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authorTorok Edwin <edwintorok@gmail.com>2010-03-17 12:07:16 +0200
committerIngo Molnar <mingo@elte.hu>2010-04-02 19:30:03 +0200
commit257ef9d21f1b008a6c7425544b36641c4325a922 (patch)
tree4ffda980fe6a93acd24efcc04cd10e130caae4c1
parentb38b24ead33417146e051453d04bf60b8d2d7e25 (diff)
perf, x86: Fix callgraphs of 32-bit processes on 64-bit kernels
When profiling a 32-bit process on a 64-bit kernel, callgraph tracing stopped after the first function, because it has seen a garbage memory address (tried to interpret the frame pointer, and return address as a 64-bit pointer). Fix this by using a struct stack_frame with 32-bit pointers when the TIF_IA32 flag is set. Note that TIF_IA32 flag must be used, and not is_compat_task(), because the latter is only set when the 32-bit process is executing a syscall, which may not always be the case (when tracing page fault events for example). Signed-off-by: Török Edwin <edwintorok@gmail.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Paul Mackerras <paulus@samba.org> Cc: x86@kernel.org Cc: linux-kernel@vger.kernel.org LKML-Reference: <1268820436-13145-1-git-send-email-edwintorok@gmail.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
-rw-r--r--arch/x86/kernel/cpu/perf_event.c44
-rw-r--r--arch/x86/kernel/dumpstack.h5
2 files changed, 44 insertions, 5 deletions
diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c
index bd28cf9d8a82..53ea4cf1a878 100644
--- a/arch/x86/kernel/cpu/perf_event.c
+++ b/arch/x86/kernel/cpu/perf_event.c
@@ -28,6 +28,7 @@
#include <asm/apic.h>
#include <asm/stacktrace.h>
#include <asm/nmi.h>
+#include <asm/compat.h>
static u64 perf_event_mask __read_mostly;
@@ -1630,14 +1631,42 @@ copy_from_user_nmi(void *to, const void __user *from, unsigned long n)
return len;
}
-static int copy_stack_frame(const void __user *fp, struct stack_frame *frame)
+#ifdef CONFIG_COMPAT
+static inline int
+perf_callchain_user32(struct pt_regs *regs, struct perf_callchain_entry *entry)
{
- unsigned long bytes;
+ /* 32-bit process in 64-bit kernel. */
+ struct stack_frame_ia32 frame;
+ const void __user *fp;
+
+ if (!test_thread_flag(TIF_IA32))
+ return 0;
+
+ fp = compat_ptr(regs->bp);
+ while (entry->nr < PERF_MAX_STACK_DEPTH) {
+ unsigned long bytes;
+ frame.next_frame = 0;
+ frame.return_address = 0;
- bytes = copy_from_user_nmi(frame, fp, sizeof(*frame));
+ bytes = copy_from_user_nmi(&frame, fp, sizeof(frame));
+ if (bytes != sizeof(frame))
+ break;
+
+ if (fp < compat_ptr(regs->sp))
+ break;
- return bytes == sizeof(*frame);
+ callchain_store(entry, frame.return_address);
+ fp = compat_ptr(frame.next_frame);
+ }
+ return 1;
}
+#else
+static inline int
+perf_callchain_user32(struct pt_regs *regs, struct perf_callchain_entry *entry)
+{
+ return 0;
+}
+#endif
static void
perf_callchain_user(struct pt_regs *regs, struct perf_callchain_entry *entry)
@@ -1653,11 +1682,16 @@ perf_callchain_user(struct pt_regs *regs, struct perf_callchain_entry *entry)
callchain_store(entry, PERF_CONTEXT_USER);
callchain_store(entry, regs->ip);
+ if (perf_callchain_user32(regs, entry))
+ return;
+
while (entry->nr < PERF_MAX_STACK_DEPTH) {
+ unsigned long bytes;
frame.next_frame = NULL;
frame.return_address = 0;
- if (!copy_stack_frame(fp, &frame))
+ bytes = copy_from_user_nmi(&frame, fp, sizeof(frame));
+ if (bytes != sizeof(frame))
break;
if ((unsigned long)fp < regs->sp)
diff --git a/arch/x86/kernel/dumpstack.h b/arch/x86/kernel/dumpstack.h
index 29e5f7c845b2..e39e77168a37 100644
--- a/arch/x86/kernel/dumpstack.h
+++ b/arch/x86/kernel/dumpstack.h
@@ -30,6 +30,11 @@ struct stack_frame {
unsigned long return_address;
};
+struct stack_frame_ia32 {
+ u32 next_frame;
+ u32 return_address;
+};
+
static inline unsigned long rewind_frame_pointer(int n)
{
struct stack_frame *frame;