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| author | Will Deacon <will.deacon@arm.com> | 2018-12-11 13:41:32 +0000 |
|---|---|---|
| committer | Will Deacon <will.deacon@arm.com> | 2018-12-11 20:07:03 +0000 |
| commit | 7faa313f05cad184e8b17750f0cbe5216ac6debb (patch) | |
| tree | c876a0fc11afaf73fb876d4756cc34a338bf5fa9 /arch/arm64 | |
| parent | 732291c4fab8b790847aa572703c01ad483b14d0 (diff) | |
| download | linux-stable-7faa313f05cad184e8b17750f0cbe5216ac6debb.tar.gz linux-stable-7faa313f05cad184e8b17750f0cbe5216ac6debb.tar.bz2 linux-stable-7faa313f05cad184e8b17750f0cbe5216ac6debb.zip | |
arm64: preempt: Fix big-endian when checking preempt count in assembly
Commit 396244692232 ("arm64: preempt: Provide our own implementation of
asm/preempt.h") extended the preempt count field in struct thread_info
to 64 bits, so that it consists of a 32-bit count plus a 32-bit flag
indicating whether or not the current task needs rescheduling.
Whilst the asm-offsets definition of TSK_TI_PREEMPT was updated to point
to this new field, the assembly usage was left untouched meaning that a
32-bit load from TSK_TI_PREEMPT on a big-endian machine actually returns
the reschedule flag instead of the count.
Whilst we could fix this by pointing TSK_TI_PREEMPT at the count field,
we're actually better off reworking the two assembly users so that they
operate on the whole 64-bit value in favour of inspecting the thread
flags separately in order to determine whether a reschedule is needed.
Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reported-by: "kernelci.org bot" <bot@kernelci.org>
Tested-by: Kevin Hilman <khilman@baylibre.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Diffstat (limited to 'arch/arm64')
| -rw-r--r-- | arch/arm64/include/asm/assembler.h | 8 | ||||
| -rw-r--r-- | arch/arm64/kernel/entry.S | 6 |
2 files changed, 5 insertions, 9 deletions
diff --git a/arch/arm64/include/asm/assembler.h b/arch/arm64/include/asm/assembler.h index ce985f13dce5..4feb6119c3c9 100644 --- a/arch/arm64/include/asm/assembler.h +++ b/arch/arm64/include/asm/assembler.h @@ -722,11 +722,9 @@ USER(\label, ic ivau, \tmp2) // invalidate I line PoU .macro if_will_cond_yield_neon #ifdef CONFIG_PREEMPT get_thread_info x0 - ldr w1, [x0, #TSK_TI_PREEMPT] - ldr x0, [x0, #TSK_TI_FLAGS] - cmp w1, #PREEMPT_DISABLE_OFFSET - csel x0, x0, xzr, eq - tbnz x0, #TIF_NEED_RESCHED, .Lyield_\@ // needs rescheduling? + ldr x0, [x0, #TSK_TI_PREEMPT] + sub x0, x0, #PREEMPT_DISABLE_OFFSET + cbz x0, .Lyield_\@ /* fall through to endif_yield_neon */ .subsection 1 .Lyield_\@ : diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index c7d050207e53..763f03dc4d9e 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -619,10 +619,8 @@ el1_irq: irq_handler #ifdef CONFIG_PREEMPT - ldr w24, [tsk, #TSK_TI_PREEMPT] // get preempt count - cbnz w24, 1f // preempt count != 0 - ldr x0, [tsk, #TSK_TI_FLAGS] // get flags - tbz x0, #TIF_NEED_RESCHED, 1f // needs rescheduling? + ldr x24, [tsk, #TSK_TI_PREEMPT] // get preempt count + cbnz x24, 1f // preempt count != 0 bl el1_preempt 1: #endif |