From: Peter Zijlstra <peterz@infradead.org>
To: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: linux-kernel@vger.kernel.org, x86@kernel.org,
Borislav Petkov <bp@alien8.de>,
Lai Jiangshan <jiangshan.ljs@antgroup.com>,
Andy Lutomirski <luto@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
"H. Peter Anvin" <hpa@zytor.com>
Subject: Re: [PATCH V3 4/7] x86/entry: move PUSH_AND_CLEAR_REGS out of error_entry
Date: Wed, 16 Mar 2022 16:07:31 +0100 [thread overview]
Message-ID: <YjH9M3MBn+j/MwPJ@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20220315073949.7541-5-jiangshanlai@gmail.com>
On Tue, Mar 15, 2022 at 03:39:46PM +0800, Lai Jiangshan wrote:
> From: Lai Jiangshan <jiangshan.ljs@antgroup.com>
>
> Moving PUSH_AND_CLEAR_REGS out of error_entry doesn't change any
> functionality.
>
> It makes error_entry() do not fiddle with the stack.
>
> It will enlarge the size:
>
> size arch/x86/entry/entry_64.o.before:
> text data bss dec hex filename
> 17916 384 0 18300 477c arch/x86/entry/entry_64.o
>
> size --format=SysV arch/x86/entry/entry_64.o.before:
> .entry.text 5528 0
> .orc_unwind 6456 0
> .orc_unwind_ip 4304 0
>
> size arch/x86/entry/entry_64.o.after:
> text data bss dec hex filename
> 26868 384 0 27252 6a74 arch/x86/entry/entry_64.o
>
> size --format=SysV arch/x86/entry/entry_64.o.after:
> .entry.text 8200 0
> .orc_unwind 10224 0
> .orc_unwind_ip 6816 0
>
> But .entry.text in x86_64 is 2M aligned, enlarging it to 8.2k doesn't
> enlarge the final text size.
So I don't much care about the orc data, that's only used when
unwinding, a relatively rare occasion, anyway. But the text increase
does bother me a little, this can blow up I$ misses on syscall heavy
workloads.
next prev parent reply other threads:[~2022-03-16 15:08 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-15 7:39 [PATCH V3 0/7] x86/entry: Clean up entry code Lai Jiangshan
2022-03-15 7:39 ` [PATCH V3 1/7] x86/entry: Use idtentry macro for entry_INT80_compat Lai Jiangshan
2022-03-16 13:48 ` Peter Zijlstra
2022-03-15 7:39 ` [PATCH V3 2/7] x86/traps: Move pt_regs only in fixup_bad_iret() Lai Jiangshan
2022-03-15 7:39 ` [PATCH V3 3/7] x86/entry: Switch the stack after error_entry() returns Lai Jiangshan
2022-03-16 2:37 ` Josh Poimboeuf
2022-03-16 3:02 ` Lai Jiangshan
2022-03-16 15:05 ` Peter Zijlstra
2022-03-16 16:43 ` Lai Jiangshan
2022-03-18 11:12 ` Peter Zijlstra
2022-03-15 7:39 ` [PATCH V3 4/7] x86/entry: move PUSH_AND_CLEAR_REGS out of error_entry Lai Jiangshan
2022-03-16 15:07 ` Peter Zijlstra [this message]
2022-03-16 16:18 ` Lai Jiangshan
2022-03-15 7:39 ` [PATCH V3 5/7] x86/entry: Move cld to the start of idtentry Lai Jiangshan
2022-03-15 7:39 ` [PATCH V3 6/7] x86/entry: Don't call error_entry for XENPV Lai Jiangshan
2022-03-16 2:59 ` Josh Poimboeuf
2022-03-16 15:09 ` Peter Zijlstra
2022-03-16 16:48 ` Lai Jiangshan
2022-03-15 7:39 ` [PATCH V3 7/7] x86/entry: Convert SWAPGS to swapgs and remove the definition of SWAPGS Lai Jiangshan
2022-03-16 15:12 ` [PATCH V3 0/7] x86/entry: Clean up entry code Peter Zijlstra
2022-03-16 15:13 ` Peter Zijlstra
2022-03-17 12:58 ` Lai Jiangshan
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