Messages in this thread Patch in this message | | | From | Török Edwin <> | Subject | [PATCH] perf: x86: fix callgraphs of 32-bit processes on 64-bit kernels V3. | Date | Wed, 17 Mar 2010 10:49:36 +0200 |
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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).
Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Paul Mackerras <paulus@samba.org> Cc: x86@kernel.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Török Edwin <edwintorok@gmail.com> --- arch/x86/kernel/cpu/perf_event.c | 38 +++++++++++++++++++++++++++++++++----- arch/x86/kernel/dumpstack.h | 5 +++++ 2 files changed, 38 insertions(+), 5 deletions(-)
diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c index 8c1c070..51f72f7 100644 --- a/arch/x86/kernel/cpu/perf_event.c +++ b/arch/x86/kernel/cpu/perf_event.c @@ -26,6 +26,7 @@ #include <asm/apic.h> #include <asm/stacktrace.h> #include <asm/nmi.h> +#include <asm/compat.h> static u64 perf_event_mask __read_mostly; @@ -2392,14 +2393,32 @@ 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 void +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 = 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)); + if (bytes != sizeof(frame)) + break; - bytes = copy_from_user_nmi(frame, fp, sizeof(*frame)); + if (fp < compat_ptr(regs->sp)) + break; - return bytes == sizeof(*frame); + callchain_store(entry, frame.return_address); + fp = compat_ptr(frame.next_frame); + } } +#endif static void perf_callchain_user(struct pt_regs *regs, struct perf_callchain_entry *entry) @@ -2415,11 +2434,20 @@ perf_callchain_user(struct pt_regs *regs, struct perf_callchain_entry *entry) callchain_store(entry, PERF_CONTEXT_USER); callchain_store(entry, regs->ip); +#ifdef CONFIG_COMPAT + if (test_thread_flag(TIF_IA32)) { + perf_callchain_user32(regs, entry); + return; + } +#endif + 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 4fd1420..3f0a242 100644 --- a/arch/x86/kernel/dumpstack.h +++ b/arch/x86/kernel/dumpstack.h @@ -29,4 +29,9 @@ struct stack_frame { struct stack_frame *next_frame; unsigned long return_address; }; + +struct stack_frame_ia32 { + u32 next_frame; + u32 return_address; +}; #endif -- 1.7.0 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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