[for-next][PATCH 00/13] tracing: Some more last minute changes and fixes

[for-next][PATCH 00/13] tracing: Some more last minute changes and fixes

[Steven Rostedt]

  git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace.git
for-next

Head SHA1: b9416997603ef7e17d4de10b6408f19da2feb72c


Anders Roxell (1):
      tracing: Allow RCU to run between postponed startup tests

Colin Ian King (1):
      tracing: Fix white space issues in parse_pred() function

Elazar Leibovich (1):
      tracing: Fix partial reading of trace event's id file

Gustavo A. R. Silva (1):
      tracing: Replace kzalloc with kcalloc

Josh Poimboeuf (1):
      x86_64: Add gap to int3 to allow for call emulation

Masami Hiramatsu (3):
      tracing: uprobes: Re-enable $comm support for uprobe events
      tracing: probeevent: Do not accumulate on ret variable
      tracing: probeevent: Fix to make the type of $comm string

Peter Zijlstra (2):
      x86_64: Allow breakpoints to emulate call instructions
      ftrace/x86_64: Emulate call function while updating in breakpoint handler

Rasmus Villemoes (1):
      tracing: Eliminate const char[] auto variables

Srivatsa S. Bhat (VMware) (1):
      tracing: Fix documentation about disabling options using trace_options

Yangtao Li (1):
      ring-buffer: Fix mispelling of Calculate

----
 arch/x86/entry/entry_64.S            | 18 ++++++++++++--
 arch/x86/include/asm/text-patching.h | 28 +++++++++++++++++++++
 arch/x86/kernel/ftrace.c             | 32 ++++++++++++++++++++----
 kernel/trace/ftrace.c                |  2 +-
 kernel/trace/ring_buffer_benchmark.c |  2 +-
 kernel/trace/trace.c                 | 40 ++++++++++++++----------------
 kernel/trace/trace_events.c          |  3 ---
 kernel/trace/trace_events_filter.c   | 48 ++++++++++++++++++------------------
 kernel/trace/trace_probe.c           | 17 +++++++------
 kernel/trace/trace_probe.h           |  1 +
 kernel/trace/trace_probe_tmpl.h      |  2 +-
 kernel/trace/trace_uprobe.c          | 13 ++++++++--
 12 files changed, 137 insertions(+), 69 deletions(-)

[for-next][PATCH 01/13] x86_64: Add gap to int3 to allow for call emulation

[Steven Rostedt]

From: Josh Poimboeuf <jpoimboe@redhat.com>

To allow an int3 handler to emulate a call instruction, it must be able to
push a return address onto the stack. Add a gap to the stack to allow the
int3 handler to push the return address and change the return from int3 to
jump straight to the emulated called function target.

Link: http://lkml.kernel.org/r/20181130183917.hxmti5josgq4clti@treble
Link: http://lkml.kernel.org/r/20190502162133.GX2623@hirez.programming.kicks-ass.net

[
  Note, this is needed to allow Live Kernel Patching to not miss calling a
  patched function when tracing is enabled. -- Steven Rostedt
]

Cc: stable@vger.kernel.org
Fixes: b700e7f03df5 ("livepatch: kernel: add support for live patching")
Tested-by: Nicolai Stange <nstange@suse.de>
Reviewed-by: Nicolai Stange <nstange@suse.de>
Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
 arch/x86/entry/entry_64.S | 18 ++++++++++++++++--
 1 file changed, 16 insertions(+), 2 deletions(-)

diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index 1f0efdb7b629..27fcc6fbdd52 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -879,7 +879,7 @@ apicinterrupt IRQ_WORK_VECTOR			irq_work_interrupt		smp_irq_work_interrupt
  * @paranoid == 2 is special: the stub will never switch stacks.  This is for
  * #DF: if the thread stack is somehow unusable, we'll still get a useful OOPS.
  */
-.macro idtentry sym do_sym has_error_code:req paranoid=0 shift_ist=-1
+.macro idtentry sym do_sym has_error_code:req paranoid=0 shift_ist=-1 create_gap=0
 ENTRY(\sym)
 	UNWIND_HINT_IRET_REGS offset=\has_error_code*8
 
@@ -899,6 +899,20 @@ ENTRY(\sym)
 	jnz	.Lfrom_usermode_switch_stack_\@
 	.endif
 
+	.if \create_gap == 1
+	/*
+	 * If coming from kernel space, create a 6-word gap to allow the
+	 * int3 handler to emulate a call instruction.
+	 */
+	testb	$3, CS-ORIG_RAX(%rsp)
+	jnz	.Lfrom_usermode_no_gap_\@
+	.rept	6
+	pushq	5*8(%rsp)
+	.endr
+	UNWIND_HINT_IRET_REGS offset=8
+.Lfrom_usermode_no_gap_\@:
+	.endif
+
 	.if \paranoid
 	call	paranoid_entry
 	.else
@@ -1130,7 +1144,7 @@ apicinterrupt3 HYPERV_STIMER0_VECTOR \
 #endif /* CONFIG_HYPERV */
 
 idtentry debug			do_debug		has_error_code=0	paranoid=1 shift_ist=DEBUG_STACK
-idtentry int3			do_int3			has_error_code=0
+idtentry int3			do_int3			has_error_code=0	create_gap=1
 idtentry stack_segment		do_stack_segment	has_error_code=1
 
 #ifdef CONFIG_XEN_PV
-- 
2.20.1

[for-next][PATCH 02/13] x86_64: Allow breakpoints to emulate call instructions

[Steven Rostedt]

From: Peter Zijlstra <peterz@infradead.org>

In order to allow breakpoints to emulate call instructions, they need to push
the return address onto the stack. The x86_64 int3 handler adds a small gap
to allow the stack to grow some. Use this gap to add the return address to
be able to emulate a call instruction at the breakpoint location.

These helper functions are added:

  int3_emulate_jmp(): changes the location of the regs->ip to return there.

 (The next two are only for x86_64)
  int3_emulate_push(): to push the address onto the gap in the stack
  int3_emulate_call(): push the return address and change regs->ip

Cc: Andy Lutomirski <luto@kernel.org>
Cc: Nicolai Stange <nstange@suse.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: the arch/x86 maintainers <x86@kernel.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Jiri Kosina <jikos@kernel.org>
Cc: Miroslav Benes <mbenes@suse.cz>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Joe Lawrence <joe.lawrence@redhat.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Mimi Zohar <zohar@linux.ibm.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Nayna Jain <nayna@linux.ibm.com>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Joerg Roedel <jroedel@suse.de>
Cc: "open list:KERNEL SELFTEST FRAMEWORK" <linux-kselftest@vger.kernel.org>
Cc: stable@vger.kernel.org
Fixes: b700e7f03df5 ("livepatch: kernel: add support for live patching")
Tested-by: Nicolai Stange <nstange@suse.de>
Reviewed-by: Nicolai Stange <nstange@suse.de>
Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
[ Modified to only work for x86_64 and added comment to int3_emulate_push() ]
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
 arch/x86/include/asm/text-patching.h | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)

diff --git a/arch/x86/include/asm/text-patching.h b/arch/x86/include/asm/text-patching.h
index e85ff65c43c3..05861cc08787 100644
--- a/arch/x86/include/asm/text-patching.h
+++ b/arch/x86/include/asm/text-patching.h
@@ -39,4 +39,32 @@ extern int poke_int3_handler(struct pt_regs *regs);
 extern void *text_poke_bp(void *addr, const void *opcode, size_t len, void *handler);
 extern int after_bootmem;
 
+static inline void int3_emulate_jmp(struct pt_regs *regs, unsigned long ip)
+{
+	regs->ip = ip;
+}
+
+#define INT3_INSN_SIZE 1
+#define CALL_INSN_SIZE 5
+
+#ifdef CONFIG_X86_64
+static inline void int3_emulate_push(struct pt_regs *regs, unsigned long val)
+{
+	/*
+	 * The int3 handler in entry_64.S adds a gap between the
+	 * stack where the break point happened, and the saving of
+	 * pt_regs. We can extend the original stack because of
+	 * this gap. See the idtentry macro's create_gap option.
+	 */
+	regs->sp -= sizeof(unsigned long);
+	*(unsigned long *)regs->sp = val;
+}
+
+static inline void int3_emulate_call(struct pt_regs *regs, unsigned long func)
+{
+	int3_emulate_push(regs, regs->ip - INT3_INSN_SIZE + CALL_INSN_SIZE);
+	int3_emulate_jmp(regs, func);
+}
+#endif
+
 #endif /* _ASM_X86_TEXT_PATCHING_H */
-- 
2.20.1

[for-next][PATCH 03/13] ftrace/x86_64: Emulate call function while updating in breakpoint handler

[Steven Rostedt]

From: Peter Zijlstra <peterz@infradead.org>

Nicolai Stange discovered[1] that if live kernel patching is enabled, and the
function tracer started tracing the same function that was patched, the
conversion of the fentry call site during the translation of going from
calling the live kernel patch trampoline to the iterator trampoline, would
have as slight window where it didn't call anything.

As live kernel patching depends on ftrace to always call its code (to
prevent the function being traced from being called, as it will redirect
it). This small window would allow the old buggy function to be called, and
this can cause undesirable results.

Nicolai submitted new patches[2] but these were controversial. As this is
similar to the static call emulation issues that came up a while ago[3].
But after some debate[4][5] adding a gap in the stack when entering the
breakpoint handler allows for pushing the return address onto the stack to
easily emulate a call.

[1] http://lkml.kernel.org/r/20180726104029.7736-1-nstange@suse.de
[2] http://lkml.kernel.org/r/20190427100639.15074-1-nstange@suse.de
[3] http://lkml.kernel.org/r/3cf04e113d71c9f8e4be95fb84a510f085aa4afa.1541711457.git.jpoimboe@redhat.com
[4] http://lkml.kernel.org/r/CAHk-=wh5OpheSU8Em_Q3Hg8qw_JtoijxOdPtHru6d+5K8TWM=A@mail.gmail.com
[5] http://lkml.kernel.org/r/CAHk-=wjvQxY4DvPrJ6haPgAa6b906h=MwZXO6G8OtiTGe=N7_w@mail.gmail.com

[
  Live kernel patching is not implemented on x86_32, thus the emulate
  calls are only for x86_64.
]

Cc: Andy Lutomirski <luto@kernel.org>
Cc: Nicolai Stange <nstange@suse.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: the arch/x86 maintainers <x86@kernel.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Jiri Kosina <jikos@kernel.org>
Cc: Miroslav Benes <mbenes@suse.cz>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Joe Lawrence <joe.lawrence@redhat.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Mimi Zohar <zohar@linux.ibm.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Nayna Jain <nayna@linux.ibm.com>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Joerg Roedel <jroedel@suse.de>
Cc: "open list:KERNEL SELFTEST FRAMEWORK" <linux-kselftest@vger.kernel.org>
Cc: stable@vger.kernel.org
Fixes: b700e7f03df5 ("livepatch: kernel: add support for live patching")
Tested-by: Nicolai Stange <nstange@suse.de>
Reviewed-by: Nicolai Stange <nstange@suse.de>
Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
[ Changed to only implement emulated calls for x86_64 ]
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
 arch/x86/kernel/ftrace.c | 32 +++++++++++++++++++++++++++-----
 1 file changed, 27 insertions(+), 5 deletions(-)

diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
index ef49517f6bb2..bd553b3af22e 100644
--- a/arch/x86/kernel/ftrace.c
+++ b/arch/x86/kernel/ftrace.c
@@ -29,6 +29,7 @@
 #include <asm/kprobes.h>
 #include <asm/ftrace.h>
 #include <asm/nops.h>
+#include <asm/text-patching.h>
 
 #ifdef CONFIG_DYNAMIC_FTRACE
 
@@ -231,6 +232,7 @@ int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr,
 }
 
 static unsigned long ftrace_update_func;
+static unsigned long ftrace_update_func_call;
 
 static int update_ftrace_func(unsigned long ip, void *new)
 {
@@ -259,6 +261,8 @@ int ftrace_update_ftrace_func(ftrace_func_t func)
 	unsigned char *new;
 	int ret;
 
+	ftrace_update_func_call = (unsigned long)func;
+
 	new = ftrace_call_replace(ip, (unsigned long)func);
 	ret = update_ftrace_func(ip, new);
 
@@ -294,13 +298,28 @@ int ftrace_int3_handler(struct pt_regs *regs)
 	if (WARN_ON_ONCE(!regs))
 		return 0;
 
-	ip = regs->ip - 1;
-	if (!ftrace_location(ip) && !is_ftrace_caller(ip))
-		return 0;
+	ip = regs->ip - INT3_INSN_SIZE;
 
-	regs->ip += MCOUNT_INSN_SIZE - 1;
+#ifdef CONFIG_X86_64
+	if (ftrace_location(ip)) {
+		int3_emulate_call(regs, (unsigned long)ftrace_regs_caller);
+		return 1;
+	} else if (is_ftrace_caller(ip)) {
+		if (!ftrace_update_func_call) {
+			int3_emulate_jmp(regs, ip + CALL_INSN_SIZE);
+			return 1;
+		}
+		int3_emulate_call(regs, ftrace_update_func_call);
+		return 1;
+	}
+#else
+	if (ftrace_location(ip) || is_ftrace_caller(ip)) {
+		int3_emulate_jmp(regs, ip + CALL_INSN_SIZE);
+		return 1;
+	}
+#endif
 
-	return 1;
+	return 0;
 }
 NOKPROBE_SYMBOL(ftrace_int3_handler);
 
@@ -859,6 +878,8 @@ void arch_ftrace_update_trampoline(struct ftrace_ops *ops)
 
 	func = ftrace_ops_get_func(ops);
 
+	ftrace_update_func_call = (unsigned long)func;
+
 	/* Do a safe modify in case the trampoline is executing */
 	new = ftrace_call_replace(ip, (unsigned long)func);
 	ret = update_ftrace_func(ip, new);
@@ -960,6 +981,7 @@ static int ftrace_mod_jmp(unsigned long ip, void *func)
 {
 	unsigned char *new;
 
+	ftrace_update_func_call = 0UL;
 	new = ftrace_jmp_replace(ip, (unsigned long)func);
 
 	return update_ftrace_func(ip, new);
-- 
2.20.1

[for-next][PATCH 04/13] tracing: uprobes: Re-enable $comm support for uprobe events

[Steven Rostedt]

From: Masami Hiramatsu <mhiramat@kernel.org>

Since commit 533059281ee5 ("tracing: probeevent: Introduce new
argument fetching code") dropped the $comm support from uprobe
events, this re-enables it.

For $comm support, uses strlcpy() instead of strncpy_from_user()
to copy current task's comm. Because it is in the kernel space,
strncpy_from_user() always fails to copy the comm.
This also uses strlen() instead of strnlen_user() to measure the
length of the comm.

Note that this uses -ECOMM as a token value to fetch the comm
string. If the user-space pointer points -ECOMM, it will be
translated to task->comm.

Link: http://lkml.kernel.org/r/155723734162.9149.4042756162201097965.stgit@devnote2

Fixes: 533059281ee5 ("tracing: probeevent: Introduce new argument fetching code")
Reported-by: Andreas Ziegler <andreas.ziegler@fau.de>
Acked-by: Andreas Ziegler <andreas.ziegler@fau.de>
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
 kernel/trace/trace_probe.h  |  1 +
 kernel/trace/trace_uprobe.c | 13 +++++++++++--
 2 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/kernel/trace/trace_probe.h b/kernel/trace/trace_probe.h
index b7737666c1a8..f9a8c632188b 100644
--- a/kernel/trace/trace_probe.h
+++ b/kernel/trace/trace_probe.h
@@ -124,6 +124,7 @@ struct fetch_insn {
 
 /* fetch + deref*N + store + mod + end <= 16, this allows N=12, enough */
 #define FETCH_INSN_MAX	16
+#define FETCH_TOKEN_COMM	(-ECOMM)
 
 /* Fetch type information table */
 struct fetch_type {
diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c
index cd8750a72768..eb7e06b54741 100644
--- a/kernel/trace/trace_uprobe.c
+++ b/kernel/trace/trace_uprobe.c
@@ -156,7 +156,10 @@ fetch_store_string(unsigned long addr, void *dest, void *base)
 	if (unlikely(!maxlen))
 		return -ENOMEM;
 
-	ret = strncpy_from_user(dst, src, maxlen);
+	if (addr == FETCH_TOKEN_COMM)
+		ret = strlcpy(dst, current->comm, maxlen);
+	else
+		ret = strncpy_from_user(dst, src, maxlen);
 	if (ret >= 0) {
 		if (ret == maxlen)
 			dst[ret - 1] = '\0';
@@ -180,7 +183,10 @@ fetch_store_strlen(unsigned long addr)
 	int len;
 	void __user *vaddr = (void __force __user *) addr;
 
-	len = strnlen_user(vaddr, MAX_STRING_SIZE);
+	if (addr == FETCH_TOKEN_COMM)
+		len = strlen(current->comm) + 1;
+	else
+		len = strnlen_user(vaddr, MAX_STRING_SIZE);
 
 	return (len > MAX_STRING_SIZE) ? 0 : len;
 }
@@ -220,6 +226,9 @@ process_fetch_insn(struct fetch_insn *code, struct pt_regs *regs, void *dest,
 	case FETCH_OP_IMM:
 		val = code->immediate;
 		break;
+	case FETCH_OP_COMM:
+		val = FETCH_TOKEN_COMM;
+		break;
 	case FETCH_OP_FOFFS:
 		val = translate_user_vaddr(code->immediate);
 		break;
-- 
2.20.1

[for-next][PATCH 05/13] tracing: probeevent: Do not accumulate on ret variable

[Steven Rostedt]

From: Masami Hiramatsu <mhiramat@kernel.org>

Do not accumulate strlen result on "ret" local variable, because
it is accumulated on "total" local variable for array case.

Link: http://lkml.kernel.org/r/155723735237.9149.3192150444705457531.stgit@devnote2

Fixes: 40b53b771806 ("tracing: probeevent: Add array type support")
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
 kernel/trace/trace_probe_tmpl.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/trace/trace_probe_tmpl.h b/kernel/trace/trace_probe_tmpl.h
index 4737bb8c07a3..c30c61f12ddd 100644
--- a/kernel/trace/trace_probe_tmpl.h
+++ b/kernel/trace/trace_probe_tmpl.h
@@ -88,7 +88,7 @@ process_fetch_insn_bottom(struct fetch_insn *code, unsigned long val,
 	/* 3rd stage: store value to buffer */
 	if (unlikely(!dest)) {
 		if (code->op == FETCH_OP_ST_STRING) {
-			ret += fetch_store_strlen(val + code->offset);
+			ret = fetch_store_strlen(val + code->offset);
 			code++;
 			goto array;
 		} else
-- 
2.20.1

[for-next][PATCH 06/13] tracing: probeevent: Fix to make the type of $comm string

[Steven Rostedt]

From: Masami Hiramatsu <mhiramat@kernel.org>

Fix to make the type of $comm "string".  If we set the other type to $comm
argument, it shows meaningless value or wrong data. Currently probe events
allow us to set string array type (e.g. ":string[2]"), or other digit types
like x8 on $comm. But since clearly $comm is just a string data, it should
not be fetched by other types including array.

Link: http://lkml.kernel.org/r/155723736241.9149.14582064184468574539.stgit@devnote2

Cc: Andreas Ziegler <andreas.ziegler@fau.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: stable@vger.kernel.org
Fixes: 533059281ee5 ("tracing: probeevent: Introduce new argument fetching code")
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
 kernel/trace/trace_probe.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
index 4cc2d467d34c..e0d1d5353464 100644
--- a/kernel/trace/trace_probe.c
+++ b/kernel/trace/trace_probe.c
@@ -533,13 +533,14 @@ static int traceprobe_parse_probe_arg_body(char *arg, ssize_t *size,
 			}
 		}
 	}
-	/*
-	 * The default type of $comm should be "string", and it can't be
-	 * dereferenced.
-	 */
-	if (!t && strcmp(arg, "$comm") == 0)
+
+	/* Since $comm can not be dereferred, we can find $comm by strcmp */
+	if (strcmp(arg, "$comm") == 0) {
+		/* The type of $comm must be "string", and not an array. */
+		if (parg->count || (t && strcmp(t, "string")))
+			return -EINVAL;
 		parg->type = find_fetch_type("string");
-	else
+	} else
 		parg->type = find_fetch_type(t);
 	if (!parg->type) {
 		trace_probe_log_err(offset + (t ? (t - arg) : 0), BAD_TYPE);
-- 
2.20.1

[for-next][PATCH 07/13] ring-buffer: Fix mispelling of Calculate

[Steven Rostedt]

From: Yangtao Li <tiny.windzz@gmail.com>

It's not "Caculate".

Link: http://lkml.kernel.org/r/20181101154640.23162-1-tiny.windzz@gmail.com

Signed-off-by: Yangtao Li <tiny.windzz@gmail.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
 kernel/trace/ring_buffer_benchmark.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/trace/ring_buffer_benchmark.c b/kernel/trace/ring_buffer_benchmark.c
index ffba6789c0e2..0564f6db0561 100644
--- a/kernel/trace/ring_buffer_benchmark.c
+++ b/kernel/trace/ring_buffer_benchmark.c
@@ -362,7 +362,7 @@ static void ring_buffer_producer(void)
 			hit--; /* make it non zero */
 		}
 
-		/* Caculate the average time in nanosecs */
+		/* Calculate the average time in nanosecs */
 		avg = NSEC_PER_MSEC / (hit + missed);
 		trace_printk("%ld ns per entry\n", avg);
 	}
-- 
2.20.1

[for-next][PATCH 08/13] tracing: Eliminate const char[] auto variables

[Steven Rostedt]

From: Rasmus Villemoes <linux@rasmusvillemoes.dk>

Automatic const char[] variables cause unnecessary code
generation. For example, the this_mod variable leads to

    3f04:       48 b8 5f 5f 74 68 69 73 5f 6d   movabs $0x6d5f736968745f5f,%rax # __this_m
    3f0e:       4c 8d 44 24 02                  lea    0x2(%rsp),%r8
    3f13:       48 8d 7c 24 10                  lea    0x10(%rsp),%rdi
    3f18:       48 89 44 24 02                  mov    %rax,0x2(%rsp)
    3f1d:       4c 89 e9                        mov    %r13,%rcx
    3f20:       b8 65 00 00 00                  mov    $0x65,%eax # e
    3f25:       48 c7 c2 00 00 00 00            mov    $0x0,%rdx
                        3f28: R_X86_64_32S      .rodata.str1.1+0x18d
    3f2c:       be 48 00 00 00                  mov    $0x48,%esi
    3f31:       c7 44 24 0a 6f 64 75 6c         movl   $0x6c75646f,0xa(%rsp) # odul
    3f39:       66 89 44 24 0e                  mov    %ax,0xe(%rsp)

i.e., the string gets built on the stack at runtime. Similar code can be
found for the other instances I'm replacing here. Putting the string
in .rodata reduces the combined .text+.rodata size and saves time and
stack space at runtime.

The simplest fix, and what I've done for the this_mod case, is to just
make the variable static.

However, for the "<faulted>" case where the same string is used twice,
that prevents the linker from merging those two literals, so instead use
a macro - that also keeps the two instances automatically in
sync (instead of only the compile-time strlen expression).

Finally, for the two runs of spaces, it turns out that the "build
these strings on the stack" is not the worst part of what gcc does -
it turns print_func_help_header_irq() into "if (tgid) { /*
print_event_info + five seq_printf calls */ } else { /* print
event_info + another five seq_printf */}". Taking inspiration from a
suggestion from Al Viro, use %.*s to make snprintf either stop after
the first two spaces or print the whole string. As a bonus, the
seq_printfs now fit on single lines (at least, they are not longer
than the existing ones in the function just above), making it easier
to see that the ascii art lines up.

x86-64 defconfig + CONFIG_FUNCTION_TRACER:

$ scripts/stackdelta /tmp/stackusage.{0,1}
./kernel/trace/ftrace.c ftrace_mod_callback     152     136     -16
./kernel/trace/trace.c  trace_default_header    56      32      -24
./kernel/trace/trace.c  tracing_mark_raw_write  96      72      -24
./kernel/trace/trace.c  tracing_mark_write      104     80      -24

bloat-o-meter

add/remove: 1/0 grow/shrink: 0/4 up/down: 14/-375 (-361)
Function                                     old     new   delta
this_mod                                       -      14     +14
ftrace_mod_callback                          577     542     -35
tracing_mark_raw_write                       444     374     -70
tracing_mark_write                           616     540     -76
trace_default_header                         600     406    -194

Link: http://lkml.kernel.org/r/20190320081757.6037-1-linux@rasmusvillemoes.dk

Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
 kernel/trace/ftrace.c |  2 +-
 kernel/trace/trace.c  | 34 +++++++++++++---------------------
 2 files changed, 14 insertions(+), 22 deletions(-)

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 433a64f49532..7765a53f1006 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -3875,7 +3875,7 @@ static int ftrace_hash_move_and_update_ops(struct ftrace_ops *ops,
 static bool module_exists(const char *module)
 {
 	/* All modules have the symbol __this_module */
-	const char this_mod[] = "__this_module";
+	static const char this_mod[] = "__this_module";
 	char modname[MAX_PARAM_PREFIX_LEN + sizeof(this_mod) + 2];
 	unsigned long val;
 	int n;
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index dcb9adb44be9..3259019cc66d 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -3593,25 +3593,18 @@ static void print_func_help_header_irq(struct trace_buffer *buf, struct seq_file
 				       unsigned int flags)
 {
 	bool tgid = flags & TRACE_ITER_RECORD_TGID;
-	const char tgid_space[] = "          ";
-	const char space[] = "  ";
+	const char *space = "          ";
+	int prec = tgid ? 10 : 2;
 
 	print_event_info(buf, m);
 
-	seq_printf(m, "#                          %s  _-----=> irqs-off\n",
-		   tgid ? tgid_space : space);
-	seq_printf(m, "#                          %s / _----=> need-resched\n",
-		   tgid ? tgid_space : space);
-	seq_printf(m, "#                          %s| / _---=> hardirq/softirq\n",
-		   tgid ? tgid_space : space);
-	seq_printf(m, "#                          %s|| / _--=> preempt-depth\n",
-		   tgid ? tgid_space : space);
-	seq_printf(m, "#                          %s||| /     delay\n",
-		   tgid ? tgid_space : space);
-	seq_printf(m, "#           TASK-PID %sCPU#  ||||    TIMESTAMP  FUNCTION\n",
-		   tgid ? "   TGID   " : space);
-	seq_printf(m, "#              | |   %s  |   ||||       |         |\n",
-		   tgid ? "     |    " : space);
+	seq_printf(m, "#                          %.*s  _-----=> irqs-off\n", prec, space);
+	seq_printf(m, "#                          %.*s / _----=> need-resched\n", prec, space);
+	seq_printf(m, "#                          %.*s| / _---=> hardirq/softirq\n", prec, space);
+	seq_printf(m, "#                          %.*s|| / _--=> preempt-depth\n", prec, space);
+	seq_printf(m, "#                          %.*s||| /     delay\n", prec, space);
+	seq_printf(m, "#           TASK-PID %.*sCPU#  ||||    TIMESTAMP  FUNCTION\n", prec, "   TGID   ");
+	seq_printf(m, "#              | |   %.*s  |   ||||       |         |\n", prec, "     |    ");
 }
 
 void
@@ -6342,13 +6335,13 @@ tracing_mark_write(struct file *filp, const char __user *ubuf,
 	struct ring_buffer *buffer;
 	struct print_entry *entry;
 	unsigned long irq_flags;
-	const char faulted[] = "<faulted>";
 	ssize_t written;
 	int size;
 	int len;
 
 /* Used in tracing_mark_raw_write() as well */
-#define FAULTED_SIZE (sizeof(faulted) - 1) /* '\0' is already accounted for */
+#define FAULTED_STR "<faulted>"
+#define FAULTED_SIZE (sizeof(FAULTED_STR) - 1) /* '\0' is already accounted for */
 
 	if (tracing_disabled)
 		return -EINVAL;
@@ -6380,7 +6373,7 @@ tracing_mark_write(struct file *filp, const char __user *ubuf,
 
 	len = __copy_from_user_inatomic(&entry->buf, ubuf, cnt);
 	if (len) {
-		memcpy(&entry->buf, faulted, FAULTED_SIZE);
+		memcpy(&entry->buf, FAULTED_STR, FAULTED_SIZE);
 		cnt = FAULTED_SIZE;
 		written = -EFAULT;
 	} else
@@ -6421,7 +6414,6 @@ tracing_mark_raw_write(struct file *filp, const char __user *ubuf,
 	struct ring_buffer_event *event;
 	struct ring_buffer *buffer;
 	struct raw_data_entry *entry;
-	const char faulted[] = "<faulted>";
 	unsigned long irq_flags;
 	ssize_t written;
 	int size;
@@ -6461,7 +6453,7 @@ tracing_mark_raw_write(struct file *filp, const char __user *ubuf,
 	len = __copy_from_user_inatomic(&entry->id, ubuf, cnt);
 	if (len) {
 		entry->id = -1;
-		memcpy(&entry->buf, faulted, FAULTED_SIZE);
+		memcpy(&entry->buf, FAULTED_STR, FAULTED_SIZE);
 		written = -EFAULT;
 	} else
 		written = cnt;
-- 
2.20.1

[for-next][PATCH 09/13] tracing: Fix white space issues in parse_pred() function

[Steven Rostedt]

From: Colin Ian King <colin.king@canonical.com>

Trivial fix to clean up an indentation issue, a whole chunk of code
has an extra space in the indentation.

Link: http://lkml.kernel.org/r/20181109132312.20994-1-colin.king@canonical.com

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
 kernel/trace/trace_events_filter.c | 48 +++++++++++++++---------------
 1 file changed, 24 insertions(+), 24 deletions(-)

diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c
index 180ecb390baa..d3e59312ef40 100644
--- a/kernel/trace/trace_events_filter.c
+++ b/kernel/trace/trace_events_filter.c
@@ -1222,30 +1222,30 @@ static int parse_pred(const char *str, void *data,
 		 * (perf doesn't use it) and grab everything.
 		 */
 		if (strcmp(field->name, "ip") != 0) {
-			 parse_error(pe, FILT_ERR_IP_FIELD_ONLY, pos + i);
-			 goto err_free;
-		 }
-		 pred->fn = filter_pred_none;
-
-		 /*
-		  * Quotes are not required, but if they exist then we need
-		  * to read them till we hit a matching one.
-		  */
-		 if (str[i] == '\'' || str[i] == '"')
-			 q = str[i];
-		 else
-			 q = 0;
-
-		 for (i++; str[i]; i++) {
-			 if (q && str[i] == q)
-				 break;
-			 if (!q && (str[i] == ')' || str[i] == '&' ||
-				    str[i] == '|'))
-				 break;
-		 }
-		 /* Skip quotes */
-		 if (q)
-			 s++;
+			parse_error(pe, FILT_ERR_IP_FIELD_ONLY, pos + i);
+			goto err_free;
+		}
+		pred->fn = filter_pred_none;
+
+		/*
+		 * Quotes are not required, but if they exist then we need
+		 * to read them till we hit a matching one.
+		 */
+		if (str[i] == '\'' || str[i] == '"')
+			q = str[i];
+		else
+			q = 0;
+
+		for (i++; str[i]; i++) {
+			if (q && str[i] == q)
+				break;
+			if (!q && (str[i] == ')' || str[i] == '&' ||
+				   str[i] == '|'))
+				break;
+		}
+		/* Skip quotes */
+		if (q)
+			s++;
 		len = i - s;
 		if (len >= MAX_FILTER_STR_VAL) {
 			parse_error(pe, FILT_ERR_OPERAND_TOO_LONG, pos + i);
-- 
2.20.1

[for-next][PATCH 10/13] tracing: Allow RCU to run between postponed startup tests

[Steven Rostedt]

From: Anders Roxell <anders.roxell@linaro.org>

When building a allmodconfig kernel for arm64 and boot that in qemu,
CONFIG_FTRACE_STARTUP_TEST gets enabled and that takes time so the
watchdog expires and prints out a message like this:
'watchdog: BUG: soft lockup - CPU#0 stuck for 22s! [swapper/0:1]'
Depending on what the what test gets called from init_trace_selftests()
it stays minutes in the loop.
Rework so that function cond_resched() gets called in the
init_trace_selftests loop.

Link: http://lkml.kernel.org/r/20181130145622.26334-1-anders.roxell@linaro.org

Co-developed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Anders Roxell <anders.roxell@linaro.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
 kernel/trace/trace.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 3259019cc66d..4269af5905e4 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -1722,6 +1722,10 @@ static __init int init_trace_selftests(void)
 	pr_info("Running postponed tracer tests:\n");
 
 	list_for_each_entry_safe(p, n, &postponed_selftests, list) {
+		/* This loop can take minutes when sanitizers are enabled, so
+		 * lets make sure we allow RCU processing.
+		 */
+		cond_resched();
 		ret = run_tracer_selftest(p->type);
 		/* If the test fails, then warn and remove from available_tracers */
 		if (ret < 0) {
-- 
2.20.1

[for-next][PATCH 11/13] tracing: Fix partial reading of trace events id file

[Steven Rostedt]

From: Elazar Leibovich <elazar@lightbitslabs.com>

When reading only part of the id file, the ppos isn't tracked correctly.
This is taken care by simple_read_from_buffer.

Reading a single byte, and then the next byte would result EOF.

While this seems like not a big deal, this breaks abstractions that
reads information from files unbuffered. See for example
https://github.com/golang/go/issues/29399

This code was mentioned as problematic in
commit cd458ba9d5a5
("tracing: Do not (ab)use trace_seq in event_id_read()")

An example C code that show this bug is:

  #include <stdio.h>
  #include <stdint.h>

  #include <sys/types.h>
  #include <sys/stat.h>
  #include <fcntl.h>
  #include <unistd.h>

  int main(int argc, char **argv) {
    if (argc < 2)
      return 1;
    int fd = open(argv[1], O_RDONLY);
    char c;
    read(fd, &c, 1);
    printf("First  %c\n", c);
    read(fd, &c, 1);
    printf("Second %c\n", c);
  }

Then run with, e.g.

  sudo ./a.out /sys/kernel/debug/tracing/events/tcp/tcp_set_state/id

You'll notice you're getting the first character twice, instead of the
first two characters in the id file.

Link: http://lkml.kernel.org/r/20181231115837.4932-1-elazar@lightbitslabs.com

Cc: Orit Wasserman <orit.was@gmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: stable@vger.kernel.org
Fixes: 23725aeeab10b ("ftrace: provide an id file for each event")
Signed-off-by: Elazar Leibovich <elazar@lightbitslabs.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
 kernel/trace/trace_events.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
index 81c038ed6cee..0ce3db67f556 100644
--- a/kernel/trace/trace_events.c
+++ b/kernel/trace/trace_events.c
@@ -1319,9 +1319,6 @@ event_id_read(struct file *filp, char __user *ubuf, size_t cnt, loff_t *ppos)
 	char buf[32];
 	int len;
 
-	if (*ppos)
-		return 0;
-
 	if (unlikely(!id))
 		return -ENODEV;
 
-- 
2.20.1

[for-next][PATCH 12/13] tracing: Replace kzalloc with kcalloc

[Steven Rostedt]

From: "Gustavo A. R. Silva" <gustavo@embeddedor.com>

Replace kzalloc() function with its 2-factor argument form, kcalloc().

This patch replaces cases of:

	kzalloc(a * b, gfp)

with:
	kcalloc(a, b, gfp)

This code was detected with the help of Coccinelle.

Link: http://lkml.kernel.org/r/20190115043408.GA23456@embeddedor

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
 kernel/trace/trace_probe.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
index e0d1d5353464..a347faced959 100644
--- a/kernel/trace/trace_probe.c
+++ b/kernel/trace/trace_probe.c
@@ -558,7 +558,7 @@ static int traceprobe_parse_probe_arg_body(char *arg, ssize_t *size,
 			 parg->count);
 	}
 
-	code = tmp = kzalloc(sizeof(*code) * FETCH_INSN_MAX, GFP_KERNEL);
+	code = tmp = kcalloc(FETCH_INSN_MAX, sizeof(*code), GFP_KERNEL);
 	if (!code)
 		return -ENOMEM;
 	code[FETCH_INSN_MAX - 1].op = FETCH_OP_END;
@@ -637,7 +637,7 @@ static int traceprobe_parse_probe_arg_body(char *arg, ssize_t *size,
 	code->op = FETCH_OP_END;
 
 	/* Shrink down the code buffer */
-	parg->code = kzalloc(sizeof(*code) * (code - tmp + 1), GFP_KERNEL);
+	parg->code = kcalloc(code - tmp + 1, sizeof(*code), GFP_KERNEL);
 	if (!parg->code)
 		ret = -ENOMEM;
 	else
-- 
2.20.1

[for-next][PATCH 13/13] tracing: Fix documentation about disabling options using trace_options

[Steven Rostedt]

From: "Srivatsa S. Bhat (VMware)" <srivatsa@csail.mit.edu>

To disable a tracing option using the trace_options file, the option
name needs to be prefixed with 'no', and not suffixed, as the README
states. Fix it.

Link: http://lkml.kernel.org/r/154872690031.47356.5739053380942044586.stgit@srivatsa-ubuntu

Signed-off-by: Srivatsa S. Bhat (VMware) <srivatsa@csail.mit.edu>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
 kernel/trace/trace.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 4269af5905e4..a3a6945a7732 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -4755,7 +4755,7 @@ static const char readme_msg[] =
 	"  instances\t\t- Make sub-buffers with: mkdir instances/foo\n"
 	"\t\t\t  Remove sub-buffer with rmdir\n"
 	"  trace_options\t\t- Set format or modify how tracing happens\n"
-	"\t\t\t  Disable an option by adding a suffix 'no' to the\n"
+	"\t\t\t  Disable an option by prefixing 'no' to the\n"
 	"\t\t\t  option name\n"
 	"  saved_cmdlines_size\t- echo command number in here to store comm-pid list\n"
 #ifdef CONFIG_DYNAMIC_FTRACE
-- 
2.20.1