From: Borislav Petkov <bp@alien8.de>
To: Juergen Gross <jgross@suse.com>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>,
LKML <linux-kernel@vger.kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Josh Poimboeuf <jpoimboe@redhat.com>,
Andy Lutomirski <luto@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>, X86 ML <x86@kernel.org>,
Lai Jiangshan <jiangshan.ljs@antgroup.com>,
Ingo Molnar <mingo@redhat.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
"H. Peter Anvin" <hpa@zytor.com>
Subject: Re: [PATCH V6 3/8] x86/entry: Move PUSH_AND_CLEAR_REGS out of error_entry()
Date: Mon, 2 May 2022 20:09:03 +0200 [thread overview]
Message-ID: <YnAePwYZwq0N1fjJ@zn.tnic> (raw)
In-Reply-To: <6c0dd7c7-593b-d8cf-347b-3d32310fcc11@suse.com>
On Mon, May 02, 2022 at 02:42:50PM +0200, Juergen Gross wrote:
> I think you could avoid the extra call/ret by doing something like:
>
> SYM_CODE_START_LOCAL(error_exit_push_and_save)
> UNWIND_HINT_FUNC
> PUSH_AND_CLEAR_REGS save_ret=1
> ENCODE_FRAME_POINTER 8
> jmp error_exit
> SYM_CODE_END(error_exit_push_and_save)
>
> ... and use this instead of patch 5:
>
> ALTERNATIVE "call error_entry_push_and_save; movq %rax, %rsp", \
> "call push_and_clear_regs", X86_FEATURE_XENPV
I'm afraid I can't follow - you still need to call error_entry on
!XENPV. You have a function error_entry_push_and_save() but above it is
called error_*exit*_push_and_save...
Bottomline is, this should be as simple as possible code - an additional
CALL/RET doesn't really matter, perf-wise.
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
next prev parent reply other threads:[~2022-05-02 18:09 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-21 14:10 [PATCH V6 0/8] x86/entry: Clean up entry code Lai Jiangshan
2022-04-21 14:10 ` [PATCH V6 1/8] x86/traps: Move pt_regs only in fixup_bad_iret() Lai Jiangshan
2022-04-21 14:10 ` [PATCH V6 2/8] x86/entry: Switch the stack after error_entry() returns Lai Jiangshan
2022-04-21 14:10 ` [PATCH V6 3/8] x86/entry: Move PUSH_AND_CLEAR_REGS out of error_entry() Lai Jiangshan
2022-04-27 17:45 ` Borislav Petkov
2022-04-28 0:33 ` Lai Jiangshan
2022-04-28 10:26 ` Borislav Petkov
2022-05-02 12:42 ` Juergen Gross
2022-05-02 18:09 ` Borislav Petkov [this message]
2022-04-21 14:10 ` [PATCH V6 4/8] x86/entry: Move cld to the start of idtentry macro Lai Jiangshan
2022-04-21 14:10 ` [PATCH V6 5/8] x86/entry: Don't call error_entry() for XENPV Lai Jiangshan
2022-04-21 14:10 ` [PATCH V6 6/8] x86/entry: Convert SWAPGS to swapgs and remove the definition of SWAPGS Lai Jiangshan
2022-04-29 9:56 ` Borislav Petkov
2022-04-29 11:45 ` Lai Jiangshan
2022-04-29 12:22 ` Borislav Petkov
2022-05-02 12:18 ` Juergen Gross
2022-05-02 17:56 ` Borislav Petkov
2022-05-03 10:43 ` Borislav Petkov
2022-04-21 14:10 ` [PATCH V6 7/8] x86/entry: Remove the branch in sync_regs() Lai Jiangshan
2022-04-21 14:10 ` [PATCH V6 8/8] x86/entry: Use idtentry macro for entry_INT80_compat() Lai Jiangshan
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