From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7E58653CA72 for ; Tue, 8 Sep 2026 12:20:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788870039; cv=none; b=evTMR+BcT9kpdEIVlNXLvHD7WvEHIhJmCasH8IQlREv1JmYaiFmbzPTRusptxmLjotpXc9h00IlB/oScgE2y/JwkfIf8sFBVvqIiEJEzwZ+xI1uuNT/NhySu9/Rf2PeF0lGvvtuAyxp9OQDTfuDMvjR019JdBOel5mBTxpm6tGc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788870039; c=relaxed/simple; bh=ON+cgnrCURWPxceq01ffPNcXrdFPlxYE6TYqehw2AY0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=bswtzrkkorjqc54Q6gv+v16awWYnBI1h34wbYVMXB6EeZwuym9VGkS0cWJFcNvNgToKU0RYXEljgUWumWs1VxIF54esBRqUePKOiR254PnZUYzW83UxQUA2CWOFb+VbSQaSE23SklKIlRDlgR47ACl8eFs6TK1JlJ7R7FCfeyRs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 Received: by smtp.kernel.org (Postfix) with ESMTPSA id 80AE61F00A3D; Tue, 8 Sep 2026 12:20:32 +0000 (UTC) From: Sasha Levin To: stable@vger.kernel.org Cc: Charlie Jenkins , Thomas Gleixner , Alexandre Ghiti , Sasha Levin Subject: [PATCH 6.1.y 1/5] entry: Inline syscall_exit_to_user_mode() Date: Tue, 8 Sep 2026 08:20:26 -0400 Message-ID: <20260908122030.2052577-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <2026090331-spouse-sprawl-968e@gregkh> References: <2026090331-spouse-sprawl-968e@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Charlie Jenkins [ Upstream commit e43b8bb56e537bfc8d9076793091e7679020fc9c ] Similar to commit 221a164035fd ("entry: Move syscall_enter_from_user_mode() to header file"), move syscall_exit_to_user_mode() to the header file as well. Testing was done with the byte-unixbench syscall benchmark (which calls getpid) and QEMU. On riscv I measured a 7.09246% improvement, on x86 a 2.98843% improvement, on loongarch a 6.07954% improvement, and on s390 a 11.1328% improvement. The Intel bot also reported "kernel test robot noticed a 1.9% improvement of stress-ng.seek.ops_per_sec". Signed-off-by: Charlie Jenkins Signed-off-by: Thomas Gleixner Reviewed-by: Alexandre Ghiti Link: https://lore.kernel.org/all/20250320-riscv_optimize_entry-v6-4-63e187e26041@rivosinc.com Link: https://lore.kernel.org/linux-riscv/202502051555.85ae6844-lkp@intel.com/ Stable-dep-of: 4a3591287fb7 ("entry: Fix seccomp bypass after ptrace with TSYNC") Signed-off-by: Sasha Levin --- include/linux/entry-common.h | 131 ++++++++++++++++++++++++++++-- kernel/entry/common.c | 149 +++-------------------------------- 2 files changed, 136 insertions(+), 144 deletions(-) diff --git a/include/linux/entry-common.h b/include/linux/entry-common.h index d95ab85f96ba5..4533799c13cda 100644 --- a/include/linux/entry-common.h +++ b/include/linux/entry-common.h @@ -7,8 +7,14 @@ #include #include #include +#include +#include +#include +#include +#include #include +#include /* * Define dummy _TIF work flags if not defined by the architecture or for @@ -98,7 +104,19 @@ static __always_inline void arch_enter_from_user_mode(struct pt_regs *regs) {} * done between establishing state and enabling interrupts. The caller must * enable interrupts before invoking syscall_enter_from_user_mode_work(). */ -void enter_from_user_mode(struct pt_regs *regs); +static __always_inline void enter_from_user_mode(struct pt_regs *regs) +{ + arch_enter_from_user_mode(regs); + lockdep_hardirqs_off(CALLER_ADDR0); + + CT_WARN_ON(__ct_state() != CONTEXT_USER); + user_exit_irqoff(); + + instrumentation_begin(); + kmsan_unpoison_entry_regs(regs); + trace_hardirqs_off_finish(); + instrumentation_end(); +} /** * syscall_enter_from_user_mode_prepare - Establish state and enable interrupts @@ -117,6 +135,9 @@ void enter_from_user_mode(struct pt_regs *regs); */ void syscall_enter_from_user_mode_prepare(struct pt_regs *regs); +long syscall_trace_enter(struct pt_regs *regs, long syscall, + unsigned long work); + /** * syscall_enter_from_user_mode_work - Check and handle work before invoking * a syscall @@ -140,7 +161,15 @@ void syscall_enter_from_user_mode_prepare(struct pt_regs *regs); * ptrace_report_syscall_entry(), __secure_computing(), trace_sys_enter() * 2) Invocation of audit_syscall_entry() */ -long syscall_enter_from_user_mode_work(struct pt_regs *regs, long syscall); +static __always_inline long syscall_enter_from_user_mode_work(struct pt_regs *regs, long syscall) +{ + unsigned long work = READ_ONCE(current_thread_info()->syscall_work); + + if (work & SYSCALL_WORK_ENTER) + syscall = syscall_trace_enter(regs, syscall, work); + + return syscall; +} /** * syscall_enter_from_user_mode - Establish state and check and handle work @@ -159,7 +188,19 @@ long syscall_enter_from_user_mode_work(struct pt_regs *regs, long syscall); * Returns: The original or a modified syscall number. See * syscall_enter_from_user_mode_work() for further explanation. */ -long syscall_enter_from_user_mode(struct pt_regs *regs, long syscall); +static __always_inline long syscall_enter_from_user_mode(struct pt_regs *regs, long syscall) +{ + long ret; + + enter_from_user_mode(regs); + + instrumentation_begin(); + local_irq_enable(); + ret = syscall_enter_from_user_mode_work(regs, syscall); + instrumentation_end(); + + return ret; +} /** * local_irq_enable_exit_to_user - Exit to user variant of local_irq_enable() @@ -258,6 +299,44 @@ static __always_inline void arch_exit_to_user_mode(void) { } */ void arch_do_signal_or_restart(struct pt_regs *regs); +/** + * exit_to_user_mode_loop - do any pending work before leaving to user space + */ +unsigned long exit_to_user_mode_loop(struct pt_regs *regs, + unsigned long ti_work); + +/** + * exit_to_user_mode_prepare - call exit_to_user_mode_loop() if required + * @regs: Pointer to pt_regs on entry stack + * + * 1) check that interrupts are disabled + * 2) call tick_nohz_user_enter_prepare() + * 3) call exit_to_user_mode_loop() if any flags from + * EXIT_TO_USER_MODE_WORK are set + * 4) check that interrupts are still disabled + */ +static __always_inline void exit_to_user_mode_prepare(struct pt_regs *regs) +{ + unsigned long ti_work; + + lockdep_assert_irqs_disabled(); + + /* Flush pending rcuog wakeup before the last need_resched() check */ + tick_nohz_user_enter_prepare(); + + ti_work = read_thread_flags(); + if (unlikely(ti_work & EXIT_TO_USER_MODE_WORK)) + ti_work = exit_to_user_mode_loop(regs, ti_work); + + arch_exit_to_user_mode_prepare(regs, ti_work); + + /* Ensure that the address limit is intact and no locks are held */ + addr_limit_user_check(); + kmap_assert_nomap(); + lockdep_assert_irqs_disabled(); + lockdep_sys_exit(); +} + /** * exit_to_user_mode - Fixup state when exiting to user mode * @@ -276,7 +355,26 @@ void arch_do_signal_or_restart(struct pt_regs *regs); * non-instrumentable. * The caller has to invoke syscall_exit_to_user_mode_work() before this. */ -void exit_to_user_mode(void); +static __always_inline void exit_to_user_mode(void) +{ + instrumentation_begin(); + trace_hardirqs_on_prepare(); + lockdep_hardirqs_on_prepare(); + instrumentation_end(); + + user_enter_irqoff(); + arch_exit_to_user_mode(); + lockdep_hardirqs_on(CALLER_ADDR0); +} + +/** + * syscall_exit_work - Handle work before returning to user mode + * @regs: Pointer to current pt_regs + * @work: Current thread syscall work + * + * Do one-time syscall specific work. + */ +void syscall_exit_work(struct pt_regs *regs, unsigned long work); /** * syscall_exit_to_user_mode_work - Handle work before returning to user mode @@ -291,7 +389,30 @@ void exit_to_user_mode(void); * make the final state transitions. Interrupts must stay disabled between * return from this function and the invocation of exit_to_user_mode(). */ -void syscall_exit_to_user_mode_work(struct pt_regs *regs); +static __always_inline void syscall_exit_to_user_mode_work(struct pt_regs *regs) +{ + unsigned long work = READ_ONCE(current_thread_info()->syscall_work); + unsigned long nr = syscall_get_nr(current, regs); + + CT_WARN_ON(ct_state() != CONTEXT_KERNEL); + + if (IS_ENABLED(CONFIG_PROVE_LOCKING)) { + if (WARN(irqs_disabled(), "syscall %lu left IRQs disabled", nr)) + local_irq_enable(); + } + + rseq_syscall(regs); + + /* + * Do one-time syscall specific work. If these work items are + * enabled, we want to run them exactly once per syscall exit with + * interrupts enabled. + */ + if (unlikely(work & SYSCALL_WORK_EXIT)) + syscall_exit_work(regs, work); + local_irq_disable_exit_to_user(); + exit_to_user_mode_prepare(regs); +} /** * syscall_exit_to_user_mode - Handle work before returning to user mode diff --git a/kernel/entry/common.c b/kernel/entry/common.c index ccf2b1e1b40be..4d890cf9a7c83 100644 --- a/kernel/entry/common.c +++ b/kernel/entry/common.c @@ -15,26 +15,6 @@ #define CREATE_TRACE_POINTS #include -/* See comment for enter_from_user_mode() in entry-common.h */ -static __always_inline void __enter_from_user_mode(struct pt_regs *regs) -{ - arch_enter_from_user_mode(regs); - lockdep_hardirqs_off(CALLER_ADDR0); - - CT_WARN_ON(__ct_state() != CONTEXT_USER); - user_exit_irqoff(); - - instrumentation_begin(); - kmsan_unpoison_entry_regs(regs); - trace_hardirqs_off_finish(); - instrumentation_end(); -} - -void noinstr enter_from_user_mode(struct pt_regs *regs) -{ - __enter_from_user_mode(regs); -} - static inline void syscall_enter_audit(struct pt_regs *regs, long syscall) { if (unlikely(audit_context())) { @@ -45,8 +25,8 @@ static inline void syscall_enter_audit(struct pt_regs *regs, long syscall) } } -static long syscall_trace_enter(struct pt_regs *regs, long syscall, - unsigned long work) +long syscall_trace_enter(struct pt_regs *regs, long syscall, + unsigned long work) { long ret = 0; @@ -91,67 +71,19 @@ static long syscall_trace_enter(struct pt_regs *regs, long syscall, return ret ? : syscall; } -static __always_inline long -__syscall_enter_from_user_work(struct pt_regs *regs, long syscall) -{ - unsigned long work = READ_ONCE(current_thread_info()->syscall_work); - - if (work & SYSCALL_WORK_ENTER) - syscall = syscall_trace_enter(regs, syscall, work); - - return syscall; -} - -long syscall_enter_from_user_mode_work(struct pt_regs *regs, long syscall) -{ - return __syscall_enter_from_user_work(regs, syscall); -} - -noinstr long syscall_enter_from_user_mode(struct pt_regs *regs, long syscall) -{ - long ret; - - __enter_from_user_mode(regs); - - instrumentation_begin(); - local_irq_enable(); - ret = __syscall_enter_from_user_work(regs, syscall); - instrumentation_end(); - - return ret; -} - noinstr void syscall_enter_from_user_mode_prepare(struct pt_regs *regs) { - __enter_from_user_mode(regs); + enter_from_user_mode(regs); instrumentation_begin(); local_irq_enable(); instrumentation_end(); } -/* See comment for exit_to_user_mode() in entry-common.h */ -static __always_inline void __exit_to_user_mode(void) -{ - instrumentation_begin(); - trace_hardirqs_on_prepare(); - lockdep_hardirqs_on_prepare(); - instrumentation_end(); - - user_enter_irqoff(); - arch_exit_to_user_mode(); - lockdep_hardirqs_on(CALLER_ADDR0); -} - -void noinstr exit_to_user_mode(void) -{ - __exit_to_user_mode(); -} - /* Workaround to allow gradual conversion of architecture code */ void __weak arch_do_signal_or_restart(struct pt_regs *regs) { } -static unsigned long exit_to_user_mode_loop(struct pt_regs *regs, - unsigned long ti_work) +__always_inline unsigned long exit_to_user_mode_loop(struct pt_regs *regs, + unsigned long ti_work) { /* * Before returning to user space ensure that all pending work @@ -196,28 +128,6 @@ static unsigned long exit_to_user_mode_loop(struct pt_regs *regs, return ti_work; } -static void exit_to_user_mode_prepare(struct pt_regs *regs) -{ - unsigned long ti_work; - - lockdep_assert_irqs_disabled(); - - /* Flush pending rcuog wakeup before the last need_resched() check */ - tick_nohz_user_enter_prepare(); - - ti_work = read_thread_flags(); - if (unlikely(ti_work & EXIT_TO_USER_MODE_WORK)) - ti_work = exit_to_user_mode_loop(regs, ti_work); - - arch_exit_to_user_mode_prepare(regs, ti_work); - - /* Ensure that the address limit is intact and no locks are held */ - addr_limit_user_check(); - kmap_assert_nomap(); - lockdep_assert_irqs_disabled(); - lockdep_sys_exit(); -} - /* * If SYSCALL_EMU is set, then the only reason to report is when * SINGLESTEP is set (i.e. PTRACE_SYSEMU_SINGLESTEP). This syscall @@ -231,7 +141,7 @@ static inline bool report_single_step(unsigned long work) return work & SYSCALL_WORK_SYSCALL_EXIT_TRAP; } -static void syscall_exit_work(struct pt_regs *regs, unsigned long work) +void syscall_exit_work(struct pt_regs *regs, unsigned long work) { bool step; @@ -258,56 +168,17 @@ static void syscall_exit_work(struct pt_regs *regs, unsigned long work) ptrace_report_syscall_exit(regs, step); } -/* - * Syscall specific exit to user mode preparation. Runs with interrupts - * enabled. - */ -static void syscall_exit_to_user_mode_prepare(struct pt_regs *regs) -{ - unsigned long work = READ_ONCE(current_thread_info()->syscall_work); - unsigned long nr = syscall_get_nr(current, regs); - - CT_WARN_ON(ct_state() != CONTEXT_KERNEL); - - if (IS_ENABLED(CONFIG_PROVE_LOCKING)) { - if (WARN(irqs_disabled(), "syscall %lu left IRQs disabled", nr)) - local_irq_enable(); - } - - rseq_syscall(regs); - - /* - * Do one-time syscall specific work. If these work items are - * enabled, we want to run them exactly once per syscall exit with - * interrupts enabled. - */ - if (unlikely(work & SYSCALL_WORK_EXIT)) - syscall_exit_work(regs, work); -} - -static __always_inline void __syscall_exit_to_user_mode_work(struct pt_regs *regs) -{ - syscall_exit_to_user_mode_prepare(regs); - local_irq_disable_exit_to_user(); - exit_to_user_mode_prepare(regs); -} - -void syscall_exit_to_user_mode_work(struct pt_regs *regs) -{ - __syscall_exit_to_user_mode_work(regs); -} - __visible noinstr void syscall_exit_to_user_mode(struct pt_regs *regs) { instrumentation_begin(); - __syscall_exit_to_user_mode_work(regs); + syscall_exit_to_user_mode_work(regs); instrumentation_end(); - __exit_to_user_mode(); + exit_to_user_mode(); } noinstr void irqentry_enter_from_user_mode(struct pt_regs *regs) { - __enter_from_user_mode(regs); + enter_from_user_mode(regs); } noinstr void irqentry_exit_to_user_mode(struct pt_regs *regs) @@ -315,7 +186,7 @@ noinstr void irqentry_exit_to_user_mode(struct pt_regs *regs) instrumentation_begin(); exit_to_user_mode_prepare(regs); instrumentation_end(); - __exit_to_user_mode(); + exit_to_user_mode(); } noinstr irqentry_state_t irqentry_enter(struct pt_regs *regs) -- 2.53.0