[PATCH 13/22] x86,segment: Remove .fixup usage

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

Create and use EX_TYPE_ZERO_REG to clear the register and retry the
segment load on exception.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
arch/x86/include/asm/extable_fixup_types.h | 1 +
arch/x86/include/asm/segment.h | 9 +--------
2 files changed, 2 insertions(+), 8 deletions(-)

--- a/arch/x86/include/asm/extable_fixup_types.h
+++ b/arch/x86/include/asm/extable_fixup_types.h
@@ -36,5 +36,6 @@
#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_NEG_REG (EX_TYPE_IMM_REG | EX_DATA_IMM(-1))
+#define EX_TYPE_ZERO_REG (EX_TYPE_IMM_REG | EX_DATA_IMM(0))

#endif
--- a/arch/x86/include/asm/segment.h
+++ b/arch/x86/include/asm/segment.h
@@ -307,14 +307,7 @@ do { \
\
asm volatile(" \n" \
"1: movl %k0,%%" #seg " \n" \
- \
- ".section .fixup,\"ax\" \n" \
- "2: xorl %k0,%k0 \n" \
- " jmp 1b \n" \
- ".previous \n" \
- \
- _ASM_EXTABLE(1b, 2b) \
- \
+ _ASM_EXTABLE_TYPE_REG(1b, 1b, EX_TYPE_ZERO_REG, %k0)\
: "+r" (__val) : : "memory"); \
} while (0)