[PATCH 1/2] perf: Pass appropriate frame pointer to dump_trace()

[PATCH 1/2] perf: Pass appropriate frame pointer to dump_trace()

[Frederic Weisbecker]

Pass the frame pointer from the regs of the interrupted path
to dump_trace() while processing the stack trace.

Currently, dump_trace() takes the current bp and starts the
callchain from dump_trace() itself. This is wasteful because
we need to walk through the entire NMI/DEBUG stack before
retrieving the interrupted point.

We can fix that by just using the frame pointer from the captured
regs. It points exactly where we want to start.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
---
 arch/x86/kernel/cpu/perf_event.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c
index c223b7e..d616c06 100644
--- a/arch/x86/kernel/cpu/perf_event.c
+++ b/arch/x86/kernel/cpu/perf_event.c
@@ -2347,7 +2347,7 @@ perf_callchain_kernel(struct pt_regs *regs, struct perf_callchain_entry *entry)
 	callchain_store(entry, PERF_CONTEXT_KERNEL);
 	callchain_store(entry, regs->ip);
 
-	dump_trace(NULL, regs, NULL, 0, &backtrace_ops, entry);
+	dump_trace(NULL, regs, NULL, regs->bp, &backtrace_ops, entry);
 }
 
 /*
-- 
1.6.2.3

[PATCH 2/2] perf: Drop useless check for ignored frame

[Frederic Weisbecker]

The check that ignores the debug and nmi stack frames is useless
now that we have a frame pointer that makes us start at the right
place. We don't anymore have to deal with these.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
---
 arch/x86/include/asm/stacktrace.h |    2 --
 arch/x86/kernel/cpu/perf_event.c  |    8 --------
 arch/x86/kernel/dumpstack_32.c    |    5 -----
 arch/x86/kernel/dumpstack_64.c    |    5 -----
 4 files changed, 0 insertions(+), 20 deletions(-)

diff --git a/arch/x86/include/asm/stacktrace.h b/arch/x86/include/asm/stacktrace.h
index 35e8912..4dab78e 100644
--- a/arch/x86/include/asm/stacktrace.h
+++ b/arch/x86/include/asm/stacktrace.h
@@ -3,8 +3,6 @@
 
 extern int kstack_depth_to_print;
 
-int x86_is_stack_id(int id, char *name);
-
 struct thread_info;
 struct stacktrace_ops;
 
diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c
index d616c06..b1bb8c5 100644
--- a/arch/x86/kernel/cpu/perf_event.c
+++ b/arch/x86/kernel/cpu/perf_event.c
@@ -2297,7 +2297,6 @@ void callchain_store(struct perf_callchain_entry *entry, u64 ip)
 
 static DEFINE_PER_CPU(struct perf_callchain_entry, pmc_irq_entry);
 static DEFINE_PER_CPU(struct perf_callchain_entry, pmc_nmi_entry);
-static DEFINE_PER_CPU(int, in_ignored_frame);
 
 
 static void
@@ -2313,10 +2312,6 @@ static void backtrace_warning(void *data, char *msg)
 
 static int backtrace_stack(void *data, char *name)
 {
-	per_cpu(in_ignored_frame, smp_processor_id()) =
-			x86_is_stack_id(NMI_STACK, name) ||
-			x86_is_stack_id(DEBUG_STACK, name);
-
 	return 0;
 }
 
@@ -2324,9 +2319,6 @@ static void backtrace_address(void *data, unsigned long addr, int reliable)
 {
 	struct perf_callchain_entry *entry = data;
 
-	if (per_cpu(in_ignored_frame, smp_processor_id()))
-		return;
-
 	if (reliable)
 		callchain_store(entry, addr);
 }
diff --git a/arch/x86/kernel/dumpstack_32.c b/arch/x86/kernel/dumpstack_32.c
index ae775ca..11540a1 100644
--- a/arch/x86/kernel/dumpstack_32.c
+++ b/arch/x86/kernel/dumpstack_32.c
@@ -18,11 +18,6 @@
 
 #include "dumpstack.h"
 
-/* Just a stub for now */
-int x86_is_stack_id(int id, char *name)
-{
-	return 0;
-}
 
 void dump_trace(struct task_struct *task, struct pt_regs *regs,
 		unsigned long *stack, unsigned long bp,
diff --git a/arch/x86/kernel/dumpstack_64.c b/arch/x86/kernel/dumpstack_64.c
index 0ad9597..676bc05 100644
--- a/arch/x86/kernel/dumpstack_64.c
+++ b/arch/x86/kernel/dumpstack_64.c
@@ -33,11 +33,6 @@ static char x86_stack_ids[][8] = {
 #endif
 };
 
-int x86_is_stack_id(int id, char *name)
-{
-	return x86_stack_ids[id - 1] == name;
-}
-
 static unsigned long *in_exception_stack(unsigned cpu, unsigned long stack,
 					 unsigned *usedp, char **idp)
 {
-- 
1.6.2.3

Re: [PATCH 1/2] perf: Pass appropriate frame pointer to dump_trace()

[Frederic Weisbecker]

On Thu, Dec 31, 2009 at 05:53:02AM +0100, Frederic Weisbecker wrote:
> Pass the frame pointer from the regs of the interrupted path
> to dump_trace() while processing the stack trace.
> 
> Currently, dump_trace() takes the current bp and starts the
> callchain from dump_trace() itself. This is wasteful because
> we need to walk through the entire NMI/DEBUG stack before
> retrieving the interrupted point.
> 
> We can fix that by just using the frame pointer from the captured
> regs. It points exactly where we want to start.



BTW, another effect of this patch: we didn't have the
nmi/debug stack frame filtering in x86-32. So the callchains
were polluted by the perf_callchain path, do_debug and so
on...

After this patch we don't need this filtering anymore
as the nmi/debug frames are zapped. It becomes clean
like in x86-64.

[tip:perf/urgent] perf: Pass appropriate frame pointer to dump_trace()

[tip-bot for Frederic Weisbecker]

Commit-ID:  48b5ba9cc98d676712da29d9931f1c88e5185ff2
Gitweb:     http://git.kernel.org/tip/48b5ba9cc98d676712da29d9931f1c88e5185ff2
Author:     Frederic Weisbecker <fweisbec@gmail.com>
AuthorDate: Thu, 31 Dec 2009 05:53:02 +0100
Committer:  Ingo Molnar <mingo@elte.hu>
CommitDate: Thu, 31 Dec 2009 13:11:31 +0100

perf: Pass appropriate frame pointer to dump_trace()

Pass the frame pointer from the regs of the interrupted path
to dump_trace() while processing the stack trace.

Currently, dump_trace() takes the current bp and starts the
callchain from dump_trace() itself. This is wasteful because
we need to walk through the entire NMI/DEBUG stack before
retrieving the interrupted point.

We can fix that by just using the frame pointer from the
captured regs. It points exactly where we want to start.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
LKML-Reference: <1262235183-5320-1-git-send-regression-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
---
 arch/x86/kernel/cpu/perf_event.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c
index c223b7e..d616c06 100644
--- a/arch/x86/kernel/cpu/perf_event.c
+++ b/arch/x86/kernel/cpu/perf_event.c
@@ -2347,7 +2347,7 @@ perf_callchain_kernel(struct pt_regs *regs, struct perf_callchain_entry *entry)
 	callchain_store(entry, PERF_CONTEXT_KERNEL);
 	callchain_store(entry, regs->ip);
 
-	dump_trace(NULL, regs, NULL, 0, &backtrace_ops, entry);
+	dump_trace(NULL, regs, NULL, regs->bp, &backtrace_ops, entry);
 }
 
 /*

[tip:perf/core] perf: Drop useless check for ignored frame

[tip-bot for Frederic Weisbecker]

Commit-ID:  0fb8ee48d9dfff6a0913ceb0be2068d8be203763
Gitweb:     http://git.kernel.org/tip/0fb8ee48d9dfff6a0913ceb0be2068d8be203763
Author:     Frederic Weisbecker <fweisbec@gmail.com>
AuthorDate: Thu, 31 Dec 2009 05:53:03 +0100
Committer:  Ingo Molnar <mingo@elte.hu>
CommitDate: Wed, 13 Jan 2010 10:09:08 +0100

perf: Drop useless check for ignored frame

The check that ignores the debug and nmi stack frames is useless
now that we have a frame pointer that makes us start at the
right place. We don't anymore have to deal with these.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
LKML-Reference: <1262235183-5320-2-git-send-regression-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
 arch/x86/include/asm/stacktrace.h |    2 --
 arch/x86/kernel/cpu/perf_event.c  |    8 --------
 arch/x86/kernel/dumpstack_32.c    |    5 -----
 arch/x86/kernel/dumpstack_64.c    |    5 -----
 4 files changed, 0 insertions(+), 20 deletions(-)

diff --git a/arch/x86/include/asm/stacktrace.h b/arch/x86/include/asm/stacktrace.h
index 35e8912..4dab78e 100644
--- a/arch/x86/include/asm/stacktrace.h
+++ b/arch/x86/include/asm/stacktrace.h
@@ -3,8 +3,6 @@
 
 extern int kstack_depth_to_print;
 
-int x86_is_stack_id(int id, char *name);
-
 struct thread_info;
 struct stacktrace_ops;
 
diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c
index d616c06..b1bb8c5 100644
--- a/arch/x86/kernel/cpu/perf_event.c
+++ b/arch/x86/kernel/cpu/perf_event.c
@@ -2297,7 +2297,6 @@ void callchain_store(struct perf_callchain_entry *entry, u64 ip)
 
 static DEFINE_PER_CPU(struct perf_callchain_entry, pmc_irq_entry);
 static DEFINE_PER_CPU(struct perf_callchain_entry, pmc_nmi_entry);
-static DEFINE_PER_CPU(int, in_ignored_frame);
 
 
 static void
@@ -2313,10 +2312,6 @@ static void backtrace_warning(void *data, char *msg)
 
 static int backtrace_stack(void *data, char *name)
 {
-	per_cpu(in_ignored_frame, smp_processor_id()) =
-			x86_is_stack_id(NMI_STACK, name) ||
-			x86_is_stack_id(DEBUG_STACK, name);
-
 	return 0;
 }
 
@@ -2324,9 +2319,6 @@ static void backtrace_address(void *data, unsigned long addr, int reliable)
 {
 	struct perf_callchain_entry *entry = data;
 
-	if (per_cpu(in_ignored_frame, smp_processor_id()))
-		return;
-
 	if (reliable)
 		callchain_store(entry, addr);
 }
diff --git a/arch/x86/kernel/dumpstack_32.c b/arch/x86/kernel/dumpstack_32.c
index ae775ca..11540a1 100644
--- a/arch/x86/kernel/dumpstack_32.c
+++ b/arch/x86/kernel/dumpstack_32.c
@@ -18,11 +18,6 @@
 
 #include "dumpstack.h"
 
-/* Just a stub for now */
-int x86_is_stack_id(int id, char *name)
-{
-	return 0;
-}
 
 void dump_trace(struct task_struct *task, struct pt_regs *regs,
 		unsigned long *stack, unsigned long bp,
diff --git a/arch/x86/kernel/dumpstack_64.c b/arch/x86/kernel/dumpstack_64.c
index 0ad9597..676bc05 100644
--- a/arch/x86/kernel/dumpstack_64.c
+++ b/arch/x86/kernel/dumpstack_64.c
@@ -33,11 +33,6 @@ static char x86_stack_ids[][8] = {
 #endif
 };
 
-int x86_is_stack_id(int id, char *name)
-{
-	return x86_stack_ids[id - 1] == name;
-}
-
 static unsigned long *in_exception_stack(unsigned cpu, unsigned long stack,
 					 unsigned *usedp, char **idp)
 {