From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965207Ab0COPfG (ORCPT ); Mon, 15 Mar 2010 11:35:06 -0400 Received: from mail-fx0-f219.google.com ([209.85.220.219]:51368 "EHLO mail-fx0-f219.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932525Ab0COPfD (ORCPT ); Mon, 15 Mar 2010 11:35:03 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=from:to:cc:subject:date:message-id:x-mailer:in-reply-to:references :mime-version:content-type:content-transfer-encoding; b=VRH/Vx1Ia1qmY8DdAI8O7FjL9QvpXrHXfdjxcg++VtEGmupkKyhcPTpO5AtF8T4U4R /J1qwcDyAKsnmnIxr9Xscv605mAx5e5e5q/Ag+UjRDgR9D16ZSItCHw8yRYvv0ufG2WC k6ORE5esAG4pVma7BtwUw2PmJOtw1DsfoEpTc= From: =?UTF-8?q?T=C3=B6r=C3=B6k=20Edwin?= To: Ingo Molnar Cc: Thomas Gleixner , "H. Peter Anvin" , Peter Zijlstra , Paul Mackerras , x86@kernel.org, linux-kernel@vger.kernel.org, =?UTF-8?q?T=C3=B6r=C3=B6k=20Edwin?= Subject: [PATCH] perf: x86: fix callgraphs of 32-bit processes on 64-bit kernels. Date: Mon, 15 Mar 2010 17:34:20 +0200 Message-Id: <1268667260-5505-2-git-send-email-edwintorok@gmail.com> X-Mailer: git-send-email 1.7.0 In-Reply-To: <1268667260-5505-1-git-send-email-edwintorok@gmail.com> References: <1268667260-5505-1-git-send-email-edwintorok@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 --- arch/x86/kernel/cpu/perf_event.c | 33 +++++++++++++++++++++++++++++++++ 1 files changed, 33 insertions(+), 0 deletions(-) diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c index 8c1c070..13ee83a 100644 --- a/arch/x86/kernel/cpu/perf_event.c +++ b/arch/x86/kernel/cpu/perf_event.c @@ -2401,6 +2401,20 @@ static int copy_stack_frame(const void __user *fp, struct stack_frame *frame) return bytes == sizeof(*frame); } +struct stack_frame_ia32 { + u32 next_frame; + u32 return_address; +}; + +static int copy_stack_frame_ia32(u32 fp, struct stack_frame_ia32 *frame) +{ + unsigned long bytes; + + bytes = copy_from_user_nmi(frame, (const void __user*)(unsigned long)fp, sizeof(*frame)); + + return bytes == sizeof(*frame); +} + static void perf_callchain_user(struct pt_regs *regs, struct perf_callchain_entry *entry) { @@ -2414,6 +2428,25 @@ perf_callchain_user(struct pt_regs *regs, struct perf_callchain_entry *entry) callchain_store(entry, PERF_CONTEXT_USER); callchain_store(entry, regs->ip); + if (test_thread_flag(TIF_IA32)) { + /* 32-bit process in 64-bit kernel. */ + u32 fp = regs->bp; + struct stack_frame_ia32 frame; + while (entry->nr < PERF_MAX_STACK_DEPTH) { + frame.next_frame = 0; + frame.return_address = 0; + + if (!copy_stack_frame_ia32(fp, &frame)) + break; + + if ((unsigned long)fp < regs->sp) + break; + + callchain_store(entry, frame.return_address); + fp = frame.next_frame; + } + return; + } while (entry->nr < PERF_MAX_STACK_DEPTH) { frame.next_frame = NULL; -- 1.7.0