On 4/19/22 21:09, Mark Rutland wrote:
> On Mon, Apr 18, 2022 at 09:22:10PM +0800, He Zhe wrote:
>> Currently stack_trace_consume_fn can only have pc of each frame of the
>> stack. Copying-beyond-the-frame-detection also needs fp of current and
>> previous frame. Other detection algorithm in the future may need more
>> information of the frame.
>>
>> We define a frame_info to include them all.
>>
>>
>> Signed-off-by: He Zhe <zhe.he@xxxxxxxxxxxxx>
>> ---
>> include/linux/stacktrace.h | 9 ++++++++-
>> kernel/stacktrace.c | 10 +++++-----
>> 2 files changed, 13 insertions(+), 6 deletions(-)
>>
>> diff --git a/include/linux/stacktrace.h b/include/linux/stacktrace.h
>> index 97455880ac41..5a61bfafe6f0 100644
>> --- a/include/linux/stacktrace.h
>> +++ b/include/linux/stacktrace.h
>> @@ -10,15 +10,22 @@ struct pt_regs;
>>
>> #ifdef CONFIG_ARCH_STACKWALK
>>
>> +struct frame_info {
>> + unsigned long pc;
>> + unsigned long fp;
>> + unsigned long prev_fp;
>> +};
> I don't think this should be exposed through a generic interface; the `fp` and
> `prev_fp` values are only meaningful with arch-specific knowledge, and they're
> *very* easy to misuse (e.g. when transitioning from one stack to another).
> There's also a bunch of other information one may or may not want, depending on
> what you're trying to achieve.
>
> I am happy to have an arch-specific internal unwinder where we can access this
> information, and *maybe* it makes sense to have a generic API that passes some
> opaque token, but I don't think we should make the structure generic.
Thanks for thoughts. I saw unwind_frame and etc was made private earlier and
took that as a hint that all further stack walk things should be based on those
functions and came up with this. But OK, good to know that arch-specific unwind
would be fine, I'll redo this series in that way.
Thanks,
Zhe
>
> Thanks,
> Mark.
>
>> +
>> /**
>> * stack_trace_consume_fn - Callback for arch_stack_walk()
>> * @cookie: Caller supplied pointer handed back by arch_stack_walk()
>> * @addr: The stack entry address to consume
>> + * @fi: The frame information to consume
>> *
>> * Return: True, if the entry was consumed or skipped
>> * False, if there is no space left to store
>> */
>> -typedef bool (*stack_trace_consume_fn)(void *cookie, unsigned long addr);
>> +typedef bool (*stack_trace_consume_fn)(void *cookie, struct frame_info *fi);
>> /**
>> * arch_stack_walk - Architecture specific function to walk the stack
>> * @consume_entry: Callback which is invoked by the architecture code for
>> diff --git a/kernel/stacktrace.c b/kernel/stacktrace.c
>> index 9ed5ce989415..2d0a2812e92b 100644
>> --- a/kernel/stacktrace.c
>> +++ b/kernel/stacktrace.c
>> @@ -79,7 +79,7 @@ struct stacktrace_cookie {
>> unsigned int len;
>> };
>>
>> -static bool stack_trace_consume_entry(void *cookie, unsigned long addr)
>> +static bool stack_trace_consume_entry(void *cookie, struct frame_info *fi)
>> {
>> struct stacktrace_cookie *c = cookie;
>>
>> @@ -90,15 +90,15 @@ static bool stack_trace_consume_entry(void *cookie, unsigned long addr)
>> c->skip--;
>> return true;
>> }
>> - c->store[c->len++] = addr;
>> + c->store[c->len++] = fi->pc;
>> return c->len < c->size;
>> }
>>
>> -static bool stack_trace_consume_entry_nosched(void *cookie, unsigned long addr)
>> +static bool stack_trace_consume_entry_nosched(void *cookie, struct frame_info *fi)
>> {
>> - if (in_sched_functions(addr))
>> + if (in_sched_functions(fi->pc))
>> return true;
>> - return stack_trace_consume_entry(cookie, addr);
>> + return stack_trace_consume_entry(cookie, fi);
>> }
>>
>> /**
>> --
>> 2.25.1
>>
