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| author | Vasily Gorbik <gor@linux.ibm.com> | 2019-11-27 19:37:51 +0300 |
|---|---|---|
| committer | Vasily Gorbik <gor@linux.ibm.com> | 2019-11-30 12:52:48 +0300 |
| commit | 222ee9087a730b1df08d09baed0d03626e67600f (patch) | |
| tree | d54f365c33449a1697ab1d0b4b07a7921ce6a837 /arch/s390/include/asm/unwind.h | |
| parent | de6921ccbd0fb2882a1f615a6d3cdfbdcd64532c (diff) | |
| download | linux-222ee9087a730b1df08d09baed0d03626e67600f.tar.xz | |
s390/unwind: start unwinding from reliable state
A comment in arch/s390/include/asm/unwind.h says:
> If 'first_frame' is not zero unwind_start skips unwind frames until it
> reaches the specified stack pointer.
> The end of the unwinding is indicated with unwind_done, this can be true
> right after unwind_start, e.g. with first_frame!=0 that can not be found.
> unwind_next_frame skips to the next frame.
> Once the unwind is completed unwind_error() can be used to check if there
> has been a situation where the unwinder could not correctly understand
> the tasks call chain.
With this change backchain unwinder now comply with behaviour
described. As well as matches orc unwinder implementation. Now unwinder
starts from reliable state, i.e. __unwind_start own stack frame is
taken or stack frame generated by __switch_to (ksp) - both known to be
valid. In case of pt_regs %r15 is better match for pt_regs psw, than
sometimes random "sp" caller passed.
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Diffstat (limited to 'arch/s390/include/asm/unwind.h')
| -rw-r--r-- | arch/s390/include/asm/unwind.h | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/arch/s390/include/asm/unwind.h b/arch/s390/include/asm/unwind.h index 5d6c8fe7a271..de9006b0cfeb 100644 --- a/arch/s390/include/asm/unwind.h +++ b/arch/s390/include/asm/unwind.h @@ -58,11 +58,11 @@ static inline bool unwind_error(struct unwind_state *state) static inline void unwind_start(struct unwind_state *state, struct task_struct *task, struct pt_regs *regs, - unsigned long sp) + unsigned long first_frame) { task = task ?: current; - sp = sp ?: get_stack_pointer(task, regs); - __unwind_start(state, task, regs, sp); + first_frame = first_frame ?: get_stack_pointer(task, regs); + __unwind_start(state, task, regs, first_frame); } static inline struct pt_regs *unwind_get_entry_regs(struct unwind_state *state) |