From: Borislav Petkov <bp@alien8.de>
To: "Lai Jiangshan" <jiangshanlai@gmail.com>,
"Jürgen Gross" <jgross@suse.com>
Cc: 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>,
Juergen Gross <jgross@suse.com>,
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>,
"Kirill A. Shutemov" <kirill@shutemov.name>
Subject: Re: [PATCH V6 6/8] x86/entry: Convert SWAPGS to swapgs and remove the definition of SWAPGS
Date: Fri, 29 Apr 2022 11:56:44 +0200 [thread overview]
Message-ID: <Ymu2XC7k8Xj/vMjG@zn.tnic> (raw)
In-Reply-To: <20220421141055.316239-7-jiangshanlai@gmail.com>
On Thu, Apr 21, 2022 at 10:10:53PM +0800, Lai Jiangshan wrote:
> diff --git a/arch/x86/entry/entry_64_compat.S b/arch/x86/entry/entry_64_compat.S
> index 4fdb007cddbd..c5aeb0819707 100644
> --- a/arch/x86/entry/entry_64_compat.S
> +++ b/arch/x86/entry/entry_64_compat.S
> @@ -50,7 +50,7 @@ SYM_CODE_START(entry_SYSENTER_compat)
> UNWIND_HINT_EMPTY
> ENDBR
> /* Interrupts are off on entry. */
> - SWAPGS
> + swapgs
>
> pushq %rax
> SWITCH_TO_KERNEL_CR3 scratch_reg=%rax
I'm not sure about this: why can't XENPV do a 32-bit syscall through the vdso?
Also, looking at this, Jürgen, it looks kinda spaghetti to me:
entry_SYSENTER_compat
...
/* XEN PV guests always use IRET path */
ALTERNATIVE "testl %eax, %eax; jz swapgs_restore_regs_and_return_to_usermode", \
"jmp swapgs_restore_regs_and_return_to_usermode", X86_FEATURE_XENPV
then at that swapgs_restore_regs_and_return_to_usermode label:
#ifdef CONFIG_XEN_PV
ALTERNATIVE "", "jmp xenpv_restore_regs_and_return_to_usermode", X86_FEATURE_XENPV
#endif
Can we simply jump directly to xenpv_restore_regs_and_return_to_usermode
from entry_SYSENTER_compat or is that CONFIG_DEBUG_ENTRY chunk there
needed?
Thx.
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
next prev parent reply other threads:[~2022-04-29 9:57 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
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 [this message]
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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