For example, after
+ *	the powerpc trap instruction executes, the ip still points to the
+ *	breakpoint instruction (ip_advancement_by_bkpt_insn = 0); but the
+ *	x86 int3 instruction (1 byte) advances the ip past the int3
+ *	(ip_advancement_by_bkpt_insn = 1).
+ * @max_insn_bytes:
+ *	The maximum length, in bytes, of an instruction in this
+ *	architecture.  This must be <= USER_BKPT_XOL_SLOT_BYTES;
+ * @strategies:
+ *	Bit-map of %USER_BKPT_HNT_* values recognized by this architecture.
+ *	Include %USER_BKPT_HNT_INLINE iff this architecture doesn't support
+ *	execution out of line.  Include %USER_BKPT_HNT_TSKINFO if
+ *	XOL of at least some instructions requires communication of
+ *	per-task state between @pre_xol() and @post_xol().
+ * @set_ip:
+ *	Set the instruction pointer in @regs to @vaddr.
+ * @validate_address:
+ *	Return 0 if @vaddr is a valid instruction address, or a negative
+ *	errno (typically -%EINVAL) otherwise.  If you don't provide
+ *	@validate_address(), any address will be accepted.  Caller
+ *	guarantees that @vaddr is in an executable VM area.  This
+ *	function typically just enforces arch-specific instruction
+ *	alignment.
+ * @read_opcode:
+ *	For task @tsk, read the opcode at @vaddr and store it in
+ *	@opcode.  Return 0 (success) or a negative errno.  Defaults to
+ *	@user_bkpt_read_opcode().
+ * @set_bkpt:
+ *	For task @tsk, store @bkpt_insn at @user_bkpt->vaddr.  Return 0
+ *	(success) or a negative errno. Defaults to @user_bkpt_set_bkpt().
+ * @set_orig_insn:
+ *	For task @tsk, restore the original opcode (@user_bkpt->opcode) at
+ *	@user_bkpt->vaddr.  If @check is true, first verify that there's
+ *	actually a breakpoint instruction there.  Return 0 (success) or
+ *	a negative errno.  Defaults to @user_bkpt_set_orig_insn().
+ * @is_bkpt_insn:
+ *	Return %true if @user_bkpt->opcode is @bkpt_insn.  Defaults to
+ *	@user_bkpt_is_bkpt_insn(), which just tests (user_bkpt->opcode ==
+ *	arch->bkpt_insn).
+ * @analyze_insn:
+ *	Analyze @user_bkpt->insn.  Return 0 if @user_bkpt->insn is an
+ *	instruction you can probe, or a negative errno (typically -%EPERM)
+ *	otherwise.  The caller sets @user_bkpt->strategy to
+ *	%USER_BKPT_HNT_INLINE to suppress XOL for this instruction (e.g.,
+ *	because we're out of XOL slots).  If the instruction can be probed
+ *	but can't be executed out of line, set @user_bkpt->strategy to
+ *	%USER_BKPT_HNT_INLINE.  Otherwise, determine what sort of
+ *	XOL-related fixups @post_xol() (and possibly @pre_xol()) will need
+ *	to do for this instruction, and annotate @user_bkpt accordingly.
+ *	You may modify @user_bkpt->insn (e.g., the x86_64 port does this
+ *	for rip-relative instructions), but if you do so, you should
+ *	retain a copy in @user_bkpt->arch_info in case you have to revert
+ *	to single-stepping inline (see @cancel_xol()).
+ * @pre_xol:
+ *	Called just before executing the instruction associated
+ *	with @user_bkpt out of line.  @user_bkpt->xol_vaddr is the address
+ *	in @tsk's virtual address space where @user_bkpt->insn has been
+ *	copied.  @pre_xol() should at least set the instruction pointer in
+ *	@regs to @user_bkpt->xol_vaddr -- which is what the default,
+ *	@user_bkpt_pre_xol(), does.  If @user_bkpt->strategy includes the
+ *	%USER_BKPT_HNT_TSKINFO flag, then @tskinfo points to a per-task
+ *	copy of struct user_bkpt_task_arch_info.
+ * @post_xol:
+ *	Called after executing the instruction associated with
+ *	@user_bkpt out of line.  @post_xol() should perform the fixups
+ *	specified in @user_bkpt->fixups, which includes ensuring that the
+ *	instruction pointer in @regs points at the next instruction in
+ *	the probed instruction stream.  @tskinfo is as for @pre_xol().
+ *	You must provide this function.
+ * @cancel_xol:
+ *	The instruction associated with @user_bkpt cannot be executed
+ *	out of line after all.  (This can happen when XOL slots
+ *	are lazily assigned, and we run out of slots before we
+ *	hit this breakpoint.  This function should never be called
+ *	if @analyze_insn() was previously called for @user_bkpt with a
+ *	non-zero value of @user_bkpt->xol_vaddr and with
+ *	%USER_BKPT_HNT_PERMSL set in @user_bkpt->strategy.)  Adjust
+ *	@user_bkpt as needed so it can be single-stepped inline.  Omit this
+ *	function if you don't need it.
+ */
+
+struct user_bkpt_arch_info {
+	user_bkpt_opcode_t bkpt_insn;
+	u8 ip_advancement_by_bkpt_insn;
+	u8 max_insn_bytes;
+	u16 strategies;
+	void (*set_ip)(struct pt_regs *regs, unsigned long vaddr);
+	int (*validate_address)(struct task_struct *tsk, unsigned long vaddr);
+	int (*read_opcode)(struct task_struct *tsk, unsigned long vaddr,
+						user_bkpt_opcode_t *opcode);
+	int (*set_bkpt)(struct task_struct *tsk, struct user_bkpt *user_bkpt);
+	int (*set_orig_insn)(struct task_struct *tsk,
+				struct user_bkpt *user_bkpt, bool check);
+	bool (*is_bkpt_insn)(struct user_bkpt *user_bkpt);
+	int (*analyze_insn)(struct task_struct *tsk,
+						struct user_bkpt *user_bkpt);
+	int (*pre_xol)(struct task_struct *tsk, struct user_bkpt *user_bkpt,
+				struct user_bkpt_task_arch_info *tskinfo,
+				struct pt_regs *regs);
+	int (*post_xol)(struct task_struct *tsk, struct user_bkpt *user_bkpt,
+				struct user_bkpt_task_arch_info *tskinfo,
+				struct pt_regs *regs);
+	void (*cancel_xol)(struct task_struct *tsk,
+						struct user_bkpt *user_bkpt);
+};
+
+/* Unexported functions & macros for use by arch-specific code */
+#define user_bkpt_opcode_sz (sizeof(user_bkpt_opcode_t))
+extern unsigned long user_bkpt_read_vm(struct task_struct *tsk,
+			void __user *vaddr, void *kbuf,
+			unsigned long nbytes);
+extern unsigned long user_bkpt_write_data(struct task_struct *tsk,
+			void __user *vaddr, const void *kbuf,
+			unsigned long nbytes);
+
+extern struct user_bkpt_arch_info user_bkpt_arch_info;
+
+#endif	/* _LINUX_USER_BKPT_H */
diff --git a/kernel/Makefile b/kernel/Makefile
index ce53fb2..f670347 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -105,6 +105,7 @@ obj-$(CONFIG_PERF_EVENTS) += perf_event.o
 obj-$(CONFIG_HAVE_HW_BREAKPOINT) += hw_breakpoint.o
 obj-$(CONFIG_USER_RETURN_NOTIFIER) += user-return-notifier.o
 obj-$(CONFIG_PADATA) += padata.o
+obj-$(CONFIG_USER_BKPT) += user_bkpt.o
 
 ifneq ($(CONFIG_SCHED_OMIT_FRAME_POINTER),y)
 # According to Alan Modra <alan@linuxcare.com.au>, the -fno-omit-frame-pointer is
diff --git a/kernel/user_bkpt.c b/kernel/user_bkpt.c
new file mode 100644
index 0000000..d596dfe
--- /dev/null
+++ b/kernel/user_bkpt.c
@@ -0,0 +1,589 @@
+/*
+ * User-space BreakPoint support (user_bkpt)
+ *
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ *
+ * Copyright (C) IBM Corporation, 2008-2010
+ * Authors:
+ *	Srikar Dronamraju
+ *	Jim Keniston
+ *	Ananth N Mavinakayanahalli
+ */
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/sched.h>
+#include <linux/ptrace.h>
+#include <linux/mm.h>
+#include <linux/user_bkpt.h>
+#include <linux/uaccess.h>
+#include <linux/highmem.h>
+#include <linux/pagemap.h>
+
+static struct user_bkpt_arch_info *arch = &user_bkpt_arch_info;
+
+static bool uses_xol_strategy(u16 strategy)
+{
+	return !(strategy & USER_BKPT_HNT_INLINE);
+}
+
+static bool validate_strategy(u16 strategy, u16 valid_bits)
+{
+	return ((strategy & (~valid_bits)) == 0);
+}
+
+/**
+ * user_bkpt_init - initialize the user_bkpt data structures
+ * @strategies indicates which breakpoint-related strategies are
+ * supported by the client:
+ *   %USER_BKPT_HNT_INLINE: Client supports only single-stepping inline.
+ *	Otherwise client must provide an instruction slot
+ *	(USER_BKPT_XOL_SLOT_BYTES bytes) in the probed process's address
+ *	space for each instruction to be executed out of line.
+ *   %USER_BKPT_HNT_TSKINFO: Client can provide and maintain one
+ *	@user_bkpt_task_arch_info object for each probed task.  (Failure to
+ *	support this will prevent XOL of rip-relative instructions on
+ *	x86_64, at least.)
+ * Upon return, @strategies is updated to reflect those strategies
+ * required by this particular architecture's implementation of user_bkpt:
+ *   %USER_BKPT_HNT_INLINE: Architecture or client supports only
+ *	single-stepping inline.
+ *   %USER_BKPT_HNT_TSKINFO: Architecture uses @user_bkpt_task_arch_info,
+ *   and will expect it to be passed to @user_bkpt_pre_sstep() and
+ *   @user_bkpt_post_sstep() as needed (see @user_bkpt_insert_bkpt()).
+ * Possible errors:
+ * -%ENOSYS: user_bkpt not supported for this architecture.
+ * -%EINVAL: unrecognized flags in @strategies
+ */
+int user_bkpt_init(u16 *strategies)
+{
+	u16 inline_bit, tskinfo_bit;
+	u16 client_strategies = *strategies;
+
+	if (!validate_strategy(client_strategies,
+			USER_BKPT_HNT_INLINE | USER_BKPT_HNT_TSKINFO))
+		return -EINVAL;
+
+	inline_bit = (client_strategies | arch->strategies) &
+						USER_BKPT_HNT_INLINE;
+	tskinfo_bit = (client_strategies & arch->strategies) &
+						USER_BKPT_HNT_TSKINFO;
+	*strategies = (inline_bit | tskinfo_bit);
+	return 0;
+}
+
+/**
+ * user_bkpt_read_vm - Read @nbytes at @vaddr from @tsk into @kbuf.
+ * @tsk: The probed task
+ * @vaddr: Source address, in user space to be read.
+ * @kbuf: Destination address, in kernel space.
+ *
+ * Context: This function may sleep.
+ *
+ * Returns number of bytes that could be copied.
+ */
+unsigned long user_bkpt_read_vm(struct task_struct *tsk, void __user *vaddr,
+					void *kbuf, unsigned long nbytes)
+{
+	if (tsk == current) {
+		unsigned long nleft = copy_from_user(kbuf, vaddr, nbytes);
+		return nbytes - nleft;
+	} else
+		return access_process_vm(tsk, (unsigned long) vaddr, kbuf,
+							nbytes, 0);
+}
+
+/**
+ * user_bkpt_write_data - Write @nbytes from @kbuf at @vaddr in @tsk.
+ * Can be used to write to stack or data VM areas, but not instructions.
+ * Not exported, but available for use by arch-specific user_bkpt code.
+ * @tsk: The probed task
+ * @vaddr: Destination address, in user space.
+ * @kbuf: Source address, in kernel space to be read.
+ *
+ * Context: This function may sleep.
+ *
+ * Return number of bytes written.
+ */
+unsigned long user_bkpt_write_data(struct task_struct *tsk,
+				void __user *vaddr, const void *kbuf,
+				unsigned long nbytes)
+{
+	unsigned long nleft;
+
+	if (tsk == current) {
+		nleft = copy_to_user(vaddr, kbuf, nbytes);
+		return nbytes - nleft;
+	} else
+		return access_process_vm(tsk, (unsigned long) vaddr,
+						(void *) kbuf, nbytes, 1);
+}
+
+static int write_opcode(struct task_struct *tsk, unsigned long vaddr,
+						user_bkpt_opcode_t opcode)
+{
+	struct mm_struct *mm;
+	struct vm_area_struct *vma;
+	struct page *old_page, *new_page;
+	void *vaddr_old, *vaddr_new;
+	pte_t orig_pte;
+	int ret = -EINVAL;
+
+	if (!tsk)
+		return ret;
+
+	mm = get_task_mm(tsk);
+	if (!mm)
+		return ret;
+
+	down_read(&mm->mmap_sem);
+
+	/* Read the page with vaddr into memory */
+	ret = get_user_pages(tsk, mm, vaddr, 1, 1, 1, &old_page, &vma);
+	if (ret <= 0)
+		goto mmput_out;
+
+	/*
+	 * check if the page we are interested is read-only mapped
+	 * Since we are interested in text pages, Our pages of interest
+	 * should be mapped read-only.
+	 */
+	if ((vma->vm_flags && (VM_READ|VM_WRITE)) != VM_READ) {
+		ret = -EINVAL;
+		goto put_out;
+	}
+
+	/* If its VM_SHARED vma, lets not write to such vma's.  */
+	if (vma->vm_flags & VM_SHARED) {
+		ret = -EINVAL;
+		goto put_out;
+	}
+
+	/* Allocate a page */
+	new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, vaddr);
+	if (!new_page) {
+		ret = -ENOMEM;
+		goto put_out;
+	}
+
+	/*
+	 * lock page will serialize against do_wp_page()'s
+	 * PageAnon() handling
+	 */
+	lock_page(old_page);
+	/* mark page RO so any concurrent access will end up in do_wp_page() */
+	if (write_protect_page(vma, old_page, &orig_pte))
+		goto unlock_out;
+
+	/* copy the page now that we've got it stable */
+	vaddr_old = kmap_atomic(old_page, KM_USER0);
+	vaddr_new = kmap_atomic(new_page, KM_USER1);
+
+	memcpy(vaddr_new, vaddr_old, PAGE_SIZE);
+	/* poke the new insn in, ASSUMES we don't cross page boundary */
+	vaddr = vaddr & (PAGE_SIZE - 1);
+	memcpy(vaddr_new + vaddr, &opcode, user_bkpt_opcode_sz);
+
+	kunmap_atomic(vaddr_new, KM_USER1);
+	kunmap_atomic(vaddr_old, KM_USER0);
+
+	lock_page(new_page);
+	/* flip pages, do_wp_page() will fail pte_same() and bail */
+	ret = replace_page(vma, old_page, new_page, orig_pte);
+
+unlock_out:
+	unlock_page(new_page);
+	unlock_page(old_page);
+	if (ret != 0)
+		page_cache_release(new_page);
+
+put_out:
+	put_page(old_page); /* we did a get_page in the beginning */
+
+mmput_out:
+	up_read(&mm->mmap_sem);
+	mmput(mm);
+	return ret;
+}
+
+/* Default implementation of arch->read_opcode */
+static int read_opcode(struct task_struct *tsk, unsigned long vaddr,
+						user_bkpt_opcode_t *opcode)
+{
+	unsigned long bytes_read;
+
+	bytes_read = user_bkpt_read_vm(tsk, (void __user *) vaddr, opcode,
+							user_bkpt_opcode_sz);
+	return (bytes_read == user_bkpt_opcode_sz ? 0 : -EFAULT);
+}
+
+/* Default implementation of arch->set_bkpt */
+static int set_bkpt(struct task_struct *tsk, struct user_bkpt *user_bkpt)
+{
+	return write_opcode(tsk, user_bkpt->vaddr, arch->bkpt_insn);
+}
+
+/* Default implementation of arch->set_orig_insn */
+static int set_orig_insn(struct task_struct *tsk,
+				struct user_bkpt *user_bkpt, bool check)
+{
+	if (check) {
+		user_bkpt_opcode_t opcode;
+		int result = arch->read_opcode(tsk, user_bkpt->vaddr,
+								&opcode);
+		if (result)
+			return result;
+		if (opcode != arch->bkpt_insn)
+			return -EINVAL;
+	}
+	return write_opcode(tsk, user_bkpt->vaddr, user_bkpt->opcode);
+}
+
+/* Return 0 if vaddr is in an executable VM area, or -EINVAL otherwise. */
+static inline int check_vma(struct task_struct *tsk, unsigned long vaddr)
+{
+	struct vm_area_struct *vma;
+	struct mm_struct *mm;
+	int ret = -EINVAL;
+
+	mm = get_task_mm(tsk);
+	if (!mm)
+		return -EINVAL;
+	down_read(&mm->mmap_sem);
+	vma = find_vma(mm, vaddr);
+	if (vma && vaddr >= vma->vm_start && (vma->vm_flags & VM_EXEC))
+		ret = 0;
+	up_read(&mm->mmap_sem);
+	mmput(mm);
+	return ret;
+}
+
+/**
+ * user_bkpt_validate_insn_addr - Validate if the instruction is an
+ * executable vma.
+ * Returns 0 if the vaddr is a valid instruction address.
+ * @tsk: the probed task
+ * @vaddr: virtual address of the instruction to be verified.
+ *
+ * Possible errors:
+ * -%EINVAL: Instruction passed is not a valid instruction address.
+ */
+int user_bkpt_validate_insn_addr(struct task_struct *tsk, unsigned long vaddr)
+{
+	int result;
+
+	result = check_vma(tsk, vaddr);
+	if (result != 0)
+		return result;
+	if (arch->validate_address)
+		result = arch->validate_address(tsk, vaddr);
+	return result;
+}
+
+static void print_insert_fail(struct task_struct *tsk,
+				struct user_bkpt *user_bkpt, const char *why)
+{
+	printk(KERN_ERR "Can't place breakpoint at pid %d vaddr %#lx: %s\n",
+					tsk->pid, user_bkpt->vaddr, why);
+}
+
+/**
+ * user_bkpt_insert_bkpt - insert breakpoint
+ * Insert a breakpoint into the process that includes @tsk, at the
+ * virtual address @user_bkpt->vaddr.
+ *
+ * @user_bkpt->strategy affects how this breakpoint will be handled:
+ *   %USER_BKPT_HNT_INLINE: Probed instruction will be single-stepped inline.
+ *   %USER_BKPT_HNT_TSKINFO: As above.
+ *   %USER_BKPT_HNT_PERMSL: An XOL instruction slot in the probed process's
+ *	address space has been allocated to this probepoint, and will
+ *	remain so allocated as long as it's needed.  @user_bkpt->xol_vaddr is
+ *	its address.  (This slot can be reallocated if
+ *	@user_bkpt_insert_bkpt() fails.)  The client is NOT required to
+ *	allocate an instruction slot before calling @user_bkpt_insert_bkpt().
+ * @user_bkpt_insert_bkpt() updates @user_bkpt->strategy as needed:
+ *   %USER_BKPT_HNT_INLINE: Architecture or client cannot do XOL for this
+ *	probepoint.
+ *   %USER_BKPT_HNT_TSKINFO: @user_bkpt_task_arch_info will be used for this
+ *	probepoint.
+ *
+ * All threads of the probed process must be stopped while
+ * @user_bkpt_insert_bkpt() runs.
+ *
+ * Possible errors:
+ * -%ENOSYS: user_bkpt not supported for this architecture
+ * -%EINVAL: unrecognized/invalid strategy flags
+ * -%EINVAL: invalid instruction address
+ * -%EEXIST: breakpoint instruction already exists at that address
+ * -%EPERM: cannot probe this instruction
+ * -%EFAULT: failed to insert breakpoint instruction
+ * [TBD: Validate xol_vaddr?]
+ */
+int user_bkpt_insert_bkpt(struct task_struct *tsk, struct user_bkpt *user_bkpt)
+{
+	int result;
+	unsigned long len;
+
+	if (!validate_strategy(user_bkpt->strategy, USER_BKPT_HNT_MASK))
+		return -EINVAL;
+
+	result = user_bkpt_validate_insn_addr(tsk, user_bkpt->vaddr);
+	if (result != 0)
+		return result;
+
+	/*
+	 * If user_bkpt_read_vm() transfers fewer bytes than the maximum
+	 * instruction size, assume that the probed instruction is smaller
+	 * than the max and near the end of the last page of instructions.
+	 * But there must be room at least for a breakpoint-size instruction.
+	 */
+	len = user_bkpt_read_vm(tsk, (void __user *) user_bkpt->vaddr,
+				user_bkpt->insn, arch->max_insn_bytes);
+	if (len < user_bkpt_opcode_sz) {
+		print_insert_fail(tsk, user_bkpt,
+				"error reading original instruction");
+		return -EFAULT;
+	}
+	memcpy(&user_bkpt->opcode, user_bkpt->insn, user_bkpt_opcode_sz);
+	if (arch->is_bkpt_insn(user_bkpt)) {
+		print_insert_fail(tsk, user_bkpt,
+					"bkpt already exists at that addr");
+		return -EEXIST;
+	}
+
+	result = arch->analyze_insn(tsk, user_bkpt);
+	if (result < 0) {
+		print_insert_fail(tsk, user_bkpt,
+					"instruction type cannot be probed");
+		return result;
+	}
+
+	result = arch->set_bkpt(tsk, user_bkpt);
+	if (result < 0) {
+		print_insert_fail(tsk, user_bkpt,
+					"failed to insert bkpt instruction");
+		return result;
+	}
+	return 0;
+}
+
+/**
+ * user_bkpt_pre_sstep - prepare to single-step the probed instruction
+ * @tsk: the probed task
+ * @user_bkpt: the probepoint information, as returned by
+ *	@user_bkpt_insert_bkpt().  Unless the %USER_BKPT_HNT_INLINE flag is
+ *	set in @user_bkpt->strategy, @user_bkpt->xol_vaddr must be the
+ *	address of an XOL instruction slot that is allocated to this
+ *	probepoint at least until after the completion of
+ *	@user_bkpt_post_sstep(), and populated with the contents of
+ *	@user_bkpt->insn.  [Need to be more precise here to account for
+ *	untimely exit or USER_BKPT_HNT_BOOSTED.]
+ * @tskinfo: points to a @user_bkpt_task_arch_info object for @tsk, if
+ *	the %USER_BKPT_HNT_TSKINFO flag is set in @user_bkpt->strategy.
+ * @regs: reflects the saved user state of @tsk.  @user_bkpt_pre_sstep()
+ *	adjusts this.  In particular, the instruction pointer is set
+ *	to the instruction to be single-stepped.
+ * Possible errors:
+ * -%EFAULT: Failed to read or write @tsk's address space as needed.
+ *
+ * The client must ensure that the contents of @user_bkpt are not
+ * changed during the single-step operation -- i.e., between when
+ * @user_bkpt_pre_sstep() is called and when @user_bkpt_post_sstep() returns.
+ * Additionally, if single-stepping inline is used for this probepoint,
+ * the client must serialize the single-step operation (so multiple
+ * threads don't step on each other while the opcode replacement is
+ * taking place).
+ */
+int user_bkpt_pre_sstep(struct task_struct *tsk, struct user_bkpt *user_bkpt,
+		struct user_bkpt_task_arch_info *tskinfo, struct pt_regs *regs)
+{
+	int result;
+
+	if (uses_xol_strategy(user_bkpt->strategy))
+		return arch->pre_xol(tsk, user_bkpt, tskinfo, regs);
+
+	/*
+	 * Single-step this instruction inline.  Replace the breakpoint
+	 * with the original opcode.
+	 */
+	result = arch->set_orig_insn(tsk, user_bkpt, false);
+	if (result == 0)
+		arch->set_ip(regs, user_bkpt->vaddr);
+	return result;
+}
+
+/**
+ * user_bkpt_post_sstep - prepare to resume execution after single-step
+ * @tsk: the probed task
+ * @user_bkpt: the probepoint information, as with @user_bkpt_pre_sstep()
+ * @tskinfo: the @user_bkpt_task_arch_info object, if any, passed to
+ *	@user_bkpt_pre_sstep()
+ * @regs: reflects the saved state of @tsk after the single-step
+ *	operation.  @user_bkpt_post_sstep() adjusts @tsk's state as needed,
+ *	including pointing the instruction pointer at the instruction
+ *	following the probed instruction.
+ * Possible errors:
+ * -%EFAULT: Failed to read or write @tsk's address space as needed.
+ */
+int user_bkpt_post_sstep(struct task_struct *tsk, struct user_bkpt *user_bkpt,
+		struct user_bkpt_task_arch_info *tskinfo, struct pt_regs *regs)
+{
+	if (uses_xol_strategy(user_bkpt->strategy))
+		return arch->post_xol(tsk, user_bkpt, tskinfo, regs);
+
+	/*
+	 * Single-stepped this instruction inline.  Put the breakpoint
+	 * instruction back.
+	 */
+	return arch->set_bkpt(tsk, user_bkpt);
+}
+
+/**
+ * user_bkpt_cancel_xol - cancel XOL for this probepoint
+ * @tsk: a task in the probed process
+ * @user_bkpt: the probepoint information
+ * Switch @user_bkpt's single-stepping strategy from out-of-line to inline.
+ * If the client employs lazy XOL-slot allocation, it can call this function
+ * if it determines that it can't provide an XOL slot for @user_bkpt.
+ * @user_bkpt_cancel_xol() adjusts @user_bkpt appropriately.
+ *
+ * @user_bkpt_cancel_xol()'s behavior is undefined if @user_bkpt_pre_sstep()
+ * has already been called for @user_bkpt.
+ *
+ * Possible errors:
+ * Can't think of any yet.
+ */
+int user_bkpt_cancel_xol(struct task_struct *tsk, struct user_bkpt *user_bkpt)
+{
+	if (arch->cancel_xol)
+		arch->cancel_xol(tsk, user_bkpt);
+	user_bkpt->strategy |= USER_BKPT_HNT_INLINE;
+	return 0;
+}
+
+/**
+ * user_bkpt_get_bkpt_addr - compute address of bkpt given post-bkpt regs
+ * @regs: Reflects the saved state of the task after it has hit a breakpoint
+ * instruction.
+ * Return the address of the breakpoint instruction.
+ */
+unsigned long user_bkpt_get_bkpt_addr(struct pt_regs *regs)
+{
+	return instruction_pointer(regs) - arch->ip_advancement_by_bkpt_insn;
+}
+
+/**
+ * user_bkpt_remove_bkpt - remove breakpoint
+ * For the process that includes @tsk, remove the breakpoint specified
+ * by @user_bkpt, restoring the original opcode.
+ *
+ * Possible errors:
+ * -%EINVAL: @user_bkpt->vaddr is not a valid instruction address.
+ * -%ENOENT: There is no breakpoint instruction at @user_bkpt->vaddr.
+ * -%EFAULT: Failed to read/write @tsk's address space as needed.
+ */
+int user_bkpt_remove_bkpt(struct task_struct *tsk, struct user_bkpt *user_bkpt)
+{
+	if (user_bkpt_validate_insn_addr(tsk, user_bkpt->vaddr) != 0)
+		return -EINVAL;
+	return arch->set_orig_insn(tsk, user_bkpt, true);
+}
+
+/**
+ * user_bkpt_set_ip - Set instruction pointer
+ * @regs: Reflects the saved state of the task
+ */
+void user_bkpt_set_ip(struct pt_regs *regs, unsigned long vaddr)
+{
+	arch->set_ip(regs, vaddr);
+}
+
+/**
+ * user_bkpt_resume_can_sleep - Check if fixup might result in sleep.
+ * @user_bkpt: the probepoint information.
+ *
+ * Returns true if fixup might result in sleep.
+ */
+bool user_bkpt_resume_can_sleep(struct user_bkpt *user_bkpt)
+{
+	return user_bkpt->fixups & USER_BKPT_FIX_SLEEPY;
+}
+
+/* Default implementation of arch->is_bkpt_insn */
+static bool is_bkpt_insn(struct user_bkpt *user_bkpt)
+{
+	return (user_bkpt->opcode == arch->bkpt_insn);
+}
+
+/* Default implementation of arch->pre_xol */
+static int pre_xol(struct task_struct *tsk,
+			struct user_bkpt *user_bkpt,
+			struct user_bkpt_task_arch_info *tskinfo,
+			struct pt_regs *regs)
+{
+	arch->set_ip(regs, user_bkpt->xol_vaddr);
+	return 0;
+}
+
+/* Validate arch-specific info during user_bkpt initialization. */
+static int bad_arch_param(const char *param_name, int value)
+{
+	printk(KERN_ERR "user_bkpt: bad value %d/%#x for parameter %s"
+		" in user_bkpt_arch_info\n", value, value, param_name);
+	return -ENOSYS;
+}
+
+static int missing_arch_func(const char *func_name)
+{
+	printk(KERN_ERR "user_bkpt: user_bkpt_arch_info lacks required "
+					"function: %s\n", func_name);
+	return -ENOSYS;
+}
+
+static int __init init_user_bkpt(void)
+{
+	int result = 0;
+
+	/* Accept any value of bkpt_insn. */
+	if (arch->max_insn_bytes < 1)
+		result = bad_arch_param("max_insn_bytes",
+						arch->max_insn_bytes);
+	if (arch->ip_advancement_by_bkpt_insn > arch->max_insn_bytes)
+		result = bad_arch_param("ip_advancement_by_bkpt_insn",
+				arch->ip_advancement_by_bkpt_insn);
+	/* Accept any value of strategies. */
+	if (!arch->set_ip)
+		result = missing_arch_func("set_ip");
+	/* Null validate_address() is OK. */
+	if (!arch->read_opcode)
+		arch->read_opcode = read_opcode;
+	if (!arch->set_bkpt)
+		arch->set_bkpt = set_bkpt;
+	if (!arch->set_orig_insn)
+		arch->set_orig_insn = set_orig_insn;
+	if (!arch->is_bkpt_insn)
+		arch->is_bkpt_insn = is_bkpt_insn;
+	if (!arch->analyze_insn)
+		result = missing_arch_func("analyze_insn");
+	if (!arch->pre_xol)
+		arch->pre_xol = pre_xol;
+	if (uses_xol_strategy(arch->strategies) && !arch->post_xol)
+		result = missing_arch_func("post_xol");
+	/* Null cancel_xol() is OK. */
+	return result;
+}
+
+module_init(init_user_bkpt);

[PATCH v5 4/14] x86 support for User space breakpoint assistance

[Srikar Dronamraju]

x86_support_for_user_bkpt.patch

From: Srikar Dronamraju <srikar@linux.vnet.ibm.com>

x86 support for user breakpoint Infrastructure

Changelog from v1:
	set USER_BKPT_FIX_SLEEPY if post_xol might sleep.

This patch provides x86 specific userspace breakpoint assistance
implementation details. It uses the "x86: instruction decoder API" patch
to do validate and analyze the instructions. This analysis is used at
the time of post-processing of breakpoint hit to do the necessary
fix-ups.

Almost all instructions are handled for traditional strategy and
execution out of line strategy. Instruction handled include the RIP
relative instructions.

This patch requires "x86: instruction decoder API" patch.
http://lkml.org/lkml/2009/6/1/459

Signed-off-by: Jim Keniston <jkenisto@us.ibm.com>
Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
---

 arch/x86/Kconfig                 |    1 
 arch/x86/include/asm/user_bkpt.h |   43 +++
 arch/x86/kernel/Makefile         |    2 
 arch/x86/kernel/user_bkpt.c      |  572 ++++++++++++++++++++++++++++++++++++++
 4 files changed, 618 insertions(+), 0 deletions(-)
 create mode 100644 arch/x86/include/asm/user_bkpt.h
 create mode 100644 arch/x86/kernel/user_bkpt.c


diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 6f77afa..db1b378 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -54,6 +54,7 @@ config X86
 	select HAVE_KERNEL_LZO
 	select HAVE_HW_BREAKPOINT
 	select HAVE_MIXED_BREAKPOINTS_REGS
+	select HAVE_USER_BKPT
 	select PERF_EVENTS
 	select HAVE_PERF_EVENTS_NMI
 	select ANON_INODES
diff --git a/arch/x86/include/asm/user_bkpt.h b/arch/x86/include/asm/user_bkpt.h
new file mode 100644
index 0000000..df8a4a0
--- /dev/null
+++ b/arch/x86/include/asm/user_bkpt.h
@@ -0,0 +1,43 @@
+#ifndef _ASM_USER_BKPT_H
+#define _ASM_USER_BKPT_H
+/*
+ * User-space BreakPoint support (user_bkpt) for x86
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ *
+ * Copyright (C) IBM Corporation, 2008-2010
+ * Authors:
+ *	Srikar Dronamraju
+ *	Jim Keniston
+ */
+
+typedef u8 user_bkpt_opcode_t;
+#define MAX_UINSN_BYTES 16
+#define USER_BKPT_XOL_SLOT_BYTES (MAX_UINSN_BYTES)
+
+#ifdef CONFIG_X86_64
+struct bkpt_arch_info {
+	unsigned long rip_target_address;
+	u8 orig_insn[MAX_UINSN_BYTES];
+};
+struct user_bkpt_task_arch_info {
+	unsigned long saved_scratch_register;
+};
+#else
+struct bkpt_arch_info {};
+struct user_bkpt_task_arch_info {};
+#endif
+
+#endif	/* _ASM_USER_BKPT_H */
diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index e77b220..53cf2af 100644
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -115,6 +115,8 @@ obj-$(CONFIG_X86_CHECK_BIOS_CORRUPTION) += check.o
 
 obj-$(CONFIG_SWIOTLB)			+= pci-swiotlb.o
 
+obj-$(CONFIG_USER_BKPT)			+= user_bkpt.o
+
 ###
 # 64 bit specific files
 ifeq ($(CONFIG_X86_64),y)
diff --git a/arch/x86/kernel/user_bkpt.c b/arch/x86/kernel/user_bkpt.c
new file mode 100644
index 0000000..eb74a8d
--- /dev/null
+++ b/arch/x86/kernel/user_bkpt.c
@@ -0,0 +1,572 @@
+/*
+ * User-space BreakPoint support (user_bkpt) for x86
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ *
+ * Copyright (C) IBM Corporation, 2008-2010
+ * Authors:
+ *	Srikar Dronamraju
+ *	Jim Keniston
+ */
+
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/ptrace.h>
+#include <linux/user_bkpt.h>
+#include <asm/insn.h>
+
+#ifdef CONFIG_X86_32
+#define is_32bit_app(tsk) 1
+#else
+#define is_32bit_app(tsk) (test_tsk_thread_flag(tsk, TIF_IA32))
+#endif
+
+#define USER_BKPT_FIX_RIP_AX	0x8000
+#define USER_BKPT_FIX_RIP_CX	0x4000
+
+/* Adaptations for mhiramat x86 decoder v14. */
+#define OPCODE1(insn) ((insn)->opcode.bytes[0])
+#define OPCODE2(insn) ((insn)->opcode.bytes[1])
+#define OPCODE3(insn) ((insn)->opcode.bytes[2])
+#define MODRM_REG(insn) X86_MODRM_REG(insn->modrm.value)
+
+static void set_ip(struct pt_regs *regs, unsigned long vaddr)
+{
+	regs->ip = vaddr;
+}
+
+#ifdef CONFIG_X86_64
+static bool is_riprel_insn(struct user_bkpt *user_bkpt)
+{
+	return ((user_bkpt->fixups &
+			(USER_BKPT_FIX_RIP_AX | USER_BKPT_FIX_RIP_CX)) != 0);
+}
+
+static void cancel_xol(struct task_struct *tsk, struct user_bkpt *user_bkpt)
+{
+	if (is_riprel_insn(user_bkpt)) {
+		/*
+		 * We rewrote user_bkpt->insn to use indirect addressing rather
+		 * than rip-relative addressing for XOL.  For
+		 * single-stepping inline, put back the original instruction.
+		 */
+		memcpy(user_bkpt->insn, user_bkpt->arch_info.orig_insn,
+							MAX_UINSN_BYTES);
+		user_bkpt->strategy &= ~USER_BKPT_HNT_TSKINFO;
+	}
+}
+#endif	/* CONFIG_X86_64 */
+
+static const u32 good_insns_64[256 / 32] = {
+	/*      0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f         */
+	/*      ----------------------------------------------         */
+	W(0x00, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 0, 0) | /* 00 */
+	W(0x10, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 0, 0) , /* 10 */
+	W(0x20, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 0, 0) | /* 20 */
+	W(0x30, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 0, 0) , /* 30 */
+	W(0x40, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) | /* 40 */
+	W(0x50, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* 50 */
+	W(0x60, 0, 0, 0, 1, 1, 1, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0) | /* 60 */
+	W(0x70, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* 70 */
+	W(0x80, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* 80 */
+	W(0x90, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* 90 */
+	W(0xa0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* a0 */
+	W(0xb0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* b0 */
+	W(0xc0, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0) | /* c0 */
+	W(0xd0, 1, 1, 1, 1, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* d0 */
+	W(0xe0, 1, 1, 1, 1, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0) | /* e0 */
+	W(0xf0, 0, 0, 1, 1, 0, 1, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1)   /* f0 */
+	/*      ----------------------------------------------         */
+	/*      0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f         */
+};
+
+/* Good-instruction tables for 32-bit apps -- copied from i386 uprobes */
+
+static const u32 good_insns_32[256 / 32] = {
+	/*      0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f         */
+	/*      ----------------------------------------------         */
+	W(0x00, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 0) | /* 00 */
+	W(0x10, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 0) , /* 10 */
+	W(0x20, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 0, 1) | /* 20 */
+	W(0x30, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 0, 1) , /* 30 */
+	W(0x40, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* 40 */
+	W(0x50, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* 50 */
+	W(0x60, 1, 1, 1, 0, 1, 1, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0) | /* 60 */
+	W(0x70, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* 70 */
+	W(0x80, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* 80 */
+	W(0x90, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* 90 */
+	W(0xa0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* a0 */
+	W(0xb0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* b0 */
+	W(0xc0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0) | /* c0 */
+	W(0xd0, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* d0 */
+	W(0xe0, 1, 1, 1, 1, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0) | /* e0 */
+	W(0xf0, 0, 0, 1, 1, 0, 1, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1)   /* f0 */
+	/*      ----------------------------------------------         */
+	/*      0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f         */
+};
+
+/* Using this for both 64-bit and 32-bit apps */
+static const u32 good_2byte_insns[256 / 32] = {
+	/*      0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f         */
+	/*      ----------------------------------------------         */
+	W(0x00, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1) | /* 00 */
+	W(0x10, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1) , /* 10 */
+	W(0x20, 1, 1, 1, 1, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1) | /* 20 */
+	W(0x30, 0, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0) , /* 30 */
+	W(0x40, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* 40 */
+	W(0x50, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* 50 */
+	W(0x60, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* 60 */
+	W(0x70, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 1, 1) , /* 70 */
+	W(0x80, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* 80 */
+	W(0x90, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* 90 */
+	W(0xa0, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 0, 1) | /* a0 */
+	W(0xb0, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1) , /* b0 */
+	W(0xc0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* c0 */
+	W(0xd0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) , /* d0 */
+	W(0xe0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1) | /* e0 */
+	W(0xf0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0)   /* f0 */
+	/*      ----------------------------------------------         */
+	/*      0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f         */
+};
+
+/*
+ * opcodes we'll probably never support:
+ * 6c-6d, e4-e5, ec-ed - in
+ * 6e-6f, e6-e7, ee-ef - out
+ * cc, cd - int3, int
+ * cf - iret
+ * d6 - illegal instruction
+ * f1 - int1/icebp
+ * f4 - hlt
+ * fa, fb - cli, sti
+ * 0f - lar, lsl, syscall, clts, sysret, sysenter, sysexit, invd, wbinvd, ud2
+ *
+ * invalid opcodes in 64-bit mode:
+ * 06, 0e, 16, 1e, 27, 2f, 37, 3f, 60-62, 82, c4-c5, d4-d5
+ *
+ * 63 - we support this opcode in x86_64 but not in i386.
+ *
+ * opcodes we may need to refine support for:
+ * 0f - 2-byte instructions: For many of these instructions, the validity
+ * depends on the prefix and/or the reg field.  On such instructions, we
+ * just consider the opcode combination valid if it corresponds to any
+ * valid instruction.
+ * 8f - Group 1 - only reg = 0 is OK
+ * c6-c7 - Group 11 - only reg = 0 is OK
+ * d9-df - fpu insns with some illegal encodings
+ * f2, f3 - repnz, repz prefixes.  These are also the first byte for
+ * certain floating-point instructions, such as addsd.
+ * fe - Group 4 - only reg = 0 or 1 is OK
+ * ff - Group 5 - only reg = 0-6 is OK
+ *
+ * others -- Do we need to support these?
+ * 0f - (floating-point?) prefetch instructions
+ * 07, 17, 1f - pop es, pop ss, pop ds
+ * 26, 2e, 36, 3e - es:, cs:, ss:, ds: segment prefixes --
+ *	but 64 and 65 (fs: and gs:) seem to be used, so we support them
+ * 67 - addr16 prefix
+ * ce - into
+ * f0 - lock prefix
+ */
+
+/*
+ * TODO:
+ * - Where necessary, examine the modrm byte and allow only valid instructions
+ * in the different Groups and fpu instructions.
+ */
+
+static bool is_prefix_bad(struct insn *insn)
+{
+	int i;
+
+	for (i = 0; i < insn->prefixes.nbytes; i++) {
+		switch (insn->prefixes.bytes[i]) {
+		case 0x26:	 /*INAT_PFX_ES   */
+		case 0x2E:	 /*INAT_PFX_CS   */
+		case 0x36:	 /*INAT_PFX_DS   */
+		case 0x3E:	 /*INAT_PFX_SS   */
+		case 0xF0:	 /*INAT_PFX_LOCK */
+			return 1;
+		}
+	}
+	return 0;
+}
+
+static void report_bad_prefix(void)
+{
+	printk(KERN_ERR "user_bkpt does not currently support probing "
+		"instructions with any of the following prefixes: "
+		"cs:, ds:, es:, ss:, lock:\n");
+}
+
+static void report_bad_1byte_opcode(int mode, user_bkpt_opcode_t op)
+{
+	printk(KERN_ERR "In %d-bit apps, "
+		"user_bkpt does not currently support probing "
+		"instructions whose first byte is 0x%2.2x\n", mode, op);
+}
+
+static void report_bad_2byte_opcode(user_bkpt_opcode_t op)
+{
+	printk(KERN_ERR "user_bkpt does not currently support probing "
+		"instructions with the 2-byte opcode 0x0f 0x%2.2x\n", op);
+}
+
+static int validate_insn_32bits(struct user_bkpt *user_bkpt, struct insn *insn)
+{
+	insn_init(insn, user_bkpt->insn, false);
+
+	/* Skip good instruction prefixes; reject "bad" ones. */
+	insn_get_opcode(insn);
+	if (is_prefix_bad(insn)) {
+		report_bad_prefix();
+		return -EPERM;
+	}
+	if (test_bit(OPCODE1(insn), (unsigned long *) good_insns_32))
+		return 0;
+	if (insn->opcode.nbytes == 2) {
+		if (test_bit(OPCODE2(insn),
+					(unsigned long *) good_2byte_insns))
+			return 0;
+		report_bad_2byte_opcode(OPCODE2(insn));
+	} else
+		report_bad_1byte_opcode(32, OPCODE1(insn));
+	return -EPERM;
+}
+
+static int validate_insn_64bits(struct user_bkpt *user_bkpt, struct insn *insn)
+{
+	insn_init(insn, user_bkpt->insn, true);
+
+	/* Skip good instruction prefixes; reject "bad" ones. */
+	insn_get_opcode(insn);
+	if (is_prefix_bad(insn)) {
+		report_bad_prefix();
+		return -EPERM;
+	}
+	if (test_bit(OPCODE1(insn), (unsigned long *) good_insns_64))
+		return 0;
+	if (insn->opcode.nbytes == 2) {
+		if (test_bit(OPCODE2(insn),
+					(unsigned long *) good_2byte_insns))
+			return 0;
+		report_bad_2byte_opcode(OPCODE2(insn));
+	} else
+		report_bad_1byte_opcode(64, OPCODE1(insn));
+	return -EPERM;
+}
+
+/*
+ * Figure out which fixups post_xol() will need to perform, and annotate
+ * user_bkpt->fixups accordingly.  To start with, user_bkpt->fixups is
+ * either zero or it reflects rip-related fixups.
+ */
+static void prepare_fixups(struct user_bkpt *user_bkpt, struct insn *insn)
+{
+	bool fix_ip = true, fix_call = false;	/* defaults */
+	insn_get_opcode(insn);	/* should be a nop */
+
+	switch (OPCODE1(insn)) {
+	case 0xc3:		/* ret/lret */
+	case 0xcb:
+	case 0xc2:
+	case 0xca:
+		/* ip is correct */
+		fix_ip = false;
+		break;
+	case 0xe8:		/* call relative - Fix return addr */
+		fix_call = true;
+		break;
+	case 0x9a:		/* call absolute - Fix return addr, not ip */
+		fix_call = true;
+		fix_ip = false;
+		break;
+	case 0xff:
+	    {
+		int reg;
+		insn_get_modrm(insn);
+		reg = MODRM_REG(insn);
+		if (reg == 2 || reg == 3) {
+			/* call or lcall, indirect */
+			/* Fix return addr; ip is correct. */
+			fix_call = true;
+			fix_ip = false;
+		} else if (reg == 4 || reg == 5) {
+			/* jmp or ljmp, indirect */
+			/* ip is correct. */
+			fix_ip = false;
+		}
+		break;
+	    }
+	case 0xea:		/* jmp absolute -- ip is correct */
+		fix_ip = false;
+		break;
+	default:
+		break;
+	}
+	if (fix_ip)
+		user_bkpt->fixups |= USER_BKPT_FIX_IP;
+	if (fix_call)
+		user_bkpt->fixups |=
+			(USER_BKPT_FIX_CALL | USER_BKPT_FIX_SLEEPY);
+}
+
+#ifdef CONFIG_X86_64
+static int handle_riprel_insn(struct user_bkpt *user_bkpt, struct insn *insn);
+#endif
+
+static int analyze_insn(struct task_struct *tsk, struct user_bkpt *user_bkpt)
+{
+	int ret;
+	struct insn insn;
+
+	user_bkpt->fixups = 0;
+#ifdef CONFIG_X86_64
+	user_bkpt->arch_info.rip_target_address = 0x0;
+#endif
+
+	if (is_32bit_app(tsk))
+		ret = validate_insn_32bits(user_bkpt, &insn);
+	else
+		ret = validate_insn_64bits(user_bkpt, &insn);
+	if (ret != 0)
+		return ret;
+	if (user_bkpt->strategy & USER_BKPT_HNT_INLINE)
+		return 0;
+#ifdef CONFIG_X86_64
+	ret = handle_riprel_insn(user_bkpt, &insn);
+	if (ret == -1)
+		/* rip-relative; can't XOL */
+		return 0;
+	else if (ret == 0)
+		/* not rip-relative */
+		user_bkpt->strategy &= ~USER_BKPT_HNT_TSKINFO;
+#endif
+	prepare_fixups(user_bkpt, &insn);
+	return 0;
+}
+
+#ifdef CONFIG_X86_64
+/*
+ * If user_bkpt->insn doesn't use rip-relative addressing, return 0.  Otherwise,
+ * rewrite the instruction so that it accesses its memory operand
+ * indirectly through a scratch register.  Set user_bkpt->fixups and
+ * user_bkpt->arch_info.rip_target_address accordingly.  (The contents of the
+ * scratch register will be saved before we single-step the modified
+ * instruction, and restored afterward.)  Return 1.
+ *
+ * (... except if the client doesn't support our USER_BKPT_HNT_TSKINFO strategy,
+ * we must suppress XOL for rip-relative instructions: return -1.)
+ *
+ * We do this because a rip-relative instruction can access only a
+ * relatively small area (+/- 2 GB from the instruction), and the XOL
+ * area typically lies beyond that area.  At least for instructions
+ * that store to memory, we can't execute the original instruction
+ * and "fix things up" later, because the misdirected store could be
+ * disastrous.
+ *
+ * Some useful facts about rip-relative instructions:
+ * - There's always a modrm byte.
+ * - There's never a SIB byte.
+ * - The displacement is always 4 bytes.
+ */
+static int handle_riprel_insn(struct user_bkpt *user_bkpt, struct insn *insn)
+{
+	u8 *cursor;
+	u8 reg;
+
+	if (!insn_rip_relative(insn))
+		return 0;
+
+	/*
+	 * We have a rip-relative instruction.  To allow this instruction
+	 * to be single-stepped out of line, the client must provide us
+	 * with a per-task user_bkpt_task_arch_info object.
+	 */
+	if (!(user_bkpt->strategy & USER_BKPT_HNT_TSKINFO)) {
+		user_bkpt->strategy |= USER_BKPT_HNT_INLINE;
+		return -1;
+	}
+	memcpy(user_bkpt->arch_info.orig_insn, user_bkpt->insn,
+							MAX_UINSN_BYTES);
+
+	/*
+	 * Point cursor at the modrm byte.  The next 4 bytes are the
+	 * displacement.  Beyond the displacement, for some instructions,
+	 * is the immediate operand.
+	 */
+	cursor = user_bkpt->insn + insn->prefixes.nbytes
+			+ insn->rex_prefix.nbytes + insn->opcode.nbytes;
+	insn_get_length(insn);
+
+	/*
+	 * Convert from rip-relative addressing to indirect addressing
+	 * via a scratch register.  Change the r/m field from 0x5 (%rip)
+	 * to 0x0 (%rax) or 0x1 (%rcx), and squeeze out the offset field.
+	 */
+	reg = MODRM_REG(insn);
+	if (reg == 0) {
+		/*
+		 * The register operand (if any) is either the A register
+		 * (%rax, %eax, etc.) or (if the 0x4 bit is set in the
+		 * REX prefix) %r8.  In any case, we know the C register
+		 * is NOT the register operand, so we use %rcx (register
+		 * #1) for the scratch register.
+		 */
+		user_bkpt->fixups = USER_BKPT_FIX_RIP_CX;
+		/* Change modrm from 00 000 101 to 00 000 001. */
+		*cursor = 0x1;
+	} else {
+		/* Use %rax (register #0) for the scratch register. */
+		user_bkpt->fixups = USER_BKPT_FIX_RIP_AX;
+		/* Change modrm from 00 xxx 101 to 00 xxx 000 */
+		*cursor = (reg << 3);
+	}
+
+	/* Target address = address of next instruction + (signed) offset */
+	user_bkpt->arch_info.rip_target_address = (long) user_bkpt->vaddr +
+				insn->length + insn->displacement.value;
+	/* Displacement field is gone; slide immediate field (if any) over. */
+	if (insn->immediate.nbytes) {
+		cursor++;
+		memmove(cursor, cursor + insn->displacement.nbytes,
+						insn->immediate.nbytes);
+	}
+	return 1;
+}
+
+/*
+ * If we're emulating a rip-relative instruction, save the contents
+ * of the scratch register and store the target address in that register.
+ */
+static int pre_xol(struct task_struct *tsk, struct user_bkpt *user_bkpt,
+		struct user_bkpt_task_arch_info *tskinfo, struct pt_regs *regs)
+{
+	BUG_ON(!user_bkpt->xol_vaddr);
+	regs->ip = user_bkpt->xol_vaddr;
+	if (user_bkpt->fixups & USER_BKPT_FIX_RIP_AX) {
+		tskinfo->saved_scratch_register = regs->ax;
+		regs->ax = user_bkpt->arch_info.rip_target_address;
+	} else if (user_bkpt->fixups & USER_BKPT_FIX_RIP_CX) {
+		tskinfo->saved_scratch_register = regs->cx;
+		regs->cx = user_bkpt->arch_info.rip_target_address;
+	}
+	return 0;
+}
+#endif
+
+/*
+ * Called by post_xol() to adjust the return address pushed by a call
+ * instruction executed out of line.
+ */
+static int adjust_ret_addr(struct task_struct *tsk, unsigned long sp,
+							long correction)
+{
+	int rasize, ncopied;
+	long ra = 0;
+
+	if (is_32bit_app(tsk))
+		rasize = 4;
+	else
+		rasize = 8;
+	ncopied = user_bkpt_read_vm(tsk, (void __user *) sp, &ra, rasize);
+	if (unlikely(ncopied != rasize))
+		goto fail;
+	ra += correction;
+	ncopied = user_bkpt_write_data(tsk, (void __user *) sp, &ra, rasize);
+	if (unlikely(ncopied != rasize))
+		goto fail;
+	return 0;
+
+fail:
+	printk(KERN_ERR
+		"user_bkpt: Failed to adjust return address after"
+		" single-stepping call instruction;"
+		" pid=%d, sp=%#lx\n", tsk->pid, sp);
+	return -EFAULT;
+}
+
+/*
+ * Called after single-stepping.  user_bkpt->vaddr is the address of the
+ * instruction whose first byte has been replaced by the "int3"
+ * instruction.  To avoid the SMP problems that can occur when we
+ * temporarily put back the original opcode to single-step, we
+ * single-stepped a copy of the instruction.  The address of this
+ * copy is user_bkpt->xol_vaddr.
+ *
+ * This function prepares to resume execution after the single-step.
+ * We have to fix things up as follows:
+ *
+ * Typically, the new ip is relative to the copied instruction.  We need
+ * to make it relative to the original instruction (FIX_IP).  Exceptions
+ * are return instructions and absolute or indirect jump or call instructions.
+ *
+ * If the single-stepped instruction was a call, the return address that
+ * is atop the stack is the address following the copied instruction.  We
+ * need to make it the address following the original instruction (FIX_CALL).
+ *
+ * If the original instruction was a rip-relative instruction such as
+ * "movl %edx,0xnnnn(%rip)", we have instead executed an equivalent
+ * instruction using a scratch register -- e.g., "movl %edx,(%rax)".
+ * We need to restore the contents of the scratch register and adjust
+ * the ip, keeping in mind that the instruction we executed is 4 bytes
+ * shorter than the original instruction (since we squeezed out the offset
+ * field).  (FIX_RIP_AX or FIX_RIP_CX)
+ */
+static int post_xol(struct task_struct *tsk, struct user_bkpt *user_bkpt,
+		struct user_bkpt_task_arch_info *tskinfo, struct pt_regs *regs)
+{
+	/* Typically, the XOL vma is at a high addr, so correction < 0. */
+	long correction = (long) (user_bkpt->vaddr - user_bkpt->xol_vaddr);
+	int result = 0;
+
+#ifdef CONFIG_X86_64
+	if (is_riprel_insn(user_bkpt)) {
+		if (user_bkpt->fixups & USER_BKPT_FIX_RIP_AX)
+			regs->ax = tskinfo->saved_scratch_register;
+		else
+			regs->cx = tskinfo->saved_scratch_register;
+		/*
+		 * The original instruction includes a displacement, and so
+		 * is 4 bytes longer than what we've just single-stepped.
+		 * Fall through to handle stuff like "jmpq *...(%rip)" and
+		 * "callq *...(%rip)".
+		 */
+		correction += 4;
+	}
+#endif
+	if (user_bkpt->fixups & USER_BKPT_FIX_IP)
+		regs->ip += correction;
+	if (user_bkpt->fixups & USER_BKPT_FIX_CALL)
+		result = adjust_ret_addr(tsk, regs->sp, correction);
+	return result;
+}
+
+struct user_bkpt_arch_info user_bkpt_arch_info = {
+	.bkpt_insn = 0xcc,
+	.ip_advancement_by_bkpt_insn = 1,
+	.max_insn_bytes = MAX_UINSN_BYTES,
+#ifdef CONFIG_X86_32
+	.strategies = 0x0,
+#else
+	/* rip-relative instructions require special handling. */
+	.strategies = USER_BKPT_HNT_TSKINFO,
+	.pre_xol = pre_xol,
+	.cancel_xol = cancel_xol,
+#endif
+	.set_ip = set_ip,
+	.analyze_insn = analyze_insn,
+	.post_xol = post_xol,
+};

[PATCH v5 5/14] Slot allocation for execution out of line (XOL)

[Srikar Dronamraju]

ubp_xol.patch

From: Srikar Dronamraju <srikar@linux.vnet.ibm.com>

Changelog form v3:
	* Added a memory barrier after the slot gets initialized.

Changelog from v2: (addressing Oleg's comments)
	* Removed code in !CONFIG_USER_BKPT_XOL
	* Functions now pass pointer to user_bkpt_xol_area instead of pointer
	  to void.

Slot allocation for Execution out of line strategy(XOL)

This patch provides slot allocation mechanism for execution out of
line strategy for use with user space breakpoint infrastructure.

Traditional method of replacing the original instructions on breakpoint
hit are racy when used on multithreaded applications.

Alternatives for the traditional method include:
	- Emulating the breakpointed instruction.
	- Execution out of line.

Emulating the instruction:
	This approach would use a in-kernel instruction emulator to
emulate the breakpointed instruction. This approach could be looked in
at a later point of time.

Execution out of line:
	In execution out of line strategy, a new vma is injected into
the target process, a copy of the instructions which are breakpointed is
stored in one of the slots. On breakpoint hit, the copy of the
instruction is single-stepped leaving the breakpoint instruction as is.
This method is architecture independent.

This method is useful while handling multithreaded processes.

This patch allocates one page per process for slots to be used to copy the
breakpointed instructions.

Current slot allocation mechanism:
1. Allocate one dedicated slot per user breakpoint. Each slot is big
enuf to accomodate the biggest instruction for that architecture. (16
bytes for x86).
2. We currently allocate only one page for slots. Hence the number of
slots is limited to active breakpoint hits on that process.
3. Bitmap to track used slots.

Signed-off-by: Jim Keniston <jkenisto@us.ibm.com>
Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
---

 arch/Kconfig                  |    4 +
 include/linux/user_bkpt_xol.h |   40 +++++
 kernel/Makefile               |    1 
 kernel/user_bkpt_xol.c        |  302 +++++++++++++++++++++++++++++++++++++++++
 4 files changed, 347 insertions(+), 0 deletions(-)
 create mode 100644 include/linux/user_bkpt_xol.h
 create mode 100644 kernel/user_bkpt_xol.c


diff --git a/arch/Kconfig b/arch/Kconfig
index 4018d49..16541af 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -94,6 +94,10 @@ config USER_RETURN_NOTIFIER
 config HAVE_USER_BKPT
 	def_bool n
 
+config USER_BKPT_XOL
+	def_bool y
+	depends on USER_BKPT
+
 config HAVE_IOREMAP_PROT
 	bool
 
diff --git a/include/linux/user_bkpt_xol.h b/include/linux/user_bkpt_xol.h
new file mode 100644
index 0000000..47e8d62
--- /dev/null
+++ b/include/linux/user_bkpt_xol.h
@@ -0,0 +1,40 @@
+#ifndef _LINUX_XOL_H
+#define _LINUX_XOL_H
+/*
+ * User-space BreakPoint support (user_bkpt) -- Allocation of instruction
+ * slots for execution out of line (XOL)
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ *
+ * Copyright (C) IBM Corporation, 2009, 2010
+ * Authors:
+ *	Srikar Dronamraju
+ *	Jim Keniston
+ */
+
+#define UINSNS_PER_PAGE	(PAGE_SIZE/USER_BKPT_XOL_SLOT_BYTES)
+#define MAX_USER_BKPT_XOL_SLOTS UINSNS_PER_PAGE
+struct user_bkpt_xol_area;
+
+extern unsigned long xol_get_insn_slot(struct user_bkpt *user_bkpt,
+				struct user_bkpt_xol_area *xol_area);
+extern void xol_free_insn_slot(unsigned long,
+				struct user_bkpt_xol_area *xol_area);
+extern int xol_validate_vaddr(struct pid *pid, unsigned long vaddr,
+				struct user_bkpt_xol_area *xol_area);
+extern struct user_bkpt_xol_area *xol_alloc_area(void);
+extern void xol_free_area(struct user_bkpt_xol_area *xol_area);
+
+#endif  /* _LINUX_XOL_H */
diff --git a/kernel/Makefile b/kernel/Makefile
index f670347..7033f49 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -106,6 +106,7 @@ obj-$(CONFIG_HAVE_HW_BREAKPOINT) += hw_breakpoint.o
 obj-$(CONFIG_USER_RETURN_NOTIFIER) += user-return-notifier.o
 obj-$(CONFIG_PADATA) += padata.o
 obj-$(CONFIG_USER_BKPT) += user_bkpt.o
+obj-$(CONFIG_USER_BKPT_XOL) += user_bkpt_xol.o
 
 ifneq ($(CONFIG_SCHED_OMIT_FRAME_POINTER),y)
 # According to Alan Modra <alan@linuxcare.com.au>, the -fno-omit-frame-pointer is
diff --git a/kernel/user_bkpt_xol.c b/kernel/user_bkpt_xol.c
new file mode 100644
index 0000000..437ddea
--- /dev/null
+++ b/kernel/user_bkpt_xol.c
@@ -0,0 +1,302 @@
+/*
+ * User-space BreakPoint support (user_bkpt) -- Allocation of instruction
+ * slots for execution out of line (XOL)
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ *
+ * Copyright (C) IBM Corporation, 2009, 2010
+ * Authors:
+ *	Srikar Dronamraju
+ *	Jim Keniston
+ */
+
+/*
+ * Every probepoint gets its own slot.  Once it's assigned a slot, it
+ * keeps that slot until the probepoint goes away. Only definite number
+ * of slots are allocated.
+ */
+#include <linux/mm.h>
+#include <linux/err.h>
+#include <linux/errno.h>
+#include <linux/mman.h>
+#include <linux/file.h>
+#include <linux/pid.h>
+#include <linux/sched.h>
+#include <linux/user_bkpt.h>
+#include <linux/user_bkpt_xol.h>
+#include <linux/slab.h>
+
+struct user_bkpt_xol_area {
+	spinlock_t lock;	/* protects bitmap and slot (de)allocation*/
+	unsigned long *bitmap;	/* 0 = free slot */
+
+	/*
+	 * We keep the vma's vm_start rather than a pointer to the vma
+	 * itself.  The probed process or a naughty kernel module could make
+	 * the vma go away, and we must handle that reasonably gracefully.
+	 */
+	unsigned long vaddr;		/* Page(s) of instruction slots */
+};
+
+static int xol_add_vma(struct user_bkpt_xol_area *area)
+{
+	struct vm_area_struct *vma;
+	struct mm_struct *mm;
+	struct file *file;
+	unsigned long addr;
+
+	mm = get_task_mm(current);
+	if (!mm)
+		return -ESRCH;
+
+	down_write(&mm->mmap_sem);
+	/*
+	 * Find the end of the top mapping and skip a page.
+	 * If there is no space for PAGE_SIZE above
+	 * that, mmap will ignore our address hint.
+	 *
+	 * We allocate a "fake" unlinked shmem file because
+	 * anonymous memory might not be granted execute
+	 * permission when the selinux security hooks have
+	 * their way.
+	 */
+	vma = rb_entry(rb_last(&mm->mm_rb), struct vm_area_struct, vm_rb);
+	addr = vma->vm_end + PAGE_SIZE;
+	file = shmem_file_setup("uprobes/xol", PAGE_SIZE, VM_NORESERVE);
+	if (!file) {
+		printk(KERN_ERR "user_bkpt_xol failed to setup shmem_file "
+			"while allocating vma for pid/tgid %d/%d for "
+			"single-stepping out of line.\n",
+			current->pid, current->tgid);
+		goto fail;
+	}
+	addr = do_mmap_pgoff(file, addr, PAGE_SIZE, PROT_EXEC, MAP_PRIVATE, 0);
+	fput(file);
+
+	if (addr & ~PAGE_MASK) {
+		printk(KERN_ERR "user_bkpt_xol failed to allocate a vma for "
+				"pid/tgid %d/%d for single-stepping out of "
+				"line.\n", current->pid, current->tgid);
+		goto fail;
+	}
+	vma = find_vma(mm, addr);
+
+	/* Don't expand vma on mremap(). */
+	vma->vm_flags |= VM_DONTEXPAND | VM_DONTCOPY;
+	area->vaddr = vma->vm_start;
+	up_write(&mm->mmap_sem);
+	mmput(mm);
+	return 0;
+
+fail:
+	up_write(&mm->mmap_sem);
+	mmput(mm);
+	return -ENOMEM;
+}
+
+/**
+ * xol_alloc_area - Allocate process's user_bkpt_xol_area.
+ * This area will be used for storing instructions for execution out of
+ * line.
+ *
+ * Called with mm->uproc->mutex locked.
+ * Returns the allocated area or NULL.
+ */
+struct user_bkpt_xol_area *xol_alloc_area(void)
+{
+	struct user_bkpt_xol_area *area = NULL;
+
+	area = kzalloc(sizeof(*area), GFP_USER);
+	if (unlikely(!area))
+		return NULL;
+
+	area->bitmap = kzalloc(BITS_TO_LONGS(UINSNS_PER_PAGE) * sizeof(long),
+								GFP_USER);
+
+	if (!area->bitmap)
+		goto fail;
+	if (xol_add_vma(area)) {
+		kfree(area->bitmap);
+		goto fail;
+	}
+	spin_lock_init(&area->lock);
+	return area;
+
+fail:
+	kfree(area);
+	return NULL;
+}
+
+/**
+ * xol_free_area - Free the area allocated for slots.
+ * @xol_area refers the unique per process user_bkpt_xol_area for
+ * this process.
+ *
+ */
+void xol_free_area(struct user_bkpt_xol_area *xol_area)
+{
+	kfree(xol_area->bitmap);
+	kfree(xol_area);
+}
+
+/*
+ * Find a slot
+ *  - searching in existing vmas for a free slot.
+ *  - If no free slot in existing vmas, return 0;
+ *
+ * Called when holding xol_area->lock
+ */
+static unsigned long xol_take_insn_slot(struct user_bkpt_xol_area *area)
+{
+	unsigned long slot_addr;
+	int slot_nr;
+
+	slot_nr = find_first_zero_bit(area->bitmap, UINSNS_PER_PAGE);
+	if (slot_nr < UINSNS_PER_PAGE) {
+		set_bit(slot_nr, area->bitmap);
+		slot_addr = area->vaddr +
+				(slot_nr * USER_BKPT_XOL_SLOT_BYTES);
+		return slot_addr;
+	}
+
+	return 0;
+}
+
+/**
+ * xol_get_insn_slot - If user_bkpt was not allocated a slot, then
+ * allocate a slot. If user_bkpt_insert_bkpt is already called, (i.e
+ * user_bkpt.vaddr != 0) then copy the instruction into the slot.
+ * @user_bkpt: probepoint information
+ * @xol_area refers the unique per process user_bkpt_xol_area for
+ * this process.
+ *
+ * Called with mm->uproc->mutex locked.
+ * Returns the allocated slot address or 0.
+ */
+unsigned long xol_get_insn_slot(struct user_bkpt *user_bkpt,
+				struct user_bkpt_xol_area *xol_area)
+{
+	unsigned long flags, xol_vaddr = 0;
+	int len;
+
+	if (unlikely(!xol_area))
+		return 0;
+
+	if (user_bkpt->xol_vaddr)
+		return user_bkpt->xol_vaddr;
+
+	spin_lock_irqsave(&xol_area->lock, flags);
+	xol_vaddr = xol_take_insn_slot(xol_area);
+	spin_unlock_irqrestore(&xol_area->lock, flags);
+
+	/*
+	 * Initialize the slot if user_bkpt->vaddr points to valid
+	 * instruction slot.
+	 */
+	if (likely(xol_vaddr) && user_bkpt->vaddr) {
+		len = access_process_vm(current, xol_vaddr, user_bkpt->insn,
+						USER_BKPT_XOL_SLOT_BYTES, 1);
+		if (unlikely(len < USER_BKPT_XOL_SLOT_BYTES))
+			printk(KERN_ERR "Failed to copy instruction at %#lx "
+					"len = %d\n", user_bkpt->vaddr, len);
+	}
+
+	/*
+	 * Update user_bkpt->xol_vaddr after giving a chance for the slot to
+	 * be initialized.
+	 */
+	mb();
+	user_bkpt->xol_vaddr = xol_vaddr;
+	return user_bkpt->xol_vaddr;
+}
+
+/**
+ * xol_free_insn_slot - If slot was earlier allocated by
+ * @xol_get_insn_slot(), make the slot available for
+ * subsequent requests.
+ * @slot_addr: slot address as returned by
+ * @xol_get_insn_area().
+ * @xol_area refers the unique per process user_bkpt_xol_area for
+ * this process.
+ */
+void xol_free_insn_slot(unsigned long slot_addr,
+				struct user_bkpt_xol_area *xol_area)
+{
+	unsigned long vma_end;
+	int found = 0;
+
+	if (unlikely(!slot_addr || IS_ERR_VALUE(slot_addr)))
+		return;
+
+	if (unlikely(!xol_area))
+		return;
+
+	vma_end = xol_area->vaddr + PAGE_SIZE;
+	if (xol_area->vaddr <= slot_addr && slot_addr < vma_end) {
+		int slot_nr;
+		unsigned long offset = slot_addr - xol_area->vaddr;
+		unsigned long flags;
+
+		BUG_ON(offset % USER_BKPT_XOL_SLOT_BYTES);
+
+		slot_nr = offset / USER_BKPT_XOL_SLOT_BYTES;
+		BUG_ON(slot_nr >= UINSNS_PER_PAGE);
+
+		spin_lock_irqsave(&xol_area->lock, flags);
+		clear_bit(slot_nr, xol_area->bitmap);
+		spin_unlock_irqrestore(&xol_area->lock, flags);
+		found = 1;
+	}
+
+	if (!found)
+		printk(KERN_ERR "%s: no XOL vma for slot address %#lx\n",
+						__func__, slot_addr);
+}
+
+/**
+ * xol_validate_vaddr - Verify if the specified address is in an
+ * executable vma, but not in an XOL vma.
+ *	- Return 0 if the specified virtual address is in an
+ *	  executable vma, but not in an XOL vma.
+ *	- Return 1 if the specified virtual address is in an
+ *	  XOL vma.
+ *	- Return -EINTR otherwise.(i.e non executable vma, or
+ *	  not a valid address
+ * @pid: the probed process
+ * @vaddr: virtual address of the instruction to be validated.
+ * @xol_area refers the unique per process user_bkpt_xol_area for
+ * this process.
+ */
+int xol_validate_vaddr(struct pid *pid, unsigned long vaddr,
+				struct user_bkpt_xol_area *xol_area)
+{
+	struct task_struct *tsk;
+	unsigned long vma_end;
+	int result;
+
+	tsk = pid_task(pid, PIDTYPE_PID);
+	result = user_bkpt_validate_insn_addr(tsk, vaddr);
+	if (result != 0)
+		return result;
+
+	if (unlikely(!xol_area))
+		return 0;
+
+	vma_end = xol_area->vaddr + PAGE_SIZE;
+	if (xol_area->vaddr <= vaddr && vaddr < vma_end)
+		result = 1;
+
+	return result;
+}

[PATCH v5 6/14] Uprobes Implementation

[Srikar Dronamraju]

uprobes_core.patch

From: Srikar Dronamraju <srikar@linux.vnet.ibm.com>

Uprobes Implementation

Changelog from v2:
    - Introduce TIF_UPROBE flag.
    - uprobes hooks now in fork/exec/exit paths instead of tracehooks.
    - uprobe_process is now part of the mm struct and is shared between
      processes that share the mm.
    - per thread information is now allocated on the fly.
	* Hence allocation and freeing of this information is lockless.
    - For now run the handler in task context. The reasons for this change
      being.
	* utask (per task meta data structure is now allocated on the
	  fly. Hence first request on the thread and first request for the
          breakpoint have to be anyway allocated in task context.
	* Measurements showed task based handler had negligible
	  overhead over interrupt based handlers.
        * Feedback from Oleg and few others.
        * Feedback at LFCS.
        * Simplicity  atleast till uprobes stabilizes.
        ( However we introduce interrupt based handlers at a later time.)
     - find_probept() takes the spinlock; unlike previously when it was
       expected that the spinlock was taken before calling it.



Changelog from v1:
	- If fixup might sleep; then do the post singlestep
	   processing in task context.

The uprobes infrastructure enables a user to dynamically establish
probepoints in user applications and collect information by executing a
handler function when a probepoint is hit.

The user specifies the virtual address and the pid of the process of
interest along with the action to be performed (handler). The handle
Uprobes is implemented on the user-space breakpoint assistance layer
and uses the execution out of line strategy. Uprobes follows lazy slot
allocation. I.e, on the first probe hit for that process, a new vma (to
hold the probed instructions for execution out of line) is allocated.
Once allocated, this vma remains for the life of the process, and is
reused as needed for subsequent probes.  A slot in the vma is allocated
for a probepoint when it is first hit.

A slot is marked for reuse when the probe gets unregistered and no
threads are using that slot.

In a multithreaded process, a probepoint once registered is active for
all threads of a process. If a thread specific action for a probepoint
is required then the handler should be implemented to do the same.

If a breakpoint already exists at a particular address (irrespective of
who inserted the breakpoint including uprobes), uprobes will refuse to
register any more probes at that address.

You need to follow this up with the uprobes patch for your
architecture.

For more information: please refer to Documentation/uprobes.txt

TODO:
1. Perf/trace events interface for uprobes.
2. Allow multiple probes at a probepoint.
3. Booster probes.
4. Allow probes to be inherited across fork.
5. probing function returns.

Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Jim Keniston <jkenisto@us.ibm.com>
---

 arch/Kconfig                       |   13 +
 arch/x86/include/asm/thread_info.h |    2 
 arch/x86/kernel/signal.c           |    5 
 fs/exec.c                          |    4 
 include/linux/mm_types.h           |    4 
 include/linux/sched.h              |    3 
 include/linux/uprobes.h            |  169 +++++++++
 kernel/Makefile                    |    1 
 kernel/fork.c                      |   21 +
 kernel/uprobes.c                   |  681 ++++++++++++++++++++++++++++++++++++
 10 files changed, 903 insertions(+), 0 deletions(-)
 create mode 100644 include/linux/uprobes.h
 create mode 100644 kernel/uprobes.c


diff --git a/arch/Kconfig b/arch/Kconfig
index 16541af..995f7f2 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -58,6 +58,16 @@ config USER_BKPT
 	  This service is used by components such as uprobes.
 	  If in doubt, say "N".
 
+config UPROBES
+	bool "User-space probes (EXPERIMENTAL)"
+	depends on MODULES && USER_BKPT_XOL
+	depends on HAVE_UPROBES
+	help
+	  Uprobes enables kernel modules to establish probepoints
+	  in user applications and execute handler functions when
+	  the probepoints are hit. For more information, refer to
+	  Documentation/uprobes.txt. If in doubt, say "N".
+
 config HAVE_EFFICIENT_UNALIGNED_ACCESS
 	bool
 	help
@@ -109,6 +119,9 @@ config HAVE_KRETPROBES
 
 config HAVE_OPTPROBES
 	bool
+
+config HAVE_UPROBES
+	def_bool n
 #
 # An arch should select this if it provides all these things:
 #
diff --git a/arch/x86/include/asm/thread_info.h b/arch/x86/include/asm/thread_info.h
index f0b6e5d..5b9c9f0 100644
--- a/arch/x86/include/asm/thread_info.h
+++ b/arch/x86/include/asm/thread_info.h
@@ -84,6 +84,7 @@ struct thread_info {
 #define TIF_SECCOMP		8	/* secure computing */
 #define TIF_MCE_NOTIFY		10	/* notify userspace of an MCE */
 #define TIF_USER_RETURN_NOTIFY	11	/* notify kernel of userspace return */
+#define TIF_UPROBE		12	/* breakpointed or singlestepping */
 #define TIF_NOTSC		16	/* TSC is not accessible in userland */
 #define TIF_IA32		17	/* 32bit process */
 #define TIF_FORK		18	/* ret_from_fork */
@@ -107,6 +108,7 @@ struct thread_info {
 #define _TIF_SECCOMP		(1 << TIF_SECCOMP)
 #define _TIF_MCE_NOTIFY		(1 << TIF_MCE_NOTIFY)
 #define _TIF_USER_RETURN_NOTIFY	(1 << TIF_USER_RETURN_NOTIFY)
+#define _TIF_UPROBE		(1 << TIF_UPROBE)
 #define _TIF_NOTSC		(1 << TIF_NOTSC)
 #define _TIF_IA32		(1 << TIF_IA32)
 #define _TIF_FORK		(1 << TIF_FORK)
diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c
index 4fd173c..851bc8d 100644
--- a/arch/x86/kernel/signal.c
+++ b/arch/x86/kernel/signal.c
@@ -848,6 +848,11 @@ do_notify_resume(struct pt_regs *regs, void *unused, __u32 thread_info_flags)
 	if (thread_info_flags & _TIF_SIGPENDING)
 		do_signal(regs);
 
+	if (thread_info_flags & _TIF_UPROBE) {
+		clear_thread_flag(TIF_UPROBE);
+		uprobe_notify_resume(regs);
+	}
+
 	if (thread_info_flags & _TIF_NOTIFY_RESUME) {
 		clear_thread_flag(TIF_NOTIFY_RESUME);
 		tracehook_notify_resume(regs);
diff --git a/fs/exec.c b/fs/exec.c
index 97d91a0..fe49384 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -1053,6 +1053,10 @@ void setup_new_exec(struct linux_binprm * bprm)
 			
 	flush_signal_handlers(current, 0);
 	flush_old_files(current->files);
+#ifdef CONFIG_UPROBES
+	if (unlikely(current->utask))
+		uprobe_free_utask(current);
+#endif
 }
 EXPORT_SYMBOL(setup_new_exec);
 
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index b8bb9a6..200c659 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -12,6 +12,7 @@
 #include <linux/completion.h>
 #include <linux/cpumask.h>
 #include <linux/page-debug-flags.h>
+#include <linux/uprobes.h>
 #include <asm/page.h>
 #include <asm/mmu.h>
 
@@ -310,6 +311,9 @@ struct mm_struct {
 #ifdef CONFIG_MMU_NOTIFIER
 	struct mmu_notifier_mm *mmu_notifier_mm;
 #endif
+#ifdef CONFIG_UPROBES
+	struct uprobe_process *uproc;	/* per mm uprobes info */
+#endif
 };
 
 /* Future-safe accessor for struct mm_struct's cpu_vm_mask. */
diff --git a/include/linux/sched.h b/include/linux/sched.h
index a61c08c..63dd4fb 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1498,6 +1498,9 @@ struct task_struct {
 		unsigned long memsw_bytes; /* uncharged mem+swap usage */
 	} memcg_batch;
 #endif
+#ifdef CONFIG_UPROBES
+	struct uprobe_task *utask;
+#endif
 };
 
 /* Future-safe accessor for struct task_struct's cpus_allowed. */
diff --git a/include/linux/uprobes.h b/include/linux/uprobes.h
new file mode 100644
index 0000000..5c0565f
--- /dev/null
+++ b/include/linux/uprobes.h
@@ -0,0 +1,169 @@
+#ifndef _LINUX_UPROBES_H
+#define _LINUX_UPROBES_H
+/*
+ * Userspace Probes (UProbes)
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ *
+ * Copyright (C) IBM Corporation, 2008-2010
+ * Authors:
+ *	Srikar Dronamraju
+ *	Jim Keniston
+ */
+#include <linux/types.h>
+#include <linux/list.h>
+#include <linux/rcupdate.h>
+#include <linux/mutex.h>
+#include <linux/wait.h>
+#include <linux/spinlock_types.h>
+#include <asm/atomic.h>
+#include <linux/user_bkpt.h>
+#include <linux/user_bkpt_xol.h>
+
+struct task_struct;
+struct pid;
+struct pt_regs;
+
+/* This is what the user supplies us. */
+struct uprobe {
+	/*
+	 * The pid of the probed process.  Currently, this can be the
+	 * thread ID (task->pid) of any active thread in the process.
+	 */
+	pid_t pid;
+
+	/* Location of the probepoint */
+	unsigned long vaddr;
+
+	/* Handler to run when the probepoint is hit */
+	void (*handler)(struct uprobe*, struct pt_regs*);
+};
+
+/*
+ * uprobe_process -- not a user-visible struct.
+ * A uprobe_process represents a probed process.  A process can have
+ * multiple probepoints (each represented by a uprobe_probept) and
+ * one or more threads (each represented by a uprobe_task).
+ *
+ * All processes/threads that share a mm share the same uprobe_process.
+ */
+struct uprobe_process {
+	/*
+	 * mutex locked for any change to the uprobe_process's
+	 * graph (including uprobe_probept, taking a slot in xol_area) --
+	 * e.g., due to probe [un]registration or special events like exit.
+	 */
+	struct mutex mutex;
+
+	/* Table of uprobe_probepts registered for this process */
+	struct list_head uprobe_list;
+
+	atomic_t refcount;
+
+	/* lock held while traversing/modifying uprobe_list and n_ppts */
+	spinlock_t pptlist_lock;	/* protects uprobe_list */
+
+	/* number of probept allocated for this process */
+	int n_ppts;
+
+	/*
+	 * Manages slots for instruction-copies to be single-stepped
+	 * out of line.
+	 */
+	void *xol_area;
+};
+
+/*
+ * uprobe_probept -- not a user-visible struct.
+ * A uprobe_probept represents a probepoint.
+ * Guarded by uproc->lock.
+ */
+struct uprobe_probept {
+	/* breakpoint/XOL details */
+	struct user_bkpt user_bkpt;
+
+	/*
+	 * ppt goes in the uprobe_process->uprobe_table when registered --
+	 * even before the breakpoint has been inserted.
+	 */
+	struct list_head ut_node;
+
+	atomic_t refcount;
+
+	/* The parent uprobe_process */
+	struct uprobe_process *uproc;
+
+	struct uprobe *uprobe;
+};
+
+enum uprobe_task_state {
+	UTASK_RUNNING,
+	UTASK_BP_HIT,
+	UTASK_SSTEP
+};
+
+/*
+ * uprobe_utask -- not a user-visible struct.
+ * Corresponds to a thread in a probed process.
+ * Guarded by uproc->mutex.
+ */
+struct uprobe_task {
+	struct user_bkpt_task_arch_info arch_info;
+
+	enum uprobe_task_state state;
+
+	struct uprobe_probept *active_ppt;
+};
+
+#ifdef CONFIG_UPROBES
+extern int uprobes_exception_notify(struct notifier_block *self,
+				unsigned long val, void *data);
+extern int uprobe_bkpt_notifier(struct pt_regs *regs);
+extern int uprobe_post_notifier(struct pt_regs *regs);
+extern void uprobe_notify_resume(struct pt_regs *regs);
+extern void arch_uprobe_enable_sstep(struct pt_regs *regs);
+extern void arch_uprobe_disable_sstep(struct pt_regs *regs);
+extern int register_uprobe(struct uprobe *u);
+extern void unregister_uprobe(struct uprobe *u);
+extern void uprobe_free_utask(struct task_struct *tsk);
+extern void uprobe_handle_fork(struct task_struct *child);
+extern void uprobe_put_uprocess(struct mm_struct *mm);
+#else	/* CONFIG_UPROBES */
+
+/*
+ * Only register_uprobe() and unregister_uprobe() are part of
+ * the client API.
+ */
+static inline int register_uprobe(struct uprobe *u)
+{
+	return -ENOSYS;
+}
+static inline void unregister_uprobe(struct uprobe *u)
+{
+}
+static inline void uprobe_free_utask(void)
+{
+}
+static inline void uprobe_handle_fork(struct task_struct *child)
+{
+}
+static inline void uprobe_notify_resume(struct pt_regs *regs)
+{
+}
+static inline void uprobe_put_uprocess(struct mm_struct *mm)
+{
+}
+#endif	/* CONFIG_UPROBES */
+#endif	/* _LINUX_UPROBES_H */
diff --git a/kernel/Makefile b/kernel/Makefile
index 7033f49..a0250b7 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -107,6 +107,7 @@ obj-$(CONFIG_USER_RETURN_NOTIFIER) += user-return-notifier.o
 obj-$(CONFIG_PADATA) += padata.o
 obj-$(CONFIG_USER_BKPT) += user_bkpt.o
 obj-$(CONFIG_USER_BKPT_XOL) += user_bkpt_xol.o
+obj-$(CONFIG_UPROBES) += uprobes.o
 
 ifneq ($(CONFIG_SCHED_OMIT_FRAME_POINTER),y)
 # According to Alan Modra <alan@linuxcare.com.au>, the -fno-omit-frame-pointer is
diff --git a/kernel/fork.c b/kernel/fork.c
index a82a65c..c932193 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -187,6 +187,11 @@ void __put_task_struct(struct task_struct *tsk)
 	delayacct_tsk_free(tsk);
 	put_signal_struct(tsk->signal);
 
+#ifdef CONFIG_UPROBES
+	if (unlikely(tsk->utask))
+		uprobe_free_utask(tsk);
+#endif
+
 	if (!profile_handoff_task(tsk))
 		free_task(tsk);
 }
@@ -522,6 +527,10 @@ void __mmdrop(struct mm_struct *mm)
 	mm_free_pgd(mm);
 	destroy_context(mm);
 	mmu_notifier_mm_destroy(mm);
+#ifdef CONFIG_UPROBES
+	if (unlikely(mm->uproc))
+		uprobe_put_uprocess(mm);
+#endif
 	free_mm(mm);
 }
 EXPORT_SYMBOL_GPL(__mmdrop);
@@ -680,6 +689,9 @@ struct mm_struct *dup_mm(struct task_struct *tsk)
 	if (mm->binfmt && !try_module_get(mm->binfmt->module))
 		goto free_pt;
 
+#ifdef CONFIG_UPROBES
+	mm->uproc = NULL;
+#endif
 	return mm;
 
 free_pt:
@@ -1186,6 +1198,9 @@ static struct task_struct *copy_process(unsigned long clone_flags,
 	INIT_LIST_HEAD(&p->pi_state_list);
 	p->pi_state_cache = NULL;
 #endif
+#ifdef CONFIG_UPROBES
+	p->utask = NULL;
+#endif
 	/*
 	 * sigaltstack should be cleared when sharing the same VM
 	 */
@@ -1284,6 +1299,12 @@ static struct task_struct *copy_process(unsigned long clone_flags,
 	proc_fork_connector(p);
 	cgroup_post_fork(p);
 	perf_event_fork(p);
+#ifdef CONFIG_UPROBES
+	if ((current->mm) && !(clone_flags & CLONE_VM)) {
+		if (unlikely(current->mm->uproc))
+			uprobe_handle_fork(p);
+	}
+#endif
 	return p;
 
 bad_fork_free_pid:
diff --git a/kernel/uprobes.c b/kernel/uprobes.c
new file mode 100644
index 0000000..1edf468
--- /dev/null
+++ b/kernel/uprobes.c
@@ -0,0 +1,681 @@
+/*
+ *  Userspace Probes (UProbes)
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ *
+ * Copyright (C) IBM Corporation, 2008-2010
+ * Authors:
+ *	Srikar Dronamraju
+ *	Jim Keniston
+ */
+#include <linux/types.h>
+#include <linux/hash.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/sched.h>
+#include <linux/err.h>
+#include <linux/uprobes.h>
+#include <linux/string.h>
+#include <linux/uaccess.h>
+#include <linux/errno.h>
+#include <linux/kdebug.h>
+#include <linux/slab.h>
+
+static u16 user_bkpt_strategies;
+
+struct notifier_block uprobes_exception_nb = {
+	.notifier_call = uprobes_exception_notify,
+	.priority = 0x7ffffff0,
+};
+
+typedef void (*uprobe_handler_t)(struct uprobe*, struct pt_regs*);
+
+/* Guards lookup, creation, and deletion of uproc. */
+static DEFINE_MUTEX(uprobe_mutex);
+
+static inline void get_probept(struct uprobe_probept *ppt)
+{
+	atomic_inc(&ppt->refcount);
+}
+
+/*
+ * Creates a uprobe_probept and connects it to uprobe and uproc.
+ * Runs with uproc->mutex locked.
+ */
+static struct uprobe_probept *add_probept(struct uprobe *u,
+					struct uprobe_process *uproc)
+{
+	struct uprobe_probept *ppt;
+
+	ppt = kzalloc(sizeof *ppt, GFP_USER);
+	if (unlikely(ppt == NULL))
+		return ERR_PTR(-ENOMEM);
+
+	ppt->user_bkpt.vaddr = u->vaddr;
+	ppt->uprobe = u;
+	ppt->user_bkpt.xol_vaddr = 0;
+
+	ppt->user_bkpt.strategy = user_bkpt_strategies;
+
+	ppt->uproc = uproc;
+	INIT_LIST_HEAD(&ppt->ut_node);
+	spin_lock(&uproc->pptlist_lock);
+	list_add(&ppt->ut_node, &uproc->uprobe_list);
+	uproc->n_ppts++;
+	spin_unlock(&uproc->pptlist_lock);
+	atomic_set(&ppt->refcount, 1);
+	return ppt;
+}
+
+static void put_probept(struct uprobe_probept *ppt)
+{
+	struct uprobe_process *uproc;
+
+	uproc = ppt->uproc;
+	if (atomic_dec_and_lock(&ppt->refcount, &uproc->pptlist_lock)) {
+		list_del(&ppt->ut_node);
+		uproc->n_ppts--;
+		xol_free_insn_slot(ppt->user_bkpt.xol_vaddr, uproc->xol_area);
+		spin_unlock(&uproc->pptlist_lock);
+		kfree(ppt);
+	}
+}
+
+/*
+ * In the given uproc's hash table of probepoints, find the one with the
+ * specified virtual address.
+ * Called with uproc->pptlist_lock acquired.
+ */
+static struct uprobe_probept *find_probept(struct uprobe_process *uproc,
+							unsigned long vaddr)
+{
+	struct uprobe_probept *ppt;
+
+	spin_lock(&uproc->pptlist_lock);
+	list_for_each_entry(ppt, &uproc->uprobe_list, ut_node) {
+		if (ppt->user_bkpt.vaddr == vaddr) {
+			spin_unlock(&uproc->pptlist_lock);
+			return ppt;
+		}
+	}
+	spin_unlock(&uproc->pptlist_lock);
+	return NULL;
+}
+
+/*
+ * Save a copy of the original instruction (so it can be single-stepped
+ * out of line), insert the breakpoint instruction.
+ * Runs with uproc->mutex locked.
+ */
+static int insert_bkpt(struct uprobe_probept *ppt, struct task_struct *tsk)
+{
+	int result;
+
+	if (tsk)
+		result = user_bkpt_insert_bkpt(tsk, &ppt->user_bkpt);
+	else
+		/* No surviving tasks associated with ppt->uproc */
+		result = -ESRCH;
+	return result;
+}
+
+ /* Runs with uproc->mutex locked. */
+static void remove_bkpt(struct uprobe_probept *ppt, struct task_struct *tsk)
+{
+	if (!tsk)
+		return;
+
+	if (user_bkpt_remove_bkpt(tsk, &ppt->user_bkpt) != 0) {
+		printk(KERN_ERR "Error removing uprobe at pid %d vaddr %#lx:"
+			" can't restore original instruction\n",
+			tsk->tgid, ppt->user_bkpt.vaddr);
+		/*
+		 * This shouldn't happen, since we were previously able
+		 * to write the breakpoint at that address.  There's not
+		 * much we can do besides let the process die with a
+		 * SIGTRAP the next time the breakpoint is hit.
+		 */
+	}
+}
+
+/* Runs with the uprobe_mutex held. */
+static struct uprobe_process *find_uprocess(struct pid *tg_leader)
+{
+	struct uprobe_process *uproc = NULL;
+	struct task_struct *tsk;
+
+	rcu_read_lock();
+	tsk = pid_task(tg_leader, PIDTYPE_PID);
+	if (!tsk || !tsk->mm)
+		goto end;
+
+	uproc = tsk->mm->uproc;
+	if (uproc)
+		atomic_inc(&uproc->refcount);
+
+end:
+	rcu_read_unlock();
+	return uproc;
+}
+
+/*
+ * uproc's process is exiting or exec-ing.
+ * The last thread of uproc's process is about to die, and its
+ * mm_struct is about to be released.
+ * Hence do the cleanup without holding locks.
+ *
+ * Called with no locks held.
+ */
+static int free_uprocess(struct uprobe_process *uproc)
+{
+	struct uprobe_probept *ppt, *pnode;
+
+	list_for_each_entry_safe(ppt, pnode, &uproc->uprobe_list, ut_node) {
+		put_probept(ppt);
+	}
+	if (uproc->xol_area)
+		xol_free_area(uproc->xol_area);
+
+	kfree(uproc);
+	return 0;
+}
+
+/* Called with no locks held */
+static void put_uprocess(struct uprobe_process *uproc)
+{
+	if (atomic_dec_and_test(&uproc->refcount))
+		free_uprocess(uproc);
+}
+
+/*
+ * Called with no locks held.
+ * Called in context of a exiting or a exec-ing thread.
+ */
+void uprobe_free_utask(struct task_struct *tsk)
+{
+	if (!tsk->utask)
+		return;
+
+	if (tsk->utask->active_ppt)
+		put_probept(tsk->utask->active_ppt);
+	kfree(tsk->utask);
+	tsk->utask = NULL;
+}
+
+/*
+ * Callback from mmput() when mm->users count reduces to zero.
+ */
+void uprobe_put_uprocess(struct mm_struct *mm)
+{
+	put_uprocess(mm->uproc);
+	mm->uproc = NULL;
+}
+
+/*
+ * Allocate a uprobe_task object for the task.
+ * Called with t "got" and uprobe_mutex locked.
+ * Called when the thread hits a breakpoint for the first time.
+ *
+ * Returns:
+ * - pointer to new uprobe_task on success
+ * - negative errno otherwise
+ */
+static struct uprobe_task *add_utask(struct uprobe_process *uproc)
+{
+	struct uprobe_task *utask;
+
+	utask = kzalloc(sizeof *utask, GFP_KERNEL);
+	if (unlikely(utask == NULL))
+		return ERR_PTR(-ENOMEM);
+
+	utask->active_ppt = NULL;
+	current->utask = utask;
+	atomic_inc(&uproc->refcount);
+
+	return utask;
+}
+
+/* Runs with uprobe_mutex held; */
+static struct uprobe_process *create_uprocess(struct pid *tg_leader)
+{
+	struct uprobe_process *uproc = ERR_PTR(-ENOMEM);
+	struct task_struct *tsk;
+	struct mm_struct *mm = NULL;
+
+	tsk = get_pid_task(tg_leader, PIDTYPE_PID);
+	if (tsk)
+		mm = get_task_mm(tsk);
+	if (!mm) {
+		if (tsk)
+			put_task_struct(tsk);
+		return ERR_PTR(-ESRCH);
+	}
+
+	uproc = kzalloc(sizeof *uproc, GFP_KERNEL);
+	if (unlikely(uproc == NULL)) {
+		uproc =  ERR_PTR(-ENOMEM);
+		goto end;
+	}
+
+	/* Initialize fields */
+	mutex_init(&uproc->mutex);
+	spin_lock_init(&uproc->pptlist_lock);
+	atomic_set(&uproc->refcount, 1);
+	INIT_LIST_HEAD(&uproc->uprobe_list);
+
+	BUG_ON(mm->uproc);
+	mm->uproc = uproc;
+
+	/*
+	 * Incrementing the refcount saves us from calling find_uprocess
+	 * in register_uprobe path.
+	 */
+	atomic_inc(&uproc->refcount);
+
+end:
+	put_task_struct(tsk);
+	mmput(mm);
+	return uproc;
+}
+
+/*
+ * Given a numeric thread ID, return a ref-counted struct pid for the
+ * task-group-leader thread.
+ */
+static struct pid *get_tg_leader(pid_t p)
+{
+	struct pid *pid = NULL;
+
+	rcu_read_lock();
+	pid = find_vpid(p);
+	if (pid) {
+		struct task_struct *t = pid_task(pid, PIDTYPE_PID);
+
+		if (!t)
+			pid = NULL;
+		else
+			pid = get_pid(task_tgid(t));
+	}
+	rcu_read_unlock();
+	return pid;
+}
+
+/* See Documentation/uprobes.txt. */
+int register_uprobe(struct uprobe *u)
+{
+	struct uprobe_process *uproc;
+	struct uprobe_probept *ppt;
+	struct pid *p;
+	int ret = 0;
+
+	if (!u || !u->handler)
+		return -EINVAL;
+
+	p = get_tg_leader(u->pid);
+	if (!p)
+		return -ESRCH;
+
+	/* Get the uprobe_process for this pid, or make a new one. */
+	mutex_lock(&uprobe_mutex);
+	uproc = find_uprocess(p);
+
+	if (!uproc) {
+		uproc = create_uprocess(p);
+		if (IS_ERR(uproc)) {
+			ret = (int) PTR_ERR(uproc);
+			mutex_unlock(&uprobe_mutex);
+			goto fail_tsk;
+		}
+	}
+	mutex_unlock(&uprobe_mutex);
+	mutex_lock(&uproc->mutex);
+
+	if (uproc->n_ppts >= MAX_USER_BKPT_XOL_SLOTS)
+		goto fail_uproc;
+
+	ret = xol_validate_vaddr(p, u->vaddr, uproc->xol_area);
+	if (ret < 0)
+		goto fail_uproc;
+
+	/* See if we already have a probepoint at the vaddr. */
+	ppt = find_probept(uproc, u->vaddr);
+	if (ppt) {
+		/*
+		 * A uprobe already exists at that address.
+		 */
+		ret = -EALREADY;
+		goto fail_uproc;
+	} else {
+		ppt = add_probept(u, uproc);
+		if (IS_ERR(ppt)) {
+			ret = (int) PTR_ERR(ppt);
+			goto fail_uproc;
+		}
+		ret = insert_bkpt(ppt, pid_task(p, PIDTYPE_PID));
+		if (ret != 0)
+			goto fail_uproc;
+	}
+
+fail_uproc:
+	mutex_unlock(&uproc->mutex);
+	put_uprocess(uproc);
+
+fail_tsk:
+	put_pid(p);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(register_uprobe);
+
+/* See Documentation/uprobes.txt. */
+void unregister_uprobe(struct uprobe *u)
+{
+	struct uprobe_process *uproc;
+	struct uprobe_probept *ppt;
+	struct pid *p;
+
+	if (!u)
+		return;
+	p = get_tg_leader(u->pid);
+	if (!p)
+		return;
+
+	/* Get the uprobe_process for this pid. */
+	mutex_lock(&uprobe_mutex);
+	uproc = find_uprocess(p);
+	mutex_unlock(&uprobe_mutex);
+	if (!uproc) {
+		put_pid(p);
+		return;
+	}
+
+	/*
+	 * Lock uproc before walking the graph, in case the process
+	 * we're probing is exiting.
+	 */
+	mutex_lock(&uproc->mutex);
+
+	ppt = find_probept(uproc, u->vaddr);
+	if (!ppt)
+		/*
+		 * This probe was never successfully registered, or
+		 * has already been unregistered.
+		 */
+		goto done;
+
+	if (ppt->uprobe != u)
+		/*
+		 * unregister request doesnt correspond to successful
+		 * register request.
+		 */
+		goto done;
+
+	remove_bkpt(ppt, pid_task(p, PIDTYPE_PID));
+
+	/*
+	 * Breakpoint is removed; however a thread could have hit the
+	 * same breakpoint and yet to find its corresponding probepoint.
+	 * Before we remove the probepoint, give the breakpointed thread a
+	 * chance to find the probepoint.
+	 */
+	mutex_unlock(&uproc->mutex);
+	synchronize_sched();
+	mutex_lock(&uproc->mutex);
+	put_probept(ppt);
+
+done:
+	mutex_unlock(&uproc->mutex);
+	put_uprocess(uproc);
+	put_pid(p);
+}
+EXPORT_SYMBOL_GPL(unregister_uprobe);
+
+/* Prepare to single-step ppt's probed instruction out of line. */
+static int pre_ssout(struct uprobe_probept *ppt, struct pt_regs *regs)
+{
+	struct uprobe_process *uproc = current->mm->uproc;
+
+	if (unlikely(!ppt->user_bkpt.xol_vaddr)) {
+		mutex_lock(&uproc->mutex);
+		if (unlikely(!uproc->xol_area))
+			uproc->xol_area = xol_alloc_area();
+		if (uproc->xol_area && !ppt->user_bkpt.xol_vaddr)
+			xol_get_insn_slot(&ppt->user_bkpt, uproc->xol_area);
+		if (unlikely(!ppt->user_bkpt.xol_vaddr))
+			goto fail;
+		mutex_unlock(&uproc->mutex);
+	}
+	user_bkpt_pre_sstep(current, &ppt->user_bkpt,
+					&current->utask->arch_info, regs);
+	user_bkpt_set_ip(regs, ppt->user_bkpt.xol_vaddr);
+	return 0;
+
+/*
+ * We failed to execute out of line.
+ * reset the instruction pointer and remove the breakpoint.
+ */
+fail:
+	remove_bkpt(ppt, current);
+	mutex_unlock(&uproc->mutex);
+	user_bkpt_set_ip(regs, ppt->user_bkpt.vaddr);
+	put_probept(ppt);
+	return -1;
+}
+
+/* Prepare to continue execution after single-stepping out of line. */
+static int post_ssout(struct uprobe_probept *ppt, struct pt_regs *regs)
+{
+	return user_bkpt_post_sstep(current, &ppt->user_bkpt,
+					&current->utask->arch_info, regs);
+}
+
+/*
+ * Verify from Instruction Pointer if singlestep has indeed occurred.
+ * If Singlestep has occurred, then do post singlestep fix-ups.
+ */
+static bool sstep_complete(struct pt_regs *regs,
+				struct uprobe_probept *ppt)
+{
+	unsigned long vaddr = instruction_pointer(regs);
+
+	/*
+	 * If we have executed out of line, Instruction pointer
+	 * cannot be same as virtual address of XOL slot.
+	 */
+	if (vaddr == ppt->user_bkpt.xol_vaddr)
+		return false;
+	post_ssout(ppt, regs);
+	return true;
+}
+
+/*
+ * Fork callback: The current task has spawned a process.
+ * NOTE: For now, we don't pass on uprobes from the parent to the
+ * child. We now do the necessary clearing of breakpoints in the
+ * child's address space.
+ * This function handles the case where vm is not shared between
+ * the parent and the child.
+ *
+ * TODO:
+ *	- Provide option for child to inherit uprobes.
+ */
+void uprobe_handle_fork(struct task_struct *child)
+{
+	struct uprobe_process *uproc;
+	struct uprobe_probept *ppt;
+	int ret;
+
+	uproc = current->mm->uproc;
+
+	/*
+	 * New process spawned by parent but not sharing the same mm.
+	 * Remove the probepoints in the child's text.
+	 *
+	 * We also hold the uproc->mutex for the parent - so no
+	 * new uprobes will be registered 'til we return.
+	 */
+	mutex_lock(&uproc->mutex);
+	list_for_each_entry(ppt, &uproc->uprobe_list, ut_node) {
+		ret = user_bkpt_remove_bkpt(child, &ppt->user_bkpt);
+		if (ret) {
+			/* Ratelimit this? */
+			printk(KERN_ERR "Pid %d forked %d; failed to"
+				" remove probepoint at %#lx in child\n",
+				current->pid, child->pid,
+				ppt->user_bkpt.vaddr);
+		}
+	}
+	mutex_unlock(&uproc->mutex);
+}
+
+/*
+ * uprobe_notify_resume gets called in task context just before returning
+ * to userspace.
+ *
+ *  If its the first time the probepoint is hit, slot gets allocated here.
+ *  If its the first time the thread hit a breakpoint, utask gets
+ *  allocated here.
+ */
+void uprobe_notify_resume(struct pt_regs *regs)
+{
+	struct uprobe_process *uproc;
+	struct uprobe_probept *ppt;
+	struct uprobe_task *utask;
+	struct uprobe *u;
+	unsigned long probept;
+
+	utask = current->utask;
+	uproc = current->mm->uproc;
+	if (unlikely(!utask)) {
+		utask = add_utask(uproc);
+
+		/* Failed to allocate utask for the current task. */
+		BUG_ON(!utask);
+		probept = user_bkpt_get_bkpt_addr(regs);
+		ppt = find_probept(uproc, probept);
+
+		/*
+		 * The probept was refcounted in uprobe_bkpt_notifier;
+		 * Hence it would be mysterious to miss ppt now
+		 */
+		WARN_ON(!ppt);
+		utask->active_ppt = ppt;
+		utask->state = UTASK_BP_HIT;
+	} else
+		ppt = utask->active_ppt;
+
+	if (utask->state == UTASK_BP_HIT) {
+		utask->state = UTASK_SSTEP;
+		u = ppt->uprobe;
+		if (u && u->handler)
+			u->handler(u, regs);
+
+		if (!pre_ssout(ppt, regs))
+			arch_uprobe_enable_sstep(regs);
+	} else if (utask->state == UTASK_SSTEP) {
+		if (sstep_complete(regs, ppt)) {
+			put_probept(ppt);
+			utask->active_ppt = NULL;
+			utask->state = UTASK_RUNNING;
+			arch_uprobe_disable_sstep(regs);
+		}
+	}
+}
+
+/*
+ * uprobe_bkpt_notifier gets called from interrupt context
+ * it gets a reference to the ppt and sets TIF_UPROBE flag,
+ */
+int uprobe_bkpt_notifier(struct pt_regs *regs)
+{
+	struct uprobe_process *uproc;
+	struct uprobe_probept *ppt;
+	struct uprobe_task *utask;
+	unsigned long probept;
+
+	if (!current->mm || !current->mm->uproc)
+		/* task is currently not uprobed */
+		return 0;
+
+	uproc = current->mm->uproc;
+	utask = current->utask;
+	probept = user_bkpt_get_bkpt_addr(regs);
+	ppt = find_probept(uproc, probept);
+	if (!ppt)
+		return 0;
+	get_probept(ppt);
+	if (utask) {
+		utask->active_ppt = ppt;
+		utask->state = UTASK_BP_HIT;
+	}
+	set_thread_flag(TIF_UPROBE);
+	return 1;
+}
+
+/*
+ * uprobe_post_notifier gets called in interrupt context.
+ * It completes the single step operation.
+ */
+int uprobe_post_notifier(struct pt_regs *regs)
+{
+	struct uprobe_probept *ppt;
+	struct uprobe_task *utask;
+
+	if (!current->mm || !current->mm->uproc || !current->utask)
+		/* task is currently not uprobed */
+		return 0;
+
+	utask = current->utask;
+
+	ppt = utask->active_ppt;
+	if (!ppt)
+		return 0;
+
+	if (user_bkpt_resume_can_sleep(&ppt->user_bkpt)) {
+		set_thread_flag(TIF_UPROBE);
+		return 1;
+	}
+	if (sstep_complete(regs, ppt)) {
+		put_probept(ppt);
+		arch_uprobe_disable_sstep(regs);
+		utask->active_ppt = NULL;
+		utask->state = UTASK_RUNNING;
+		return 1;
+	}
+	return 0;
+}
+
+
+static int __init init_uprobes(void)
+{
+	int ret;
+
+	user_bkpt_strategies = USER_BKPT_HNT_TSKINFO;
+	ret = user_bkpt_init(&user_bkpt_strategies);
+	if (ret != 0) {
+		printk(KERN_ERR "Can't start uprobes: user_bkpt_init() returned %d\n",
+								ret);
+		return ret;
+	}
+
+	register_die_notifier(&uprobes_exception_nb);
+	return 0;
+}
+
+static void __exit exit_uprobes(void)
+{
+}
+
+module_init(init_uprobes);
+module_exit(exit_uprobes);

[PATCH v5 7/14] x86 support for Uprobes

[Srikar Dronamraju]

uprobes_x86.patch

From: Srikar Dronamraju <srikar@linux.vnet.ibm.com>

X86 support for Uprobes

This patch provides x86 specific details for uprobes.
This includes interrupt notifier for uprobes, enabling/disabling
singlestep.

Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
---

 arch/x86/Kconfig          |    1 +
 arch/x86/kernel/Makefile  |    1 +
 arch/x86/kernel/signal.c  |   12 +++++++
 arch/x86/kernel/uprobes.c |   77 +++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 91 insertions(+), 0 deletions(-)
 create mode 100644 arch/x86/kernel/uprobes.c


diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index db1b378..a2bf479 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -55,6 +55,7 @@ config X86
 	select HAVE_HW_BREAKPOINT
 	select HAVE_MIXED_BREAKPOINTS_REGS
 	select HAVE_USER_BKPT
+	select HAVE_UPROBES
 	select PERF_EVENTS
 	select HAVE_PERF_EVENTS_NMI
 	select ANON_INODES
diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index 53cf2af..e2c4262 100644
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -116,6 +116,7 @@ obj-$(CONFIG_X86_CHECK_BIOS_CORRUPTION) += check.o
 obj-$(CONFIG_SWIOTLB)			+= pci-swiotlb.o
 
 obj-$(CONFIG_USER_BKPT)			+= user_bkpt.o
+obj-$(CONFIG_UPROBES)			+= uprobes.o
 
 ###
 # 64 bit specific files
diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c
index 851bc8d..dde9a42 100644
--- a/arch/x86/kernel/signal.c
+++ b/arch/x86/kernel/signal.c
@@ -850,7 +850,19 @@ do_notify_resume(struct pt_regs *regs, void *unused, __u32 thread_info_flags)
 
 	if (thread_info_flags & _TIF_UPROBE) {
 		clear_thread_flag(TIF_UPROBE);
+#ifdef CONFIG_X86_32
+		/*
+		 * On x86_32, do_notify_resume() gets called with
+		 * interrupts disabled. Hence enable interrupts if they
+		 * are still disabled.
+		 */
+		native_irq_enable();
+#endif
 		uprobe_notify_resume(regs);
+
+#ifdef CONFIG_X86_32
+		native_irq_disable();
+#endif
 	}
 
 	if (thread_info_flags & _TIF_NOTIFY_RESUME) {
diff --git a/arch/x86/kernel/uprobes.c b/arch/x86/kernel/uprobes.c
new file mode 100644
index 0000000..5643b96
--- /dev/null
+++ b/arch/x86/kernel/uprobes.c
@@ -0,0 +1,77 @@
+/*
+ *  Userspace Probes (UProbes)
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ *
+ * Copyright (C) IBM Corporation, 2010
+ * Authors:
+ *	Srikar Dronamraju
+ *	Ananth N Mavinakayanahalli
+ */
+
+#include <linux/sched.h>
+#include <linux/kdebug.h>
+#include <linux/uprobes.h>
+
+/*
+ * Wrapper routine for handling exceptions.
+ */
+int uprobes_exception_notify(struct notifier_block *self,
+				       unsigned long val, void *data)
+{
+	struct die_args *args = data;
+	struct pt_regs *regs = args->regs;
+	int ret = NOTIFY_DONE;
+
+	/* We are only interested in userspace traps */
+	if (regs && !user_mode_vm(regs))
+		return NOTIFY_DONE;
+
+	switch (val) {
+	case DIE_INT3:
+		/* Run your handler here */
+		if (uprobe_bkpt_notifier(regs))
+			ret = NOTIFY_STOP;
+		break;
+	case DIE_DEBUG:
+		if (uprobe_post_notifier(regs))
+			ret = NOTIFY_STOP;
+	default:
+		break;
+	}
+	return ret;
+}
+
+void arch_uprobe_enable_sstep(struct pt_regs *regs)
+{
+	/*
+	 * Enable single-stepping by
+	 * - Set TF on stack
+	 * - Set TIF_SINGLESTEP: Guarantees that TF is set when
+	 *	returning to user mode.
+	 *  - Indicate that TF is set by us.
+	 */
+	regs->flags |= X86_EFLAGS_TF;
+	set_thread_flag(TIF_SINGLESTEP);
+	set_thread_flag(TIF_FORCED_TF);
+}
+
+void arch_uprobe_disable_sstep(struct pt_regs *regs)
+{
+		/* Disable single-stepping by clearing what we set */
+		clear_thread_flag(TIF_SINGLESTEP);
+		clear_thread_flag(TIF_FORCED_TF);
+		regs->flags &= ~X86_EFLAGS_TF;
+}

[PATCH v5 8/14] samples: Uprobes samples

[Srikar Dronamraju]

samples.patch

From: Srikar Dronamraju <srikar@linux.vnet.ibm.com>

Uprobes Samples

This provides an example uprobes module in the samples directory.

To run this module run (as root)
 insmod uprobe_example.ko vaddr=<vaddr> pid=<pid>
	 Where <vaddr> is the address where we want to place the probe.
		<pid> is the pid of the process we are interested to probe.

 example: -
# cd samples/uprobes

[get the virtual address to place the probe.]
# vaddr=0x$(objdump -T /bin/bash |awk '/echo_builtin/ {print $1}')

[Run a bash shell in the background; have it echo 4 lines.]
# (sleep 10; echo 1; echo 2; echo 3; echo 4) &
[Probe calls echo_builtin() in the background bash process.]

# insmod uprobe_example.ko vaddr=$vaddr pid=$!
# sleep 10
# rmmod uprobe_example
# dmesg | tail -n 3
Registering uprobe on pid 10875, vaddr 0x45aa30
Unregistering uprobe on pid 10875, vaddr 0x45aa30
Probepoint was hit 4 times
#
[ Output shows that echo_builtin function was hit 4 times. ]

Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
---

 samples/Kconfig                  |    7 +++
 samples/Makefile                 |    2 -
 samples/uprobes/Makefile         |   17 ++++++++
 samples/uprobes/uprobe_example.c |   83 ++++++++++++++++++++++++++++++++++++++
 4 files changed, 108 insertions(+), 1 deletions(-)
 create mode 100644 samples/uprobes/Makefile
 create mode 100644 samples/uprobes/uprobe_example.c


diff --git a/samples/Kconfig b/samples/Kconfig
index 8924f72..50b8b1c 100644
--- a/samples/Kconfig
+++ b/samples/Kconfig
@@ -44,4 +44,11 @@ config SAMPLE_HW_BREAKPOINT
 	help
 	  This builds kernel hardware breakpoint example modules.
 
+config SAMPLE_UPROBES
+	tristate "Build uprobes example -- loadable module only"
+	depends on UPROBES && m
+	help
+	  This builds uprobes example module.
+
+
 endif # SAMPLES
diff --git a/samples/Makefile b/samples/Makefile
index 0f15e6d..c8fe6f9 100644
--- a/samples/Makefile
+++ b/samples/Makefile
@@ -1,4 +1,4 @@
 # Makefile for Linux samples code
 
 obj-$(CONFIG_SAMPLES)	+= kobject/ kprobes/ tracepoints/ trace_events/ \
-			   hw_breakpoint/
+			   hw_breakpoint/ uprobes/
diff --git a/samples/uprobes/Makefile b/samples/uprobes/Makefile
new file mode 100644
index 0000000..f535f6f
--- /dev/null
+++ b/samples/uprobes/Makefile
@@ -0,0 +1,17 @@
+# builds the uprobes example kernel modules;
+# then to use one (as root):
+# insmod <module_name.ko> vaddr=<vaddr> pid=<pid>
+#
+#
+# example: -
+# vaddr=0x$(objdump -T /bin/bash |awk '/echo_builtin/ print $1}')
+# (sleep 10; echo 1; echo 2; echo 3; echo 4) &
+# insmod uprobe_example.ko vaddr=$vaddr pid=$!
+# sleep 10
+# rmmod uprobe_example
+# dmesg | tail -n 3
+#	Registering uprobe on pid 3920, vaddr 0x45aa30
+#	Unregistering uprobe on pid 3920, vaddr 0x45aa30
+#	Probepoint was hit 4 times
+
+obj-$(CONFIG_SAMPLE_UPROBES) += uprobe_example.o
diff --git a/samples/uprobes/uprobe_example.c b/samples/uprobes/uprobe_example.c
new file mode 100644
index 0000000..f625bae
--- /dev/null
+++ b/samples/uprobes/uprobe_example.c
@@ -0,0 +1,83 @@
+/*
+ * Uprobes Example
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ *
+ * Copyright (C) IBM Corporation, 2008-2010
+ * Authors:
+ *	Srikar Dronamraju
+ *	Jim Keniston
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/uprobes.h>
+
+/*
+ * Usage: insmod uprobe_example.ko pid=<pid> vaddr=<address> [verbose=0]
+ * where <pid> identifies the probed process and <address> is the virtual
+ * address of the probed instruction.
+ */
+
+static int pid;
+module_param(pid, int, 0);
+MODULE_PARM_DESC(pid, "pid");
+
+static int verbose;
+module_param(verbose, int, 0);
+MODULE_PARM_DESC(verbose, "verbose");
+
+static long vaddr;
+module_param(vaddr, long, 0);
+MODULE_PARM_DESC(vaddr, "vaddr");
+
+static int nhits;
+static struct uprobe usp;
+
+static void uprobe_handler(struct uprobe *u, struct pt_regs *regs)
+{
+	nhits++;
+	if (verbose)
+		printk(KERN_INFO "Hit #%d on probepoint at %#lx\n",
+			nhits, u->vaddr);
+}
+
+int __init init_module(void)
+{
+	int ret;
+	usp.pid = pid;
+	usp.vaddr = vaddr;
+	usp.handler = uprobe_handler;
+	printk(KERN_INFO "Registering uprobe on pid %d, vaddr %#lx\n",
+		usp.pid, usp.vaddr);
+	ret = register_uprobe(&usp);
+	if (ret != 0) {
+		printk(KERN_ERR "register_uprobe() failed, returned %d\n", ret);
+		printk(KERN_ERR "Usage: insmod uprobe_example.ko pid=<pid> "
+						"vaddr=<address>\n");
+		return ret;
+	}
+	return 0;
+}
+
+void __exit cleanup_module(void)
+{
+	printk(KERN_INFO "Unregistering uprobe on pid %d, vaddr %#lx\n",
+		usp.pid, usp.vaddr);
+	printk(KERN_INFO "Probepoint was hit %d times\n", nhits);
+	unregister_uprobe(&usp);
+}
+MODULE_LICENSE("GPL");

[PATCH v5 9/14] Uprobes documentation.

[Srikar Dronamraju]

uprobes-documentation.patch

From: Srikar Dronamraju <srikar@linux.vnet.ibm.com>

Changelog from v3: Updated measurements.

Changelog from v2: Updated measurements.

Changelog from v1: Addressed comments from Randy Dunlap.
		 : Updated measurements.

Signed-off-by: Jim Keniston <jkenisto@us.ibm.com>
Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
---

 Documentation/uprobes.txt |  236 +++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 236 insertions(+), 0 deletions(-)
 create mode 100644 Documentation/uprobes.txt


diff --git a/Documentation/uprobes.txt b/Documentation/uprobes.txt
new file mode 100644
index 0000000..c922d5f
--- /dev/null
+++ b/Documentation/uprobes.txt
@@ -0,0 +1,236 @@
+Title	: User-Space Probes (Uprobes)
+Authors	: Jim Keniston <jkenisto@us.ibm.com>
+	: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
+
+CONTENTS
+
+1. Concepts: Uprobes
+2. Architectures Supported
+3. Configuring Uprobes
+4. API Reference
+5. Uprobes Features and Limitations
+6. Probe Overhead
+7. TODO
+8. Uprobes Team
+9. Uprobes Example
+
+1. Concepts: Uprobes
+
+Uprobes enables you to dynamically break into any routine in a
+user application and collect debugging and performance information
+non-disruptively. You can trap at any code address, specifying a
+kernel handler routine to be invoked when the breakpoint is hit.
+
+A uprobe can be inserted on any instruction in the application's
+virtual address space.  The registration function register_uprobe()
+specifies which process is to be probed, where the probe is to be
+inserted, and what handler is to be called when the probe is hit.
+
+Uprobes-based instrumentation can be packaged as a kernel
+module.  In the simplest case, the module's init function installs
+("registers") one or more probes, and the exit function unregisters
+them.
+
+1.1 How Does a Uprobe Work?
+
+When a uprobe is registered, Uprobes makes a copy of the probed
+instruction, stops the probed application, replaces the first byte(s)
+of the probed instruction with a breakpoint instruction (e.g., int3
+on i386 and x86_64), and allows the probed application to continue.
+(When inserting the breakpoint, Uprobes uses background page
+replacement mechanism, so that the breakpoint affects only that
+process, and not any other process running that program.  This is
+true even if the probed instruction is in a shared library.)
+
+When a CPU hits the breakpoint instruction, a trap occurs, the CPU's
+user-mode registers are saved, and uprobes notifier code finds the
+associated uprobe.  It then executes the handler associated with the
+uprobe, passing the handler the addresses of the uprobe struct and the
+saved registers. The handler can run either in interrupt context or in
+task context; this is specified by the user at the time of registration.
+When run in task context, the handler may block, but keep in mind that
+the probed thread remains stopped while your handler runs.
+
+Next, Uprobes single-steps its copy of the probed instruction and
+resumes execution of the probed process at the instruction following
+the probepoint.  (It would be simpler to single-step the actual
+instruction in place, but then Uprobes would have to temporarily
+remove the breakpoint instruction.  This would create problems in a
+multithreaded application.  For example, it would open a time window
+when another thread could sail right past the probepoint.)
+
+Instruction copies to be single-stepped are stored in a per-process
+"execution out of line (XOL) area," which is a little VM area
+created by Uprobes in each probed process's address space.
+
+Uprobes handles interesting events in the lifetime of the probed
+process, such as fork, clone, exec, and exit.
+
+1.2 Multithreaded Applications
+
+Uprobes supports the probing of multithreaded applications.  Uprobes
+imposes no limit on the number of threads in a probed application.
+All threads in a process use the same text pages, so every probe
+in a process affects all threads; of course, each thread hits the
+probepoint (and runs the handler) independently.  Multiple threads
+may run the same handler simultaneously.  If you want a particular
+thread or set of threads to run a particular handler, your handler
+should check current or current->pid to determine which thread has
+hit the probepoint.
+
+When a process clones a new thread, that thread automatically shares
+all current and future probes established for that process.
+
+2. Architectures Supported
+
+This user_bkpt based version of Uprobes is implemented on the following
+architectures:
+
+- x86
+
+3. Configuring Uprobes
+
+When configuring the kernel using make menuconfig/xconfig/oldconfig,
+ensure that CONFIG_UPROBES is set to "y". Under "General setup" select
+"User-space breakpoint assistance" then select "User-space probes".
+
+So that you can load and unload Uprobes-based instrumentation modules,
+make sure "Loadable module support" (CONFIG_MODULES) and "Module
+unloading" (CONFIG_MODULE_UNLOAD) are set to "y".
+
+4. API Reference
+
+The Uprobes API includes a "register" function and an "unregister"
+function for uprobes.  Here are terse, mini-man-page specifications for
+these functions and the associated probe handlers that you'll write.
+See the latter half of this document for examples.
+
+4.1 register_uprobe
+
+#include <linux/uprobes.h>
+int register_uprobe(struct uprobe *u);
+
+Sets a breakpoint at virtual address u->vaddr in the process whose
+pid is u->pid.  When the breakpoint is hit, Uprobes calls u->handler.
+If u->handler_in_interrupt is set, the handler runs in interrupt
+context. Otherwise it runs in task context.
+
+register_uprobe() returns 0 on success, or a negative errno
+otherwise.
+
+User's handler (u->handler):
+#include <linux/uprobes.h>
+#include <linux/ptrace.h>
+void handler(struct uprobe *u, struct pt_regs *regs);
+
+Called with u pointing to the uprobe associated with the breakpoint,
+and regs pointing to the struct containing the registers saved when
+the breakpoint was hit.
+
+4.2 unregister_uprobe
+
+#include <linux/uprobes.h>
+void unregister_uprobe(struct uprobe *u);
+
+Removes the specified probe.  The unregister function can be called
+at any time after the probe has been registered, and can be called
+from a uprobe handler.
+
+5. Uprobes Features and Limitations
+
+The user is expected to assign values to the following members
+of struct uprobe: pid, vaddr, handler, and handler_in_interrupt.
+Uprobes may produce unexpected results if you:
+- change the contents of a uprobe object while it is registered; or
+- attempt to register a uprobe that is already registered.
+
+In this implementation, Uprobes allows only one uprobe at a particular
+address.
+
+Any number of kernel modules may probe a particular process
+simultaneously, and a particular module may probe any number of
+processes simultaneously.
+
+Probes are shared by all threads in a process (including newly
+created threads).
+
+If a probed process exits or execs, Uprobes automatically
+unregisters all uprobes associated with that process.  Subsequent
+attempts to unregister these probes will be treated as no-ops.
+
+On the other hand, if a probed memory area is removed from the
+process's virtual memory map (e.g., via dlclose(3) or munmap(2)),
+it's currently up to you to unregister the probes first.
+
+There is no way to specify that probes should be inherited across fork;
+Uprobes removes all probepoints in the newly created child process.
+
+To avoid interfering with interactive debuggers, Uprobes will refuse
+to insert a probepoint where a breakpoint instruction already exists.
+Some architectures may refuse to insert probes on other types of
+instructions.
+
+If you install a probe in an inline-able function, Uprobes makes
+no attempt to chase down all inline instances of the function and
+install probes there.  gcc may inline a function without being asked,
+so keep this in mind if you're not seeing the probe hits you expect.
+
+A probe handler can modify the environment of the probed function
+-- e.g., by modifying data structures, or by modifying the
+contents of the pt_regs struct (which are restored to the registers
+upon return from the breakpoint).  So Uprobes can be used, for example,
+to install a bug fix or to inject faults for testing.  Uprobes, of
+course, has no way to distinguish the deliberately injected faults
+from the accidental ones.  Don't drink and probe.
+
+When Uprobes establishes a probepoint on a previous unprobed page
+of text, Linux creates a new copy of the page via its copy-on-write
+mechanism.  When probepoints are removed, Uprobes makes no attempt
+to consolidate identical copies of the same page.  This could affect
+memory availability if you probe many, many pages in many, many
+long-running processes.
+
+6. Probe Overhead
+
+Probe overhead is measured on a benchmark that hits the same probepoint
+repeatedly, firing a simple handler each time. Probe overhead
+changes with different cpus/archs/probe handlers and the number of
+iterations.
+
+Here are sample overhead figures (in usec) for x86 architecture.
+
+i686: Intel(R) Xeon(TM) CPU 2.40GHz
+Without probe module.
+100000 interations in 0.000687 sec i.e 0.006870 usec per iteration
+
+With probes
+100000 interations in 0.314938 sec i.e 3.149380 usec per iteration
+probe overhead is 3.142510 usec per probe hit.
+
+x86_64: Intel(R) Xeon(R) CPU           X7350  @ 2.93GHz
+Without probe module.
+100000 interations in 0.000432 sec i.e 0.004320 usec per iteration
+
+With probes
+100000 interations in 0.101276 sec i.e 1.012760 usec per iteration
+Probe overhead is 1.301738 usec per probe hit.
+
+7. TODO
+
+a. Support for other architectures.
+b. Support for multiple probes at the same address.
+c. Support for boosted probes.
+d. Support return probes.
+
+8. Uprobes Team
+
+The following people have made major contributions to Uprobes:
+Jim Keniston - jkenisto@us.ibm.com
+Srikar Dronamraju - srikar@linux.vnet.ibm.com
+Ananth Mavinakayanahalli - ananth@in.ibm.com
+Prasanna Panchamukhi - prasanna@in.ibm.com
+Dave Wilder - dwilder@us.ibm.com
+
+9. Uprobes Example
+
+samples/uprobes/uprobe_example.c

[PATCH v5 10/14] trace: Common code for kprobes/uprobes traceevents

[Srikar Dronamraju]

share_traceevents.patch.

From: Srikar Dronamraju <srikar@linux.vnet.ibm.com>

Changelog from v5: Addressed comments from Masami.
        Also shared lot more code from kprobes traceevents.

Move common parts of trace_kprobe.c and trace_uprobec.
Adjust kernel/trace/trace_kprobe.c after moving common code to
kernel/trace/trace_probe.h. However they still have few duplicate
functions.

TODO: Merge both events to a single probe event.

Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
---

 kernel/trace/trace_kprobe.c |  141 +--------------------------------------
 kernel/trace/trace_probe.h  |  157 +++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 161 insertions(+), 137 deletions(-)
 create mode 100644 kernel/trace/trace_probe.h


diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c
index f52b5f5..f546e73 100644
--- a/kernel/trace/trace_kprobe.c
+++ b/kernel/trace/trace_kprobe.c
@@ -20,32 +20,12 @@
 #include <linux/module.h>
 #include <linux/uaccess.h>
 #include <linux/kprobes.h>
-#include <linux/seq_file.h>
-#include <linux/slab.h>
-#include <linux/smp.h>
-#include <linux/debugfs.h>
-#include <linux/types.h>
-#include <linux/string.h>
-#include <linux/ctype.h>
-#include <linux/ptrace.h>
-#include <linux/perf_event.h>
-#include <linux/stringify.h>
-#include <asm/bitsperlong.h>
-
-#include "trace.h"
-#include "trace_output.h"
-
-#define MAX_TRACE_ARGS 128
-#define MAX_ARGSTR_LEN 63
-#define MAX_EVENT_NAME_LEN 64
-#define KPROBE_EVENT_SYSTEM "kprobes"
 
-/* Reserved field names */
-#define FIELD_STRING_IP "__probe_ip"
-#define FIELD_STRING_RETIP "__probe_ret_ip"
-#define FIELD_STRING_FUNC "__probe_func"
+#include "trace_probe.h"
+
+#define KPROBE_EVENT_SYSTEM "kprobes"
 
-const char *reserved_field_names[] = {
+static const char *reserved_field_names[] = {
 	"common_type",
 	"common_flags",
 	"common_preempt_count",
@@ -57,70 +37,9 @@ const char *reserved_field_names[] = {
 	FIELD_STRING_FUNC,
 };
 
-/* Printing function type */
-typedef int (*print_type_func_t)(struct trace_seq *, const char *, void *);
-#define PRINT_TYPE_FUNC_NAME(type)	print_type_##type
-#define PRINT_TYPE_FMT_NAME(type)	print_type_format_##type
-
-/* Printing  in basic type function template */
-#define DEFINE_BASIC_PRINT_TYPE_FUNC(type, fmt, cast)			\
-static __kprobes int PRINT_TYPE_FUNC_NAME(type)(struct trace_seq *s,	\
-						const char *name, void *data)\
-{									\
-	return trace_seq_printf(s, " %s=" fmt, name, (cast)*(type *)data);\
-}									\
-static const char PRINT_TYPE_FMT_NAME(type)[] = fmt;
-
-DEFINE_BASIC_PRINT_TYPE_FUNC(u8, "%x", unsigned int)
-DEFINE_BASIC_PRINT_TYPE_FUNC(u16, "%x", unsigned int)
-DEFINE_BASIC_PRINT_TYPE_FUNC(u32, "%lx", unsigned long)
-DEFINE_BASIC_PRINT_TYPE_FUNC(u64, "%llx", unsigned long long)
-DEFINE_BASIC_PRINT_TYPE_FUNC(s8, "%d", int)
-DEFINE_BASIC_PRINT_TYPE_FUNC(s16, "%d", int)
 DEFINE_BASIC_PRINT_TYPE_FUNC(s32, "%ld", long)
 DEFINE_BASIC_PRINT_TYPE_FUNC(s64, "%lld", long long)
 
-/* Data fetch function type */
-typedef	void (*fetch_func_t)(struct pt_regs *, void *, void *);
-
-struct fetch_param {
-	fetch_func_t	fn;
-	void *data;
-};
-
-static __kprobes void call_fetch(struct fetch_param *fprm,
-				 struct pt_regs *regs, void *dest)
-{
-	return fprm->fn(regs, fprm->data, dest);
-}
-
-#define FETCH_FUNC_NAME(kind, type)	fetch_##kind##_##type
-/*
- * Define macro for basic types - we don't need to define s* types, because
- * we have to care only about bitwidth at recording time.
- */
-#define DEFINE_BASIC_FETCH_FUNCS(kind)  \
-DEFINE_FETCH_##kind(u8)			\
-DEFINE_FETCH_##kind(u16)		\
-DEFINE_FETCH_##kind(u32)		\
-DEFINE_FETCH_##kind(u64)
-
-#define CHECK_BASIC_FETCH_FUNCS(kind, fn)	\
-	((FETCH_FUNC_NAME(kind, u8) == fn) ||	\
-	 (FETCH_FUNC_NAME(kind, u16) == fn) ||	\
-	 (FETCH_FUNC_NAME(kind, u32) == fn) ||	\
-	 (FETCH_FUNC_NAME(kind, u64) == fn))
-
-/* Data fetch function templates */
-#define DEFINE_FETCH_reg(type)						\
-static __kprobes void FETCH_FUNC_NAME(reg, type)(struct pt_regs *regs,	\
-					  void *offset, void *dest)	\
-{									\
-	*(type *)dest = (type)regs_get_register(regs,			\
-				(unsigned int)((unsigned long)offset));	\
-}
-DEFINE_BASIC_FETCH_FUNCS(reg)
-
 #define DEFINE_FETCH_stack(type)					\
 static __kprobes void FETCH_FUNC_NAME(stack, type)(struct pt_regs *regs,\
 					  void *offset, void *dest)	\
@@ -234,15 +153,6 @@ static __kprobes void free_deref_fetch_param(struct deref_fetch_param *data)
 	kfree(data);
 }
 
-/* Default (unsigned long) fetch type */
-#define __DEFAULT_FETCH_TYPE(t) u##t
-#define _DEFAULT_FETCH_TYPE(t) __DEFAULT_FETCH_TYPE(t)
-#define DEFAULT_FETCH_TYPE _DEFAULT_FETCH_TYPE(BITS_PER_LONG)
-#define DEFAULT_FETCH_TYPE_STR __stringify(DEFAULT_FETCH_TYPE)
-
-#define ASSIGN_FETCH_FUNC(kind, type)	\
-	.kind = FETCH_FUNC_NAME(kind, type)
-
 #define ASSIGN_FETCH_TYPE(ptype, ftype, sign)	\
 	{.name = #ptype,			\
 	 .size = sizeof(ftype),			\
@@ -306,18 +216,6 @@ static __kprobes void fetch_stack_address(struct pt_regs *regs,
  * Kprobe event core functions
  */
 
-struct probe_arg {
-	struct fetch_param	fetch;
-	unsigned int		offset;	/* Offset from argument entry */
-	const char		*name;	/* Name of this argument */
-	const char		*comm;	/* Command of this argument */
-	const struct fetch_type	*type;	/* Type of this argument */
-};
-
-/* Flags for trace_probe */
-#define TP_FLAG_TRACE	1
-#define TP_FLAG_PROFILE	2
-
 struct trace_probe {
 	struct list_head	list;
 	struct kretprobe	rp;	/* Use rp.kp for kprobe use */
@@ -355,19 +253,6 @@ static LIST_HEAD(probe_list);
 static int kprobe_dispatcher(struct kprobe *kp, struct pt_regs *regs);
 static int kretprobe_dispatcher(struct kretprobe_instance *ri,
 				struct pt_regs *regs);
-
-/* Check the name is good for event/group */
-static int check_event_name(const char *name)
-{
-	if (!isalpha(*name) && *name != '_')
-		return 0;
-	while (*++name != '\0') {
-		if (!isalpha(*name) && !isdigit(*name) && *name != '_')
-			return 0;
-	}
-	return 1;
-}
-
 /*
  * Allocate new trace_probe and initialize it (including kprobes).
  */
@@ -537,8 +422,6 @@ static int split_symbol_offset(char *symbol, unsigned long *offset)
 	return 0;
 }
 
-#define PARAM_MAX_ARGS 16
-#define PARAM_MAX_STACK (THREAD_SIZE / sizeof(unsigned long))
 
 static int parse_probe_vars(char *arg, const struct fetch_type *t,
 			    struct fetch_param *f, int is_return)
@@ -1214,22 +1097,6 @@ static void probe_event_disable(struct ftrace_event_call *call)
 	}
 }
 
-static int probe_event_raw_init(struct ftrace_event_call *event_call)
-{
-	return 0;
-}
-
-#undef DEFINE_FIELD
-#define DEFINE_FIELD(type, item, name, is_signed)			\
-	do {								\
-		ret = trace_define_field(event_call, #type, name,	\
-					 offsetof(typeof(field), item),	\
-					 sizeof(field.item), is_signed, \
-					 FILTER_OTHER);			\
-		if (ret)						\
-			return ret;					\
-	} while (0)
-
 static int kprobe_event_define_fields(struct ftrace_event_call *event_call)
 {
 	int ret, i;
diff --git a/kernel/trace/trace_probe.h b/kernel/trace/trace_probe.h
new file mode 100644
index 0000000..b4c5763
--- /dev/null
+++ b/kernel/trace/trace_probe.h
@@ -0,0 +1,157 @@
+/*
+ * Common header file for probe-based Dynamic events.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ *
+ * Copyright (C) IBM Corporation, 2010
+ * Author:	Srikar Dronamraju
+ */
+
+#include <linux/seq_file.h>
+#include <linux/slab.h>
+#include <linux/smp.h>
+#include <linux/debugfs.h>
+#include <linux/types.h>
+#include <linux/string.h>
+#include <linux/ctype.h>
+#include <linux/ptrace.h>
+#include <linux/perf_event.h>
+
+#include "trace.h"
+#include "trace_output.h"
+
+#define MAX_TRACE_ARGS 128
+#define MAX_ARGSTR_LEN 63
+#define MAX_EVENT_NAME_LEN 64
+
+/* Reserved field names */
+#define FIELD_STRING_IP "__probe_ip"
+#define FIELD_STRING_RETIP "__probe_ret_ip"
+#define FIELD_STRING_FUNC "__probe_func"
+
+#define WRITE_BUFSIZE 128
+
+#undef DEFINE_FIELD
+#define DEFINE_FIELD(type, item, name, is_signed)			\
+	do {								\
+		ret = trace_define_field(event_call, #type, name,	\
+					 offsetof(typeof(field), item),	\
+					 sizeof(field.item), is_signed, \
+					 FILTER_OTHER);			\
+		if (ret)						\
+			return ret;					\
+	} while (0)
+
+/* Printing function type */
+typedef int (*print_type_func_t)(struct trace_seq *, const char *, void *);
+#define PRINT_TYPE_FUNC_NAME(type)	print_type_##type
+#define PRINT_TYPE_FMT_NAME(type)	print_type_format_##type
+
+/* Printing  in basic type function template */
+#define DEFINE_BASIC_PRINT_TYPE_FUNC(type, fmt, cast)			\
+static __kprobes int PRINT_TYPE_FUNC_NAME(type)(struct trace_seq *s,	\
+						const char *name, void *data)\
+{									\
+	return trace_seq_printf(s, " %s=" fmt, name, (cast)*(type *)data);\
+}									\
+static const char PRINT_TYPE_FMT_NAME(type)[] = fmt;
+
+DEFINE_BASIC_PRINT_TYPE_FUNC(u8, "%x", unsigned int)
+DEFINE_BASIC_PRINT_TYPE_FUNC(u16, "%x", unsigned int)
+DEFINE_BASIC_PRINT_TYPE_FUNC(u32, "%lx", unsigned long)
+DEFINE_BASIC_PRINT_TYPE_FUNC(u64, "%llx", unsigned long long)
+DEFINE_BASIC_PRINT_TYPE_FUNC(s8, "%d", int)
+DEFINE_BASIC_PRINT_TYPE_FUNC(s16, "%d", int)
+
+/* Data fetch function type */
+typedef	void (*fetch_func_t)(struct pt_regs *, void *, void *);
+
+struct fetch_param {
+	fetch_func_t	fn;
+	void *data;
+};
+
+#define FETCH_FUNC_NAME(kind, type)	fetch_##kind##_##type
+/*
+ * Define macro for basic types - we don't need to define s* types, because
+ * we have to care only about bitwidth at recording time.
+ */
+#define DEFINE_BASIC_FETCH_FUNCS(kind)  \
+DEFINE_FETCH_##kind(u8)			\
+DEFINE_FETCH_##kind(u16)		\
+DEFINE_FETCH_##kind(u32)		\
+DEFINE_FETCH_##kind(u64)
+
+#define CHECK_BASIC_FETCH_FUNCS(kind, fn)	\
+	((FETCH_FUNC_NAME(kind, u8) == fn) ||	\
+	 (FETCH_FUNC_NAME(kind, u16) == fn) ||	\
+	 (FETCH_FUNC_NAME(kind, u32) == fn) ||	\
+	 (FETCH_FUNC_NAME(kind, u64) == fn))
+
+/* Data fetch function templates */
+#define DEFINE_FETCH_reg(type)						\
+static __kprobes void FETCH_FUNC_NAME(reg, type)(struct pt_regs *regs,	\
+					  void *offset, void *dest)	\
+{									\
+	*(type *)dest = (type)regs_get_register(regs,			\
+				(unsigned int)((unsigned long)offset));	\
+}
+DEFINE_BASIC_FETCH_FUNCS(reg)
+
+/* Default (unsigned long) fetch type */
+#define __DEFAULT_FETCH_TYPE(t) u##t
+#define _DEFAULT_FETCH_TYPE(t) __DEFAULT_FETCH_TYPE(t)
+#define DEFAULT_FETCH_TYPE _DEFAULT_FETCH_TYPE(BITS_PER_LONG)
+#define DEFAULT_FETCH_TYPE_STR __stringify(DEFAULT_FETCH_TYPE)
+
+#define ASSIGN_FETCH_FUNC(kind, type)	\
+	.kind = FETCH_FUNC_NAME(kind, type)
+
+/* Flags for trace_probe */
+#define TP_FLAG_TRACE	1
+#define TP_FLAG_PROFILE	2
+
+#define PARAM_MAX_ARGS 16
+#define PARAM_MAX_STACK (THREAD_SIZE / sizeof(unsigned long))
+
+struct probe_arg {
+	struct fetch_param	fetch;
+	unsigned int		offset;	/* Offset from argument entry */
+	const char		*name;	/* Name of this argument */
+	const char		*comm;	/* Command of this argument */
+	const struct fetch_type	*type;	/* Type of this argument */
+};
+
+static __kprobes void call_fetch(struct fetch_param *fprm,
+				 struct pt_regs *regs, void *dest)
+{
+	return fprm->fn(regs, fprm->data, dest);
+}
+
+/* Check the name is good for event/group */
+static inline int check_event_name(const char *name)
+{
+	if (!isalpha(*name) && *name != '_')
+		return 0;
+	while (*++name != '\0') {
+		if (!isalpha(*name) && !isdigit(*name) && *name != '_')
+			return 0;
+	}
+	return 1;
+}
+
+static int probe_event_raw_init(struct ftrace_event_call *event_call)
+{
+	return 0;
+}

[PATCH v5 11/14] trace: uprobes trace_event interface

[Srikar Dronamraju]

Changelog from v4: (Merged to 2.6.35-rc3-tip)

From: Srikar Dronamraju <srikar@linux.vnet.ibm.com>

Changelog from v2/v3: (Addressing comments from Steven Rostedt
					and Frederic Weisbecker)
	* removed pit field from uprobe_trace_entry.
	* share common parts with kprobe trace events.
	* use trace_create_file instead of debugfs_create_file.

The following patch implements trace_event support for uprobes. In its
current form it can be used to put probes at a specified text address
in a process and dump the required registers when the code flow reaches
the probed address.

The following example shows how to dump the instruction pointer and %ax a
register at the probed text address.

Start a process to trace. Get the address to trace.
  [Here pid is asssumed as 6016]
  [Address to trace is 0x0000000000446420]
  [Registers to be dumped are %ip and %ax]

# cd /sys/kernel/debug/tracing/
# echo 'p 6016:0x0000000000446420 %ip %ax' > uprobe_events
# cat uprobe_events
p:uprobes/p_6016_0x0000000000446420 6016:0x0000000000446420 %ip=%ip %ax=%ax
# cat events/uprobes/p_6016_0x0000000000446420/enable
0
[enable the event]
# echo 1 > events/uprobes/p_6016_0x0000000000446420/enable
# cat events/uprobes/p_6016_0x0000000000446420/enable
1
# #### do some activity on the program so that it hits the breakpoint
# cat uprobe_profile
  6016 p_6016_0x0000000000446420                                234
# tracer: nop
#
#           TASK-PID    CPU#    TIMESTAMP  FUNCTION
#              | |       |          |         |
             zsh-6016  [004] 227931.093579: p_6016_0x0000000000446420: (0x446420) %ip=446421 %ax=79
             zsh-6016  [005] 227931.097541: p_6016_0x0000000000446420: (0x446420) %ip=446421 %ax=79
             zsh-6016  [000] 227931.124909: p_6016_0x0000000000446420: (0x446420) %ip=446421 %ax=79
             zsh-6016  [001] 227933.128565: p_6016_0x0000000000446420: (0x446420) %ip=446421 %ax=79
             zsh-6016  [004] 227933.132756: p_6016_0x0000000000446420: (0x446420) %ip=446421 %ax=79
             zsh-6016  [000] 227933.158802: p_6016_0x0000000000446420: (0x446420) %ip=446421 %ax=79
             zsh-6016  [001] 227935.161602: p_6016_0x0000000000446420: (0x446420) %ip=446421 %ax=79
             zsh-6016  [004] 227935.165229: p_6016_0x0000000000446420: (0x446420) %ip=446421 %ax=79

TODO: Documentation/trace/uprobetrace.txt

Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
---

 kernel/trace/Kconfig        |   13 +
 kernel/trace/Makefile       |    1 
 kernel/trace/trace.h        |    5 
 kernel/trace/trace_probe.h  |    2 
 kernel/trace/trace_uprobe.c |  921 +++++++++++++++++++++++++++++++++++++++++++
 5 files changed, 942 insertions(+), 0 deletions(-)
 create mode 100644 kernel/trace/trace_uprobe.c


diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index f669092..1d980f3 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -509,6 +509,19 @@ config RING_BUFFER_BENCHMARK
 
 	  If unsure, say N.
 
+config UPROBE_EVENT
+	depends on UPROBES
+	bool "Enable uprobes-based dynamic events"
+	select TRACING
+	default y
+	help
+	  This allows the user to add tracing events on top of userspace dynamic
+	  events (similar to tracepoints) on the fly via the traceevents interface.
+	  Those events can be inserted wherever uprobes can probe, and record
+	  various registers.
+	  This option is required if you plan to use perf-probe subcommand of perf
+	  tools on user space applications.
+
 endif # FTRACE
 
 endif # TRACING_SUPPORT
diff --git a/kernel/trace/Makefile b/kernel/trace/Makefile
index 469a1c7..28c79fa 100644
--- a/kernel/trace/Makefile
+++ b/kernel/trace/Makefile
@@ -55,5 +55,6 @@ obj-$(CONFIG_EVENT_TRACING) += trace_events_filter.o
 obj-$(CONFIG_KPROBE_EVENT) += trace_kprobe.o
 obj-$(CONFIG_KSYM_TRACER) += trace_ksym.o
 obj-$(CONFIG_EVENT_TRACING) += power-traces.o
+obj-$(CONFIG_UPROBE_EVENT) += trace_uprobe.o
 
 libftrace-y := ftrace.o
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 01ce088..0b446e6 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -99,6 +99,11 @@ struct kretprobe_trace_entry_head {
 	unsigned long		ret_ip;
 };
 
+struct uprobe_trace_entry_head {
+	struct trace_entry	ent;
+	unsigned long		ip;
+};
+
 /*
  * trace_flag_type is an enumeration that holds different
  * states when a trace occurs. These are:
diff --git a/kernel/trace/trace_probe.h b/kernel/trace/trace_probe.h
index b4c5763..5e43196 100644
--- a/kernel/trace/trace_probe.h
+++ b/kernel/trace/trace_probe.h
@@ -39,6 +39,7 @@
 #define FIELD_STRING_IP "__probe_ip"
 #define FIELD_STRING_RETIP "__probe_ret_ip"
 #define FIELD_STRING_FUNC "__probe_func"
+#define FIELD_STRING_PID "__probe_pid"
 
 #define WRITE_BUFSIZE 128
 
@@ -121,6 +122,7 @@ DEFINE_BASIC_FETCH_FUNCS(reg)
 /* Flags for trace_probe */
 #define TP_FLAG_TRACE	1
 #define TP_FLAG_PROFILE	2
+#define TP_FLAG_UPROBE	4
 
 #define PARAM_MAX_ARGS 16
 #define PARAM_MAX_STACK (THREAD_SIZE / sizeof(unsigned long))
diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
new file mode 100644
index 0000000..0685c49
--- /dev/null
+++ b/kernel/trace/trace_uprobe.c
@@ -0,0 +1,921 @@
+/*
+ * uprobes-based tracing events
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ *
+ * Copyright (C) IBM Corporation, 2010
+ * Author:	Srikar Dronamraju
+ */
+
+#include <linux/module.h>
+#include <linux/uaccess.h>
+#include <linux/uprobes.h>
+#include <linux/kprobes.h>
+
+#include "trace_probe.h"
+
+#define UPROBE_EVENT_SYSTEM "uprobes"
+
+static const char *reserved_field_names[] = {
+	"common_type",
+	"common_flags",
+	"common_preempt_count",
+	"common_pid",
+	"common_tgid",
+	"common_lock_depth",
+	FIELD_STRING_IP,
+	FIELD_STRING_RETIP,
+	FIELD_STRING_FUNC,
+	FIELD_STRING_PID,
+};
+
+
+#define ASSIGN_FETCH_TYPE(ptype, ftype, sign)	\
+	{.name = #ptype,			\
+	 .size = sizeof(ftype),			\
+	 .is_signed = sign,			\
+	 .print = PRINT_TYPE_FUNC_NAME(ptype),	\
+	 .fmt = PRINT_TYPE_FMT_NAME(ptype),	\
+ASSIGN_FETCH_FUNC(reg, ftype),			\
+	}
+
+/* Fetch type information table */
+static const struct fetch_type {
+	const char	*name;		/* Name of type */
+	size_t		size;		/* Byte size of type */
+	int		is_signed;	/* Signed flag */
+	print_type_func_t	print;	/* Print functions */
+	const char	*fmt;		/* Fromat string */
+	/* Fetch functions */
+	fetch_func_t	reg;
+} fetch_type_table[] = {
+	ASSIGN_FETCH_TYPE(u8,  u8,  0),
+	ASSIGN_FETCH_TYPE(u16, u16, 0),
+	ASSIGN_FETCH_TYPE(u32, u32, 0),
+	ASSIGN_FETCH_TYPE(u64, u64, 0),
+	ASSIGN_FETCH_TYPE(s8,  u8,  1),
+	ASSIGN_FETCH_TYPE(s16, u16, 1),
+};
+
+static const struct fetch_type *find_fetch_type(const char *type)
+{
+	int i;
+
+	if (!type)
+		type = DEFAULT_FETCH_TYPE_STR;
+
+	for (i = 0; i < ARRAY_SIZE(fetch_type_table); i++)
+		if (strcmp(type, fetch_type_table[i].name) == 0)
+			return &fetch_type_table[i];
+	return NULL;
+}
+
+/**
+ * uprobe event core functions
+ */
+
+struct trace_uprobe {
+	struct list_head	list;
+	struct uprobe		up;
+	unsigned long		nhit;
+	unsigned int		flags;	/* For TP_FLAG_* */
+	struct ftrace_event_class	class;
+	struct ftrace_event_call	call;
+	ssize_t			size;		/* trace entry size */
+	unsigned int		nr_args;
+	struct probe_arg	args[];
+};
+
+#define SIZEOF_TRACE_UPROBE(n)			\
+	(offsetof(struct trace_uprobe, args) +	\
+	(sizeof(struct probe_arg) * (n)))
+
+static int register_uprobe_event(struct trace_uprobe *tp);
+static void unregister_uprobe_event(struct trace_uprobe *tp);
+
+static DEFINE_MUTEX(uprobe_lock);
+static LIST_HEAD(uprobe_list);
+
+static void uprobe_dispatcher(struct uprobe *up, struct pt_regs *regs);
+
+/*
+ * Allocate new trace_uprobe and initialize it (including uprobes).
+ */
+static struct trace_uprobe *alloc_trace_uprobe(const char *group,
+					const char *event,
+					void *addr,
+					pid_t pid, int nargs)
+{
+	struct trace_uprobe *tp;
+
+	if (!event || !check_event_name(event))
+		return ERR_PTR(-EINVAL);
+
+	if (!group || !check_event_name(group))
+		return ERR_PTR(-EINVAL);
+
+	tp = kzalloc(SIZEOF_TRACE_UPROBE(nargs), GFP_KERNEL);
+	if (!tp)
+		return ERR_PTR(-ENOMEM);
+
+	tp->up.vaddr = (unsigned long)addr;
+	tp->up.pid = pid;
+	tp->up.handler = uprobe_dispatcher;
+
+	tp->call.class = &tp->class;
+	tp->call.name = kstrdup(event, GFP_KERNEL);
+	if (!tp->call.name)
+		goto error;
+
+	tp->class.system = kstrdup(group, GFP_KERNEL);
+	if (!tp->class.system)
+		goto error;
+
+	INIT_LIST_HEAD(&tp->list);
+	return tp;
+error:
+	kfree(tp->call.name);
+	kfree(tp);
+	return ERR_PTR(-ENOMEM);
+}
+
+static void free_probe_arg(struct probe_arg *arg)
+{
+	kfree(arg->name);
+	kfree(arg->comm);
+}
+
+static void free_trace_uprobe(struct trace_uprobe *tp)
+{
+	int i;
+
+	for (i = 0; i < tp->nr_args; i++)
+		free_probe_arg(&tp->args[i]);
+
+	kfree(tp->call.class->system);
+	kfree(tp->call.name);
+	kfree(tp);
+}
+
+static struct trace_uprobe *find_probe_event(const char *event,
+					const char *group)
+{
+	struct trace_uprobe *tp;
+
+	list_for_each_entry(tp, &uprobe_list, list)
+		if (strcmp(tp->call.name, event) == 0 &&
+		    strcmp(tp->call.class->system, group) == 0)
+			return tp;
+	return NULL;
+}
+
+/* Unregister a trace_uprobe and probe_event: call with locking uprobe_lock */
+static void unregister_trace_uprobe(struct trace_uprobe *tp)
+{
+	if (tp->flags & TP_FLAG_UPROBE)
+		unregister_uprobe(&tp->up);
+	list_del(&tp->list);
+	unregister_uprobe_event(tp);
+}
+
+/* Register a trace_uprobe and probe_event */
+static int register_trace_uprobe(struct trace_uprobe *tp)
+{
+	struct trace_uprobe *old_tp;
+	int ret;
+
+	mutex_lock(&uprobe_lock);
+
+	/* register as an event */
+	old_tp = find_probe_event(tp->call.name, tp->call.class->system);
+	if (old_tp) {
+		/* delete old event */
+		unregister_trace_uprobe(old_tp);
+		free_trace_uprobe(old_tp);
+	}
+	ret = register_uprobe_event(tp);
+	if (ret) {
+		pr_warning("Failed to register probe event(%d)\n", ret);
+		goto end;
+	}
+
+	list_add_tail(&tp->list, &uprobe_list);
+end:
+	mutex_unlock(&uprobe_lock);
+	return ret;
+}
+
+/* Recursive argument parser */
+static int __parse_probe_arg(char *arg, const struct fetch_type *t,
+			     struct fetch_param *f)
+{
+	int ret;
+
+	switch (arg[0]) {
+	case '%':	/* named register */
+		ret = regs_query_register_offset(arg + 1);
+		if (ret >= 0) {
+			f->fn = t->reg;
+			f->data = (void *)(unsigned long)ret;
+			ret = 0;
+		}
+		return ret;
+	default:
+		/* TODO: support custom handler */
+		return -EINVAL;
+	}
+}
+
+/* String length checking wrapper */
+static int parse_probe_arg(char *arg, struct trace_uprobe *tp,
+			   struct probe_arg *parg)
+{
+	const char *t;
+
+	if (strlen(arg) > MAX_ARGSTR_LEN) {
+		pr_info("Argument is too long.: %s\n",  arg);
+		return -ENOSPC;
+	}
+	parg->comm = kstrdup(arg, GFP_KERNEL);
+	if (!parg->comm) {
+		pr_info("Failed to allocate memory for command '%s'.\n", arg);
+		return -ENOMEM;
+	}
+	t = strchr(parg->comm, ':');
+	if (t) {
+		arg[t - parg->comm] = '\0';
+		t++;
+	}
+	parg->type = find_fetch_type(t);
+	if (!parg->type) {
+		pr_info("Unsupported type: %s\n", t);
+		return -EINVAL;
+	}
+	parg->offset = tp->size;
+	tp->size += parg->type->size;
+	return __parse_probe_arg(arg, parg->type, &parg->fetch);
+}
+
+/* Return 1 if name is reserved or already used by another argument */
+static int conflict_field_name(const char *name,
+			       struct probe_arg *args, int narg)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(reserved_field_names); i++)
+		if (strcmp(reserved_field_names[i], name) == 0)
+			return 1;
+	for (i = 0; i < narg; i++)
+		if (strcmp(args[i].name, name) == 0)
+			return 1;
+	return 0;
+}
+
+static int create_trace_probe(int argc, char **argv)
+{
+	/*
+	 * Argument syntax:
+	 *  - Add uprobe: p[:[GRP/]EVENT] VADDR@PID [%REG]
+	 *
+	 *  - Remove uprobe: -:[GRP/]EVENT
+	 */
+	struct trace_uprobe *tp;
+	int i, ret = 0;
+	int is_delete = 0;
+	char *arg = NULL, *event = NULL, *group = NULL;
+	void *addr = NULL;
+	pid_t pid = 0;
+	char buf[MAX_EVENT_NAME_LEN];
+	char *tmp;
+
+	/* argc must be >= 1 */
+	if (argv[0][0] == '-')
+		is_delete = 1;
+	else if (argv[0][0] != 'p') {
+		pr_info("Probe definition must be started with 'p', 'r' or"
+			" '-'.\n");
+		return -EINVAL;
+	}
+
+	if (argv[0][1] == ':') {
+		event = &argv[0][2];
+		if (strchr(event, '/')) {
+			group = event;
+			event = strchr(group, '/') + 1;
+			event[-1] = '\0';
+			if (strlen(group) == 0) {
+				pr_info("Group name is not specified\n");
+				return -EINVAL;
+			}
+		}
+		if (strlen(event) == 0) {
+			pr_info("Event name is not specified\n");
+			return -EINVAL;
+		}
+	}
+	if (!group)
+		group = UPROBE_EVENT_SYSTEM;
+
+	if (is_delete) {
+		if (!event) {
+			pr_info("Delete command needs an event name.\n");
+			return -EINVAL;
+		}
+		mutex_lock(&uprobe_lock);
+		tp = find_probe_event(event, group);
+		if (!tp) {
+			mutex_unlock(&uprobe_lock);
+			pr_info("Event %s/%s doesn't exist.\n", group, event);
+			return -ENOENT;
+		}
+		/* delete an event */
+		unregister_trace_uprobe(tp);
+		free_trace_uprobe(tp);
+		mutex_unlock(&uprobe_lock);
+		return 0;
+	}
+
+	if (argc < 2) {
+		pr_info("Probe point is not specified.\n");
+		return -EINVAL;
+	}
+	if (isdigit(argv[1][0])) {
+		/* an address specified */
+		arg = strchr(argv[1], ':');
+		if (!arg)
+			goto fail_address_parse;
+
+		*arg++ = '\0';
+		ret = strict_strtoul(&argv[1][0], 0, (unsigned long *)&pid);
+		if (ret)
+			goto fail_address_parse;
+
+		ret = strict_strtoul(arg, 0, (unsigned long *)&addr);
+		if (ret)
+			goto fail_address_parse;
+	}
+	argc -= 2; argv += 2;
+
+	/* setup a probe */
+	if (!event) {
+		snprintf(buf, MAX_EVENT_NAME_LEN, "%c_%d_0x%p", 'p',
+							pid, addr);
+		event = buf;
+	}
+	tp = alloc_trace_uprobe(group, event, addr, pid, argc);
+	if (IS_ERR(tp)) {
+		pr_info("Failed to allocate trace_uprobe.(%d)\n",
+			(int)PTR_ERR(tp));
+		return PTR_ERR(tp);
+	}
+
+	/* parse arguments */
+	ret = 0;
+	for (i = 0; i < argc && i < MAX_TRACE_ARGS; i++) {
+		/* Parse argument name */
+		arg = strchr(argv[i], '=');
+		if (arg)
+			*arg++ = '\0';
+		else
+			arg = argv[i];
+
+		tp->args[i].name = kstrdup(argv[i], GFP_KERNEL);
+		if (!tp->args[i].name) {
+			pr_info("Failed to allocate argument%d name '%s'.\n",
+				i, argv[i]);
+			ret = -ENOMEM;
+			goto error;
+		}
+		tmp = strchr(tp->args[i].name, ':');
+		if (tmp)
+			*tmp = '_';	/* convert : to _ */
+
+		if (conflict_field_name(tp->args[i].name, tp->args, i)) {
+			pr_info("Argument%d name '%s' conflicts with "
+				"another field.\n", i, argv[i]);
+			ret = -EINVAL;
+			goto error;
+		}
+
+		/* Parse fetch argument */
+		ret = parse_probe_arg(arg, tp, &tp->args[i]);
+		if (ret) {
+			pr_info("Parse error at argument%d. (%d)\n", i, ret);
+			kfree(tp->args[i].name);
+			goto error;
+		}
+
+		tp->nr_args++;
+	}
+
+	ret = register_trace_uprobe(tp);
+	if (ret)
+		goto error;
+	return 0;
+
+error:
+	free_trace_uprobe(tp);
+	return ret;
+
+fail_address_parse:
+	pr_info("Failed to parse address.\n");
+	return ret;
+}
+
+static void cleanup_all_probes(void)
+{
+	struct trace_uprobe *tp;
+
+	mutex_lock(&uprobe_lock);
+	/* TODO: Use batch unregistration */
+	while (!list_empty(&uprobe_list)) {
+		tp = list_entry(uprobe_list.next, struct trace_uprobe, list);
+		unregister_trace_uprobe(tp);
+		free_trace_uprobe(tp);
+	}
+	mutex_unlock(&uprobe_lock);
+}
+
+
+/* Probes listing interfaces */
+static void *probes_seq_start(struct seq_file *m, loff_t *pos)
+{
+	mutex_lock(&uprobe_lock);
+	return seq_list_start(&uprobe_list, *pos);
+}
+
+static void *probes_seq_next(struct seq_file *m, void *v, loff_t *pos)
+{
+	return seq_list_next(v, &uprobe_list, pos);
+}
+
+static void probes_seq_stop(struct seq_file *m, void *v)
+{
+	mutex_unlock(&uprobe_lock);
+}
+
+static int probes_seq_show(struct seq_file *m, void *v)
+{
+	struct trace_uprobe *tp = v;
+	int i;
+
+	seq_printf(m, "%c", 'p');
+	seq_printf(m, ":%s/%s", tp->call.class->system, tp->call.name);
+
+	seq_printf(m, " %d:0x%p", tp->up.pid, (void *)tp->up.vaddr);
+
+	for (i = 0; i < tp->nr_args; i++)
+		seq_printf(m, " %s=%s", tp->args[i].name, tp->args[i].comm);
+	seq_printf(m, "\n");
+
+	return 0;
+}
+
+static const struct seq_operations probes_seq_op = {
+	.start  = probes_seq_start,
+	.next   = probes_seq_next,
+	.stop   = probes_seq_stop,
+	.show   = probes_seq_show
+};
+
+static int probes_open(struct inode *inode, struct file *file)
+{
+	if ((file->f_mode & FMODE_WRITE) &&
+	    (file->f_flags & O_TRUNC))
+		cleanup_all_probes();
+
+	return seq_open(file, &probes_seq_op);
+}
+
+static int command_trace_probe(const char *buf)
+{
+	char **argv;
+	int argc = 0, ret = 0;
+
+	argv = argv_split(GFP_KERNEL, buf, &argc);
+	if (!argv)
+		return -ENOMEM;
+
+	if (argc)
+		ret = create_trace_probe(argc, argv);
+
+	argv_free(argv);
+	return ret;
+}
+
+#define WRITE_BUFSIZE 128
+
+static ssize_t probes_write(struct file *file, const char __user *buffer,
+			    size_t count, loff_t *ppos)
+{
+	char *kbuf, *tmp;
+	int ret = 0;
+	size_t done = 0;
+	size_t size;
+
+	kbuf = kmalloc(WRITE_BUFSIZE, GFP_KERNEL);
+	if (!kbuf)
+		return -ENOMEM;
+
+	while (done < count) {
+		size = count - done;
+		if (size >= WRITE_BUFSIZE)
+			size = WRITE_BUFSIZE - 1;
+		if (copy_from_user(kbuf, buffer + done, size)) {
+			ret = -EFAULT;
+			goto out;
+		}
+		kbuf[size] = '\0';
+		tmp = strchr(kbuf, '\n');
+		if (tmp) {
+			*tmp = '\0';
+			size = tmp - kbuf + 1;
+		} else if (done + size < count) {
+			pr_warning("Line length is too long: "
+				   "Should be less than %d.", WRITE_BUFSIZE);
+			ret = -EINVAL;
+			goto out;
+		}
+		done += size;
+		/* Remove comments */
+		tmp = strchr(kbuf, '#');
+		if (tmp)
+			*tmp = '\0';
+
+		ret = command_trace_probe(kbuf);
+		if (ret)
+			goto out;
+	}
+	ret = done;
+out:
+	kfree(kbuf);
+	return ret;
+}
+
+static const struct file_operations uprobe_events_ops = {
+	.owner          = THIS_MODULE,
+	.open           = probes_open,
+	.read           = seq_read,
+	.llseek         = seq_lseek,
+	.release        = seq_release,
+	.write		= probes_write,
+};
+
+/* Probes profiling interfaces */
+static int probes_profile_seq_show(struct seq_file *m, void *v)
+{
+	struct trace_uprobe *tp = v;
+
+	seq_printf(m, "  %d %-44s %15lu\n", tp->up.pid, tp->call.name,
+								tp->nhit);
+	return 0;
+}
+
+static const struct seq_operations profile_seq_op = {
+	.start  = probes_seq_start,
+	.next   = probes_seq_next,
+	.stop   = probes_seq_stop,
+	.show   = probes_profile_seq_show
+};
+
+static int profile_open(struct inode *inode, struct file *file)
+{
+	return seq_open(file, &profile_seq_op);
+}
+
+static const struct file_operations uprobe_profile_ops = {
+	.owner          = THIS_MODULE,
+	.open           = profile_open,
+	.read           = seq_read,
+	.llseek         = seq_lseek,
+	.release        = seq_release,
+};
+
+/* uprobe handler */
+static void uprobe_trace_func(struct uprobe *up, struct pt_regs *regs)
+{
+	struct trace_uprobe *tp = container_of(up, struct trace_uprobe, up);
+	struct uprobe_trace_entry_head *entry;
+	struct ring_buffer_event *event;
+	struct ring_buffer *buffer;
+	u8 *data;
+	int size, i, pc;
+	unsigned long irq_flags;
+	struct ftrace_event_call *call = &tp->call;
+
+	tp->nhit++;
+
+	local_save_flags(irq_flags);
+	pc = preempt_count();
+
+	size = sizeof(*entry) + tp->size;
+
+	event = trace_current_buffer_lock_reserve(&buffer, call->event.type,
+						  size, irq_flags, pc);
+	if (!event)
+		return;
+
+	entry = ring_buffer_event_data(event);
+	entry->ip = (unsigned long)up->vaddr;
+	data = (u8 *)&entry[1];
+	for (i = 0; i < tp->nr_args; i++)
+		call_fetch(&tp->args[i].fetch, regs, data + tp->args[i].offset);
+
+	if (!filter_current_check_discard(buffer, call, entry, event))
+		trace_buffer_unlock_commit(buffer, event, irq_flags, pc);
+}
+
+/* Event entry printers */
+enum print_line_t
+print_uprobe_event(struct trace_iterator *iter, int flags,
+		   struct trace_event *event)
+{
+	struct uprobe_trace_entry_head *field;
+	struct trace_seq *s = &iter->seq;
+	struct trace_uprobe *tp;
+	u8 *data;
+	int i;
+
+	field = (struct uprobe_trace_entry_head *)iter->ent;
+	tp = container_of(event, struct trace_uprobe, call.event);
+
+	if (!trace_seq_printf(s, "%s: (", tp->call.name))
+		goto partial;
+
+	if (!seq_print_ip_sym(s, field->ip, flags | TRACE_ITER_SYM_OFFSET))
+		goto partial;
+
+	if (!trace_seq_puts(s, ")"))
+		goto partial;
+
+	data = (u8 *)&field[1];
+	for (i = 0; i < tp->nr_args; i++)
+		if (!tp->args[i].type->print(s, tp->args[i].name,
+					     data + tp->args[i].offset))
+			goto partial;
+
+	if (!trace_seq_puts(s, "\n"))
+		goto partial;
+
+	return TRACE_TYPE_HANDLED;
+partial:
+	return TRACE_TYPE_PARTIAL_LINE;
+}
+
+
+static int probe_event_enable(struct ftrace_event_call *call)
+{
+	int ret = 0;
+	struct trace_uprobe *tp = (struct trace_uprobe *)call->data;
+
+	if (!(tp->flags & TP_FLAG_UPROBE)) {
+		ret = register_uprobe(&tp->up);
+		if (!ret)
+			tp->flags |= (TP_FLAG_UPROBE | TP_FLAG_TRACE);
+	}
+	return ret;
+}
+
+static void probe_event_disable(struct ftrace_event_call *call)
+{
+	struct trace_uprobe *tp = (struct trace_uprobe *)call->data;
+
+	if (tp->flags & TP_FLAG_UPROBE) {
+		unregister_uprobe(&tp->up);
+		tp->flags &= ~(TP_FLAG_UPROBE | TP_FLAG_TRACE);
+	}
+}
+
+static int uprobe_event_define_fields(struct ftrace_event_call *event_call)
+{
+	int ret, i;
+	struct uprobe_trace_entry_head field;
+	struct trace_uprobe *tp = (struct trace_uprobe *)event_call->data;
+
+	DEFINE_FIELD(unsigned long, ip, FIELD_STRING_IP, 0);
+	/* Set argument names as fields */
+	for (i = 0; i < tp->nr_args; i++) {
+		ret = trace_define_field(event_call, tp->args[i].type->name,
+					 tp->args[i].name,
+					 sizeof(field) + tp->args[i].offset,
+					 tp->args[i].type->size,
+					 tp->args[i].type->is_signed,
+					 FILTER_OTHER);
+		if (ret)
+			return ret;
+	}
+	return 0;
+}
+
+static int __set_print_fmt(struct trace_uprobe *tp, char *buf, int len)
+{
+	int i;
+	int pos = 0;
+
+	const char *fmt, *arg;
+
+	fmt = "(%lx)";
+	arg = "REC->" FIELD_STRING_IP;
+
+	/* When len=0, we just calculate the needed length */
+#define LEN_OR_ZERO (len ? len - pos : 0)
+
+	pos += snprintf(buf + pos, LEN_OR_ZERO, "\"%s", fmt);
+
+	for (i = 0; i < tp->nr_args; i++) {
+		pos += snprintf(buf + pos, LEN_OR_ZERO, " %s=%s",
+				tp->args[i].name, tp->args[i].type->fmt);
+	}
+
+	pos += snprintf(buf + pos, LEN_OR_ZERO, "\", %s", arg);
+
+	for (i = 0; i < tp->nr_args; i++) {
+		pos += snprintf(buf + pos, LEN_OR_ZERO, ", REC->%s",
+				tp->args[i].name);
+	}
+
+#undef LEN_OR_ZERO
+
+	/* return the length of print_fmt */
+	return pos;
+}
+
+static int set_print_fmt(struct trace_uprobe *tp)
+{
+	int len;
+	char *print_fmt;
+
+	/* First: called with 0 length to calculate the needed length */
+	len = __set_print_fmt(tp, NULL, 0);
+	print_fmt = kmalloc(len + 1, GFP_KERNEL);
+	if (!print_fmt)
+		return -ENOMEM;
+
+	/* Second: actually write the @print_fmt */
+	__set_print_fmt(tp, print_fmt, len + 1);
+	tp->call.print_fmt = print_fmt;
+
+	return 0;
+}
+
+#ifdef CONFIG_PERF_EVENTS
+
+/* uprobe profile handler */
+static void uprobe_perf_func(struct uprobe *up,
+					 struct pt_regs *regs)
+{
+	struct trace_uprobe *tp = container_of(up, struct trace_uprobe, up);
+	struct ftrace_event_call *call = &tp->call;
+	struct uprobe_trace_entry_head *entry;
+	struct hlist_head *head;
+	u8 *data;
+	int size, __size, i;
+	int rctx;
+
+	__size = sizeof(*entry) + tp->size;
+	size = ALIGN(__size + sizeof(u32), sizeof(u64));
+	size -= sizeof(u32);
+	if (WARN_ONCE(size > PERF_MAX_TRACE_SIZE,
+		     "profile buffer not large enough"))
+		return;
+
+	entry = perf_trace_buf_prepare(size, call->event.type, regs, &rctx);
+	if (!entry)
+		return;
+
+	entry->ip = (unsigned long)up->vaddr;
+	data = (u8 *)&entry[1];
+	for (i = 0; i < tp->nr_args; i++)
+		call_fetch(&tp->args[i].fetch, regs, data + tp->args[i].offset);
+
+	head = this_cpu_ptr(call->perf_events);
+	perf_trace_buf_submit(entry, size, rctx, entry->ip, 1, regs, head);
+}
+
+static int probe_perf_enable(struct ftrace_event_call *call)
+{
+	int ret = 0;
+	struct trace_uprobe *tp = (struct trace_uprobe *)call->data;
+
+	if (!(tp->flags & TP_FLAG_UPROBE)) {
+		ret = register_uprobe(&tp->up);
+		if (!ret)
+			tp->flags |= (TP_FLAG_UPROBE | TP_FLAG_PROFILE);
+	}
+	return ret;
+}
+
+static void probe_perf_disable(struct ftrace_event_call *call)
+{
+	struct trace_uprobe *tp = (struct trace_uprobe *)call->data;
+
+	if (tp->flags & TP_FLAG_UPROBE) {
+		unregister_uprobe(&tp->up);
+		tp->flags &= ~(TP_FLAG_UPROBE | TP_FLAG_PROFILE);
+	}
+}
+#endif	/* CONFIG_PERF_EVENTS */
+
+static
+int uprobe_register(struct ftrace_event_call *event, enum trace_reg type)
+{
+	switch (type) {
+	case TRACE_REG_REGISTER:
+		return probe_event_enable(event);
+	case TRACE_REG_UNREGISTER:
+		probe_event_disable(event);
+		return 0;
+
+#ifdef CONFIG_PERF_EVENTS
+	case TRACE_REG_PERF_REGISTER:
+		return probe_perf_enable(event);
+	case TRACE_REG_PERF_UNREGISTER:
+		probe_perf_disable(event);
+		return 0;
+#endif
+	}
+	return 0;
+}
+
+static void uprobe_dispatcher(struct uprobe *up, struct pt_regs *regs)
+{
+	struct trace_uprobe *tp = container_of(up, struct trace_uprobe, up);
+
+	if (tp->flags & TP_FLAG_TRACE)
+		uprobe_trace_func(up, regs);
+#ifdef CONFIG_PERF_EVENTS
+	if (tp->flags & TP_FLAG_PROFILE)
+		uprobe_perf_func(up, regs);
+#endif
+}
+
+
+static struct trace_event_functions uprobe_funcs = {
+	.trace		= print_uprobe_event
+};
+
+static int register_uprobe_event(struct trace_uprobe *tp)
+{
+	struct ftrace_event_call *call = &tp->call;
+	int ret;
+
+	/* Initialize ftrace_event_call */
+	INIT_LIST_HEAD(&call->class->fields);
+	call->event.funcs = &uprobe_funcs;
+	call->class->raw_init = probe_event_raw_init;
+	call->class->define_fields = uprobe_event_define_fields;
+	if (set_print_fmt(tp) < 0)
+		return -ENOMEM;
+	ret = register_ftrace_event(&call->event);
+	if (!ret) {
+		kfree(call->print_fmt);
+		return -ENODEV;
+	}
+	call->flags = 0;
+	call->class->reg = uprobe_register;
+	call->data = tp;
+	ret = trace_add_event_call(call);
+	if (ret) {
+		pr_info("Failed to register uprobe event: %s\n", call->name);
+		kfree(call->print_fmt);
+		unregister_ftrace_event(&call->event);
+	}
+	return ret;
+}
+
+static void unregister_uprobe_event(struct trace_uprobe *tp)
+{
+	/* tp->event is unregistered in trace_remove_event_call() */
+	trace_remove_event_call(&tp->call);
+	kfree(tp->call.print_fmt);
+}
+
+/* Make a trace interface for controling probe points */
+static __init int init_uprobe_trace(void)
+{
+	struct dentry *d_tracer;
+	struct dentry *entry;
+
+	d_tracer = tracing_init_dentry();
+	if (!d_tracer)
+		return 0;
+
+	entry = trace_create_file("uprobe_events", 0644, d_tracer,
+				    NULL, &uprobe_events_ops);
+	/* Profile interface */
+	entry = trace_create_file("uprobe_profile", 0444, d_tracer,
+				    NULL, &uprobe_profile_ops);
+	return 0;
+}
+fs_initcall(init_uprobe_trace);

[PATCH v5 12/14] perf: Dont adjust symbols on name lookup

[Srikar Dronamraju]

perf_adjust_symbol_name.patch

From: Srikar Dronamraju <srikar@linux.vnet.ibm.com>

Adjusting symbols is not needed if we are searching by name even
if the symbols correspond to user space objects.
Infact if we adjust and search symbols by name, we get incorrect
results.

Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
---

 tools/perf/util/symbol.c |    6 ++++--
 1 files changed, 4 insertions(+), 2 deletions(-)


diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
index b63e571..2d53dfc 100644
--- a/tools/perf/util/symbol.c
+++ b/tools/perf/util/symbol.c
@@ -992,12 +992,14 @@ static int dso__load_sym(struct dso *self, struct map *map, const char *name,
 	nr_syms = shdr.sh_size / shdr.sh_entsize;
 
 	memset(&sym, 0, sizeof(sym));
-	if (self->kernel == DSO_TYPE_USER) {
+	if (self->kernel != DSO_TYPE_USER || symbol_conf.sort_by_name)
+		self->adjust_symbols = 0;
+	else {
 		self->adjust_symbols = (ehdr.e_type == ET_EXEC ||
 				elf_section_by_name(elf, &ehdr, &shdr,
 						     ".gnu.prelink_undo",
 						     NULL) != NULL);
-	} else self->adjust_symbols = 0;
+	}
 
 	elf_symtab__for_each_symbol(syms, nr_syms, idx, sym) {
 		struct symbol *f;

[PATCH v5 13/14] perf: Re-Add make_absolute_path

[Srikar Dronamraju]

revert_make_absolute_path.patch

From: Srikar Dronamraju <srikar@linux.vnet.ibm.com>

perf probe for uprobes would use make_absolute_path.
make_absolute_path can be used to convert a file name to a dso name.

so if user specifies the function to be traced as malloc@/lib/libc.so.6
it needs to be converted to malloc@libc-2.5.so

This patch reverts a part of a41794cdd7ee94a5199e14f642c26d649d383fa5
---

 tools/perf/util/abspath.c |   81 +++++++++++++++++++++++++++++++++++++++++++++
 tools/perf/util/cache.h   |    1 +
 2 files changed, 82 insertions(+), 0 deletions(-)


diff --git a/tools/perf/util/abspath.c b/tools/perf/util/abspath.c
index 0e76aff..a791dd4 100644
--- a/tools/perf/util/abspath.c
+++ b/tools/perf/util/abspath.c
@@ -1,5 +1,86 @@
 #include "cache.h"
 
+/*
+ * Do not use this for inspecting *tracked* content.  When path is a
+ * symlink to a directory, we do not want to say it is a directory when
+ * dealing with tracked content in the working tree.
+ */
+static int is_directory(const char *path)
+{
+	struct stat st;
+	return (!stat(path, &st) && S_ISDIR(st.st_mode));
+}
+
+/* We allow "recursive" symbolic links. Only within reason, though. */
+#define MAXDEPTH 5
+
+const char *make_absolute_path(const char *path)
+{
+	static char bufs[2][PATH_MAX + 1], *buf = bufs[0], *next_buf = bufs[1];
+	char cwd[1024] = "";
+	int buf_index = 1, len;
+
+	int depth = MAXDEPTH;
+	char *last_elem = NULL;
+	struct stat st;
+
+	if (strlcpy(buf, path, PATH_MAX) >= PATH_MAX)
+		die ("Too long path: %.*s", 60, path);
+
+	while (depth--) {
+		if (!is_directory(buf)) {
+			char *last_slash = strrchr(buf, '/');
+			if (last_slash) {
+				*last_slash = '\0';
+				last_elem = xstrdup(last_slash + 1);
+			} else {
+				last_elem = xstrdup(buf);
+				*buf = '\0';
+			}
+		}
+
+		if (*buf) {
+			if (!*cwd && !getcwd(cwd, sizeof(cwd)))
+				die ("Could not get current working directory");
+
+			if (chdir(buf))
+				die ("Could not switch to '%s'", buf);
+		}
+		if (!getcwd(buf, PATH_MAX))
+			die ("Could not get current working directory");
+
+		if (last_elem) {
+			len = strlen(buf);
+
+			if (len + strlen(last_elem) + 2 > PATH_MAX)
+				die ("Too long path name: '%s/%s'",
+						buf, last_elem);
+			buf[len] = '/';
+			strcpy(buf + len + 1, last_elem);
+			free(last_elem);
+			last_elem = NULL;
+		}
+
+		if (!lstat(buf, &st) && S_ISLNK(st.st_mode)) {
+			len = readlink(buf, next_buf, PATH_MAX);
+			if (len < 0)
+				die ("Invalid symlink: %s", buf);
+			if (PATH_MAX <= len)
+				die("symbolic link too long: %s", buf);
+			next_buf[len] = '\0';
+			buf = next_buf;
+			buf_index = 1 - buf_index;
+			next_buf = bufs[buf_index];
+		} else
+			break;
+	}
+
+	if (*cwd && chdir(cwd))
+		die ("Could not change back to '%s'", cwd);
+
+	return buf;
+}
+
 static const char *get_pwd_cwd(void)
 {
 	static char cwd[PATH_MAX + 1];
diff --git a/tools/perf/util/cache.h b/tools/perf/util/cache.h
index 27e9ebe..0dfed40 100644
--- a/tools/perf/util/cache.h
+++ b/tools/perf/util/cache.h
@@ -73,6 +73,7 @@ static inline int is_absolute_path(const char *path)
 	return path[0] == '/';
 }
 
+const char *make_absolute_path(const char *path);
 const char *make_nonrelative_path(const char *path);
 char *strip_path_suffix(const char *path, const char *suffix);
 

[PATCH v5 14/14] perf: perf interface for uprobes.

[Srikar Dronamraju]

perf-events.patch

From: Srikar Dronamraju <srikar@linux.vnet.ibm.com>

Changelog from v4: Merged to 2.6.35-rc3-tip.

This patch enhances perf probe to accept pid and user vaddr.
This patch provides very basic support for uprobes.

Changelog from v3: (addressed comments from Masami Hiramatsu)
	* Every process id has a different group name.
	* event name starts with function name.
	* If vaddr is specified, event name has vaddr appended
	  along with function name, (this is to avoid subsequent probes
	  using same event name.)
	* warning if -p and --list options are used together.

	Also dso can either be a short name or absolute path.

TODO:
Update perf-probes.txt.
Global tracing.

Here is a terminal snapshot of placing, using and removing a probe on a
process with pid 3591 (corresponding to zsh)

[ Probing a function in the executable using function name  ]
-------------------------------------------------------------
[root@ABCD]# perf probe -p 3591 zfree@zsh
Added new event:
  probe_3591:zfree                       (on 0x446420)

You can now use it on all perf tools, such as:

	perf record -e probe_3591:zfree -a sleep 1
[root@ABCD]# perf probe --list
probe_3591:zfree                       (on 3591:0x0000000000446420)
[root@ABCD]# cat /sys/kernel/debug/tracing/uprobe_events
p:probe_3591/zfree 3591:0x0000000000446420
[root@ABCD]# perf record -f -e probe_3591:zfree -a sleep 10
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.039 MB perf.data (~1716 samples) ]
[root@ABCD]# perf probe -p 3591 --del probe_3591:zfree
Remove event: probe_3591:zfree
[root@ABCD]# perf report
# Samples: 447
#
# Overhead          Command  Shared Object  Symbol
# ........  ...............  .............  ......
#
   100.00%              zsh  zsh            [.] zfree


#
# (For a higher level overview, try: perf report --sort comm,dso)
#

[ Probing a function + offset ]
-------------------------------
[root@ABCD]# perf probe -p 3591 zfree@zsh+5
Added new event:
  probe_3591:zfree                         (on 0x446425)

You can now use it on all perf tools, such as:

	perf record -e probe_3591:zfree -a sleep 1
[root@ABCD]# perf probe --list
probe_3591:zfree                       (on 3591:0x0000000000446425)
[root@ABCD]# cat /sys/kernel/debug/tracing/uprobe_events
p:probe_3591/zfree 3591:0x0000000000446425
[root@ABCD]# perf record -f -e probe_3591:zfree -a sleep 10
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.036 MB perf.data (~1590 samples) ]
[root@ABCD]# perf probe -p 3591 --del probe_3591:zfree
Remove event: probe_3591:zfree
[root@ABCD]# perf report
# Samples: 18
#
# Overhead          Command  Shared Object  Symbol
# ........  ...............  .............  ......
#
   100.00%              zsh  zsh            [.] zfree


#
# (For a higher level overview, try: perf report --sort comm,dso)
#


[ Probing a library function using function name ]
--------------------------------------------------
[root@ABCD]# perf probe -p 3591 write@libc-2.5.so
Added new event:
  probe_3591:write                       (on 0x36010c6060)

You can now use it on all perf tools, such as:

	perf record -e probe_3591:write -a sleep 1
[root@ABCD]# perf probe --list
probe_3591:write                       (on 3591:0x00000036010c6060)
[root@ABCD]# cat /sys/kernel/debug/tracing/uprobe_events
p:probe_3591/write 3591:0x00000036010c6060
[root@ABCD]# perf record -f -e probe_3591:write -a sleep 10
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.040 MB perf.data (~1738 samples) ]
[root@ABCD]# perf probe -p 3591 --del probe_3591:write
Remove event: probe_3591:write
[root@ABCD]# perf report
# Samples: 11
#
# Overhead          Command       Shared Object  Symbol
# ........  ...............  ..................  ......
#
   100.00%              zsh  libc-2.5.so         [.] __GI___libc_write


#
# (For a higher level overview, try: perf report --sort comm,dso)
#

[ Probing a library function using function name and absolute path ]
---------------------------------------------------------------------
[root@ABCD]# perf probe -p 3591 write@/lib64/libc-2.5.so
Added new event:
  probe_3591:write                       (on 0x36010c6060)

You can now use it on all perf tools, such as:

	perf record -e probe_3591:write -a sleep 1
[root@ABCD]# perf probe --list
probe_3591:write                       (on 3591:0x00000036010c6060)
[root@ABCD]# cat /sys/kernel/debug/tracing/uprobe_events
p:probe_3591/write 3591:0x00000036010c6060
[root@ABCD]# perf record -f -e probe_3591:write -a sleep 10
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.040 MB perf.data (~1738 samples) ]
[root@ABCD]# perf probe -p 3591 --del probe_3591:write
Remove event: probe_3591:write
[root@ABCD]# perf report
# Samples: 11
#
# Overhead          Command       Shared Object  Symbol
# ........  ...............  ..................  ......
#
   100.00%              zsh  libc-2.5.so         [.] __GI___libc_write


#
# (For a higher level overview, try: perf report --sort comm,dso)
#

[ Probing using vaddr 0x0000000000446420 (corresponding to zfree)]
-------------------------------------------------------------------
[root@ABCD]# perf probe -p 3591 0x0000000000446420
Added new event:
  probe_3591:zfree_446420          (on 0x0000000000446420)

You can now use it on all perf tools, such as:

        perf record -e probe_3591:zfree_446420 -a sleep 1

[root@ABCD]# perf record -e probe_3591:zfree_446420 -a sleep 10
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.041 MB perf.data (~1797 samples) ]
[root@ABCD]# perf report
#
# Samples: 628
#
# Overhead          Command  Shared Object  Symbol
# ........  ...............  .............  ......
#
   100.00%              zsh  zsh            [.] zfree


#
# (For a higher level overview, try: perf report --sort comm,dso)
#
[root@ABCD]# perf report --sort comm,dso
# Samples: 628
#
# Overhead          Command  Shared Object
# ........  ...............  .............
#
   100.00%              zsh  zsh


[root@ABCD]# perf probe --list
  probe_3591:zfree_446420          (on 3591:0x0000000000446420)
[root@ABCD]#  perf list | grep probe
  probe_3591:zfree_446420            [Tracepoint event]
[root@ABCD]# perf probe -p 3591 --del probe_3591:zfree_446420
Remove event: probe_3591:zfree_446420
[root@ABCD]#


Another example for a shared library: write stub in libc. (corresponds to
0x00000036010c6060)

on a vaddr
[ Probing a libc vaddr 0x00000036010c6060 (corresponding to write) ]
[root@ABCD]# perf probe -p 3591 0x00000036010c6060
dded new event:
  probe_3591:__GI___libc_write_36010c6060          (on 0x00000036010c6060)

You can now use it on all perf tools, such as:

        perf record -e probe_3591:__GI___libc_write_36010c6060 -a sleep 1

[root@ABCD]# perf record -f -e probe_3591:__GI___libc_write_36010c6060 -a sleep 10
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.040 MB perf.data (~1748 samples) ]
[root@ABCD]# perf report
# Samples: 24
#
# Overhead          Command       Shared Object  Symbol
# ........  ...............  ..................  ......
#
   100.00%              zsh  libc-2.5.so         [.] __GI___libc_write


#
# (For a higher level overview, try: perf report --sort comm,dso)
#
[root@ABCD]#

[ Probing using a function without specifying a dso (corresponding to zfree)]
-------------------------------------------------------------------
[root@ABCD]# perf probe -p 3591 zfree
Added new event:
  probe_3591:zfree		          (on 0x0000000000446420)

You can now use it on all perf tools, such as:

        perf record -e probe_3591:zfree -a sleep 1

[root@ABCD]# perf record -e probe_3591:zfree -a sleep 10
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.041 MB perf.data (~1797 samples) ]
[root@ABCD]# perf report
#
# Samples: 628
#
# Overhead          Command  Shared Object  Symbol
# ........  ...............  .............  ......
#
   100.00%              zsh  zsh            [.] zfree


#
# (For a higher level overview, try: perf report --sort comm,dso)
#
[root@ABCD]#

Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
---

 tools/perf/builtin-probe.c     |   13 +
 tools/perf/builtin-top.c       |   20 --
 tools/perf/util/event.c        |   20 ++
 tools/perf/util/event.h        |    1 
 tools/perf/util/probe-event.c  |  466 ++++++++++++++++++++++++++++------------
 tools/perf/util/probe-event.h  |   37 +--
 tools/perf/util/probe-finder.c |   20 +-
 tools/perf/util/probe-finder.h |    6 -
 8 files changed, 385 insertions(+), 198 deletions(-)


diff --git a/tools/perf/builtin-probe.c b/tools/perf/builtin-probe.c
index e4a4da3..99124a2 100644
--- a/tools/perf/builtin-probe.c
+++ b/tools/perf/builtin-probe.c
@@ -55,6 +55,7 @@ static struct {
 	struct strlist *dellist;
 	struct line_range line_range;
 	int max_probe_points;
+	pid_t upid;
 } params;
 
 
@@ -73,6 +74,7 @@ static int parse_probe_event(const char *str)
 	/* Parse a perf-probe command into event */
 	ret = parse_perf_probe_command(str, pev);
 	pr_debug("%d arguments\n", pev->nargs);
+	pev->upid = params.upid;
 
 	return ret;
 }
@@ -186,6 +188,8 @@ static const struct option options[] = {
 	OPT__DRY_RUN(&probe_event_dry_run),
 	OPT_INTEGER('\0', "max-probes", &params.max_probe_points,
 		 "Set how many probe points can be found for a probe."),
+	OPT_INTEGER('p', "pid", &params.upid,
+	"specify a pid for a uprobes based probe"),
 	OPT_END()
 };
 
@@ -223,6 +227,10 @@ int cmd_probe(int argc, const char **argv, const char *prefix __used)
 			pr_err("  Error: Don't use --list with --line.\n");
 			usage_with_options(probe_usage, options);
 		}
+		if (params.upid) {
+			pr_warning("  Error: Don't use --list with --pid.\n");
+			usage_with_options(probe_usage, options);
+		}
 		ret = show_perf_probe_events();
 		if (ret < 0)
 			pr_err("  Error: Failed to show event list. (%d)\n",
@@ -231,7 +239,7 @@ int cmd_probe(int argc, const char **argv, const char *prefix __used)
 	}
 
 #ifdef DWARF_SUPPORT
-	if (params.show_lines) {
+	if (params.show_lines && !params.upid) {
 		if (params.nevents != 0 || params.dellist) {
 			pr_warning("  Error: Don't use --line with"
 				   " --add/--del.\n");
@@ -246,7 +254,7 @@ int cmd_probe(int argc, const char **argv, const char *prefix __used)
 #endif
 
 	if (params.dellist) {
-		ret = del_perf_probe_events(params.dellist);
+		ret = del_perf_probe_events(params.dellist, params.upid);
 		strlist__delete(params.dellist);
 		if (ret < 0) {
 			pr_err("  Error: Failed to delete events. (%d)\n", ret);
@@ -265,4 +273,3 @@ int cmd_probe(int argc, const char **argv, const char *prefix __used)
 	}
 	return 0;
 }
-
diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c
index 1e8e92e..b513e40 100644
--- a/tools/perf/builtin-top.c
+++ b/tools/perf/builtin-top.c
@@ -1082,26 +1082,6 @@ static void event__process_sample(const event_t *self,
 	}
 }
 
-static int event__process(event_t *event, struct perf_session *session)
-{
-	switch (event->header.type) {
-	case PERF_RECORD_COMM:
-		event__process_comm(event, session);
-		break;
-	case PERF_RECORD_MMAP:
-		event__process_mmap(event, session);
-		break;
-	case PERF_RECORD_FORK:
-	case PERF_RECORD_EXIT:
-		event__process_task(event, session);
-		break;
-	default:
-		break;
-	}
-
-	return 0;
-}
-
 struct mmap_data {
 	int			counter;
 	void			*base;
diff --git a/tools/perf/util/event.c b/tools/perf/util/event.c
index a746086..3ebcfd7 100644
--- a/tools/perf/util/event.c
+++ b/tools/perf/util/event.c
@@ -550,6 +550,26 @@ int event__process_task(event_t *self, struct perf_session *session)
 	return 0;
 }
 
+int event__process(event_t *event, struct perf_session *session)
+{
+	switch (event->header.type) {
+	case PERF_RECORD_COMM:
+		event__process_comm(event, session);
+		break;
+	case PERF_RECORD_MMAP:
+		event__process_mmap(event, session);
+		break;
+	case PERF_RECORD_FORK:
+	case PERF_RECORD_EXIT:
+		event__process_task(event, session);
+		break;
+	default:
+		break;
+	}
+
+	return 0;
+}
+
 void thread__find_addr_map(struct thread *self,
 			   struct perf_session *session, u8 cpumode,
 			   enum map_type type, pid_t pid, u64 addr,
diff --git a/tools/perf/util/event.h b/tools/perf/util/event.h
index 887ee63..8e790da 100644
--- a/tools/perf/util/event.h
+++ b/tools/perf/util/event.h
@@ -154,6 +154,7 @@ int event__process_comm(event_t *self, struct perf_session *session);
 int event__process_lost(event_t *self, struct perf_session *session);
 int event__process_mmap(event_t *self, struct perf_session *session);
 int event__process_task(event_t *self, struct perf_session *session);
+int event__process(event_t *event, struct perf_session *session);
 
 struct addr_location;
 int event__preprocess_sample(const event_t *self, struct perf_session *session,
diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
index 914c670..f315004 100644
--- a/tools/perf/util/probe-event.c
+++ b/tools/perf/util/probe-event.c
@@ -1,5 +1,5 @@
 /*
- * probe-event.c : perf-probe definition to kprobe_events format converter
+ * probe-event.c : perf-probe definition to probe_events format converter
  *
  * Written by Masami Hiramatsu <mhiramat@redhat.com>
  *
@@ -46,6 +46,7 @@
 #include "trace-event.h"	/* For __unused */
 #include "probe-event.h"
 #include "probe-finder.h"
+#include "session.h"
 
 #define MAX_CMDLEN 256
 #define MAX_PROBE_ARGS 128
@@ -109,6 +110,18 @@ out:
 	return ret;
 }
 
+static int convert_to_perf_probe_point(struct probe_trace_point *tp,
+					struct perf_probe_point *pp)
+{
+	pp->function = strdup(tp->symbol);
+	if (pp->function == NULL)
+		return -ENOMEM;
+	pp->offset = tp->offset;
+	pp->retprobe = tp->retprobe;
+
+	return 0;
+}
+
 #ifdef DWARF_SUPPORT
 static int open_vmlinux(void)
 {
@@ -120,8 +133,12 @@ static int open_vmlinux(void)
 	return open(machine.vmlinux_maps[MAP__FUNCTION]->dso->long_name, O_RDONLY);
 }
 
-/* Convert trace point to probe point with debuginfo */
-static int convert_to_perf_probe_point(struct kprobe_trace_point *tp,
+/*
+ * Convert trace point to probe point with debuginfo
+ * Currently only handles kprobes.
+ */
+
+static int kprobe_convert_to_perf_probe(struct probe_trace_point *tp,
 				       struct perf_probe_point *pp)
 {
 	struct symbol *sym;
@@ -152,7 +169,7 @@ static int convert_to_perf_probe_point(struct kprobe_trace_point *tp,
 
 /* Try to find perf_probe_event with debuginfo */
 static int try_to_find_kprobe_trace_events(struct perf_probe_event *pev,
-					   struct kprobe_trace_event **tevs,
+					   struct probe_trace_event **tevs,
 					   int max_tevs)
 {
 	bool need_dwarf = perf_probe_event_need_dwarf(pev);
@@ -308,20 +325,14 @@ end:
 
 #else	/* !DWARF_SUPPORT */
 
-static int convert_to_perf_probe_point(struct kprobe_trace_point *tp,
-					struct perf_probe_point *pp)
+static int kprobe_convert_to_perf_probe(struct probe_trace_point *tp,
+				       struct perf_probe_point *pp)
 {
-	pp->function = strdup(tp->symbol);
-	if (pp->function == NULL)
-		return -ENOMEM;
-	pp->offset = tp->offset;
-	pp->retprobe = tp->retprobe;
-
-	return 0;
+	return convert_to_perf_probe_point(tp, pp);
 }
 
 static int try_to_find_kprobe_trace_events(struct perf_probe_event *pev,
-				struct kprobe_trace_event **tevs __unused,
+				struct probe_trace_event **tevs __unused,
 				int max_tevs __unused)
 {
 	if (perf_probe_event_need_dwarf(pev)) {
@@ -403,6 +414,81 @@ static bool check_event_name(const char *name)
 	return true;
 }
 
+/*
+ * uprobe_events only accepts address:
+ * Convert function and any offset to address
+ */
+static void convert_name_to_addr(struct perf_probe_event *pev)
+{
+	struct perf_probe_point *pp = &pev->point;
+	struct perf_session *session;
+	struct thread *thread;
+	struct symbol *sym;
+	struct map *map;
+	char *name;
+	unsigned long long vaddr;
+
+	/* check if user has specifed a virtual address */
+	vaddr = strtoul(pp->function, NULL, 0);
+	session = perf_session__new(NULL, O_WRONLY, false, false);
+	DIE_IF(session == NULL);
+	symbol_conf.try_vmlinux_path = false;
+	if (!vaddr)
+		symbol_conf.sort_by_name = true;
+	if (symbol__init() < 0)
+		semantic_error("Cannot initialize symbols.");
+
+	event__synthesize_thread(pev->upid, event__process, session);
+
+	thread = perf_session__findnew(session, pev->upid);
+	DIE_IF(thread == NULL);
+
+	if (vaddr) {
+		if (pev->event)
+			return;
+
+		pev->event = zalloc(sizeof(char *) * MAX_PROBE_ARGS);
+		sym = map_groups__find_symbol(&thread->mg, MAP__FUNCTION,
+							vaddr, NULL, NULL);
+		if (!sym)
+			snprintf(pev->event, MAX_PROBE_ARGS, "p_%llx", vaddr);
+		else
+			snprintf(pev->event, MAX_PROBE_ARGS, "%s_%llx",
+							sym->name, vaddr);
+		return;
+	}
+
+	if (!pp->file)
+		/* Lets find the function in the executable. */
+		name = strdup(thread->comm);
+	else
+		name = basename(make_absolute_path(pp->file));
+
+	DIE_IF(name == NULL);
+
+	map = map_groups__find_by_name(&thread->mg, MAP__FUNCTION, name);
+	if (!map)
+		semantic_error("Cannot find appropriate DSO.");
+
+	sym = map__find_symbol_by_name(map, pp->function, NULL);
+	if (!sym)
+		semantic_error("Cannot find appropriate Symbol.");
+
+	if (map->start > sym->start)
+		vaddr = map->start;
+	vaddr += sym->start + pp->offset + map->pgoff;
+	pp->offset = 0;
+
+	if (!pev->event)
+		pev->event = pp->function;
+	else
+		free(pp->function);
+	pp->function = zalloc(sizeof(char *) * MAX_PROBE_ARGS);
+	if (!pp->function)
+		die("Failed to allocate memory by zalloc.");
+	e_snprintf(pp->function, MAX_PROBE_ARGS, "0x%llx", vaddr);
+}
+
 /* Parse probepoint definition. */
 static int parse_perf_probe_point(char *arg, struct perf_probe_event *pev)
 {
@@ -542,6 +628,11 @@ static int parse_perf_probe_point(char *arg, struct perf_probe_event *pev)
 		return -EINVAL;
 	}
 
+	if (pev->upid && !pp->function) {
+		semantic_error("No function specified for uprobes");
+		return -EINVAL;
+	}
+
 	if ((pp->offset || pp->line || pp->lazy_line) && pp->retprobe) {
 		semantic_error("Offset/Line/Lazy pattern can't be used with "
 			       "return probe.");
@@ -551,6 +642,9 @@ static int parse_perf_probe_point(char *arg, struct perf_probe_event *pev)
 	pr_debug("symbol:%s file:%s line:%d offset:%lu return:%d lazy:%s\n",
 		 pp->function, pp->file, pp->line, pp->offset, pp->retprobe,
 		 pp->lazy_line);
+
+	if (pev->upid)
+		convert_name_to_addr(pev);
 	return 0;
 }
 
@@ -693,16 +787,17 @@ bool perf_probe_event_need_dwarf(struct perf_probe_event *pev)
 	return false;
 }
 
-/* Parse kprobe_events event into struct probe_point */
-int parse_kprobe_trace_command(const char *cmd, struct kprobe_trace_event *tev)
+/* Parse probe_events (uprobe_events) event into struct probe_point */
+static int parse_probe_trace_command(const char *cmd,
+					struct probe_trace_event *tev)
 {
-	struct kprobe_trace_point *tp = &tev->point;
+	struct probe_trace_point *tp = &tev->point;
 	char pr;
 	char *p;
 	int ret, i, argc;
 	char **argv;
 
-	pr_debug("Parsing kprobe_events: %s\n", cmd);
+	pr_debug("Parsing probe_events: %s\n", cmd);
 	argv = argv_split(cmd, &argc);
 	if (!argv) {
 		pr_debug("Failed to split arguments.\n");
@@ -734,7 +829,7 @@ int parse_kprobe_trace_command(const char *cmd, struct kprobe_trace_event *tev)
 		tp->offset = 0;
 
 	tev->nargs = argc - 2;
-	tev->args = zalloc(sizeof(struct kprobe_trace_arg) * tev->nargs);
+	tev->args = zalloc(sizeof(struct probe_trace_arg) * tev->nargs);
 	if (tev->args == NULL) {
 		ret = -ENOMEM;
 		goto out;
@@ -877,13 +972,13 @@ char *synthesize_perf_probe_command(struct perf_probe_event *pev)
 }
 #endif
 
-static int __synthesize_kprobe_trace_arg_ref(struct kprobe_trace_arg_ref *ref,
+static int __synthesize_probe_trace_arg_ref(struct probe_trace_arg_ref *ref,
 					     char **buf, size_t *buflen,
 					     int depth)
 {
 	int ret;
 	if (ref->next) {
-		depth = __synthesize_kprobe_trace_arg_ref(ref->next, buf,
+		depth = __synthesize_probe_trace_arg_ref(ref->next, buf,
 							 buflen, depth + 1);
 		if (depth < 0)
 			goto out;
@@ -901,7 +996,7 @@ out:
 
 }
 
-static int synthesize_kprobe_trace_arg(struct kprobe_trace_arg *arg,
+static int synthesize_probe_trace_arg(struct probe_trace_arg *arg,
 				       char *buf, size_t buflen)
 {
 	int ret, depth = 0;
@@ -919,7 +1014,7 @@ static int synthesize_kprobe_trace_arg(struct kprobe_trace_arg *arg,
 
 	/* Dereferencing arguments */
 	if (arg->ref) {
-		depth = __synthesize_kprobe_trace_arg_ref(arg->ref, &buf,
+		depth = __synthesize_probe_trace_arg_ref(arg->ref, &buf,
 							  &buflen, 1);
 		if (depth < 0)
 			return depth;
@@ -951,9 +1046,9 @@ static int synthesize_kprobe_trace_arg(struct kprobe_trace_arg *arg,
 	return buf - tmp;
 }
 
-char *synthesize_kprobe_trace_command(struct kprobe_trace_event *tev)
+char *synthesize_probe_trace_command(struct probe_trace_event *tev)
 {
-	struct kprobe_trace_point *tp = &tev->point;
+	struct probe_trace_point *tp = &tev->point;
 	char *buf;
 	int i, len, ret;
 
@@ -961,15 +1056,27 @@ char *synthesize_kprobe_trace_command(struct kprobe_trace_event *tev)
 	if (buf == NULL)
 		return NULL;
 
-	len = e_snprintf(buf, MAX_CMDLEN, "%c:%s/%s %s+%lu",
-			 tp->retprobe ? 'r' : 'p',
-			 tev->group, tev->event,
-			 tp->symbol, tp->offset);
+	if (tev->upid)
+		len = e_snprintf(buf, MAX_CMDLEN, "%c:%s/%s %d:%s\n",
+				 tp->retprobe ? 'r' : 'p',
+				 tev->group, tev->event,
+				 tev->upid, tp->symbol);
+	else if (tp->offset)
+		len = e_snprintf(buf, MAX_CMDLEN, "%c:%s/%s %s+%lu",
+				 tp->retprobe ? 'r' : 'p',
+				 tev->group, tev->event,
+				 tp->symbol, tp->offset);
+	else
+		len = e_snprintf(buf, MAX_CMDLEN, "%c:%s/%s %s",
+				 tp->retprobe ? 'r' : 'p',
+				 tev->group, tev->event,
+				 tp->symbol);
+
 	if (len <= 0)
 		goto error;
 
 	for (i = 0; i < tev->nargs; i++) {
-		ret = synthesize_kprobe_trace_arg(&tev->args[i], buf + len,
+		ret = synthesize_probe_trace_arg(&tev->args[i], buf + len,
 						  MAX_CMDLEN - len);
 		if (ret <= 0)
 			goto error;
@@ -982,8 +1089,8 @@ error:
 	return NULL;
 }
 
-int convert_to_perf_probe_event(struct kprobe_trace_event *tev,
-				struct perf_probe_event *pev)
+static int convert_to_perf_probe_event(struct probe_trace_event *tev,
+				struct perf_probe_event *pev, bool is_kprobe)
 {
 	char buf[64] = "";
 	int i, ret;
@@ -995,7 +1102,11 @@ int convert_to_perf_probe_event(struct kprobe_trace_event *tev,
 		return -ENOMEM;
 
 	/* Convert trace_point to probe_point */
-	ret = convert_to_perf_probe_point(&tev->point, &pev->point);
+	if (is_kprobe)
+		ret = kprobe_convert_to_perf_probe(&tev->point, &pev->point);
+	else
+		ret = convert_to_perf_probe_point(&tev->point, &pev->point);
+
 	if (ret < 0)
 		return ret;
 
@@ -1008,7 +1119,7 @@ int convert_to_perf_probe_event(struct kprobe_trace_event *tev,
 		if (tev->args[i].name)
 			pev->args[i].name = strdup(tev->args[i].name);
 		else {
-			ret = synthesize_kprobe_trace_arg(&tev->args[i],
+			ret = synthesize_probe_trace_arg(&tev->args[i],
 							  buf, 64);
 			pev->args[i].name = strdup(buf);
 		}
@@ -1059,9 +1170,9 @@ void clear_perf_probe_event(struct perf_probe_event *pev)
 	memset(pev, 0, sizeof(*pev));
 }
 
-void clear_kprobe_trace_event(struct kprobe_trace_event *tev)
+static void clear_probe_trace_event(struct probe_trace_event *tev)
 {
-	struct kprobe_trace_arg_ref *ref, *next;
+	struct probe_trace_arg_ref *ref, *next;
 	int i;
 
 	if (tev->event)
@@ -1089,7 +1200,7 @@ void clear_kprobe_trace_event(struct kprobe_trace_event *tev)
 	memset(tev, 0, sizeof(*tev));
 }
 
-static int open_kprobe_events(bool readwrite)
+static int open_probe_events(bool readwrite, bool is_kprobe)
 {
 	char buf[PATH_MAX];
 	const char *__debugfs;
@@ -1100,8 +1211,13 @@ static int open_kprobe_events(bool readwrite)
 		pr_warning("Debugfs is not mounted.\n");
 		return -ENOENT;
 	}
+	if (is_kprobe)
+		ret = e_snprintf(buf, PATH_MAX, "%stracing/kprobe_events",
+							__debugfs);
+	else
+		ret = e_snprintf(buf, PATH_MAX, "%stracing/uprobe_events",
+							__debugfs);
 
-	ret = e_snprintf(buf, PATH_MAX, "%stracing/kprobe_events", __debugfs);
 	if (ret >= 0) {
 		pr_debug("Opening %s write=%d\n", buf, readwrite);
 		if (readwrite && !probe_event_dry_run)
@@ -1112,17 +1228,30 @@ static int open_kprobe_events(bool readwrite)
 
 	if (ret < 0) {
 		if (errno == ENOENT)
-			pr_warning("kprobe_events file does not exist - please"
-				 " rebuild kernel with CONFIG_KPROBE_EVENT.\n");
+			pr_warning("%s file does not exist - please"
+				" rebuild kernel with CONFIG_%s_EVENT.\n",
+				is_kprobe ? "kprobe_events" : "uprobe_events",
+				is_kprobe ? "KPROBE" : "UPROBE");
 		else
-			pr_warning("Failed to open kprobe_events file: %s\n",
-				   strerror(errno));
+			pr_warning("Failed to open %s file: %s\n",
+				is_kprobe ? "kprobe_events" : "uprobe_events",
+				strerror(errno));
 	}
 	return ret;
 }
 
-/* Get raw string list of current kprobe_events */
-static struct strlist *get_kprobe_trace_command_rawlist(int fd)
+static int open_kprobe_events(bool readwrite)
+{
+	return open_probe_events(readwrite, 1);
+}
+
+static int open_uprobe_events(bool readwrite)
+{
+	return open_probe_events(readwrite, 0);
+}
+
+/* Get raw string list of current kprobe_events  or uprobe_events */
+static struct strlist *get_probe_trace_command_rawlist(int fd)
 {
 	int ret, idx;
 	FILE *fp;
@@ -1186,64 +1315,78 @@ static int show_perf_probe_event(struct perf_probe_event *pev)
 	return ret;
 }
 
-/* List up current perf-probe events */
-int show_perf_probe_events(void)
+static int __show_perf_probe_events(int fd, bool is_kprobe)
 {
-	int fd, ret;
-	struct kprobe_trace_event tev;
+	int ret = 0;
+	struct probe_trace_event tev;
 	struct perf_probe_event pev;
 	struct strlist *rawlist;
 	struct str_node *ent;
 
-	setup_pager();
-	ret = init_vmlinux();
-	if (ret < 0)
-		return ret;
-
 	memset(&tev, 0, sizeof(tev));
 	memset(&pev, 0, sizeof(pev));
 
-	fd = open_kprobe_events(false);
-	if (fd < 0)
-		return fd;
-
-	rawlist = get_kprobe_trace_command_rawlist(fd);
-	close(fd);
+	rawlist = get_probe_trace_command_rawlist(fd);
 	if (!rawlist)
 		return -ENOENT;
 
 	strlist__for_each(ent, rawlist) {
-		ret = parse_kprobe_trace_command(ent->s, &tev);
+		ret = parse_probe_trace_command(ent->s, &tev);
 		if (ret >= 0) {
-			ret = convert_to_perf_probe_event(&tev, &pev);
+			ret = convert_to_perf_probe_event(&tev, &pev,
+								is_kprobe);
 			if (ret >= 0)
 				ret = show_perf_probe_event(&pev);
 		}
 		clear_perf_probe_event(&pev);
-		clear_kprobe_trace_event(&tev);
+		clear_probe_trace_event(&tev);
 		if (ret < 0)
 			break;
 	}
 	strlist__delete(rawlist);
+	return ret;
+}
+
+/* List up current perf-probe events */
+int show_perf_probe_events(void)
+{
+	int fd, ret;
+
+	setup_pager();
+	fd = open_kprobe_events(false);
+	if (fd < 0)
+		return fd;
+
+	ret = init_vmlinux();
+	if (ret < 0)
+		return ret;
+
+	ret = __show_perf_probe_events(fd, true);
+	close(fd);
+
+	fd = open_uprobe_events(false);
+	if (fd >= 0) {
+		ret = __show_perf_probe_events(fd, false);
+		close(fd);
+	}
 
 	return ret;
 }
 
 /* Get current perf-probe event names */
-static struct strlist *get_kprobe_trace_event_names(int fd, bool include_group)
+static struct strlist *get_probe_trace_event_names(int fd, bool include_group)
 {
 	char buf[128];
 	struct strlist *sl, *rawlist;
 	struct str_node *ent;
-	struct kprobe_trace_event tev;
+	struct probe_trace_event tev;
 	int ret = 0;
 
 	memset(&tev, 0, sizeof(tev));
-
-	rawlist = get_kprobe_trace_command_rawlist(fd);
+	rawlist = get_probe_trace_command_rawlist(fd);
 	sl = strlist__new(true, NULL);
 	strlist__for_each(ent, rawlist) {
-		ret = parse_kprobe_trace_command(ent->s, &tev);
+		ret = parse_probe_trace_command(ent->s, &tev);
 		if (ret < 0)
 			break;
 		if (include_group) {
@@ -1253,7 +1396,7 @@ static struct strlist *get_kprobe_trace_event_names(int fd, bool include_group)
 				ret = strlist__add(sl, buf);
 		} else
 			ret = strlist__add(sl, tev.event);
-		clear_kprobe_trace_event(&tev);
+		clear_probe_trace_event(&tev);
 		if (ret < 0)
 			break;
 	}
@@ -1266,13 +1409,13 @@ static struct strlist *get_kprobe_trace_event_names(int fd, bool include_group)
 	return sl;
 }
 
-static int write_kprobe_trace_event(int fd, struct kprobe_trace_event *tev)
+static int write_probe_trace_event(int fd, struct probe_trace_event *tev)
 {
 	int ret = 0;
-	char *buf = synthesize_kprobe_trace_command(tev);
+	char *buf = synthesize_probe_trace_command(tev);
 
 	if (!buf) {
-		pr_debug("Failed to synthesize kprobe trace event.\n");
+		pr_debug("Failed to synthesize probe trace event.\n");
 		return -EINVAL;
 	}
 
@@ -1325,21 +1468,24 @@ static int get_new_event_name(char *buf, size_t len, const char *base,
 	return ret;
 }
 
-static int __add_kprobe_trace_events(struct perf_probe_event *pev,
-				     struct kprobe_trace_event *tevs,
+static int __add_probe_trace_events(struct perf_probe_event *pev,
+				     struct probe_trace_event *tevs,
 				     int ntevs, bool allow_suffix)
 {
 	int i, fd, ret;
-	struct kprobe_trace_event *tev = NULL;
+	struct probe_trace_event *tev = NULL;
 	char buf[64];
 	const char *event, *group;
 	struct strlist *namelist;
 
-	fd = open_kprobe_events(true);
+	if (pev->upid)
+		fd = open_uprobe_events(true);
+	else
+		fd = open_kprobe_events(true);
 	if (fd < 0)
 		return fd;
 	/* Get current event names */
-	namelist = get_kprobe_trace_event_names(fd, false);
+	namelist = get_probe_trace_event_names(fd, false);
 	if (!namelist) {
 		pr_debug("Failed to get current event list.\n");
 		return -EIO;
@@ -1349,17 +1495,28 @@ static int __add_kprobe_trace_events(struct perf_probe_event *pev,
 	printf("Add new event%s\n", (ntevs > 1) ? "s:" : ":");
 	for (i = 0; i < ntevs; i++) {
 		tev = &tevs[i];
-		if (pev->event)
-			event = pev->event;
-		else
-			if (pev->point.function)
-				event = pev->point.function;
-			else
-				event = tev->point.symbol;
+
 		if (pev->group)
 			group = pev->group;
-		else
+		else if (!pev->upid)
 			group = PERFPROBE_GROUP;
+		else {
+			/*
+			 * For uprobes based probes create a group
+			 * probe_<pid>.
+			 */
+			snprintf(buf, 64, "%s_%d", PERFPROBE_GROUP, pev->upid);
+			group = buf;
+		}
+
+		tev->group = strdup(group);
+
+		if (pev->event)
+			event = pev->event;
+		else if (pev->point.function)
+			event = pev->point.function;
+		else
+			event = tev->point.symbol;
 
 		/* Get an unused new event name */
 		ret = get_new_event_name(buf, 64, event,
@@ -1367,14 +1524,13 @@ static int __add_kprobe_trace_events(struct perf_probe_event *pev,
 		if (ret < 0)
 			break;
 		event = buf;
-
 		tev->event = strdup(event);
-		tev->group = strdup(group);
+
 		if (tev->event == NULL || tev->group == NULL) {
 			ret = -ENOMEM;
 			break;
 		}
-		ret = write_kprobe_trace_event(fd, tev);
+		ret = write_probe_trace_event(fd, tev);
 		if (ret < 0)
 			break;
 		/* Add added event name to namelist */
@@ -1411,21 +1567,25 @@ static int __add_kprobe_trace_events(struct perf_probe_event *pev,
 	return ret;
 }
 
-static int convert_to_kprobe_trace_events(struct perf_probe_event *pev,
-					  struct kprobe_trace_event **tevs,
+static int convert_to_probe_trace_events(struct perf_probe_event *pev,
+					  struct probe_trace_event **tevs,
 					  int max_tevs)
 {
 	struct symbol *sym;
 	int ret = 0, i;
-	struct kprobe_trace_event *tev;
+	struct probe_trace_event *tev;
 
-	/* Convert perf_probe_event with debuginfo */
-	ret = try_to_find_kprobe_trace_events(pev, tevs, max_tevs);
-	if (ret != 0)
-		return ret;
+	if (pev->upid)
+		convert_name_to_addr(pev);
+	else {
+		/* Convert perf_probe_event with debuginfo */
+		ret = try_to_find_kprobe_trace_events(pev, tevs, max_tevs);
+		if (ret != 0)
+			return ret;
+	}
 
 	/* Allocate trace event buffer */
-	tev = *tevs = zalloc(sizeof(struct kprobe_trace_event));
+	tev = *tevs = zalloc(sizeof(struct probe_trace_event));
 	if (tev == NULL)
 		return -ENOMEM;
 
@@ -1438,7 +1598,7 @@ static int convert_to_kprobe_trace_events(struct perf_probe_event *pev,
 	tev->point.offset = pev->point.offset;
 	tev->nargs = pev->nargs;
 	if (tev->nargs) {
-		tev->args = zalloc(sizeof(struct kprobe_trace_arg)
+		tev->args = zalloc(sizeof(struct probe_trace_arg)
 				   * tev->nargs);
 		if (tev->args == NULL) {
 			ret = -ENOMEM;
@@ -1467,6 +1627,11 @@ static int convert_to_kprobe_trace_events(struct perf_probe_event *pev,
 		}
 	}
 
+	if (pev->upid) {
+		tev->upid = pev->upid;
+		return 1;
+	}
+
 	/* Currently just checking function name from symbol map */
 	sym = map__find_symbol_by_name(machine.vmlinux_maps[MAP__FUNCTION],
 				       tev->point.symbol, NULL);
@@ -1479,7 +1644,7 @@ static int convert_to_kprobe_trace_events(struct perf_probe_event *pev,
 
 	return 1;
 error:
-	clear_kprobe_trace_event(tev);
+	clear_probe_trace_event(tev);
 	free(tev);
 	*tevs = NULL;
 	return ret;
@@ -1487,30 +1652,32 @@ error:
 
 struct __event_package {
 	struct perf_probe_event		*pev;
-	struct kprobe_trace_event	*tevs;
+	struct probe_trace_event	*tevs;
 	int				ntevs;
 };
 
 int add_perf_probe_events(struct perf_probe_event *pevs, int npevs,
 			  bool force_add, int max_tevs)
 {
-	int i, j, ret;
+	int i, j, ret = 0;
 	struct __event_package *pkgs;
 
 	pkgs = zalloc(sizeof(struct __event_package) * npevs);
 	if (pkgs == NULL)
 		return -ENOMEM;
 
-	/* Init vmlinux path */
-	ret = init_vmlinux();
-	if (ret < 0)
-		return ret;
+	if (!pevs->upid) {
+		/* Init vmlinux path */
+		ret = init_vmlinux();
+		if (ret < 0)
+			return ret;
+	}
 
 	/* Loop 1: convert all events */
 	for (i = 0; i < npevs; i++) {
 		pkgs[i].pev = &pevs[i];
 		/* Convert with or without debuginfo */
-		ret  = convert_to_kprobe_trace_events(pkgs[i].pev,
+		ret  = convert_to_probe_trace_events(pkgs[i].pev,
 						      &pkgs[i].tevs, max_tevs);
 		if (ret < 0)
 			goto end;
@@ -1519,24 +1686,24 @@ int add_perf_probe_events(struct perf_probe_event *pevs, int npevs,
 
 	/* Loop 2: add all events */
 	for (i = 0; i < npevs && ret >= 0; i++)
-		ret = __add_kprobe_trace_events(pkgs[i].pev, pkgs[i].tevs,
+		ret = __add_probe_trace_events(pkgs[i].pev, pkgs[i].tevs,
 						pkgs[i].ntevs, force_add);
 end:
 	/* Loop 3: cleanup trace events  */
 	for (i = 0; i < npevs; i++)
 		for (j = 0; j < pkgs[i].ntevs; j++)
-			clear_kprobe_trace_event(&pkgs[i].tevs[j]);
+			clear_probe_trace_event(&pkgs[i].tevs[j]);
 
 	return ret;
 }
 
-static int __del_trace_kprobe_event(int fd, struct str_node *ent)
+static int __del_trace_probe_event(int fd, struct str_node *ent)
 {
 	char *p;
 	char buf[128];
 	int ret;
 
-	/* Convert from perf-probe event to trace-kprobe event */
+	/* Convert from perf-probe event to trace-probe event */
 	ret = e_snprintf(buf, 128, "-:%s", ent->s);
 	if (ret < 0)
 		goto error;
@@ -1562,24 +1729,16 @@ error:
 	return ret;
 }
 
-static int del_trace_kprobe_event(int fd, const char *group,
-				  const char *event, struct strlist *namelist)
+static int del_trace_probe_event(int fd, const char *buf,
+						  struct strlist *namelist)
 {
-	char buf[128];
 	struct str_node *ent, *n;
-	int found = 0, ret = 0;
-
-	ret = e_snprintf(buf, 128, "%s:%s", group, event);
-	if (ret < 0) {
-		pr_err("Failed to copy event.");
-		return ret;
-	}
+	int ret = -1;
 
 	if (strpbrk(buf, "*?")) { /* Glob-exp */
 		strlist__for_each_safe(ent, n, namelist)
 			if (strglobmatch(ent->s, buf)) {
-				found++;
-				ret = __del_trace_kprobe_event(fd, ent);
+				ret = __del_trace_probe_event(fd, ent);
 				if (ret < 0)
 					break;
 				strlist__remove(namelist, ent);
@@ -1587,40 +1746,44 @@ static int del_trace_kprobe_event(int fd, const char *group,
 	} else {
 		ent = strlist__find(namelist, buf);
 		if (ent) {
-			found++;
-			ret = __del_trace_kprobe_event(fd, ent);
+			ret = __del_trace_probe_event(fd, ent);
 			if (ret >= 0)
 				strlist__remove(namelist, ent);
 		}
 	}
-	if (found == 0 && ret >= 0)
-		pr_info("Info: Event \"%s\" does not exist.\n", buf);
-
 	return ret;
 }
 
-int del_perf_probe_events(struct strlist *dellist)
+int del_perf_probe_events(struct strlist *dellist, pid_t pid)
 {
-	int fd, ret = 0;
+	int ret = -1, ufd = -1, kfd = -1;
+	char buf[128];
 	const char *group, *event;
 	char *p, *str;
 	struct str_node *ent;
-	struct strlist *namelist;
+	struct strlist *namelist = NULL, *unamelist = NULL;
 
-	fd = open_kprobe_events(true);
-	if (fd < 0)
-		return fd;
 
 	/* Get current event names */
-	namelist = get_kprobe_trace_event_names(fd, true);
-	if (namelist == NULL)
-		return -EINVAL;
+	if (!pid) {
+		kfd = open_kprobe_events(true);
+		if (kfd < 0)
+			return kfd;
+		namelist = get_probe_trace_event_names(kfd, true);
+	}
+
+	ufd = open_uprobe_events(true);
+	if (ufd >= 0)
+		unamelist = get_probe_trace_event_names(ufd, true);
+
+	if (namelist == NULL && unamelist == NULL)
+		goto error;
 
 	strlist__for_each(ent, dellist) {
 		str = strdup(ent->s);
 		if (str == NULL) {
 			ret = -ENOMEM;
-			break;
+			goto error;
 		}
 		pr_debug("Parsing: %s\n", str);
 		p = strchr(str, ':');
@@ -1632,15 +1795,36 @@ int del_perf_probe_events(struct strlist *dellist)
 			group = "*";
 			event = str;
 		}
+
+		ret = e_snprintf(buf, 128, "%s:%s", group, event);
+		if (ret < 0) {
+			pr_err("Failed to copy event.");
+			free(str);
+			goto error;
+		}
+
 		pr_debug("Group: %s, Event: %s\n", group, event);
-		ret = del_trace_kprobe_event(fd, group, event, namelist);
+		if (!pid && namelist)
+			ret = del_trace_probe_event(kfd, buf, namelist);
+		if (unamelist && ret != 0)
+			ret = del_trace_probe_event(ufd, buf, unamelist);
+
 		free(str);
-		if (ret < 0)
-			break;
+		if (ret != 0)
+			pr_info("Info: Event \"%s\" does not exist.\n", buf);
 	}
-	strlist__delete(namelist);
-	close(fd);
 
+error:
+	if (kfd >= 0) {
+		if (namelist)
+			strlist__delete(namelist);
+		close(kfd);
+	}
+
+	if (ufd >= 0) {
+		if (unamelist)
+			strlist__delete(unamelist);
+		close(ufd);
+	}
 	return ret;
 }
-
diff --git a/tools/perf/util/probe-event.h b/tools/perf/util/probe-event.h
index e9db1a2..61514a8 100644
--- a/tools/perf/util/probe-event.h
+++ b/tools/perf/util/probe-event.h
@@ -6,34 +6,35 @@
 
 extern bool probe_event_dry_run;
 
-/* kprobe-tracer tracing point */
-struct kprobe_trace_point {
+/* kprobe-tracer and uprobe-tracer tracing point */
+struct probe_trace_point {
 	char		*symbol;	/* Base symbol */
 	unsigned long	offset;		/* Offset from symbol */
 	bool		retprobe;	/* Return probe flag */
 };
 
-/* kprobe-tracer tracing argument referencing offset */
-struct kprobe_trace_arg_ref {
-	struct kprobe_trace_arg_ref	*next;	/* Next reference */
+/* probe-tracer tracing argument referencing offset */
+struct probe_trace_arg_ref {
+	struct probe_trace_arg_ref	*next;	/* Next reference */
 	long				offset;	/* Offset value */
 };
 
-/* kprobe-tracer tracing argument */
-struct kprobe_trace_arg {
+/* kprobe-tracer and uprobe-tracer tracing argument */
+struct probe_trace_arg {
 	char				*name;	/* Argument name */
 	char				*value;	/* Base value */
 	char				*type;	/* Type name */
-	struct kprobe_trace_arg_ref	*ref;	/* Referencing offset */
+	struct probe_trace_arg_ref	*ref;	/* Referencing offset */
 };
 
-/* kprobe-tracer tracing event (point + arg) */
-struct kprobe_trace_event {
+/* kprobe-tracer and uprobe-tracer tracing event (point + arg) */
+struct probe_trace_event {
 	char				*event;	/* Event name */
 	char				*group;	/* Group name */
-	struct kprobe_trace_point	point;	/* Trace point */
+	struct probe_trace_point	point;	/* Trace point */
 	int				nargs;	/* Number of args */
-	struct kprobe_trace_arg		*args;	/* Arguments */
+	pid_t				upid;	/* uprobes only */
+	struct probe_trace_arg		*args;	/* Arguments */
 };
 
 /* Perf probe probing point */
@@ -67,6 +68,7 @@ struct perf_probe_event {
 	char			*group;	/* Group name */
 	struct perf_probe_point	point;	/* Probe point */
 	int			nargs;	/* Number of arguments */
+	pid_t			upid;
 	struct perf_probe_arg	*args;	/* Arguments */
 };
 
@@ -91,25 +93,18 @@ struct line_range {
 /* Command string to events */
 extern int parse_perf_probe_command(const char *cmd,
 				    struct perf_probe_event *pev);
-extern int parse_kprobe_trace_command(const char *cmd,
-				      struct kprobe_trace_event *tev);
 
 /* Events to command string */
 extern char *synthesize_perf_probe_command(struct perf_probe_event *pev);
-extern char *synthesize_kprobe_trace_command(struct kprobe_trace_event *tev);
+extern char *synthesize_probe_trace_command(struct probe_trace_event *tev);
 extern int synthesize_perf_probe_arg(struct perf_probe_arg *pa, char *buf,
 				     size_t len);
 
 /* Check the perf_probe_event needs debuginfo */
 extern bool perf_probe_event_need_dwarf(struct perf_probe_event *pev);
 
-/* Convert from kprobe_trace_event to perf_probe_event */
-extern int convert_to_perf_probe_event(struct kprobe_trace_event *tev,
-				       struct perf_probe_event *pev);
-
 /* Release event contents */
 extern void clear_perf_probe_event(struct perf_probe_event *pev);
-extern void clear_kprobe_trace_event(struct kprobe_trace_event *tev);
 
 /* Command string to line-range */
 extern int parse_line_range_desc(const char *cmd, struct line_range *lr);
@@ -117,7 +112,7 @@ extern int parse_line_range_desc(const char *cmd, struct line_range *lr);
 
 extern int add_perf_probe_events(struct perf_probe_event *pevs, int npevs,
 				 bool force_add, int max_probe_points);
-extern int del_perf_probe_events(struct strlist *dellist);
+extern int del_perf_probe_events(struct strlist *dellist, pid_t pid);
 extern int show_perf_probe_events(void);
 extern int show_line_range(struct line_range *lr);
 
diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
index d964cb1..7a5c954 100644
--- a/tools/perf/util/probe-finder.c
+++ b/tools/perf/util/probe-finder.c
@@ -363,7 +363,7 @@ static int convert_location(Dwarf_Op *op, struct probe_finder *pf)
 	Dwarf_Word offs = 0;
 	bool ref = false;
 	const char *regs;
-	struct kprobe_trace_arg *tvar = pf->tvar;
+	struct probe_trace_arg *tvar = pf->tvar;
 
 	/* If this is based on frame buffer, set the offset */
 	if (op->atom == DW_OP_fbreg) {
@@ -405,7 +405,7 @@ static int convert_location(Dwarf_Op *op, struct probe_finder *pf)
 		return -ENOMEM;
 
 	if (ref) {
-		tvar->ref = zalloc(sizeof(struct kprobe_trace_arg_ref));
+		tvar->ref = zalloc(sizeof(struct probe_trace_arg_ref));
 		if (tvar->ref == NULL)
 			return -ENOMEM;
 		tvar->ref->offset = (long)offs;
@@ -414,7 +414,7 @@ static int convert_location(Dwarf_Op *op, struct probe_finder *pf)
 }
 
 static int convert_variable_type(Dwarf_Die *vr_die,
-				 struct kprobe_trace_arg *targ)
+				 struct probe_trace_arg *targ)
 {
 	Dwarf_Die type;
 	char buf[16];
@@ -454,10 +454,10 @@ static int convert_variable_type(Dwarf_Die *vr_die,
 
 static int convert_variable_fields(Dwarf_Die *vr_die, const char *varname,
 				    struct perf_probe_arg_field *field,
-				    struct kprobe_trace_arg_ref **ref_ptr,
+				    struct probe_trace_arg_ref **ref_ptr,
 				    Dwarf_Die *die_mem)
 {
-	struct kprobe_trace_arg_ref *ref = *ref_ptr;
+	struct probe_trace_arg_ref *ref = *ref_ptr;
 	Dwarf_Die type;
 	Dwarf_Word offs;
 	int ret;
@@ -486,7 +486,7 @@ static int convert_variable_fields(Dwarf_Die *vr_die, const char *varname,
 			return -EINVAL;
 		}
 
-		ref = zalloc(sizeof(struct kprobe_trace_arg_ref));
+		ref = zalloc(sizeof(struct probe_trace_arg_ref));
 		if (ref == NULL)
 			return -ENOMEM;
 		if (*ref_ptr)
@@ -618,7 +618,7 @@ static int find_variable(Dwarf_Die *sp_die, struct probe_finder *pf)
 /* Show a probe point to output buffer */
 static int convert_probe_point(Dwarf_Die *sp_die, struct probe_finder *pf)
 {
-	struct kprobe_trace_event *tev;
+	struct probe_trace_event *tev;
 	Dwarf_Addr eaddr;
 	Dwarf_Die die_mem;
 	const char *name;
@@ -683,7 +683,7 @@ static int convert_probe_point(Dwarf_Die *sp_die, struct probe_finder *pf)
 
 	/* Find each argument */
 	tev->nargs = pf->pev->nargs;
-	tev->args = zalloc(sizeof(struct kprobe_trace_arg) * tev->nargs);
+	tev->args = zalloc(sizeof(struct probe_trace_arg) * tev->nargs);
 	if (tev->args == NULL)
 		return -ENOMEM;
 	for (i = 0; i < pf->pev->nargs; i++) {
@@ -942,7 +942,7 @@ static int find_probe_point_by_func(struct probe_finder *pf)
 
 /* Find kprobe_trace_events specified by perf_probe_event from debuginfo */
 int find_kprobe_trace_events(int fd, struct perf_probe_event *pev,
-			     struct kprobe_trace_event **tevs, int max_tevs)
+			     struct probe_trace_event **tevs, int max_tevs)
 {
 	struct probe_finder pf = {.pev = pev, .max_tevs = max_tevs};
 	struct perf_probe_point *pp = &pev->point;
@@ -952,7 +952,7 @@ int find_kprobe_trace_events(int fd, struct perf_probe_event *pev,
 	Dwarf *dbg;
 	int ret = 0;
 
-	pf.tevs = zalloc(sizeof(struct kprobe_trace_event) * max_tevs);
+	pf.tevs = zalloc(sizeof(struct probe_trace_event) * max_tevs);
 	if (pf.tevs == NULL)
 		return -ENOMEM;
 	*tevs = pf.tevs;
diff --git a/tools/perf/util/probe-finder.h b/tools/perf/util/probe-finder.h
index e1f61dc..73aabb2 100644
--- a/tools/perf/util/probe-finder.h
+++ b/tools/perf/util/probe-finder.h
@@ -18,7 +18,7 @@ static inline int is_c_varname(const char *name)
 #ifdef DWARF_SUPPORT
 /* Find kprobe_trace_events specified by perf_probe_event from debuginfo */
 extern int find_kprobe_trace_events(int fd, struct perf_probe_event *pev,
-				    struct kprobe_trace_event **tevs,
+				    struct probe_trace_event **tevs,
 				    int max_tevs);
 
 /* Find a perf_probe_point from debuginfo */
@@ -33,7 +33,7 @@ extern int find_line_range(int fd, struct line_range *lr);
 
 struct probe_finder {
 	struct perf_probe_event	*pev;		/* Target probe event */
-	struct kprobe_trace_event *tevs;	/* Result trace events */
+	struct probe_trace_event *tevs;		/* Result trace events */
 	int			ntevs;		/* Number of trace events */
 	int			max_tevs;	/* Max number of trace events */
 
@@ -50,7 +50,7 @@ struct probe_finder {
 #endif
 	Dwarf_Op		*fb_ops;	/* Frame base attribute */
 	struct perf_probe_arg	*pvar;		/* Current target variable */
-	struct kprobe_trace_arg	*tvar;		/* Current result variable */
+	struct probe_trace_arg	*tvar;		/* Current result variable */
 };
 
 struct line_finder {

Re: [PATCH v5 6/14] Uprobes Implementation

[Randy Dunlap]

On Mon, 14 Jun 2010 13:59:03 +0530 Srikar Dronamraju wrote:

> diff --git a/arch/Kconfig b/arch/Kconfig
> index 16541af..995f7f2 100644
> --- a/arch/Kconfig
> +++ b/arch/Kconfig
> @@ -58,6 +58,16 @@ config USER_BKPT
>  	  This service is used by components such as uprobes.
>  	  If in doubt, say "N".
>  
> +config UPROBES
> +	bool "User-space probes (EXPERIMENTAL)"
> +	depends on MODULES && USER_BKPT_XOL

depends on having CONFIG_MODULES enabled.  Please explain.


> +	depends on HAVE_UPROBES
> +	help
> +	  Uprobes enables kernel modules to establish probepoints
> +	  in user applications and execute handler functions when
> +	  the probepoints are hit. For more information, refer to
> +	  Documentation/uprobes.txt. If in doubt, say "N".
> +
>  config HAVE_EFFICIENT_UNALIGNED_ACCESS
>  	bool
>  	help


---
~Randy
*** Remember to use Documentation/SubmitChecklist when testing your code ***

Re: [PATCH v5 1/14] X86 instruction analysis: Move Macro W to insn.h

[Christoph Hellwig]

On Mon, Jun 14, 2010 at 01:58:03PM +0530, Srikar Dronamraju wrote:
> move_W_to_insn.patch
> 
> From: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
> 
> Move Macro W to asm/insn.h
> 
> Macro W used to know if the instructions are valid for
> user-space/kernel space.  This macro is used by kprobes and
> user_bkpt. (i.e user space breakpoint assistance layer.) So moving it
> to a common header file asm/insn.h.

I don't think W is a good name for a macro in a header file.

Re: [PATCH v5 3/14] User Space Breakpoint Assistance Layer

[Christoph Hellwig]

On Mon, Jun 14, 2010 at 01:58:32PM +0530, Srikar Dronamraju wrote:
> User Space Breakpoint Assistance Layer (USER_BKPT)
> Changelog from V3: (reimplement background page replacement)
> 	* Replemented background page replacement based on inputs
> 	  from Peter Zijlstra.
> 
> Changelog from v2: (addressing comments from Oleg)

FYI the changelog should be under the --- marker so that it doesn't
get included into the final commit message.

Re: [PATCH v5 2/14] mm: Move replace_page to mm/memory.c

[Christoph Hellwig]

On Mon, Jun 14, 2010 at 01:58:18PM +0530, Srikar Dronamraju wrote:
> move_replace_page.patch
> 
> From: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
> 
> Move replace_page() and write_protect_page() to mm/memory.c
> 
> User bkpt will use background page replacement approach to insert/delete
> breakpoints. Background page replacement approach will be based on
> replace_page and write_protect_page.
> Now replace_page() loses its static attribute.

Neither of these actually gets used in this series.  So you can drop
the patch for now.

Re: [PATCH v5 8/14] samples: Uprobes samples

[Christoph Hellwig]

On Mon, Jun 14, 2010 at 01:59:23PM +0530, Srikar Dronamraju wrote:
> samples.patch
> 
> From: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
> 
> Uprobes Samples
> 
> This provides an example uprobes module in the samples directory.
> 
> To run this module run (as root)
>  insmod uprobe_example.ko vaddr=<vaddr> pid=<pid>
> 	 Where <vaddr> is the address where we want to place the probe.
> 		<pid> is the pid of the process we are interested to probe.

What's the point of this sample?  It's a sub-set of what the perf
uprobes inteface supports, and writing kernel modules to probe userspace
code is braindead to start with.  So if you remove this example of what
people should not do we can also get rid of all the exports.

Re: [PATCH v5 3/14] User Space Breakpoint Assistance Layer

[Christoph Hellwig]

On Mon, Jun 14, 2010 at 01:58:32PM +0530, Srikar Dronamraju wrote:
> TODO: Merge user_bkpt layer with uprobes.

Yes, I don't think there's any point in that split.  What's the
timeframe for you to finish that merge?

> +	depends on MODULES

This doesn't make too much sense - the only real user of this is not
modular at all.

> +	depends on HAVE_USER_BKPT

Should this be ARCH_HAVE_USER_BKPT or similar?

Re: [PATCH v5 5/14] Slot allocation for execution out of line (XOL)

[Christoph Hellwig]

What's the point of adding another header for a few prototypes when
all users include user_bkpt.h anyway?

Re: [PATCH v5 7/14] x86 support for Uprobes

[Christoph Hellwig]

On Mon, Jun 14, 2010 at 01:59:13PM +0530, Srikar Dronamraju wrote:
> @@ -850,7 +850,19 @@ do_notify_resume(struct pt_regs *regs, void *unused, __u32 thread_info_flags)
>  
>  	if (thread_info_flags & _TIF_UPROBE) {
>  		clear_thread_flag(TIF_UPROBE);
> +#ifdef CONFIG_X86_32
> +		/*
> +		 * On x86_32, do_notify_resume() gets called with
> +		 * interrupts disabled. Hence enable interrupts if they
> +		 * are still disabled.
> +		 */
> +		native_irq_enable();
> +#endif
>  		uprobe_notify_resume(regs);
> +
> +#ifdef CONFIG_X86_32
> +		native_irq_disable();
> +#endif

I'm no x86 port guru, but this looks rather worriesome to me.  Why does
do_notify_resume have different calling conventions on 32 vs 64-bit?
And if there is a good reason that 32-bit has them disabled, why is
enabling them in the middle of do_notify_resume okay?

> +void arch_uprobe_disable_sstep(struct pt_regs *regs)
> +{
> +		/* Disable single-stepping by clearing what we set */
> +		clear_thread_flag(TIF_SINGLESTEP);
> +		clear_thread_flag(TIF_FORCED_TF);
> +		regs->flags &= ~X86_EFLAGS_TF;
> +}

This seems to have one layer of indentation too much.

Re: [PATCH v5 2/14] mm: Move replace_page to mm/memory.c

[Srikar Dronamraju]

> On Mon, Jun 14, 2010 at 01:58:18PM +0530, Srikar Dronamraju wrote:
> > move_replace_page.patch
> > 
> > From: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
> > 
> > Move replace_page() and write_protect_page() to mm/memory.c
> > 
> > User bkpt will use background page replacement approach to insert/delete
> > breakpoints. Background page replacement approach will be based on
> > replace_page and write_protect_page.
> > Now replace_page() loses its static attribute.
> 
> Neither of these actually gets used in this series.  So you can drop
> the patch for now.
 
replace_page() and write_protect_page() are used in write_opcode() to
insert/remove a breakpoint in the user-space breakpoint insertion layer. 
i.e "[PATCH v5 3/14] User Space Breakpoint Assistance Layer"

Even if we merge uprobes and user_bkpt layers, we would still need
write_opcode function while inserting/deleting a breakpoint.

--
Thanks and Regards
Srikar

Re: [PATCH v5 10/14] trace: Common code for kprobes/uprobes traceevents

[Masami Hiramatsu]

Srikar Dronamraju wrote:
> share_traceevents.patch.
> 
> From: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
> 
> Changelog from v5: Addressed comments from Masami.
>         Also shared lot more code from kprobes traceevents.
> 
> Move common parts of trace_kprobe.c and trace_uprobec.
> Adjust kernel/trace/trace_kprobe.c after moving common code to
> kernel/trace/trace_probe.h. However they still have few duplicate
> functions.

Hi Shriker,

OK, sharing fetch codes between them is acceptable.

> diff --git a/kernel/trace/trace_probe.h b/kernel/trace/trace_probe.h
> new file mode 100644
> index 0000000..b4c5763
> --- /dev/null
> +++ b/kernel/trace/trace_probe.h
[...]

> +/* Printing  in basic type function template */
> +#define DEFINE_BASIC_PRINT_TYPE_FUNC(type, fmt, cast)			\
> +static __kprobes int PRINT_TYPE_FUNC_NAME(type)(struct trace_seq *s,	\
> +						const char *name, void *data)\
> +{									\
> +	return trace_seq_printf(s, " %s=" fmt, name, (cast)*(type *)data);\
> +}									\
> +static const char PRINT_TYPE_FMT_NAME(type)[] = fmt;
> +
> +DEFINE_BASIC_PRINT_TYPE_FUNC(u8, "%x", unsigned int)
> +DEFINE_BASIC_PRINT_TYPE_FUNC(u16, "%x", unsigned int)
> +DEFINE_BASIC_PRINT_TYPE_FUNC(u32, "%lx", unsigned long)
> +DEFINE_BASIC_PRINT_TYPE_FUNC(u64, "%llx", unsigned long long)
> +DEFINE_BASIC_PRINT_TYPE_FUNC(s8, "%d", int)
> +DEFINE_BASIC_PRINT_TYPE_FUNC(s16, "%d", int)

Please do NOT define static variables in header file...
It should be in trace_probe_common.c.

> +
> +/* Data fetch function type */
> +typedef	void (*fetch_func_t)(struct pt_regs *, void *, void *);
> +
> +struct fetch_param {
> +	fetch_func_t	fn;
> +	void *data;
> +};
> +
> +#define FETCH_FUNC_NAME(kind, type)	fetch_##kind##_##type
> +/*
> + * Define macro for basic types - we don't need to define s* types, because
> + * we have to care only about bitwidth at recording time.
> + */
> +#define DEFINE_BASIC_FETCH_FUNCS(kind)  \
> +DEFINE_FETCH_##kind(u8)			\
> +DEFINE_FETCH_##kind(u16)		\
> +DEFINE_FETCH_##kind(u32)		\
> +DEFINE_FETCH_##kind(u64)
> +
> +#define CHECK_BASIC_FETCH_FUNCS(kind, fn)	\
> +	((FETCH_FUNC_NAME(kind, u8) == fn) ||	\
> +	 (FETCH_FUNC_NAME(kind, u16) == fn) ||	\
> +	 (FETCH_FUNC_NAME(kind, u32) == fn) ||	\
> +	 (FETCH_FUNC_NAME(kind, u64) == fn))
> +
> +/* Data fetch function templates */
> +#define DEFINE_FETCH_reg(type)						\
> +static __kprobes void FETCH_FUNC_NAME(reg, type)(struct pt_regs *regs,	\
> +					  void *offset, void *dest)	\
> +{									\
> +	*(type *)dest = (type)regs_get_register(regs,			\
> +				(unsigned int)((unsigned long)offset));	\
> +}
> +DEFINE_BASIC_FETCH_FUNCS(reg)
> +
> +/* Default (unsigned long) fetch type */
> +#define __DEFAULT_FETCH_TYPE(t) u##t
> +#define _DEFAULT_FETCH_TYPE(t) __DEFAULT_FETCH_TYPE(t)
> +#define DEFAULT_FETCH_TYPE _DEFAULT_FETCH_TYPE(BITS_PER_LONG)
> +#define DEFAULT_FETCH_TYPE_STR __stringify(DEFAULT_FETCH_TYPE)
> +
> +#define ASSIGN_FETCH_FUNC(kind, type)	\
> +	.kind = FETCH_FUNC_NAME(kind, type)

And, please do not split these macros and function bodies.
I think we should make a new .c and put them into there.
Maybe, we need a new interface for generating new fetch_arg
according to its type (and access region, user/kernel).

> +
> +/* Flags for trace_probe */
> +#define TP_FLAG_TRACE	1
> +#define TP_FLAG_PROFILE	2
> +
> +#define PARAM_MAX_ARGS 16
> +#define PARAM_MAX_STACK (THREAD_SIZE / sizeof(unsigned long))
> +
> +struct probe_arg {
> +	struct fetch_param	fetch;
> +	unsigned int		offset;	/* Offset from argument entry */
> +	const char		*name;	/* Name of this argument */
> +	const char		*comm;	/* Command of this argument */
> +	const struct fetch_type	*type;	/* Type of this argument */
> +};
> +
> +static __kprobes void call_fetch(struct fetch_param *fprm,
> +				 struct pt_regs *regs, void *dest)
> +{
> +	return fprm->fn(regs, fprm->data, dest);
> +}
> +
> +/* Check the name is good for event/group */
> +static inline int check_event_name(const char *name)
> +{
> +	if (!isalpha(*name) && *name != '_')
> +		return 0;
> +	while (*++name != '\0') {
> +		if (!isalpha(*name) && !isdigit(*name) && *name != '_')
> +			return 0;
> +	}
> +	return 1;
> +}
> +
> +static int probe_event_raw_init(struct ftrace_event_call *event_call)
> +{
> +	return 0;
> +}

Exporting these interfaces are OK.

Thank you,

Re: [PATCH v5 2/14] mm: Move replace_page to mm/memory.c

[Christoph Hellwig]

On Tue, Jun 15, 2010 at 09:30:01AM +0530, Srikar Dronamraju wrote:
> replace_page() and write_protect_page() are used in write_opcode() to
> insert/remove a breakpoint in the user-space breakpoint insertion layer. 
> i.e "[PATCH v5 3/14] User Space Breakpoint Assistance Layer"

You're right.  I did a git-grep, but that didn't find the newly added
files..

Re: [PATCH v5 7/14] x86 support for Uprobes

[Srikar Dronamraju]

* Christoph Hellwig <hch@infradead.org> [2010-06-14 13:54:23]:

> On Mon, Jun 14, 2010 at 01:59:13PM +0530, Srikar Dronamraju wrote:
> > @@ -850,7 +850,19 @@ do_notify_resume(struct pt_regs *regs, void *unused, __u32 thread_info_flags)
> >  
> >  	if (thread_info_flags & _TIF_UPROBE) {
> >  		clear_thread_flag(TIF_UPROBE);
> > +#ifdef CONFIG_X86_32
> > +		/*
> > +		 * On x86_32, do_notify_resume() gets called with
> > +		 * interrupts disabled. Hence enable interrupts if they
> > +		 * are still disabled.
> > +		 */
> > +		native_irq_enable();
> > +#endif
> >  		uprobe_notify_resume(regs);
> > +
> > +#ifdef CONFIG_X86_32
> > +		native_irq_disable();
> > +#endif
> 
> I'm no x86 port guru, but this looks rather worriesome to me.  Why does
> do_notify_resume have different calling conventions on 32 vs 64-bit?
> And if there is a good reason that 32-bit has them disabled, why is
> enabling them in the middle of do_notify_resume okay?

Thanks for bringing this up. I have no idea about why do_notify_resume()
gets called with interrupts disabled in 32 bit. I would be happy to know
the reason and rework based on inputs. I did query a few people about
this but I havent got an answer on why we they are disabled on 32 bit and
if its Okay to enable at this place. 

Ingo, Is there any person whom I could check with to get to know why the
interrupts are disabled on x86_32?

> 
> > +void arch_uprobe_disable_sstep(struct pt_regs *regs)
> > +{
> > +		/* Disable single-stepping by clearing what we set */
> > +		clear_thread_flag(TIF_SINGLESTEP);
> > +		clear_thread_flag(TIF_FORCED_TF);
> > +		regs->flags &= ~X86_EFLAGS_TF;
> > +}
> 
> This seems to have one layer of indentation too much.

Okay, I shall fix this in the next iteration.

--
Thanks and Regards
Srikar

Re: [PATCH v5 1/14] X86 instruction analysis: Move Macro W to insn.h

[Srikar Dronamraju]

* Christoph Hellwig <hch@infradead.org> [2010-06-14 13:39:26]:

> On Mon, Jun 14, 2010 at 01:58:03PM +0530, Srikar Dronamraju wrote:
> > move_W_to_insn.patch
> > 
> > From: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
> > 
> > Move Macro W to asm/insn.h
> > 
> > Macro W used to know if the instructions are valid for
> > user-space/kernel space.  This macro is used by kprobes and
> > user_bkpt. (i.e user space breakpoint assistance layer.) So moving it
> > to a common header file asm/insn.h.
> 
> I don't think W is a good name for a macro in a header file.

Agree, Masami has also given the same comment earlier, I plan to move to
using inat tables instead of this macro. 

--
Thanks and Regards
Srikar

Re: [PATCH v5 3/14] User Space Breakpoint Assistance Layer

[Srikar Dronamraju]

* Christoph Hellwig <hch@infradead.org> [2010-06-14 13:50:48]:

> On Mon, Jun 14, 2010 at 01:58:32PM +0530, Srikar Dronamraju wrote:
> > TODO: Merge user_bkpt layer with uprobes.
> 
> Yes, I don't think there's any point in that split.  What's the
> timeframe for you to finish that merge?

I will take this up in v6.

> 
> > +	depends on MODULES
> 
> This doesn't make too much sense - the only real user of this is not
> modular at all.

Okay. 

> 
> > +	depends on HAVE_USER_BKPT
> 
> Should this be ARCH_HAVE_USER_BKPT or similar?

Okay I shall change from HAVE_USER_BKPT to ARCH_HAVE_USER_BKPT.

--
Thanks and Regards
Srikar

Re: [PATCH v5 6/14] Uprobes Implementation

[Srikar Dronamraju]

* Randy Dunlap <randy.dunlap@oracle.com> [2010-06-14 07:27:06]:

> On Mon, 14 Jun 2010 13:59:03 +0530 Srikar Dronamraju wrote:
> 
> > diff --git a/arch/Kconfig b/arch/Kconfig
> > index 16541af..995f7f2 100644
> > --- a/arch/Kconfig
> > +++ b/arch/Kconfig
> > @@ -58,6 +58,16 @@ config USER_BKPT
> >  	  This service is used by components such as uprobes.
> >  	  If in doubt, say "N".
> >  
> > +config UPROBES
> > +	bool "User-space probes (EXPERIMENTAL)"
> > +	depends on MODULES && USER_BKPT_XOL
> 
> depends on having CONFIG_MODULES enabled.  Please explain.
> 

As Christoph suggested, I will remove the samples and hence the
dependency on CONFIG_MODULES.

Re: [PATCH v5 7/14] x86 support for Uprobes

[Oleg Nesterov]

On 06/15, Srikar Dronamraju wrote:
>
> * Christoph Hellwig <hch@infradead.org> [2010-06-14 13:54:23]:
>
> > On Mon, Jun 14, 2010 at 01:59:13PM +0530, Srikar Dronamraju wrote:
> > > @@ -850,7 +850,19 @@ do_notify_resume(struct pt_regs *regs, void *unused, __u32 thread_info_flags)
> > >
> > >  	if (thread_info_flags & _TIF_UPROBE) {
> > >  		clear_thread_flag(TIF_UPROBE);
> > > +#ifdef CONFIG_X86_32
> > > +		/*
> > > +		 * On x86_32, do_notify_resume() gets called with
> > > +		 * interrupts disabled. Hence enable interrupts if they
> > > +		 * are still disabled.
> > > +		 */
> > > +		native_irq_enable();
> > > +#endif
> > >  		uprobe_notify_resume(regs);
> > > +
> > > +#ifdef CONFIG_X86_32
> > > +		native_irq_disable();
> > > +#endif
> >
> > I'm no x86 port guru, but this looks rather worriesome to me.  Why does
> > do_notify_resume have different calling conventions on 32 vs 64-bit?
> > And if there is a good reason that 32-bit has them disabled, why is
> > enabling them in the middle of do_notify_resume okay?
>
> Thanks for bringing this up. I have no idea about why do_notify_resume()
> gets called with interrupts disabled in 32 bit.

Perhaps just because there is no reason to explicitly enable irqs?

> I would be happy to know
> the reason and rework based on inputs. I did query a few people about
> this but I havent got an answer on why we they are disabled on 32 bit and
> if its Okay to enable at this place.

I think it is OK to enable interrupts. do_notify_resume() calls do_signal()
which enables them anyway.

But there is another question I already asked. Why the code uses
native_irq_enable()? IIRC, you explained that local_irq_enable() doesn't
work for unkown reason. This is strange, and imho should be explained.

And I do not see a need to disable irqs again.

Oleg.

Re: [PATCH v5 7/14] x86 support for Uprobes

[Srikar Dronamraju]

> > >
> > > I'm no x86 port guru, but this looks rather worriesome to me.  Why does
> > > do_notify_resume have different calling conventions on 32 vs 64-bit?
> > > And if there is a good reason that 32-bit has them disabled, why is
> > > enabling them in the middle of do_notify_resume okay?
> >
> > Thanks for bringing this up. I have no idea about why do_notify_resume()
> > gets called with interrupts disabled in 32 bit.
> 
> Perhaps just because there is no reason to explicitly enable irqs?
> 
> > I would be happy to know
> > the reason and rework based on inputs. I did query a few people about
> > this but I havent got an answer on why we they are disabled on 32 bit and
> > if its Okay to enable at this place.
> 
> I think it is OK to enable interrupts. do_notify_resume() calls do_signal()
> which enables them anyway.
> 
> But there is another question I already asked. Why the code uses
> native_irq_enable()? IIRC, you explained that local_irq_enable() doesn't
> work for unkown reason. This is strange, and imho should be explained.
> 

local_irq_enable() translates to raw_local_irq_enable().
However raw_local_irq_enable on x86 seems to depend on CONFIG_PARAVIRT.
On a machine, where CONFIG_PARAVIRT was defined, local_irq_enable
translates to something other than native_irq_enable.
It translates to PVOP_VCALLEE0(pv_irq_ops.irq_enable);

Is it okay to use local_irq_enable() and then make CONFIG_UPROBES depend
on !CONFIG_PARAVIRT?



> And I do not see a need to disable irqs again.
> 
> Oleg.
> 

Re: [PATCH v5 7/14] x86 support for Uprobes

[Oleg Nesterov]

On 06/15, Srikar Dronamraju wrote:
>
> > I think it is OK to enable interrupts. do_notify_resume() calls do_signal()
> > which enables them anyway.
> >
> > But there is another question I already asked. Why the code uses
> > native_irq_enable()? IIRC, you explained that local_irq_enable() doesn't
> > work for unkown reason. This is strange, and imho should be explained.
>
> local_irq_enable() translates to raw_local_irq_enable().
> However raw_local_irq_enable on x86 seems to depend on CONFIG_PARAVIRT.
> On a machine, where CONFIG_PARAVIRT was defined, local_irq_enable
> translates to something other than native_irq_enable.
> It translates to PVOP_VCALLEE0(pv_irq_ops.irq_enable);

I see, and my question is why PVOP_VCALLEE0(pv_irq_ops.irq_enable) doesn't
work ? If it doesn't here, why it works for other callers of local_irq_enable?

I think we should ask paravirt developers.

> Is it okay to use local_irq_enable() and then make CONFIG_UPROBES depend
> on !CONFIG_PARAVIRT?

I dunno, and I know nothing about paravirt.

But please note that currently native_irq_enable has the only caller,
raw_local_irq_enable(). It is really strange that do_notify_resume()
has to use it, and it uses it to bypass the paravirt layer which perhaps
can introduce other problems.

Oleg.

Re: [PATCH v5 5/14] Slot allocation for execution out of line (XOL)

[Srikar Dronamraju]

* Christoph Hellwig <hch@infradead.org> [2010-06-14 13:52:27]:

> What's the point of adding another header for a few prototypes when
> all users include user_bkpt.h anyway?
> 

Okay, 

Should we be moving the user_bkpt_xol also into uprobes when we move the
user_bkpt layer into uprobes?

--
Thanks and Regards
Srikar

Re: [PATCH v5 3/14] User Space Breakpoint Assistance Layer

[Steven Rostedt]

On Mon, 2010-06-14 at 13:58 +0530, Srikar Dronamraju wrote:
> user_bkpt_core.patch
> 
> From: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
> 

> +/**
> + * user_bkpt_write_data - Write @nbytes from @kbuf at @vaddr in @tsk.
> + * Can be used to write to stack or data VM areas, but not instructions.
> + * Not exported, but available for use by arch-specific user_bkpt code.
> + * @tsk: The probed task
> + * @vaddr: Destination address, in user space.
> + * @kbuf: Source address, in kernel space to be read.

I'm curious. Anything prevent this from being called on instructions, or
is this just "Don't do that?". 

> + *
> + * Context: This function may sleep.
> + *
> + * Return number of bytes written.
> + */
> +unsigned long user_bkpt_write_data(struct task_struct *tsk,
> +				void __user *vaddr, const void *kbuf,
> +				unsigned long nbytes)
> +{
> +	unsigned long nleft;
> +
> +	if (tsk == current) {
> +		nleft = copy_to_user(vaddr, kbuf, nbytes);
> +		return nbytes - nleft;
> +	} else
> +		return access_process_vm(tsk, (unsigned long) vaddr,
> +						(void *) kbuf, nbytes, 1);
> +}
> +
> +static int write_opcode(struct task_struct *tsk, unsigned long vaddr,
> +						user_bkpt_opcode_t opcode)
> +{
> +	struct mm_struct *mm;
> +	struct vm_area_struct *vma;
> +	struct page *old_page, *new_page;
> +	void *vaddr_old, *vaddr_new;
> +	pte_t orig_pte;
> +	int ret = -EINVAL;
> +
> +	if (!tsk)
> +		return ret;
> +
> +	mm = get_task_mm(tsk);
> +	if (!mm)
> +		return ret;
> +
> +	down_read(&mm->mmap_sem);
> +
> +	/* Read the page with vaddr into memory */
> +	ret = get_user_pages(tsk, mm, vaddr, 1, 1, 1, &old_page, &vma);
> +	if (ret <= 0)
> +		goto mmput_out;
> +
> +	/*
> +	 * check if the page we are interested is read-only mapped
> +	 * Since we are interested in text pages, Our pages of interest
> +	 * should be mapped read-only.
> +	 */
> +	if ((vma->vm_flags && (VM_READ|VM_WRITE)) != VM_READ) {
> +		ret = -EINVAL;
> +		goto put_out;
> +	}
> +
> +	/* If its VM_SHARED vma, lets not write to such vma's.  */
> +	if (vma->vm_flags & VM_SHARED) {
> +		ret = -EINVAL;
> +		goto put_out;
> +	}
> +
> +	/* Allocate a page */
> +	new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, vaddr);
> +	if (!new_page) {
> +		ret = -ENOMEM;
> +		goto put_out;
> +	}
> +
> +	/*
> +	 * lock page will serialize against do_wp_page()'s
> +	 * PageAnon() handling
> +	 */
> +	lock_page(old_page);
> +	/* mark page RO so any concurrent access will end up in do_wp_page() */
> +	if (write_protect_page(vma, old_page, &orig_pte))
> +		goto unlock_out;
> +
> +	/* copy the page now that we've got it stable */
> +	vaddr_old = kmap_atomic(old_page, KM_USER0);
> +	vaddr_new = kmap_atomic(new_page, KM_USER1);
> +
> +	memcpy(vaddr_new, vaddr_old, PAGE_SIZE);
> +	/* poke the new insn in, ASSUMES we don't cross page boundary */
> +	vaddr = vaddr & (PAGE_SIZE - 1);

This should probably be vaddr = vaddr & ~PAGE_MASK;


-- Steve

> +	memcpy(vaddr_new + vaddr, &opcode, user_bkpt_opcode_sz);
> +
> +	kunmap_atomic(vaddr_new, KM_USER1);
> +	kunmap_atomic(vaddr_old, KM_USER0);
> +
> +	lock_page(new_page);
> +	/* flip pages, do_wp_page() will fail pte_same() and bail */
> +	ret = replace_page(vma, old_page, new_page, orig_pte);
> +
> +unlock_out:
> +	unlock_page(new_page);
> +	unlock_page(old_page);
> +	if (ret != 0)
> +		page_cache_release(new_page);
> +
> +put_out:
> +	put_page(old_page); /* we did a get_page in the beginning */
> +
> +mmput_out:
> +	up_read(&mm->mmap_sem);
> +	mmput(mm);
> +	return ret;
> +}
> +

Re: [PATCH v5 7/14] x86 support for Uprobes

[Steven Rostedt]

On Tue, 2010-06-15 at 17:45 +0530, Srikar Dronamraju wrote:

> local_irq_enable() translates to raw_local_irq_enable().
> However raw_local_irq_enable on x86 seems to depend on CONFIG_PARAVIRT.
> On a machine, where CONFIG_PARAVIRT was defined, local_irq_enable
> translates to something other than native_irq_enable.
> It translates to PVOP_VCALLEE0(pv_irq_ops.irq_enable);
> 
> Is it okay to use local_irq_enable() and then make CONFIG_UPROBES depend
> on !CONFIG_PARAVIRT?
> 

It should still work under paravirt. If it does not, we need to figurure
out why.

On boot up, when CONFIG_PARAVIRT is set but the kernel is running on
bare metal, a lot of the calls to things like "pv_irq_ops.irq_enabled"
are converted to the native caller anyway. Perhaps the conversion messed
up?

-- Steve

Re: [PATCH v5 10/14] trace: Common code for kprobes/uprobes traceevents

[Steven Rostedt]

On Mon, 2010-06-14 at 13:59 +0530, Srikar Dronamraju wrote:
> share_traceevents.patch.
> 
> From: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
> 
> Changelog from v5: Addressed comments from Masami.
>         Also shared lot more code from kprobes traceevents.
> 
> Move common parts of trace_kprobe.c and trace_uprobec.
> Adjust kernel/trace/trace_kprobe.c after moving common code to
> kernel/trace/trace_probe.h. However they still have few duplicate
> functions.
> 
> TODO: Merge both events to a single probe event.
> 
> Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
> ---
> 
>  kernel/trace/trace_kprobe.c |  141 +--------------------------------------
>  kernel/trace/trace_probe.h  |  157 +++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 161 insertions(+), 137 deletions(-)
>  create mode 100644 kernel/trace/trace_probe.h
> 

> diff --git a/kernel/trace/trace_probe.h b/kernel/trace/trace_probe.h
> new file mode 100644
> index 0000000..b4c5763
> --- /dev/null
> +++ b/kernel/trace/trace_probe.h
> @@ -0,0 +1,157 @@
> +/*
> + * Common header file for probe-based Dynamic events.
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program; if not, write to the Free Software
> + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
> + *
> + * Copyright (C) IBM Corporation, 2010
> + * Author:	Srikar Dronamraju

Note, when moving stuff from one file to another, you still need to keep
the copyright and author of the original file. You can add your name and
copyright as well, when you add your stuff to it.

-- Steve

Re: [PATCH v5 3/14] User Space Breakpoint Assistance Layer

[Steven Rostedt]

On Mon, 2010-06-14 at 13:40 -0400, Christoph Hellwig wrote:
> On Mon, Jun 14, 2010 at 01:58:32PM +0530, Srikar Dronamraju wrote:
> > User Space Breakpoint Assistance Layer (USER_BKPT)
> > Changelog from V3: (reimplement background page replacement)
> > 	* Replemented background page replacement based on inputs
> > 	  from Peter Zijlstra.
> > 
> > Changelog from v2: (addressing comments from Oleg)
> 
> FYI the changelog should be under the --- marker so that it doesn't
> get included into the final commit message.
> 

Actually, I find the version'ing of a patch in the changelog useful. It
gives a bit of history to how the patch was created.

-- Steve

Re: [PATCH v5 11/14] trace: uprobes trace_event interface

[Steven Rostedt]

On Mon, 2010-06-14 at 14:00 +0530, Srikar Dronamraju wrote:

> +config UPROBE_EVENT
> +	depends on UPROBES
> +	bool "Enable uprobes-based dynamic events"
> +	select TRACING
> +	default y

Why is this default y?

-- Steve

> +	help
> +	  This allows the user to add tracing events on top of userspace dynamic
> +	  events (similar to tracepoints) on the fly via the traceevents interface.
> +	  Those events can be inserted wherever uprobes can probe, and record
> +	  various registers.
> +	  This option is required if you plan to use perf-probe subcommand of perf
> +	  tools on user space applications.
> +
>  endif # FTRACE
>  
>  

Re: [PATCH v5 11/14] trace: uprobes trace_event interface

[Srikar Dronamraju]

> 
> > +config UPROBE_EVENT
> > +	depends on UPROBES
> > +	bool "Enable uprobes-based dynamic events"
> > +	select TRACING
> > +	default y
> 
> Why is this default y?

As you see UPROBE_EVENT is gated on UPROBES. I think if UPROBES is
enabled, then UPROBE_EVENT should be enabled. Esp with Christoph
suggesting for module support to be removed, I think it becomes all the
more reason for UPROBE_EVENT to be enabled by default. Otherwise there
is no point in having uprobes code and having no enabled users.
I was even looking at "select UPROBE_EVENT" on enabling UPROBES.

Do you have any specific reason why UPROBE_EVENT should not be enabled
by default? 


--
Thanks and Regards
Srikar

Re: [PATCH v5 3/14] User Space Breakpoint Assistance Layer

[Srikar Dronamraju]

> > +/**
> > + * user_bkpt_write_data - Write @nbytes from @kbuf at @vaddr in @tsk.
> > + * Can be used to write to stack or data VM areas, but not instructions.
> > + * Not exported, but available for use by arch-specific user_bkpt code.
> > + * @tsk: The probed task
> > + * @vaddr: Destination address, in user space.
> > + * @kbuf: Source address, in kernel space to be read.
> 
> I'm curious. Anything prevent this from being called on instructions, or
> is this just "Don't do that?". 
> 

Both, 
copy_to_user doesnt work on writes to text.
And if I am right, copy_to_user isnt preferred while writing to text
pages too.

> > +
> > +	memcpy(vaddr_new, vaddr_old, PAGE_SIZE);
> > +	/* poke the new insn in, ASSUMES we don't cross page boundary */
> > +	vaddr = vaddr & (PAGE_SIZE - 1);
> 
> This should probably be vaddr = vaddr & ~PAGE_MASK;

Okay, I will make the corresponding change.
> 
> 

Re: [PATCH v5 10/14] trace: Common code for kprobes/uprobes traceevents

[Srikar Dronamraju]

* Steven Rostedt <rostedt@goodmis.org> [2010-06-21 10:18:19]:

> On Mon, 2010-06-14 at 13:59 +0530, Srikar Dronamraju wrote:
> > share_traceevents.patch.
> > 
> > From: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
> > 
> > Changelog from v5: Addressed comments from Masami.
> >         Also shared lot more code from kprobes traceevents.
> > 
> > Move common parts of trace_kprobe.c and trace_uprobec.
> > Adjust kernel/trace/trace_kprobe.c after moving common code to
> > kernel/trace/trace_probe.h. However they still have few duplicate
> > functions.
> > 
> > TODO: Merge both events to a single probe event.
> > 
> > Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
> > ---
> > 
> >  kernel/trace/trace_kprobe.c |  141 +--------------------------------------
> >  kernel/trace/trace_probe.h  |  157 +++++++++++++++++++++++++++++++++++++++++++
> >  2 files changed, 161 insertions(+), 137 deletions(-)
> >  create mode 100644 kernel/trace/trace_probe.h
> > 
> 
> > diff --git a/kernel/trace/trace_probe.h b/kernel/trace/trace_probe.h
> > new file mode 100644
> > index 0000000..b4c5763
> > --- /dev/null
> > +++ b/kernel/trace/trace_probe.h
> > @@ -0,0 +1,157 @@
> > +/*
> > + * Common header file for probe-based Dynamic events.
> > + *
> > + * This program is free software; you can redistribute it and/or modify
> > + * it under the terms of the GNU General Public License version 2 as
> > + * published by the Free Software Foundation.
> > + *
> > + * This program is distributed in the hope that it will be useful,
> > + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> > + * GNU General Public License for more details.
> > + *
> > + * You should have received a copy of the GNU General Public License
> > + * along with this program; if not, write to the Free Software
> > + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
> > + *
> > + * Copyright (C) IBM Corporation, 2010
> > + * Author:	Srikar Dronamraju
> 
> Note, when moving stuff from one file to another, you still need to keep
> the copyright and author of the original file. You can add your name and
> copyright as well, when you add your stuff to it.

Okay .. will modify as suggested by you.

--
Thanks and Regards
Srikar
> 
> -- Steve
> 
> 

Re: [PATCH v5 11/14] trace: uprobes trace_event interface

[Christoph Hellwig]

On Tue, Jun 22, 2010 at 09:45:29AM +0530, Srikar Dronamraju wrote:
> As you see UPROBE_EVENT is gated on UPROBES. I think if UPROBES is
> enabled, then UPROBE_EVENT should be enabled. Esp with Christoph
> suggesting for module support to be removed, I think it becomes all the
> more reason for UPROBE_EVENT to be enabled by default. Otherwise there
> is no point in having uprobes code and having no enabled users.
> I was even looking at "select UPROBE_EVENT" on enabling UPROBES.
> 
> Do you have any specific reason why UPROBE_EVENT should not be enabled
> by default? 

default y generally is a big hammer.  But given that it depends on
UPROBES it might be fine here.  Then again the big question is why
we even bother with separate config options?  At least in this form
UPROBES just is supported for UPROBE_EVENT.  So it makes sense either
to remove the UPROBES option entirely, or at least make it invisible
to the user and let UPROBE_EVENT select it.