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arm64: update 32-bit kuser helpers to ARMv8 

This patch updates the barrier semantics in the kuser helper functions
to take advantage of the ARMv8 additions to AArch32, which are
guaranteed to be available in situations where these functions will be
called.

Note that this slightly changes the cmpxchg functions in that they are
no longer necessarily full barriers if they return 1. However, the
documentation only states they include their own barriers "as needed",
not that they are obligated to act as a full barrier for the caller.

Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Acked-by: Will Deacon <will.deacon@arm.com>
CC: Matthew Leach <matthew.leach@arm.com>
CC: Dave Martin <dave.martin@arm.com>
CC: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
Robin Murphy 2013-10-07 18:30:34 +01:00 committed by Catalin Marinas
parent c019de3de6
commit d0f38f9130
1 changed files with 6 additions and 9 deletions
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15
arch/arm64/kernel/kuser32.S
View File

@ -38,33 +38,30 @@ __kuser_cmpxchg64: // 0xffff0f60
.inst 0xe92d00f0 // push {r4, r5, r6, r7}
.inst 0xe1c040d0 // ldrd r4, r5, [r0]
.inst 0xe1c160d0 // ldrd r6, r7, [r1]
.inst 0xf57ff05f // dmb sy
.inst 0xe1b20f9f // 1: ldrexd r0, r1, [r2]
.inst 0xe1b20e9f // 1: ldaexd r0, r1, [r2]
.inst 0xe0303004 // eors r3, r0, r4
.inst 0x00313005 // eoreqs r3, r1, r5
.inst 0x01a23f96 // strexdeq r3, r6, [r2]
.inst 0x01a23e96 // stlexdeq r3, r6, [r2]
.inst 0x03330001 // teqeq r3, #1
.inst 0x0afffff9 // beq 1b
.inst 0xf57ff05f // dmb sy
.inst 0xe2730000 // rsbs r0, r3, #0
.inst 0xe8bd00f0 // pop {r4, r5, r6, r7}
.inst 0xe12fff1e // bx lr
.align 5
__kuser_memory_barrier: // 0xffff0fa0
.inst 0xf57ff05f // dmb sy
.inst 0xf57ff05b // dmb ish
.inst 0xe12fff1e // bx lr
.align 5
__kuser_cmpxchg: // 0xffff0fc0
.inst 0xf57ff05f // dmb sy
.inst 0xe1923f9f // 1: ldrex r3, [r2]
.inst 0xe1923e9f // 1: ldaex r3, [r2]
.inst 0xe0533000 // subs r3, r3, r0
.inst 0x01823f91 // strexeq r3, r1, [r2]
.inst 0x01823e91 // stlexeq r3, r1, [r2]
.inst 0x03330001 // teqeq r3, #1
.inst 0x0afffffa // beq 1b
.inst 0xe2730000 // rsbs r0, r3, #0
.inst 0xeaffffef // b <__kuser_memory_barrier>
.inst 0xe12fff1e // bx lr
.align 5
__kuser_get_tls: // 0xffff0fe0