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authorYang Shi <yang.shi@linaro.org>2016-02-11 13:53:10 -0800
committerWill Deacon <will.deacon@arm.com>2016-02-12 15:53:51 +0000
commita80a0eb70c358f8c7dda4bb62b2278dc6285217b (patch)
treea0fda0517271586316fbd476aed280734a245151 /arch
parente04a28d45ff343b47a4ffc4dee3a3e279e76ddfa (diff)
downloadlinux-a80a0eb70c358f8c7dda4bb62b2278dc6285217b.tar.bz2
arm64: make irq_stack_ptr more robust
Switching between stacks is only valid if we are tracing ourselves while on the irq_stack, so it is only valid when in current and non-preemptible context, otherwise is is just zeroed off. Fixes: 132cd887b5c5 ("arm64: Modify stack trace and dump for use with irq_stack") Acked-by: James Morse <james.morse@arm.com> Tested-by: James Morse <james.morse@arm.com> Signed-off-by: Yang Shi <yang.shi@linaro.org> Signed-off-by: Will Deacon <will.deacon@arm.com>
Diffstat (limited to 'arch')
-rw-r--r--arch/arm64/kernel/stacktrace.c13
-rw-r--r--arch/arm64/kernel/traps.c11
2 files changed, 16 insertions, 8 deletions
diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c
index 12a18cbc4295..d9751a4769e7 100644
--- a/arch/arm64/kernel/stacktrace.c
+++ b/arch/arm64/kernel/stacktrace.c
@@ -44,14 +44,13 @@ int notrace unwind_frame(struct task_struct *tsk, struct stackframe *frame)
unsigned long irq_stack_ptr;
/*
- * Use raw_smp_processor_id() to avoid false-positives from
- * CONFIG_DEBUG_PREEMPT. get_wchan() calls unwind_frame() on sleeping
- * task stacks, we can be pre-empted in this case, so
- * {raw_,}smp_processor_id() may give us the wrong value. Sleeping
- * tasks can't ever be on an interrupt stack, so regardless of cpu,
- * the checks will always fail.
+ * Switching between stacks is valid when tracing current and in
+ * non-preemptible context.
*/
- irq_stack_ptr = IRQ_STACK_PTR(raw_smp_processor_id());
+ if (tsk == current && !preemptible())
+ irq_stack_ptr = IRQ_STACK_PTR(smp_processor_id());
+ else
+ irq_stack_ptr = 0;
low = frame->sp;
/* irq stacks are not THREAD_SIZE aligned */
diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c
index cbedd724f48e..c5392081b49b 100644
--- a/arch/arm64/kernel/traps.c
+++ b/arch/arm64/kernel/traps.c
@@ -146,9 +146,18 @@ static void dump_instr(const char *lvl, struct pt_regs *regs)
static void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
{
struct stackframe frame;
- unsigned long irq_stack_ptr = IRQ_STACK_PTR(smp_processor_id());
+ unsigned long irq_stack_ptr;
int skip;
+ /*
+ * Switching between stacks is valid when tracing current and in
+ * non-preemptible context.
+ */
+ if (tsk == current && !preemptible())
+ irq_stack_ptr = IRQ_STACK_PTR(smp_processor_id());
+ else
+ irq_stack_ptr = 0;
+
pr_debug("%s(regs = %p tsk = %p)\n", __func__, regs, tsk);
if (!tsk)