crash_setup_regs() currently moves segment registers (ss, cs, ds, es)
into pt_regs via a general purpose register (%eax). Update the code to
avoid the intermediate register and store segment registers directly
to their destination fields. This reduces the generated code from:
131: 8c d0 mov %ss,%eax
133: 66 89 84 24 a0 00 00 mov %ax,0xa0(%rsp)
13a: 00
13b: 8c c8 mov %cs,%eax
13d: 66 89 84 24 88 00 00 mov %ax,0x88(%rsp)
144: 00
to:
131: 8c 94 24 a0 00 00 00 mov %ss,0xa0(%rsp)
138: 8c 8c 24 88 00 00 00 mov %cs,0x88(%rsp)
No functional change intended.
Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Cc: Thomas Gleixner <tglx@kernel.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
---
arch/x86/include/asm/kexec.h | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/arch/x86/include/asm/kexec.h b/arch/x86/include/asm/kexec.h
index 5cfb27f26583..ad7ef567452b 100644
--- a/arch/x86/include/asm/kexec.h
+++ b/arch/x86/include/asm/kexec.h
@@ -106,11 +106,11 @@ static inline void crash_setup_regs(struct pt_regs *newregs,
asm volatile("mov %%r14,%0" : "=m"(newregs->r14));
asm volatile("mov %%r15,%0" : "=m"(newregs->r15));
#endif
- asm volatile("mov %%ss,%k0" : "=a"(newregs->ss));
- asm volatile("mov %%cs,%k0" : "=a"(newregs->cs));
+ asm volatile("mov %%ss,%0" : "=m"(newregs->ss));
+ asm volatile("mov %%cs,%0" : "=m"(newregs->cs));
#ifdef CONFIG_X86_32
- asm volatile("mov %%ds,%k0" : "=a"(newregs->ds));
- asm volatile("mov %%es,%k0" : "=a"(newregs->es));
+ asm volatile("mov %%ds,%0" : "=m"(newregs->ds));
+ asm volatile("mov %%es,%0" : "=m"(newregs->es));
#endif
asm volatile("pushf\n\t"
"pop %0" : "=m"(newregs->flags));
--
2.53.0