On 22/12/2025 12:47, Jinjie Ruan wrote:
> In the generic entry code, the beginning of
> syscall_exit_to_user_mode_work() can be reused on arm64 so it makes
> sense to split it.
>
> In preparation for moving arm64 over to the generic entry
> code, split out syscall_exit_to_user_mode_work_prepare() helper from
> syscall_exit_to_user_mode_work().
>
> No functional changes.
>
> Reviewed-by: Kevin Brodsky <[email protected]>
> Reviewed-by: Thomas Gleixner <[email protected]>
> Signed-off-by: Jinjie Ruan <[email protected]>
> ---
> include/linux/entry-common.h | 35 ++++++++++++++++++++++-------------
> 1 file changed, 22 insertions(+), 13 deletions(-)
>
> diff --git a/include/linux/entry-common.h b/include/linux/entry-common.h
> index 87efb38b7081..0de0e60630e1 100644
> --- a/include/linux/entry-common.h
> +++ b/include/linux/entry-common.h
> @@ -121,20 +121,11 @@ static __always_inline long
> syscall_enter_from_user_mode(struct pt_regs *regs, l
> */
> void syscall_exit_work(struct pt_regs *regs, unsigned long work);
>
> -/**
> - * syscall_exit_to_user_mode_work - Handle work before returning to user mode
> - * @regs: Pointer to currents pt_regs
> - *
> - * Same as step 1 and 2 of syscall_exit_to_user_mode() but without calling
> - * exit_to_user_mode() to perform the final transition to user mode.
> - *
> - * Calling convention is the same as for syscall_exit_to_user_mode() and it
> - * returns with all work handled and interrupts disabled. The caller must
> - * invoke exit_to_user_mode() before actually switching to user mode to
> - * make the final state transitions. Interrupts must stay disabled between
> - * return from this function and the invocation of exit_to_user_mode().
> +/*
> + * Syscall specific exit to user mode preparation. Runs with interrupts
> + * enabled.
> */
> -static __always_inline void syscall_exit_to_user_mode_work(struct pt_regs
> *regs)
> +static __always_inline void syscall_exit_to_user_mode_work_prepare(struct
> pt_regs *regs)
> {
> unsigned long work = READ_ONCE(current_thread_info()->syscall_work);
> unsigned long nr = syscall_get_nr(current, regs);
> @@ -155,6 +146,24 @@ static __always_inline void
> syscall_exit_to_user_mode_work(struct pt_regs *regs)
> */
> if (unlikely(work & SYSCALL_WORK_EXIT))
> syscall_exit_work(regs, work);
> +}
> +
> +/**
> + * syscall_exit_to_user_mode_work - Handle work before returning to user mode
> + * @regs: Pointer to currents pt_regs
> + *
> + * Same as step 1 and 2 of syscall_exit_to_user_mode() but without calling
> + * exit_to_user_mode() to perform the final transition to user mode.
> + *
> + * Calling convention is the same as for syscall_exit_to_user_mode() and it
> + * returns with all work handled and interrupts disabled. The caller must
> + * invoke exit_to_user_mode() before actually switching to user mode to
> + * make the final state transitions. Interrupts must stay disabled between
> + * return from this function and the invocation of exit_to_user_mode().
> + */
> +static __always_inline void syscall_exit_to_user_mode_work(struct pt_regs
> *regs)
> +{
> + syscall_exit_to_user_mode_work_prepare(regs);
The naming is getting awfully confusing, with the separate introduction
of syscall_exit_to_user_mode_prepare().
Having had a closer look, do we really need
syscall_exit_to_user_mode_work() as it currently stands? Nothing calls
it except the generic syscall_exit_to_user_mode(). Which makes me think:
how about moving the two lines below into syscall_exit_to_user_mode()
instead of creating a new helper? IOW:
@@ -155,8 +155,6 @@ static __always_inline void
syscall_exit_to_user_mode_work(struct pt_regs *regs)
*/
if (unlikely(work & SYSCALL_WORK_EXIT))
syscall_exit_work(regs, work);
- local_irq_disable_exit_to_user();
- syscall_exit_to_user_mode_prepare(regs);
}
/**
@@ -192,6 +190,8 @@ static __always_inline void
syscall_exit_to_user_mode(struct pt_regs *regs)
{
instrumentation_begin();
syscall_exit_to_user_mode_work(regs);
+ local_irq_disable_exit_to_user();
+ syscall_exit_to_user_mode_prepare(regs);
instrumentation_end();
exit_to_user_mode();
}
- Kevin
> local_irq_disable_exit_to_user();
> syscall_exit_to_user_mode_prepare(regs);
> }
