From: Sven Schnelle <svens@stackframe.org>
To: deller@gmx.de
Cc: linux-parisc@vger.kernel.org, Sven Schnelle <svens@stackframe.org>
Subject: [PATCH v2 6/6] parisc: add dynamic ftrace
Date: Tue, 4 Jun 2019 20:34:35 +0200 [thread overview]
Message-ID: <20190604183435.20175-7-svens@stackframe.org> (raw)
In-Reply-To: <20190604183435.20175-1-svens@stackframe.org>
This patch implements dynamic ftrace for PA-RISC. The required mcount
call sequences can get pretty long, so instead of patching the
whole call sequence out of the functions, we are using
-fpatchable-function-entry from gcc. This puts a configurable amount of
NOPS before/at the start of the function. Taking do_sys_open() as example,
which would look like this when the call is patched out:
1036b248: 08 00 02 40 nop
1036b24c: 08 00 02 40 nop
1036b250: 08 00 02 40 nop
1036b254: 08 00 02 40 nop
1036b258 <do_sys_open>:
1036b258: 08 00 02 40 nop
1036b25c: 08 03 02 41 copy r3,r1
1036b260: 6b c2 3f d9 stw rp,-14(sp)
1036b264: 08 1e 02 43 copy sp,r3
1036b268: 6f c1 01 00 stw,ma r1,80(sp)
When ftrace gets enabled for this function the kernel will patch these
NOPs to:
1036b248: 10 19 57 20 <address of ftrace>
1036b24c: 6f c1 00 80 stw,ma r1,40(sp)
1036b250: 48 21 3f d1 ldw -18(r1),r1
1036b254: e8 20 c0 02 bv,n r0(r1)
1036b258 <do_sys_open>:
1036b258: e8 3f 1f df b,l,n .-c,r1
1036b25c: 08 03 02 41 copy r3,r1
1036b260: 6b c2 3f d9 stw rp,-14(sp)
1036b264: 08 1e 02 43 copy sp,r3
1036b268: 6f c1 01 00 stw,ma r1,80(sp)
So the first NOP in do_sys_open() will be patched to jump backwards into
some minimal trampoline code which pushes a stackframe, saves r1 which
holds the return address, loads the address of the real ftrace function,
and branches to that location. For 64 Bit things are getting a bit more
complicated (and longer) because we must make sure that the address of
ftrace location is 8 byte aligned, and the offset passed to ldd for
fetching the address is 8 byte aligned as well.
Note that gcc has a bug which misplaces the function label, and needs a
patch to make dynamic ftrace work. See
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90751 for details.
Signed-off-by: Sven Schnelle <svens@stackframe.org>
---
arch/parisc/Kconfig | 2 +
arch/parisc/Makefile | 18 +++++
arch/parisc/include/asm/ftrace.h | 15 +++-
arch/parisc/kernel/Makefile | 9 ++-
arch/parisc/kernel/entry.S | 64 +++++++++++++++
arch/parisc/kernel/ftrace.c | 129 +++++++++++++++++++++++++++---
arch/parisc/kernel/module.c | 20 ++++-
arch/parisc/kernel/module.lds | 7 ++
arch/parisc/kernel/vmlinux.lds.S | 2 +
arch/parisc/mm/fixmap.c | 4 +-
include/asm-generic/vmlinux.lds.h | 7 ++
11 files changed, 259 insertions(+), 18 deletions(-)
create mode 100644 arch/parisc/kernel/module.lds
diff --git a/arch/parisc/Kconfig b/arch/parisc/Kconfig
index 4860efa91d7b..42875ff15671 100644
--- a/arch/parisc/Kconfig
+++ b/arch/parisc/Kconfig
@@ -59,6 +59,8 @@ config PARISC
select HAVE_ARCH_KGDB
select HAVE_KPROBES
select HAVE_KRETPROBES
+ select HAVE_DYNAMIC_FTRACE if $(cc-option,-fpatchable-function-entry=1,1)
+ select HAVE_FTRACE_MCOUNT_RECORD if HAVE_DYNAMIC_FTRACE
help
The PA-RISC microprocessor is designed by Hewlett-Packard and used
diff --git a/arch/parisc/Makefile b/arch/parisc/Makefile
index c19af26febe6..58d46665cad9 100644
--- a/arch/parisc/Makefile
+++ b/arch/parisc/Makefile
@@ -47,6 +47,24 @@ ifneq ($(SUBARCH),$(UTS_MACHINE))
endif
endif
+ifdef CONFIG_DYNAMIC_FTRACE
+ifdef CONFIG_64BIT
+NOP_COUNT := 8
+else
+NOP_COUNT := 5
+endif
+
+export CC_USING_RECORD_MCOUNT:=1
+export CC_USING_PATCHABLE_FUNCTION_ENTRY:=1
+
+KBUILD_AFLAGS += -DCC_USING_PATCHABLE_FUNCTION_ENTRY=1
+KBUILD_CFLAGS += -DCC_USING_PATCHABLE_FUNCTION_ENTRY=1 \
+ -DFTRACE_PATCHABLE_FUNCTION_SIZE=$(NOP_COUNT)
+
+CC_FLAGS_FTRACE := -fpatchable-function-entry=$(NOP_COUNT),$(shell echo $$(($(NOP_COUNT)-1)))
+KBUILD_LDFLAGS_MODULE += -T $(srctree)/arch/parisc/kernel/module.lds
+endif
+
OBJCOPY_FLAGS =-O binary -R .note -R .comment -S
cflags-y := -pipe
diff --git a/arch/parisc/include/asm/ftrace.h b/arch/parisc/include/asm/ftrace.h
index 42b2c75a1645..958c0aa5dbb2 100644
--- a/arch/parisc/include/asm/ftrace.h
+++ b/arch/parisc/include/asm/ftrace.h
@@ -5,12 +5,23 @@
#ifndef __ASSEMBLY__
extern void mcount(void);
-#define MCOUNT_INSN_SIZE 4
-
+#define MCOUNT_ADDR ((unsigned long)mcount)
+#define MCOUNT_INSN_SIZE 4
+#define CC_USING_NOP_MCOUNT
extern unsigned long sys_call_table[];
extern unsigned long return_address(unsigned int);
+#ifdef CONFIG_DYNAMIC_FTRACE
+extern void ftrace_caller(void);
+
+struct dyn_arch_ftrace {
+};
+
+unsigned long ftrace_call_adjust(unsigned long addr);
+
+#endif
+
#define ftrace_return_address(n) return_address(n)
#endif /* __ASSEMBLY__ */
diff --git a/arch/parisc/kernel/Makefile b/arch/parisc/kernel/Makefile
index fc0df5c44468..c232266b517c 100644
--- a/arch/parisc/kernel/Makefile
+++ b/arch/parisc/kernel/Makefile
@@ -14,10 +14,11 @@ obj-y := cache.o pacache.o setup.o pdt.o traps.o time.o irq.o \
ifdef CONFIG_FUNCTION_TRACER
# Do not profile debug and lowlevel utilities
-CFLAGS_REMOVE_ftrace.o = -pg
-CFLAGS_REMOVE_cache.o = -pg
-CFLAGS_REMOVE_perf.o = -pg
-CFLAGS_REMOVE_unwind.o = -pg
+CFLAGS_REMOVE_ftrace.o = $(CC_FLAGS_FTRACE)
+CFLAGS_REMOVE_cache.o = $(CC_FLAGS_FTRACE)
+CFLAGS_REMOVE_perf.o = $(CC_FLAGS_FTRACE)
+CFLAGS_REMOVE_unwind.o = $(CC_FLAGS_FTRACE)
+CFLAGS_REMOVE_patch.o = $(CC_FLAGS_FTRACE)
endif
obj-$(CONFIG_SMP) += smp.o
diff --git a/arch/parisc/kernel/entry.S b/arch/parisc/kernel/entry.S
index a1fc04570ade..c246cefa0737 100644
--- a/arch/parisc/kernel/entry.S
+++ b/arch/parisc/kernel/entry.S
@@ -2025,6 +2025,70 @@ ftrace_stub:
#endif
ENDPROC_CFI(mcount)
+#ifdef CONFIG_DYNAMIC_FTRACE
+
+#ifdef CONFIG_64BIT
+#define FTRACE_FRAME_SIZE (2*FRAME_SIZE)
+#else
+#define FTRACE_FRAME_SIZE FRAME_SIZE
+#endif
+ENTRY_CFI(ftrace_caller, caller,frame=FTRACE_FRAME_SIZE,CALLS,SAVE_RP,SAVE_SP)
+ftrace_caller:
+ .global ftrace_caller
+
+ STREG %r3, -FTRACE_FRAME_SIZE+1*REG_SZ(%sp)
+ ldo -FTRACE_FRAME_SIZE(%sp), %r3
+ STREG %rp, -RP_OFFSET(%r3)
+
+ /* Offset 0 is already allocated for %r1 */
+ STREG %r23, 2*REG_SZ(%r3)
+ STREG %r24, 3*REG_SZ(%r3)
+ STREG %r25, 4*REG_SZ(%r3)
+ STREG %r26, 5*REG_SZ(%r3)
+ STREG %r28, 6*REG_SZ(%r3)
+ STREG %r29, 7*REG_SZ(%r3)
+#ifdef CONFIG_64BIT
+ STREG %r19, 8*REG_SZ(%r3)
+ STREG %r20, 9*REG_SZ(%r3)
+ STREG %r21, 10*REG_SZ(%r3)
+ STREG %r22, 11*REG_SZ(%r3)
+ STREG %r27, 12*REG_SZ(%r3)
+ STREG %r31, 13*REG_SZ(%r3)
+ loadgp
+ ldo -16(%sp),%r29
+#endif
+ LDREG 0(%r3), %r25
+ copy %rp, %r26
+ ldo -8(%r25), %r25
+ b,l ftrace_function_trampoline, %rp
+ copy %r3, %r24
+
+ LDREG -RP_OFFSET(%r3), %rp
+ LDREG 2*REG_SZ(%r3), %r23
+ LDREG 3*REG_SZ(%r3), %r24
+ LDREG 4*REG_SZ(%r3), %r25
+ LDREG 5*REG_SZ(%r3), %r26
+ LDREG 6*REG_SZ(%r3), %r28
+ LDREG 7*REG_SZ(%r3), %r29
+#ifdef CONFIG_64BIT
+ LDREG 8*REG_SZ(%r3), %r19
+ LDREG 9*REG_SZ(%r3), %r20
+ LDREG 10*REG_SZ(%r3), %r21
+ LDREG 11*REG_SZ(%r3), %r22
+ LDREG 12*REG_SZ(%r3), %r27
+ LDREG 13*REG_SZ(%r3), %r31
+#endif
+ LDREG 1*REG_SZ(%r3), %r3
+
+ LDREGM -FTRACE_FRAME_SIZE(%sp), %r1
+ /* Adjust return point to jump back to beginning of traced function */
+ ldo -4(%r1), %r1
+ bv,n (%r1)
+
+ENDPROC_CFI(ftrace_caller)
+
+#endif
+
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
.align 8
ENTRY_CFI(return_to_handler, caller,frame=FRAME_SIZE)
diff --git a/arch/parisc/kernel/ftrace.c b/arch/parisc/kernel/ftrace.c
index a28f915993b1..d784ccdd8fef 100644
--- a/arch/parisc/kernel/ftrace.c
+++ b/arch/parisc/kernel/ftrace.c
@@ -7,17 +7,17 @@
* Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
*
* future possible enhancements:
- * - add CONFIG_DYNAMIC_FTRACE
* - add CONFIG_STACK_TRACER
*/
#include <linux/init.h>
#include <linux/ftrace.h>
+#include <linux/uaccess.h>
#include <asm/assembly.h>
#include <asm/sections.h>
#include <asm/ftrace.h>
-
+#include <asm/patch.h>
#define __hot __attribute__ ((__section__ (".text.hot")))
@@ -50,13 +50,11 @@ void notrace __hot ftrace_function_trampoline(unsigned long parent,
unsigned long self_addr,
unsigned long org_sp_gr3)
{
- extern ftrace_func_t ftrace_trace_function; /* depends on CONFIG_DYNAMIC_FTRACE */
-
- if (ftrace_trace_function != ftrace_stub) {
- /* struct ftrace_ops *op, struct pt_regs *regs); */
- ftrace_trace_function(parent, self_addr, NULL, NULL);
- return;
- }
+#ifndef CONFIG_DYNAMIC_FTRACE
+ extern ftrace_func_t ftrace_trace_function;
+#endif
+ if (ftrace_trace_function != ftrace_stub)
+ ftrace_trace_function(self_addr, parent, NULL, NULL);
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
if (ftrace_graph_return != (trace_func_graph_ret_t) ftrace_stub ||
@@ -75,3 +73,116 @@ void notrace __hot ftrace_function_trampoline(unsigned long parent,
#endif
}
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+int ftrace_enable_ftrace_graph_caller(void)
+{
+ return 0;
+}
+
+int ftrace_disable_ftrace_graph_caller(void)
+{
+ return 0;
+}
+#endif
+
+#ifdef CONFIG_DYNAMIC_FTRACE
+
+int __init ftrace_dyn_arch_init(void)
+{
+ return 0;
+}
+int ftrace_update_ftrace_func(ftrace_func_t func)
+{
+ return 0;
+}
+
+unsigned long ftrace_call_adjust(unsigned long addr)
+{
+ return addr+(FTRACE_PATCHABLE_FUNCTION_SIZE-1)*4;
+}
+
+int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
+{
+ u32 insn[FTRACE_PATCHABLE_FUNCTION_SIZE];
+ u32 *tramp;
+ int size, ret, i;
+ void *ip;
+
+#ifdef CONFIG_64BIT
+ unsigned long addr2 =
+ (unsigned long)dereference_function_descriptor((void *)addr);
+
+ u32 ftrace_trampoline[] = {
+ 0x73c10208, /* std,ma r1,100(sp) */
+ 0x0c2110c1, /* ldd -10(r1),r1 */
+ 0xe820d002, /* bve,n (r1) */
+ addr2 >> 32,
+ addr2 & 0xffffffff,
+ 0xe83f1fd7, /* b,l,n .-14,r1 */
+ };
+
+ u32 ftrace_trampoline_unaligned[] = {
+ addr2 >> 32,
+ addr2 & 0xffffffff,
+ 0x37de0200, /* ldo 100(sp),sp */
+ 0x73c13e01, /* std r1,-100(sp) */
+ 0x34213ff9, /* ldo -4(r1),r1 */
+ 0x50213fc1, /* ldd -20(r1),r1 */
+ 0xe820d002, /* bve,n (r1) */
+ 0xe83f1fcf, /* b,l,n .-20,r1 */
+ };
+
+ BUILD_BUG_ON(ARRAY_SIZE(ftrace_trampoline_unaligned) >
+ FTRACE_PATCHABLE_FUNCTION_SIZE);
+#else
+ u32 ftrace_trampoline[] = {
+ (u32)addr,
+ 0x6fc10080, /* stw,ma r1,40(sp) */
+ 0x48213fd1, /* ldw -18(r1),r1 */
+ 0xe820c002, /* bv,n r0(r1) */
+ 0xe83f1fdf, /* b,l,n .-c,r1 */
+ };
+#endif
+
+ BUILD_BUG_ON(ARRAY_SIZE(ftrace_trampoline) >
+ FTRACE_PATCHABLE_FUNCTION_SIZE);
+
+ size = sizeof(ftrace_trampoline);
+ tramp = ftrace_trampoline;
+
+#ifdef CONFIG_64BIT
+ if (rec->ip & 0x4) {
+ size = sizeof(ftrace_trampoline_unaligned);
+ tramp = ftrace_trampoline_unaligned;
+ }
+#endif
+
+ ip = (void *)(rec->ip + 4 - size);
+
+ ret = probe_kernel_read(insn, ip, size);
+ if (ret)
+ return ret;
+
+ for (i = 0; i < size / 4; i++) {
+ if (insn[i] != INSN_NOP)
+ return -EINVAL;
+ }
+
+ __patch_text_multiple(ip, tramp, size);
+ return 0;
+}
+
+int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec,
+ unsigned long addr)
+{
+ u32 insn[FTRACE_PATCHABLE_FUNCTION_SIZE];
+ int i;
+
+ for (i = 0; i < ARRAY_SIZE(insn); i++)
+ insn[i] = INSN_NOP;
+
+ __patch_text_multiple((void *)rec->ip + 4 - sizeof(insn),
+ insn, sizeof(insn));
+ return 0;
+}
+#endif
diff --git a/arch/parisc/kernel/module.c b/arch/parisc/kernel/module.c
index 3ff3b48df6e6..ed6640527534 100644
--- a/arch/parisc/kernel/module.c
+++ b/arch/parisc/kernel/module.c
@@ -873,6 +873,7 @@ int module_finalize(const Elf_Ehdr *hdr,
const char *strtab = NULL;
const Elf_Shdr *s;
char *secstrings;
+ int err, symindex = -1;
Elf_Sym *newptr, *oldptr;
Elf_Shdr *symhdr = NULL;
#ifdef DEBUG
@@ -899,6 +900,7 @@ int module_finalize(const Elf_Ehdr *hdr,
if(sechdrs[i].sh_type == SHT_SYMTAB
&& (sechdrs[i].sh_flags & SHF_ALLOC)) {
int strindex = sechdrs[i].sh_link;
+ symindex = i;
/* FIXME: AWFUL HACK
* The cast is to drop the const from
* the sechdrs pointer */
@@ -954,8 +956,24 @@ int module_finalize(const Elf_Ehdr *hdr,
if (!strcmp(".altinstructions", secname))
/* patch .altinstructions */
apply_alternatives(aseg, aseg + s->sh_size, me->name);
- }
+ /* For 32 bit kernels we're compiling modules with
+ * -ffunction-sections so we must relocate the addresses in the
+ *__mcount_loc section.
+ */
+ if (symindex != -1 && !strcmp(secname, "__mcount_loc")) {
+ if (s->sh_type == SHT_REL)
+ err = apply_relocate((Elf_Shdr *)sechdrs,
+ strtab, symindex,
+ s - sechdrs, me);
+ else if (s->sh_type == SHT_RELA)
+ err = apply_relocate_add((Elf_Shdr *)sechdrs,
+ strtab, symindex,
+ s - sechdrs, me);
+ if (err)
+ return err;
+ }
+ }
return 0;
}
diff --git a/arch/parisc/kernel/module.lds b/arch/parisc/kernel/module.lds
new file mode 100644
index 000000000000..1a9a92aca5c8
--- /dev/null
+++ b/arch/parisc/kernel/module.lds
@@ -0,0 +1,7 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+SECTIONS {
+ __mcount_loc : {
+ *(__patchable_function_entries)
+ }
+}
diff --git a/arch/parisc/kernel/vmlinux.lds.S b/arch/parisc/kernel/vmlinux.lds.S
index cd33b4feacb1..99cd24f2ea01 100644
--- a/arch/parisc/kernel/vmlinux.lds.S
+++ b/arch/parisc/kernel/vmlinux.lds.S
@@ -18,6 +18,8 @@
*(.data..vm0.pgd) \
*(.data..vm0.pte)
+#define CC_USING_PATCHABLE_FUNCTION_ENTRY
+
#include <asm-generic/vmlinux.lds.h>
/* needed for the processor specific cache alignment size */
diff --git a/arch/parisc/mm/fixmap.c b/arch/parisc/mm/fixmap.c
index 36321bcd75ba..474cd241c150 100644
--- a/arch/parisc/mm/fixmap.c
+++ b/arch/parisc/mm/fixmap.c
@@ -10,7 +10,7 @@
#include <asm/cacheflush.h>
#include <asm/fixmap.h>
-void set_fixmap(enum fixed_addresses idx, phys_addr_t phys)
+void notrace set_fixmap(enum fixed_addresses idx, phys_addr_t phys)
{
unsigned long vaddr = __fix_to_virt(idx);
pgd_t *pgd = pgd_offset_k(vaddr);
@@ -28,7 +28,7 @@ void set_fixmap(enum fixed_addresses idx, phys_addr_t phys)
flush_tlb_kernel_range(vaddr, vaddr + PAGE_SIZE);
}
-void clear_fixmap(enum fixed_addresses idx)
+void notrace clear_fixmap(enum fixed_addresses idx)
{
unsigned long vaddr = __fix_to_virt(idx);
pgd_t *pgd = pgd_offset_k(vaddr);
diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index 088987e9a3ea..ca42182992a5 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -110,10 +110,17 @@
#endif
#ifdef CONFIG_FTRACE_MCOUNT_RECORD
+#ifdef CC_USING_PATCHABLE_FUNCTION_ENTRY
+#define MCOUNT_REC() . = ALIGN(8); \
+ __start_mcount_loc = .; \
+ KEEP(*(__patchable_function_entries)) \
+ __stop_mcount_loc = .;
+#else
#define MCOUNT_REC() . = ALIGN(8); \
__start_mcount_loc = .; \
KEEP(*(__mcount_loc)) \
__stop_mcount_loc = .;
+#endif
#else
#define MCOUNT_REC()
#endif
--
2.20.1
prev parent reply other threads:[~2019-06-04 18:35 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-04 18:34 [PATCH v2 0/6] Dynamic FTRACE for PA-RISC Sven Schnelle
2019-06-04 18:34 ` [PATCH v2 1/6] parisc: add support for patching multiple words Sven Schnelle
2019-06-04 19:21 ` Rolf Eike Beer
2019-06-05 20:21 ` Sven Schnelle
2019-06-04 18:34 ` [PATCH v2 2/6] parisc: add spinlock to patch function Sven Schnelle
2019-06-04 18:34 ` [PATCH v2 3/6] parisc: add WARN_ON() to clear_fixmap Sven Schnelle
2019-06-04 18:34 ` [PATCH v2 4/6] parisc: use pr_debug() in kernel/module.c Sven Schnelle
2019-06-04 18:34 ` [PATCH v2 5/6] compiler.h: add CC_USING_PATCHABLE_FUNCTION_ENTRY Sven Schnelle
2019-06-04 18:34 ` Sven Schnelle [this message]
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