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Commit ffc4bc9c authored by H. Peter Anvin's avatar H. Peter Anvin Committed by H. Peter Anvin
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x86, paravirt: Replace GET_CR2_INTO_RCX with GET_CR2_INTO_RAX 



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: default avatarH. 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>
parent 84f4fc52

arch/x86/include/asm/paravirt.h

+2 −4
Original line number Diff line number Diff line
@@ -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), \

arch/x86/kernel/head_64.S

+3 −3
Original line number Diff line number Diff line
@@ -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.