On 2026-05-21 18:35:32-0400, Steven Rostedt wrote:
> From: Steven Rostedt <[email protected]>
>
> Add system calls to register and unregister sframes that can be used by
> dynamic linkers to tell the kernel where the sframe section is in memory
> for libraries it loads.
How is this system call related to the prctl() with the same
functionality from Jens' series? I guess it will replace it,
but some explanation would be nice.
(...)
> diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
> index f5639d5ac331..992ccc401c5e 100644
> --- a/include/linux/syscalls.h
> +++ b/include/linux/syscalls.h
> @@ -999,6 +999,8 @@ asmlinkage long sys_lsm_get_self_attr(unsigned int attr,
> struct lsm_ctx __user *
> asmlinkage long sys_lsm_set_self_attr(unsigned int attr, struct lsm_ctx
> __user *ctx,
> u32 size, u32 flags);
> asmlinkage long sys_lsm_list_modules(u64 __user *ids, u32 __user *size, u32
> flags);
> +asmlinkage long sys_sframe_register(void *data, unsigned int size);
> +asmlinkage long sys_sframe_unregister(void *data, unsigned int size);
Why not use the actual structure here?
> /*
> * Architecture-specific system calls
(...)
> diff --git a/include/uapi/linux/sframe.h b/include/uapi/linux/sframe.h
> new file mode 100644
> index 000000000000..137a2ebf91f4
> --- /dev/null
> +++ b/include/uapi/linux/sframe.h
> @@ -0,0 +1,12 @@
> +/* SPDX-License-Identifier: GPL-2.0+ WITH Linux-syscall-note */
> +#ifndef _UAPI_LINUX_SFRAME_H
> +#define _UAPI_LINUX_SFRAME_H
> +
> +struct sframe_setup {
> + unsigned long sframe_start;
> + unsigned long sframe_size;
> + unsigned long text_start;
> + unsigned long text_size;
> +};
This will break for compat processes, as they use a different 'unsigned
long' than the host kernel. Maybe just use __u64.
> +
> +#endif /* _UAPI_LINUX_SFRAME_H */
(...)
> +/**
> + * sys_sframe_register - register an address for user space stacktrace
> walking.
> + * @data: Structure of sframe data used to register the sframe section
> + * @size: The size of the given structure.
> + *
> + * This system call is used by dynamic library utilities to inform the kernel
> + * of meta data that it loaded that can be used by the kernel to know how
> + * to stack walk the given text locations.
> + *
> + * Return: 0 if successful, otherwise a negative error.
> + */
> +SYSCALL_DEFINE2(sframe_register, __user struct sframe_setup *, data,
> unsigned int, size)
AFAIK the normal place for the '__user' is right before '*':
struct sframe_setup __user *, data,
Use __kernel_size_t for 'size'?
> +{
> + struct sframe_setup sframe;
(...)
