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x86, paravirt: Replace GET_CR2_INTO_RCX with GET_CR2_INTO_RAX

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GET_CR2_INTO_RCX is asinine: it is only used in one place, the actual
paravirt call returns the value in %rax, not %rcx; and the one place
that wants it wants the result in %r9.  We actually generate as a
result of this call:

       call ...
       movq %rax, %rcx
       xorq %rax, %rax		/* this value isn't even used... */
       movq %rcx, %r9

At least make the macro do what the paravirt call does, which is put
the value into %rax.

Nevermind the fact that the macro clobbers all the volatile registers.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Link: http://lkml.kernel.org/r/1334794610-5546-4-git-send-email-hpa@zytor.com
Cc: Glauber de Oliveira Costa <glommer@parallels.com>
This commit is contained in:
H. Peter Anvin 2012-04-18 17:16:48 -07:00 committed by H. Peter Anvin
parent 84f4fc524e
commit ffc4bc9c6f
2 changed files with 5 additions and 7 deletions
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6
arch/x86/include/asm/paravirt.h
View File

@ -1023,10 +1023,8 @@ extern void default_banner(void);
call PARA_INDIRECT(pv_cpu_ops+PV_CPU_swapgs) \
)
#define GET_CR2_INTO_RCX \
call PARA_INDIRECT(pv_mmu_ops+PV_MMU_read_cr2); \
movq %rax, %rcx; \
xorq %rax, %rax;
#define GET_CR2_INTO_RAX \
call PARA_INDIRECT(pv_mmu_ops+PV_MMU_read_cr2)
#define PARAVIRT_ADJUST_EXCEPTION_FRAME \
PARA_SITE(PARA_PATCH(pv_irq_ops, PV_IRQ_adjust_exception_frame), \

6
arch/x86/kernel/head_64.S
View File

@ -23,8 +23,9 @@
#ifdef CONFIG_PARAVIRT
#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_RCX movq %cr2, %rcx
#define GET_CR2_INTO(reg) movq %cr2, reg
#endif
/* we are not able to switch in one step to the final KERNEL ADDRESS SPACE
@ -286,8 +287,7 @@ ENTRY(early_idt_handler)
cmpl $2,early_recursion_flag(%rip)
jz 1f
incl early_recursion_flag(%rip)
GET_CR2_INTO_RCX
movq %rcx,%r9
GET_CR2_INTO(%r9)
xorl %r8d,%r8d # zero for error code
movl %esi,%ecx # get vector number
# Test %ecx against mask of vectors that push error code.