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This may cause false positives for KASAN, like the following: BUG: KASAN: stack-out-of-bounds in profile_pc+0x5b/0x90 Read of size 8 at addr ffff8881062a7a00 by task id/130040 CPU: 1 PID: 130040 Comm: id Kdump: loaded Not tainted 5.15.93+ #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014 Call Trace: dump_stack_lvl+0x4c/0x64 ? profile_pc+0x5b/0x90 print_address_description.constprop.8.cold.12+0x10/0x36b ? profile_pc+0x5b/0x90 ? profile_pc+0x5b/0x90 ? tick_sched_handle.isra.20+0xa0/0xa0 kasan_report.cold.13+0x7f/0x11b ? scheduler_tick+0x30/0x150 ? profile_pc+0x5b/0x90 ? _raw_spin_lock+0x82/0xd0 profile_pc+0x5b/0x90 profile_tick+0x78/0xb0 ? tick_sched_handle.isra.20+0x83/0xa0 tick_sched_timer+0x94/0xb0 ? enqueue_hrtimer+0x100/0x100 ? _raw_write_lock_irqsave+0xd0/0xd0 ? recalibrate_cpu_khz+0x10/0x10 ? ktime_get_update_offsets_now+0x148/0x1a0 hrtimer_interrupt+0x1b9/0x390 ? sched_ttwu_pending+0xf1/0x150 __sysvec_apic_timer_interrupt+0x7c/0x150 sysvec_apic_timer_interrupt+0x61/0x80 asm_sysvec_apic_timer_interrupt+0x16/0x20 RIP: 0010:_raw_spin_lock+0x82/0xd0 The KASAN checking is already disabled in the ORC unwinder, so let's make profile_pc() use arch_stack_walk() to get pc, which fixes the above BUG and also avoids open-coding of unwind logic. Signed-off-by: Qi Zheng --- arch/x86/kernel/time.c | 36 +++++++++++++++++------------------- 1 file changed, 17 insertions(+), 19 deletions(-) diff --git a/arch/x86/kernel/time.c b/arch/x86/kernel/time.c index e42faa792c07..eee884306d36 100644 --- a/arch/x86/kernel/time.c +++ b/arch/x86/kernel/time.c @@ -17,6 +17,7 @@ #include #include #include +#include #include #include @@ -25,27 +26,24 @@ #include #include +static bool profile_pc_cb(void *arg, unsigned long pc) +{ + unsigned long *prof_pc = arg; + + if (in_lock_functions(pc)) + return true; + + *prof_pc = pc; + return false; +} + unsigned long profile_pc(struct pt_regs *regs) { - unsigned long pc = instruction_pointer(regs); - - if (!user_mode(regs) && in_lock_functions(pc)) { -#ifdef CONFIG_FRAME_POINTER - return *(unsigned long *)(regs->bp + sizeof(long)); -#else - unsigned long *sp = (unsigned long *)regs->sp; - /* - * Return address is either directly at stack pointer - * or above a saved flags. Eflags has bits 22-31 zero, - * kernel addresses don't. - */ - if (sp[0] >> 22) - return sp[0]; - if (sp[1] >> 22) - return sp[1]; -#endif - } - return pc; + unsigned long prof_pc = 0; + + arch_stack_walk(profile_pc_cb, &prof_pc, current, regs); + + return prof_pc; } EXPORT_SYMBOL(profile_pc); From patchwork Thu Mar 30 08:15:52 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Qi Zheng X-Patchwork-Id: 76942 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:a59:b0ea:0:b0:3b6:4342:cba0 with SMTP id b10csp962690vqo; Thu, 30 Mar 2023 01:21:31 -0700 (PDT) X-Google-Smtp-Source: AKy350am1CInJt6e6tNp5tiwma5Ws2o+UZJJ5d9Tc6vFvIYe7zCe0+xQAHyTjRodKSE8f214skA/ X-Received: by 2002:a17:906:f212:b0:8f6:dc49:337f with SMTP id gt18-20020a170906f21200b008f6dc49337fmr21641363ejb.43.1680164491256; Thu, 30 Mar 2023 01:21:31 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1680164491; cv=none; d=google.com; s=arc-20160816; b=xS8TrpVvdp7SKgTWSxQP9kwzaZmPBYEXwBSeUSMmiUFMEYrdlRjFrVgPPNT0WzRSdA 926LfDWuUu8rpdtsHrf93ckamj//4pGvev3w3ZSLDUOgn2gwLsh3M8ZOr38qAmegzbxA TTLH5IbAyWNIipMo8SPIuHb8uXs115Gy3m3GbloBOIFP6sLzhYZ+6DI6R0as7Ic9xPIS El9ZI+F/bGTbpHSnef+FdBwolJCYQRQjKGqq+i4AM62duGyMBLJCSFkJbg2XagSOFOX1 mlxsRNTEgwKyZWjDYBMcLcxSGmqAwC2UU6whJ5RMPcA1VpE+vUxrEHI83hmLAmV2VQ8X ukhQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:content-transfer-encoding:mime-version :references:in-reply-to:message-id:date:subject:cc:to:from :dkim-signature; bh=BOI7aF7UFpggKDWXdppF1ANUfbw7Suxw6cG2yN/yOEM=; b=iNcN1dqpnI8D2dsVz6zN7/6rLfJX+SE8UYlGPfncSSpt0B/uX+2NtTttYa++URHaSp bqA73X+1UUxDExWr+Xn72qHBZk+o6leWUNDhGKRZO8jrHY0zojozDNgpmcCHIzixGftq QUFfE7n5wVF7sEgPvwYkXeF+ISlNXroKg7/FLVafukFzy+ft33F1hseues53Z63WGGAK vvGTWp1p/GL5/6J3Pg5/9vdYFC0ljES73lFFH/vCYJdy64+CViOQOJBxPKibzPlJuMbZ FNf7XbMR8Pgo1KSRrSa1T1n+YVE+oT8/4xDWt+bigv/EVzYiP43sG/nLWdBrId0kDI1I MU6Q== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@bytedance.com header.s=google header.b=CieFy9DL; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=QUARANTINE sp=QUARANTINE dis=NONE) header.from=bytedance.com Received: from out1.vger.email (out1.vger.email. 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Signed-off-by: Qi Zheng --- arch/x86/kernel/process.c | 22 ++++++++++++---------- 1 file changed, 12 insertions(+), 10 deletions(-) diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c index 3ab62ac98c2c..a6ff18fa6d5d 100644 --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c @@ -1000,6 +1000,17 @@ unsigned long arch_randomize_brk(struct mm_struct *mm) return randomize_page(mm->brk, 0x02000000); } +static bool get_wchan_cb(void *arg, unsigned long pc) +{ + unsigned long *addr = arg; + + if (in_sched_functions(pc)) + return true; + + *addr = pc; + return false; +} + /* * Called from fs/proc with a reference on @p to find the function * which called into schedule(). This needs to be done carefully @@ -1008,21 +1019,12 @@ unsigned long arch_randomize_brk(struct mm_struct *mm) */ unsigned long __get_wchan(struct task_struct *p) { - struct unwind_state state; unsigned long addr = 0; if (!try_get_task_stack(p)) return 0; - for (unwind_start(&state, p, NULL, NULL); !unwind_done(&state); - unwind_next_frame(&state)) { - addr = unwind_get_return_address(&state); - if (!addr) - break; - if (in_sched_functions(addr)) - continue; - break; - } + arch_stack_walk(get_wchan_cb, &addr, p, NULL); put_task_stack(p);