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,
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
>
