# Re: \[PATCH v10 03/14\] unwind\_user: Add compat mode frame pointer support

- From: Peter Zijlstra \<peterz@infradead.org\>
- Date: 2025-06-18 13:46:53 
- List: linux-trace-kernel
- Page: https://ratatoskr.run/linux-trace-kernel/2025/06/3097458
- Thread: https://ratatoskr.run/linux-trace-kernel/2025/06/3086227/t.md

```text
On Tue, Jun 10, 2025 at 08:54:24PM -0400, Steven Rostedt wrote:
> diff --git a/kernel/unwind/user.c b/kernel/unwind/user.c
> index 4fc550356b33..29e1f497a26e 100644
> --- a/kernel/unwind/user.c
> +++ b/kernel/unwind/user.c
> @@ -12,12 +12,32 @@ static struct unwind_user_frame fp_frame = {
>  	ARCH_INIT_USER_FP_FRAME
>  };
>  
> +static struct unwind_user_frame compat_fp_frame = {
> +	ARCH_INIT_USER_COMPAT_FP_FRAME
> +};
> +
>  static inline bool fp_state(struct unwind_user_state *state)
>  {
>  	return IS_ENABLED(CONFIG_HAVE_UNWIND_USER_FP) &&
>  	       state->type == UNWIND_USER_TYPE_FP;
>  }
>  
> +static inline bool compat_state(struct unwind_user_state *state)

Consistency would mandate this thing be called: compat_fp_state().

> +{
> +	return IS_ENABLED(CONFIG_HAVE_UNWIND_USER_COMPAT_FP) &&
> +	       state->type == UNWIND_USER_TYPE_COMPAT_FP;
> +}
> +
> +#define UNWIND_GET_USER_LONG(to, from, state)				\

Do we have to shout this?

> +({									\
> +	int __ret;							\
> +	if (compat_state(state))					\
> +		__ret = get_user(to, (u32 __user *)(from));		\
> +	else								\
> +		__ret = get_user(to, (unsigned long __user *)(from));	\
> +	__ret;								\
> +})
> +
>  int unwind_user_next(struct unwind_user_state *state)
>  {
>  	struct unwind_user_frame *frame;
```