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arm64: Modify stack trace and dump for use with irq_stack

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This patch allows unwind_frame() to traverse from interrupt stack to task
stack correctly. It requires data from a dummy stack frame, created
during irq_stack_entry(), added by a later patch.

A similar approach is taken to modify dump_backtrace(), which expects to
find struct pt_regs underneath any call to functions marked __exception.
When on an irq_stack, the struct pt_regs is stored on the old task stack,
the location of which is stored in the dummy stack frame.

Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
[james.morse: merged two patches, reworked for per_cpu irq_stacks, and
 no alignment guarantees, added irq_stack definitions]
Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
This commit is contained in:
AKASHI Takahiro
2015-12-04 11:02:26 +00:00
committed by Will Deacon
parent 6cdf9c7ca6
commit 132cd887b5
4 changed files with 75 additions and 3 deletions
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14
arch/arm64/kernel/traps.c
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@@ -146,6 +146,7 @@ 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());
pr_debug("%s(regs = %p tsk = %p)\n", __func__, regs, tsk);
@@ -180,9 +181,20 @@ static void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk)
if (ret < 0)
break;
stack = frame.sp;
if (in_exception_text(where))
if (in_exception_text(where)) {
/*
* If we switched to the irq_stack before calling this
* exception handler, then the pt_regs will be on the
* task stack. The easiest way to tell is if the large
* pt_regs would overlap with the end of the irq_stack.
*/
if (stack < irq_stack_ptr &&
(stack + sizeof(struct pt_regs)) > irq_stack_ptr)
stack = IRQ_STACK_TO_TASK_STACK(irq_stack_ptr);
dump_mem("", "Exception stack", stack,
stack + sizeof(struct pt_regs), false);
}
}
}