[PATCH V2 7/7] x86/entry: Convert SWAPGS to swapgs and remove the definition of SWAPGS

From: Lai Jiangshan
Date: Wed Mar 02 2022 - 22:54:55 EST


From: Lai Jiangshan <jiangshan.ljs@xxxxxxxxxxxx>

XENPV doesn't use swapgs_restore_regs_and_return_to_usermode(),
error_entry() and entry_SYSENTER_compat(), so the PV-awared SWAPGS in
them can be changed to swapgs. There is no user of the SWAPGS anymore
after this change.

The INTERRUPT_RETURN in swapgs_restore_regs_and_return_to_usermode()
is also converted.

Cc: xen-devel@xxxxxxxxxxxxxxxxxxxx
Reviewed-by: Juergen Gross <jgross@xxxxxxxx>
Signed-off-by: Lai Jiangshan <jiangshan.ljs@xxxxxxxxxxxx>
---
arch/x86/entry/entry_64.S | 10 +++++-----
arch/x86/entry/entry_64_compat.S | 2 +-
arch/x86/include/asm/irqflags.h | 2 --
3 files changed, 6 insertions(+), 8 deletions(-)

diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index 88b61f310289..d9c885400034 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -644,8 +644,8 @@ SYM_INNER_LABEL(swapgs_restore_regs_and_return_to_usermode, SYM_L_GLOBAL)

/* Restore RDI. */
popq %rdi
- SWAPGS
- INTERRUPT_RETURN
+ swapgs
+ jmp native_iret


SYM_INNER_LABEL(restore_regs_and_return_to_kernel, SYM_L_GLOBAL)
@@ -1007,7 +1007,7 @@ SYM_CODE_START_LOCAL(error_entry)
* We entered from user mode or we're pretending to have entered
* from user mode due to an IRET fault.
*/
- SWAPGS
+ swapgs
FENCE_SWAPGS_USER_ENTRY
/* We have user CR3. Change to kernel CR3. */
SWITCH_TO_KERNEL_CR3 scratch_reg=%rax
@@ -1039,7 +1039,7 @@ SYM_CODE_START_LOCAL(error_entry)
* gsbase and proceed. We'll fix up the exception and land in
* .Lgs_change's error handler with kernel gsbase.
*/
- SWAPGS
+ swapgs

/*
* Issue an LFENCE to prevent GS speculation, regardless of whether it is a
@@ -1060,7 +1060,7 @@ SYM_CODE_START_LOCAL(error_entry)
* We came from an IRET to user mode, so we have user
* gsbase and CR3. Switch to kernel gsbase and CR3:
*/
- SWAPGS
+ swapgs
FENCE_SWAPGS_USER_ENTRY
SWITCH_TO_KERNEL_CR3 scratch_reg=%rax

diff --git a/arch/x86/entry/entry_64_compat.S b/arch/x86/entry/entry_64_compat.S
index a4fcea0cab14..72e017c3941f 100644
--- a/arch/x86/entry/entry_64_compat.S
+++ b/arch/x86/entry/entry_64_compat.S
@@ -49,7 +49,7 @@
SYM_CODE_START(entry_SYSENTER_compat)
UNWIND_HINT_EMPTY
/* Interrupts are off on entry. */
- SWAPGS
+ swapgs

pushq %rax
SWITCH_TO_KERNEL_CR3 scratch_reg=%rax
diff --git a/arch/x86/include/asm/irqflags.h b/arch/x86/include/asm/irqflags.h
index 87761396e8cc..ac2e4cc47210 100644
--- a/arch/x86/include/asm/irqflags.h
+++ b/arch/x86/include/asm/irqflags.h
@@ -140,13 +140,11 @@ static __always_inline void arch_local_irq_restore(unsigned long flags)
#else
#ifdef CONFIG_X86_64
#ifdef CONFIG_XEN_PV
-#define SWAPGS ALTERNATIVE "swapgs", "", X86_FEATURE_XENPV
#define INTERRUPT_RETURN \
ANNOTATE_RETPOLINE_SAFE; \
ALTERNATIVE_TERNARY("jmp *paravirt_iret(%rip);", \
X86_FEATURE_XENPV, "jmp xen_iret;", "jmp native_iret;")
#else
-#define SWAPGS swapgs
#define INTERRUPT_RETURN jmp native_iret
#endif
#endif
--
2.19.1.6.gb485710b