Re: [RFC][PATCH] unwind: Add stacktrace_setup system call

[Mathieu Desnoyers <mathieu.desnoyers@efficios.com>]

On 2026-04-29 11:43, Steven Rostedt wrote:
[...]

AFAIU this is a functional iteration of my prior RFC here:

https://lore.kernel.org/lkml/2fa31347-3021-4604-bec3-e5a2d57b77b5@efficios.com/

perhaps it would be valuable to refer to that thread ?

>   }
> +
> +/**
> + * sys_stacktrace_setup - register an address for user space stacktrace walking.
> + * @op: Type of operation to perform
> + * @addr_start: The virtual address of the stacktrace information
> + * @addr_length: The length of the stacktrace information
> + * @text_start: The virtual address of the text that @addr_start represents
> + * @text_length: The length of teh text

the

also, perhaps add @flags just in case ? This allows changing the
behavior without having to insert entirely new set of ops.

> + *
> + * This system call is used by dynamic library utilities to inform the kernel

Out of curiosity: what would happen if the application chooses to invoke
this system call to register sframe for the main executable ? Should it be
allowed ?

> + * of meta data that it loaded that can be used by the kernel to know how
> + * to stack walk the given text locations.
> + *
> + * Currently only sframes are supported, but in the future, this may be used
> + * to tell the kernel about JIT code which will most likely have a different
> + * format.
> + *
> + * The type command may be extended and parameters may be used for other
> + * purposes.

"type" or "op" ?

Thanks,

Mathieu

> + *
> + * Return: 0 if successful, otherwise a negative error.
> + */
> +SYSCALL_DEFINE5(stacktrace_setup, int, op, unsigned long, addr_start,
> +		unsigned long, addr_length, unsigned long, text_start,
> +		unsigned long, text_length)
> +{
> +	switch (op) {
> +	case STACKTRACE_REGISTER_SFRAME:
> +		return sframe_add_section(addr_start, addr_start + addr_length,
> +					  text_start, text_start+text_length);
> +	case STACKTRACE_UNREGISTER_SFRAME:
> +		return sframe_remove_section(addr_start);
> +	}
> +	return -EINVAL;
> +}

-- 
Mathieu Desnoyers
EfficiOS Inc.
https://www.efficios.com