linux-kernel - Re: [PATCH v11 09/14] entry: Rework syscall_exit_to_user_mode

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <56978cb8-f9de-4bf2-b1fc-b5564fec7387@arm.com>
Date: Thu, 29 Jan 2026 13:06:49 +0100
From: Kevin Brodsky <kevin.brodsky@....com>
To: Jinjie Ruan <ruanjinjie@...wei.com>, catalin.marinas@....com,
 will@...nel.org, oleg@...hat.com, tglx@...utronix.de, peterz@...radead.org,
 luto@...nel.org, shuah@...nel.org, kees@...nel.org, wad@...omium.org,
 deller@....de, akpm@...ux-foundation.org, charlie@...osinc.com,
 mark.rutland@....com, anshuman.khandual@....com, song@...nel.org,
 ryan.roberts@....com, thuth@...hat.com, ada.coupriediaz@....com,
 broonie@...nel.org, pengcan@...inos.cn, liqiang01@...inos.cn, kmal@...k.li,
 dvyukov@...gle.com, reddybalavignesh9979@...il.com,
 richard.weiyang@...il.com, linux-arm-kernel@...ts.infradead.org,
 linux-kernel@...r.kernel.org, linux-kselftest@...r.kernel.org
Subject: Re: [PATCH v11 09/14] entry: Rework syscall_exit_to_user_mode_work()
 for arch reuse

On 28/01/2026 04:19, 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 rework it.
>
> In preparation for moving arm64 over to the generic entry
> code, as nothing calls syscall_exit_to_user_mode_work() except for
> syscall_exit_to_user_mode(), move local_irq_disable_exit_to_user() and
> syscall_exit_to_user_mode_prepare() out from
> syscall_exit_to_user_mode_work() to the only one caller.
>
> Also update the comment and no functional changes.
>
> Reviewed-by: Kevin Brodsky <kevin.brodsky@....com>
> Reviewed-by: Thomas Gleixner <tglx@...utronix.de>
> Signed-off-by: Jinjie Ruan <ruanjinjie@...wei.com>
> ---
>  include/linux/entry-common.h | 16 ++++++++--------
>  1 file changed, 8 insertions(+), 8 deletions(-)
>
> diff --git a/include/linux/entry-common.h b/include/linux/entry-common.h
> index e4a8287af822..c4fea642d931 100644
> --- a/include/linux/entry-common.h
> +++ b/include/linux/entry-common.h
> @@ -125,14 +125,14 @@ 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
> + * Same as step 1 of syscall_exit_to_user_mode() but without calling
> + * local_irq_disable(), syscall_exit_to_user_mode_prepare() and
>   * 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().
> + * Calling convention is the same as for syscall_exit_to_user_mode(). The
> + * caller must invoke local_irq_disable(), __exit_to_user_mode_prepare() and

Shouldn't it be syscall_exit_to_user_mode_prepare() rather than
__exit_to_user_mode_prepare()? The former has extra calls (e.g. rseq).

- Kevin

> + * exit_to_user_mode() before actually switching to user mode to
> + * make the final state transitions.
>   */
>  static __always_inline void syscall_exit_to_user_mode_work(struct pt_regs *regs)
>  {
> @@ -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();
>  }