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arm64: fix access to preempt_count from assembly code

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preempt_count is defined as an int. Oddly enough, we access it
as a 64bit value. Things become interesting when running a BE
kernel, and looking at the current CPU number, which is stored
as an int next to preempt_count. Like in a per-cpu interrupt
handler, for example...

Using a 32bit access fixes the issue for good.

Cc: Matthew Leach <matthew.leach@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
Marc Zyngier 2013-11-04 20:14:58 +00:00 committed by Catalin Marinas
parent 7ade67b598
commit 717321fcb5
1 changed files with 11 additions and 11 deletions
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22
arch/arm64/kernel/entry.S
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@ -311,14 +311,14 @@ el1_irq:
#endif
#ifdef CONFIG_PREEMPT
get_thread_info tsk
ldr x24, [tsk, #TI_PREEMPT] // get preempt count
add x0, x24, #1 // increment it
str x0, [tsk, #TI_PREEMPT]
ldr w24, [tsk, #TI_PREEMPT] // get preempt count
add w0, w24, #1 // increment it
str w0, [tsk, #TI_PREEMPT]
#endif
irq_handler
#ifdef CONFIG_PREEMPT
str x24, [tsk, #TI_PREEMPT] // restore preempt count
cbnz x24, 1f // preempt count != 0
str w24, [tsk, #TI_PREEMPT] // restore preempt count
cbnz w24, 1f // preempt count != 0
ldr x0, [tsk, #TI_FLAGS] // get flags
tbz x0, #TIF_NEED_RESCHED, 1f // needs rescheduling?
bl el1_preempt
@ -509,15 +509,15 @@ el0_irq_naked:
#endif
get_thread_info tsk
#ifdef CONFIG_PREEMPT
ldr x24, [tsk, #TI_PREEMPT] // get preempt count
add x23, x24, #1 // increment it
str x23, [tsk, #TI_PREEMPT]
ldr w24, [tsk, #TI_PREEMPT] // get preempt count
add w23, w24, #1 // increment it
str w23, [tsk, #TI_PREEMPT]
#endif
irq_handler
#ifdef CONFIG_PREEMPT
ldr x0, [tsk, #TI_PREEMPT]
str x24, [tsk, #TI_PREEMPT]
cmp x0, x23
ldr w0, [tsk, #TI_PREEMPT]
str w24, [tsk, #TI_PREEMPT]
cmp w0, w23
b.eq 1f
mov x1, #0
str x1, [x1] // BUG