arm64: fix access to preempt_count from assembly code
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>
diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
index 3881fd1..e116614 100644
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S
@@ -311,14 +311,14 @@
#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 @@
#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