Re: [PATCH V6 6/8] x86/entry: Convert SWAPGS to swapgs and remove the definition of SWAPGS

[Borislav Petkov]

On Fri, Apr 29, 2022 at 07:45:43PM +0800, Lai Jiangshan wrote:
> Adding ALTERNATIVE in swapgs_restore_regs_and_return_to_usermode()

All I'm saying is to do this:

diff --git a/arch/x86/entry/entry_64_compat.S b/arch/x86/entry/entry_64_compat.S
index c5aeb0819707..79f0511a4791 100644
--- a/arch/x86/entry/entry_64_compat.S
+++ b/arch/x86/entry/entry_64_compat.S
@@ -140,7 +140,7 @@ SYM_INNER_LABEL(entry_SYSENTER_compat_after_hwframe, SYM_L_GLOBAL)
 	call	do_SYSENTER_32
 	/* 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
+		    "jmp xenpv_restore_regs_and_return_to_usermode", X86_FEATURE_XENPV
 	jmp	sysret32_from_system_call
 
 .Lsysenter_fix_flags:

which eliminates one JMP in the XENPV case if the CONFIG_DEBUG_ENTRY
thing is not relevant to XENPV.

But let's see what Jürgen says first...

-- 
Regards/Gruss,
    Boris.

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