arm64: make irq_stack_ptr more robust

[deliverable/linux.git] / arch / arm64 / kernel / traps.c

diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c
index cbedd724f48efcf487e443fa3fc21516d8d898a6..c5392081b49ba4ac4f48d9a0782442ac888ed222 100644 (file)
--- 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)