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| author | Ard Biesheuvel <ard.biesheuvel@linaro.org> | 2016-01-01 15:02:12 +0100 |
|---|---|---|
| committer | Catalin Marinas <catalin.marinas@arm.com> | 2016-02-24 15:57:26 +0100 |
| commit | 6c94f27ac847ff8ef15b3da5b200574923bd6287 (patch) | |
| tree | e7a5384289c44b3d10a0ffb92dd7fb912998cfa6 /arch/arm64/include/asm/futex.h | |
| parent | extable: add support for relative extables to search and sort routines (diff) | |
| download | linux-6c94f27ac847ff8ef15b3da5b200574923bd6287.tar.xz linux-6c94f27ac847ff8ef15b3da5b200574923bd6287.zip | |
arm64: switch to relative exception tables
Instead of using absolute addresses for both the exception location
and the fixup, use offsets relative to the exception table entry values.
Not only does this cut the size of the exception table in half, it is
also a prerequisite for KASLR, since absolute exception table entries
are subject to dynamic relocation, which is incompatible with the sorting
of the exception table that occurs at build time.
This patch also introduces the _ASM_EXTABLE preprocessor macro (which
exists on x86 as well) and its _asm_extable assembly counterpart, as
shorthands to emit exception table entries.
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Diffstat (limited to 'arch/arm64/include/asm/futex.h')
| -rw-r--r-- | arch/arm64/include/asm/futex.h | 12 |
1 files changed, 4 insertions, 8 deletions
diff --git a/arch/arm64/include/asm/futex.h b/arch/arm64/include/asm/futex.h index 5f3ab8c1db55..f2585cdd32c2 100644 --- a/arch/arm64/include/asm/futex.h +++ b/arch/arm64/include/asm/futex.h @@ -42,10 +42,8 @@ "4: mov %w0, %w5\n" \ " b 3b\n" \ " .popsection\n" \ -" .pushsection __ex_table,\"a\"\n" \ -" .align 3\n" \ -" .quad 1b, 4b, 2b, 4b\n" \ -" .popsection\n" \ + _ASM_EXTABLE(1b, 4b) \ + _ASM_EXTABLE(2b, 4b) \ ALTERNATIVE("nop", SET_PSTATE_PAN(1), ARM64_HAS_PAN, \ CONFIG_ARM64_PAN) \ : "=&r" (ret), "=&r" (oldval), "+Q" (*uaddr), "=&r" (tmp) \ @@ -134,10 +132,8 @@ ALTERNATIVE("nop", SET_PSTATE_PAN(0), ARM64_HAS_PAN, CONFIG_ARM64_PAN) "4: mov %w0, %w6\n" " b 3b\n" " .popsection\n" -" .pushsection __ex_table,\"a\"\n" -" .align 3\n" -" .quad 1b, 4b, 2b, 4b\n" -" .popsection\n" + _ASM_EXTABLE(1b, 4b) + _ASM_EXTABLE(2b, 4b) ALTERNATIVE("nop", SET_PSTATE_PAN(1), ARM64_HAS_PAN, CONFIG_ARM64_PAN) : "+r" (ret), "=&r" (val), "+Q" (*uaddr), "=&r" (tmp) : "r" (oldval), "r" (newval), "Ir" (-EFAULT) |