[PATCH 17/22] x86,kvm: Remove .fixup usage

Peter Zijlstra
2021-11-05T17:24:21Z

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: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
arch/x86/kvm/emulate.c | 16 ++++------------
1 file changed, 4 insertions(+), 12 deletions(-)

--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -315,7 +315,7 @@ static int fastop(struct x86_emulate_ctx
__FOP_FUNC(#name)

#define __FOP_RET(name) \
- "ret \n\t" \
+ "11: ret \n\t" \
".size " name ", .-" name "\n\t"

#define FOP_RET(name) \
@@ -344,7 +344,7 @@ static int fastop(struct x86_emulate_ctx
__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_ctx
#op " %al \n\t" \
__FOP_RET(#op)

-asm(".pushsection .fixup, \"ax\"\n"
- "kvm_fastop_exception: xor %esi, %esi; ret\n"
- ".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; \
})