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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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29
arch/arm64/kernel/stacktrace.c
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@@ -20,6 +20,7 @@
#include <linux/sched.h>
#include <linux/stacktrace.h>
#include <asm/irq.h>
#include <asm/stacktrace.h>
/*
@@ -39,17 +40,41 @@ int notrace unwind_frame(struct stackframe *frame)
{
unsigned long high, low;
unsigned long fp = frame->fp;
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.
*/
irq_stack_ptr = IRQ_STACK_PTR(raw_smp_processor_id());
low = frame->sp;
high = ALIGN(low, THREAD_SIZE);
/* irq stacks are not THREAD_SIZE aligned */
if (on_irq_stack(frame->sp, raw_smp_processor_id()))
high = irq_stack_ptr;
else
high = ALIGN(low, THREAD_SIZE) - 0x20;
if (fp < low || fp > high - 0x18 || fp & 0xf)
if (fp < low || fp > high || fp & 0xf)
return -EINVAL;
frame->sp = fp + 0x10;
frame->fp = *(unsigned long *)(fp);
frame->pc = *(unsigned long *)(fp + 8);
/*
* Check whether we are going to walk through from interrupt stack
* to task stack.
* If we reach the end of the stack - and its an interrupt stack,
* read the original task stack pointer from the dummy frame.
*/
if (frame->sp == irq_stack_ptr)
frame->sp = IRQ_STACK_TO_TASK_STACK(irq_stack_ptr);
return 0;
}