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author | Will Deacon <will.deacon@arm.com> | 2015-12-09 13:58:42 +0000 |
---|---|---|
committer | Alex Shi <alex.shi@linaro.org> | 2016-05-11 15:57:01 +0800 |
commit | 306fe6c320ec846544b25130a2fe61e3d394cb6f (patch) | |
tree | 66badbd3d9005d48d1fdbd2f3801e7334579eae7 /crypto/rmd160.c | |
parent | ea288f7a80b63d6956d23f50dd04fa70f8e7368f (diff) |
arm64: irq: fix walking from irq stack to task stack
Running with CONFIG_DEBUG_SPINLOCK=y can trigger a BUG with the new IRQ
stack code:
BUG: spinlock lockup suspected on CPU#1
This is due to the IRQ_STACK_TO_TASK_STACK macro incorrectly retrieving
the task stack pointer stashed at the top of the IRQ stack.
Sayeth James:
| Yup, this is what is happening. Its an off-by-one due to broken
| thinking about how the stack works. My broken thinking was:
|
| > top ------------
| > | dummy_lr | <- irq_stack_ptr
| > ------------
| > | x29 |
| > ------------
| > | x19 | <- irq_stack_ptr - 0x10
| > ------------
| > | xzr |
| > ------------
|
| But the stack-pointer is decreased before use. So it actually looks
| like this:
|
| > ------------
| > | | <- irq_stack_ptr
| > top ------------
| > | dummy_lr |
| > ------------
| > | x29 | <- irq_stack_ptr - 0x10
| > ------------
| > | x19 |
| > ------------
| > | xzr | <- irq_stack_ptr - 0x20
| > ------------
|
| The value being used as the original stack is x29, which in all the
| tests is sp but without the current frames data, hence there are no
| missing frames in the output.
|
| Jungseok Lee picked it up with a 32bit user space because aarch32
| can't use x29, so it remains 0 forever. The fix he posted is correct.
This patch fixes the macro and adds some of this wisdom to a comment,
so that the layout of the IRQ stack is well understood.
Cc: James Morse <james.morse@arm.com>
Reported-by: Jungseok Lee <jungseoklee85@gmail.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
(cherry picked from commit 7596abf2e5661d52c4f414f37addeed54e098880)
Signed-off-by: Alex Shi <alex.shi@linaro.org>
Diffstat (limited to 'crypto/rmd160.c')
0 files changed, 0 insertions, 0 deletions