Commit c9a34c3f authored by Peter Zijlstra's avatar Peter Zijlstra
Browse files

x86/kvm: Remove .fixup usage 



KVM instruction emulation has a gnarly hack where the .fixup does a
return, however there's already a ret right after the 10b label, so
mark that as 11 and have the exception clear %esi to remove the
.fixup.

Suggested-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: default avatarJosh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/20211110101325.722157053@infradead.org
parent 5fc77b91

arch/x86/include/asm/extable_fixup_types.h

+1 −0
Original line number Diff line number Diff line
@@ -46,5 +46,6 @@ 
#define	EX_TYPE_IMM_REG			17 /* reg := (long)imm */

#define	EX_TYPE_EFAULT_REG		(EX_TYPE_IMM_REG | EX_DATA_IMM(-EFAULT))

#define	EX_TYPE_ZERO_REG		(EX_TYPE_IMM_REG | EX_DATA_IMM(0))

#define	EX_TYPE_ONE_REG			(EX_TYPE_IMM_REG | EX_DATA_IMM(1))



#endif

arch/x86/kvm/emulate.c

+4 −12
Original line number Diff line number Diff line
@@ -315,7 +315,7 @@ static int fastop(struct x86_emulate_ctxt *ctxt, fastop_t fop); 
	__FOP_FUNC(#name)



#define __FOP_RET(name) \

	ASM_RET \

	"11: " ASM_RET \

	".size " name ", .-" name "\n\t"



#define FOP_RET(name) \
@@ -344,7 +344,7 @@ static int fastop(struct x86_emulate_ctxt *ctxt, fastop_t fop); 
	__FOP_RET(#op "_" #dst)



#define FOP1EEX(op,  dst) \

	FOP1E(op, dst) _ASM_EXTABLE(10b, kvm_fastop_exception)

	FOP1E(op, dst) _ASM_EXTABLE_TYPE_REG(10b, 11b, EX_TYPE_ZERO_REG, %%esi)



#define FASTOP1(op) \

	FOP_START(op) \
@@ -434,10 +434,6 @@ static int fastop(struct x86_emulate_ctxt *ctxt, fastop_t fop); 
	#op " %al \n\t" \

	__FOP_RET(#op)



asm(".pushsection .fixup, \"ax\"\n"

    "kvm_fastop_exception: xor %esi, %esi; " ASM_RET

    ".popsection");



FOP_START(setcc)

FOP_SETCC(seto)

FOP_SETCC(setno)
@@ -473,12 +469,8 @@ FOP_END; 
 \

	asm volatile("1:" insn "\n" \

	             "2:\n" \

	             ".pushsection .fixup, \"ax\"\n" \

	             "3: movl $1, %[_fault]\n" \

	             "   jmp  2b\n" \

	             ".popsection\n" \

	             _ASM_EXTABLE(1b, 3b) \

	             : [_fault] "+qm"(_fault) inoutclob ); \

		     _ASM_EXTABLE_TYPE_REG(1b, 2b, EX_TYPE_ONE_REG, %[_fault]) \

	             : [_fault] "+r"(_fault) inoutclob ); \

 \

	_fault ? X86EMUL_UNHANDLEABLE : X86EMUL_CONTINUE; \

})