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author | Torok Edwin <edwintorok@gmail.com> | 2010-03-17 12:07:16 +0200 |
---|---|---|
committer | Ingo Molnar <mingo@elte.hu> | 2010-04-02 19:30:03 +0200 |
commit | 257ef9d21f1b008a6c7425544b36641c4325a922 (patch) | |
tree | 4ffda980fe6a93acd24efcc04cd10e130caae4c1 | |
parent | b38b24ead33417146e051453d04bf60b8d2d7e25 (diff) | |
download | op-kernel-dev-257ef9d21f1b008a6c7425544b36641c4325a922.zip op-kernel-dev-257ef9d21f1b008a6c7425544b36641c4325a922.tar.gz |
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.c | 44 | ||||
-rw-r--r-- | arch/x86/kernel/dumpstack.h | 5 |
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 bd28cf9..53ea4cf 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 29e5f7c..e39e771 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; |