From: Josh Poimboeuf <jpoimboe@kernel.org>
To: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: peterz@infradead.org, keescook@chromium.org,
dave.hansen@linux.intel.com, bp@alien8.de, mingo@redhat.com,
tglx@linutronix.de, rostedt@goodmis.org, x86@kernel.org,
linux-kernel@vger.kernel.org,
Chen Zhongjin <chenzhongjin@huawei.com>,
Andi Kleen <ak@linux.intel.com>
Subject: Re: [PATCH 1/2] x86: make profile_pc() use arch_stack_walk()
Date: Fri, 7 Apr 2023 21:56:19 -0700 [thread overview]
Message-ID: <20230408045619.m5zfbispodf4zjvz@treble> (raw)
In-Reply-To: <20230330081552.54178-2-zhengqi.arch@bytedance.com>
On Thu, Mar 30, 2023 at 04:15:51PM +0800, Qi Zheng wrote:
> The profile_pc() try to get pc by doing a trick to read
> the contents of the stack. 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
I don't think this was actually a false positive. The !FRAME_POINTER
code in profile_pc() has been badly broken for many years.
BTW, there was a similar patch here:
https://lore.kernel.org/lkml/20230224021858.120078-1-chenzhongjin@huawei.com/
I thought CONFIG_PROFILING was obsolete but Andi said previously he
wants to keep it for at least boot-time profiling.
Andi did suggest removing the lock profiling hacks, which means all the
profile_pc() implementations can just be removed in favor of the generic
instruction_pointer().
--
Josh
next prev parent reply other threads:[~2023-04-08 4:56 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-30 8:15 [PATCH 0/2] some fixes and cleanups for x86 Qi Zheng
2023-03-30 8:15 ` [PATCH 1/2] x86: make profile_pc() use arch_stack_walk() Qi Zheng
2023-04-08 4:56 ` Josh Poimboeuf [this message]
2023-04-08 5:26 ` Qi Zheng
2023-03-30 8:15 ` [PATCH 2/2] x86: make __get_wchan() " Qi Zheng
2023-04-08 5:08 ` Josh Poimboeuf
2023-04-08 5:36 ` Qi Zheng
2023-04-08 22:12 ` Josh Poimboeuf
2023-04-09 6:30 ` Qi Zheng
2023-04-12 5:20 ` Josh Poimboeuf
2023-04-12 7:10 ` Qi Zheng
2023-04-12 13:15 ` Peter Zijlstra
2023-04-12 13:23 ` Peter Zijlstra
2023-04-12 17:24 ` Qi Zheng
2023-04-07 3:47 ` [PATCH 0/2] some fixes and cleanups for x86 Qi Zheng
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