From: Denys Vlasenko <dvlasenk@redhat.com>
To: Andy Lutomirski <luto@amacapital.net>
Cc: Ingo Molnar <mingo@kernel.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Steven Rostedt <rostedt@goodmis.org>,
Borislav Petkov <bp@alien8.de>, "H. Peter Anvin" <hpa@zytor.com>,
Oleg Nesterov <oleg@redhat.com>,
Frederic Weisbecker <fweisbec@gmail.com>,
Alexei Starovoitov <ast@plumgrid.com>,
Will Drewry <wad@chromium.org>, Kees Cook <keescook@chromium.org>,
X86 ML <x86@kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 4/5] x86/asm/entry/32: Replace RESTORE_RSI_RDI[_RDX] with open-coded 32-bit reads
Date: Tue, 09 Jun 2015 21:03:59 +0200 [thread overview]
Message-ID: <5577389F.4090301@redhat.com> (raw)
In-Reply-To: <CALCETrUasq4cFacbHhzK-TVBsHD3An3YDSW93kONvaxwnvPv1w@mail.gmail.com>
On 06/09/2015 09:01 PM, Andy Lutomirski wrote:
> On Tue, Jun 9, 2015 at 11:54 AM, Denys Vlasenko <dvlasenk@redhat.com> wrote:
>> This doesn't change much, but this uses shorter 32-bit insns:
>>
>> -48 8b 74 24 68 mov 0x68(%rsp),%rsi
>> -48 8b 7c 24 70 mov 0x70(%rsp),%rdi
>> -48 8b 54 24 60 mov 0x60(%rsp),%rdx
>> +8b 74 24 68 mov 0x68(%rsp),%esi
>> +8b 7c 24 70 mov 0x70(%rsp),%edi
>> +8b 54 24 60 mov 0x60(%rsp),%edx
>>
>> Since these are the only uses of RESTORE_RSI_RDI[_RDX], drop these macros.
>>
>
> It probably doesn't matter for these fast paths, but, for the full
> slow path return, we really do need to restore the full pt_regs.
> After all, the syscall we're returning from might be sigreturn.
This is compat 32-bit syscall handling code.
IIUC we do not restore high half of any registers for 32-bit tasks.
Am I missing something?
next prev parent reply other threads:[~2015-06-09 19:04 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-09 18:54 [PATCH 1/5] x86/asm/entry/32: Fix fallout from r9 trick removal in SYSCALL code Denys Vlasenko
2015-06-09 18:54 ` [PATCH 2/5] x86/asm/entry/32: Explain reloading of registers after __audit_syscall_entry Denys Vlasenko
2015-06-10 7:09 ` [tip:x86/asm] x86/asm/entry/32: Explain reloading of registers after __audit_syscall_entry() tip-bot for Denys Vlasenko
2015-06-09 18:54 ` [PATCH 3/5] x86/asm/entry/32: Shorten __audit_syscall_entry args preparation Denys Vlasenko
2015-06-10 6:21 ` Ingo Molnar
2015-06-12 23:28 ` Andy Lutomirski
2015-06-10 7:10 ` [tip:x86/asm] x86/asm/entry/32: Shorten __audit_syscall_entry() " tip-bot for Denys Vlasenko
2015-06-09 18:54 ` [PATCH 4/5] x86/asm/entry/32: Replace RESTORE_RSI_RDI[_RDX] with open-coded 32-bit reads Denys Vlasenko
2015-06-09 19:01 ` Andy Lutomirski
2015-06-09 19:03 ` Denys Vlasenko [this message]
2015-06-09 19:11 ` Andy Lutomirski
2015-06-09 19:18 ` Denys Vlasenko
2015-06-09 19:27 ` Andy Lutomirski
2015-06-14 8:40 ` Ingo Molnar
2015-06-14 15:21 ` Denys Vlasenko
2015-06-15 20:20 ` Ingo Molnar
2015-06-16 0:24 ` Denys Vlasenko
2015-06-18 9:31 ` Ingo Molnar
2015-06-18 10:59 ` Denys Vlasenko
2015-06-09 18:54 ` [PATCH 5/5] x86/asm/entry/32: Simplify ptrace register shuffling Denys Vlasenko
2015-06-09 18:59 ` Andy Lutomirski
2015-06-09 19:14 ` Denys Vlasenko
2015-06-18 9:33 ` Ingo Molnar
2015-06-10 7:09 ` [tip:x86/asm] x86/asm/entry/32: Fix fallout from the R9 trick removal in the SYSCALL code tip-bot for Denys Vlasenko
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