Messages in this thread Patch in this message | | | Date | Fri, 05 Nov 2021 18:10:37 +0100 | From | Peter Zijlstra <> | Subject | [PATCH 14/22] x86,vmx: Remove .fixup usage |
| |
In the vmread exceptin path, use the, thus far, unused output register to push the @fault argument onto the stack. This, in turn, enables the exception handler to not do pushes and only modify that register when an exception does occur.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Paolo Bonzini <pbonzini@redhat.com> --- arch/x86/include/asm/extable_fixup_types.h | 1 + arch/x86/kvm/vmx/vmx_ops.h | 14 ++++++-------- 2 files changed, 7 insertions(+), 8 deletions(-)
--- a/arch/x86/include/asm/extable_fixup_types.h +++ b/arch/x86/include/asm/extable_fixup_types.h @@ -42,5 +42,6 @@ #define EX_TYPE_EFAULT_REG (EX_TYPE_IMM_REG | EX_DATA_IMM(-EFAULT)) #define EX_TYPE_NEG_REG (EX_TYPE_IMM_REG | EX_DATA_IMM(-1)) #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 --- a/arch/x86/kvm/vmx/vmx_ops.h +++ b/arch/x86/kvm/vmx/vmx_ops.h @@ -80,9 +80,11 @@ static __always_inline unsigned long __v * @field, and bounce through the trampoline to preserve * volatile registers. */ - "push $0\n\t" + "xorl %k1, %k1\n\t" + "2:\n\t" + "push %1\n\t" "push %2\n\t" - "2:call vmread_error_trampoline\n\t" + "call vmread_error_trampoline\n\t" /* * Unwind the stack. Note, the trampoline zeros out the @@ -93,12 +95,8 @@ static __always_inline unsigned long __v "3:\n\t" /* VMREAD faulted. As above, except push '1' for @fault. */ - ".pushsection .fixup, \"ax\"\n\t" - "4: push $1\n\t" - "push %2\n\t" - "jmp 2b\n\t" - ".popsection\n\t" - _ASM_EXTABLE(1b, 4b) + _ASM_EXTABLE_TYPE_REG(1b, 2b, EX_TYPE_ONE_REG, %1) + : ASM_CALL_CONSTRAINT, "=r"(value) : "r"(field) : "cc"); return value; }
| |