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authorPeter Zijlstra <peterz@infradead.org>2019-07-11 13:40:55 +0200
committerThomas Gleixner <tglx@linutronix.de>2019-07-17 23:17:37 +0200
commit55aedddb6149ab71bec9f050846855113977b033 (patch)
treed9154c2a76eea96bdb139f1862a6f0ec72613a2d /arch/x86/kernel/head_64.S
parent406de552c2be6ded524c75d14a73cf7f027f587e (diff)
downloadlinux-55aedddb6149ab71bec9f050846855113977b033.tar.bz2
x86/paravirt: Make read_cr2() CALLEE_SAVE
The one paravirt read_cr2() implementation (Xen) is actually quite trivial and doesn't need to clobber anything other than the return register. Making read_cr2() CALLEE_SAVE avoids all the PUSH/POP nonsense and allows more convenient use from assembly. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Juergen Gross <jgross@suse.com> Cc: bp@alien8.de Cc: rostedt@goodmis.org Cc: luto@kernel.org Cc: torvalds@linux-foundation.org Cc: hpa@zytor.com Cc: dave.hansen@linux.intel.com Cc: zhe.he@windriver.com Cc: joel@joelfernandes.org Cc: devel@etsukata.com Link: https://lkml.kernel.org/r/20190711114335.887392493@infradead.org
Diffstat (limited to 'arch/x86/kernel/head_64.S')
-rw-r--r--arch/x86/kernel/head_64.S4
1 files changed, 1 insertions, 3 deletions
diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S
index bcd206c8ac90..0e2d72929a8c 100644
--- a/arch/x86/kernel/head_64.S
+++ b/arch/x86/kernel/head_64.S
@@ -29,9 +29,7 @@
#ifdef CONFIG_PARAVIRT_XXL
#include <asm/asm-offsets.h>
#include <asm/paravirt.h>
-#define GET_CR2_INTO(reg) GET_CR2_INTO_RAX ; movq %rax, reg
#else
-#define GET_CR2_INTO(reg) movq %cr2, reg
#define INTERRUPT_RETURN iretq
#endif
@@ -323,7 +321,7 @@ early_idt_handler_common:
cmpq $14,%rsi /* Page fault? */
jnz 10f
- GET_CR2_INTO(%rdi) /* Can clobber any volatile register if pv */
+ GET_CR2_INTO(%rdi) /* can clobber %rax if pv */
call early_make_pgtable
andl %eax,%eax
jz 20f /* All good */