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From: Guenter Roeck <linux@roeck-us.net>
To: Lai Jiangshan <jiangshanlai@gmail.com>,
	Josh Poimboeuf <jpoimboe@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>, X86 ML <x86@kernel.org>,
	LKML <linux-kernel@vger.kernel.org>,
	Josh Poimboeuf <jpoimboe@redhat.com>,
	Brian Gerst <brgerst@gmail.com>,
	Andrew Cooper <Andrew.Cooper3@citrix.com>,
	Mark Rutland <mark.rutland@arm.com>, Borislav Petkov <bp@suse.de>
Subject: Re: [PATCH 3/6] x86/entry: Use PUSH_AND_CLEAR_REGS for compat
Date: Thu, 19 May 2022 19:46:24 -0700	[thread overview]
Message-ID: <3b34ce31-486b-7e4d-7b4b-bb97902117a7@roeck-us.net> (raw)
In-Reply-To: <CAJhGHyC0sztc2_jTT+U1M2+OSNxfNgmaKJyZgySwYqKM06q7hg@mail.gmail.com>

On 5/19/22 18:11, Lai Jiangshan wrote:
> On Fri, May 20, 2022 at 1:35 AM Josh Poimboeuf <jpoimboe@kernel.org> wrote:
>>
>> diff --git a/arch/x86/entry/entry_64_compat.S b/arch/x86/entry/entry_64_compat.S
>> index ed2be3615b50..f76e674d22c4 100644
>> --- a/arch/x86/entry/entry_64_compat.S
>> +++ b/arch/x86/entry/entry_64_compat.S
>> @@ -200,7 +200,7 @@ SYM_INNER_LABEL(entry_SYSCALL_compat_safe_stack, SYM_L_GLOBAL)
>>   SYM_INNER_LABEL(entry_SYSCALL_compat_after_hwframe, SYM_L_GLOBAL)
>>          movl    %eax, %eax              /* discard orig_ax high bits */
>>          pushq   %rax                    /* pt_regs->orig_ax */
>> -       PUSH_AND_CLEAR_REGS rax=$-ENOSYS
>> +       PUSH_AND_CLEAR_REGS rcx=%rbp rax=$-ENOSYS
> 
> Some comments need to be here to explain why %rcx is stashed in %rbp.
> 

I am curious. That comment wasn't needed before the problem fixed here
was introduced. The comment is unrelated to the bug fix. Why is it needed
now, and why would it be a prerequisite for fixing a critical bug ?
Shouldn't that comment be added in a separate patch ?

Thanks,
Guenter

  reply	other threads:[~2022-05-20  2:46 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-05-06 12:14 [PATCH 0/6] x86: Various cleanups and fixes Peter Zijlstra
2022-05-06 12:14 ` [PATCH 1/6] x86/mm: Simplify RESERVE_BRK() Peter Zijlstra
2022-05-06 15:09   ` [tip: x86/asm] " tip-bot2 for Josh Poimboeuf
2022-05-06 12:14 ` [PATCH 2/6] x86/entry: Simplify entry_INT80_compat() Peter Zijlstra
2022-05-06 15:09   ` [tip: x86/asm] " tip-bot2 for Linus Torvalds
2022-05-06 12:14 ` [PATCH 3/6] x86/entry: Use PUSH_AND_CLEAR_REGS for compat Peter Zijlstra
2022-05-06 15:09   ` [tip: x86/asm] " tip-bot2 for Peter Zijlstra
2022-05-07  2:54   ` [PATCH 3/6] " Lai Jiangshan
2022-05-19 16:24   ` Guenter Roeck
2022-05-19 17:00     ` Peter Zijlstra
2022-05-19 17:11       ` Josh Poimboeuf
2022-05-19 17:35         ` Josh Poimboeuf
2022-05-20  1:11           ` Lai Jiangshan
2022-05-20  2:46             ` Guenter Roeck [this message]
2022-05-20 15:55             ` Josh Poimboeuf
2022-05-06 12:14 ` [PATCH 4/6] x86/entry: Remove skip_r11rcx Peter Zijlstra
2022-05-06 15:09   ` [tip: x86/asm] " tip-bot2 for Peter Zijlstra
2022-05-07  2:52   ` [PATCH 4/6] " Lai Jiangshan
2022-05-06 12:14 ` [PATCH 5/6] linkage: Fix issue with missing symbol size Peter Zijlstra
2022-05-06 15:08   ` [tip: x86/asm] " tip-bot2 for Peter Zijlstra
2022-05-06 12:14 ` [PATCH 6/6] objtool: Fix STACK_FRAME_NON_STANDARD reloc type Peter Zijlstra
2022-05-06 15:08   ` [tip: x86/asm] " tip-bot2 for Peter Zijlstra
2022-05-06 16:05   ` [PATCH 6/6] " Josh Poimboeuf
2022-05-06 20:26   ` [tip: x86/asm] " tip-bot2 for Peter Zijlstra
2022-05-19 18:31 [PATCH 3/6] x86/entry: Use PUSH_AND_CLEAR_REGS for compat Guenter Roeck

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