From: Peter Zijlstra <peterz@infradead.org>
To: Petr Mladek <pmladek@suse.com>
Cc: Brian Gerst <brgerst@gmail.com>,
jpoimboe@kernel.org, linux-kernel@vger.kernel.org,
x86@kernel.org, Thomas Gleixner <tglx@linutronix.de>,
Borislav Petkov <bp@alien8.de>, "H . Peter Anvin" <hpa@zytor.com>,
Sami Tolvanen <samitolvanen@google.com>,
alyssa.milburn@linux.intel.com, keescook@chromium.org,
joao@overdrivepizza.com, tim.c.chen@linux.intel.com,
live-patching@vger.kernel.org
Subject: Re: [PATCH v2 2/2] x86: Rewrite ret_from_fork() in C
Date: Wed, 19 Jul 2023 22:02:22 +0200 [thread overview]
Message-ID: <20230719200222.GD3529734@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <ZLf_Z5dCSm7zKDel@alley>
On Wed, Jul 19, 2023 at 05:21:11PM +0200, Petr Mladek wrote:
> This patch broke livepatching. Kthreads never have a reliable stack.
> It works when I revert it.
> > +SYM_CODE_START(ret_from_fork_asm)
> > + UNWIND_HINT_REGS
It works again when I change the above hint to UNWIND_HINT_END_OF_STACK,
so yeah. Doing this makes objtool unhappy with something else though,
so I'll go prod at things with something sharp...
Thanks!
> > ANNOTATE_NOENDBR // copy_thread
> > CALL_DEPTH_ACCOUNT
> >
> > + movq %rax, %rdi /* prev */
> > + movq %rsp, %rsi /* regs */
> > + movq %rbx, %rdx /* fn */
> > + movq %r12, %rcx /* fn_arg */
> > + call ret_from_fork
> >
> > +SYM_CODE_END(ret_from_fork_asm)
next prev parent reply other threads:[~2023-07-19 20:02 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-06-23 22:55 [PATCH v2 0/2] Rewrite ret_from_fork() in C Brian Gerst
2023-06-23 22:55 ` [PATCH v2 1/2] x86/32: Remove schedule_tail_wrapper() Brian Gerst
2023-07-10 8:13 ` [tip: x86/urgent] " tip-bot2 for Brian Gerst
2023-06-23 22:55 ` [PATCH v2 2/2] x86: Rewrite ret_from_fork() in C Brian Gerst
2023-07-10 8:13 ` [tip: x86/urgent] " tip-bot2 for Brian Gerst
2023-07-19 15:21 ` [PATCH v2 2/2] " Petr Mladek
2023-07-19 20:02 ` Peter Zijlstra [this message]
2023-07-19 20:15 ` Peter Zijlstra
2023-07-19 20:50 ` Peter Zijlstra
2023-07-19 23:31 ` Josh Poimboeuf
2023-07-20 5:22 ` Peter Zijlstra
2023-07-20 9:28 ` Peter Zijlstra
2023-07-20 8:18 ` Petr Mladek
2023-07-21 9:20 ` [tip: x86/urgent] x86: Fix kthread unwind tip-bot2 for Peter Zijlstra
2023-07-19 20:33 ` [PATCH v2 2/2] x86: Rewrite ret_from_fork() in C Joe Lawrence
2023-07-19 20:41 ` Peter Zijlstra
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