x86/segment: Remove .fixup usage

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>
Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/20211110101325.663529463@infradead.org

diff --git a/arch/x86/include/asm/extable_fixup_types.h b/arch/x86/include/asm/extable_fixup_types.h
index 7469038..a43b8c1 100644 (file)
--- a/arch/x86/include/asm/extable_fixup_types.h
+++ b/arch/x86/include/asm/extable_fixup_types.h
@@ -45,5 +45,6 @@
 
 #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))
 
 #endif

diff --git a/arch/x86/include/asm/segment.h b/arch/x86/include/asm/segment.h
index 8dd8e8e..b228c9d 100644 (file)
--- 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)