From 96e2fbccd0fc806364a964fdf072bfc858a66109 Mon Sep 17 00:00:00 2001 From: Sven Schnelle Date: Tue, 1 Dec 2020 15:27:53 +0100 Subject: [PATCH] entry_Add_enter_from_user_mode_wrapper To be called from architecture specific code if the combo interfaces are not suitable. It simply calls __enter_from_user_mode(). This way __enter_from_user_mode will still be inlined because it is declared static __always_inline. [ tglx: Amend comments and move it to a different location in the header ] Signed-off-by: Sven Schnelle Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/r/20201201142755.31931-4-svens@linux.ibm.com --- include/linux/entry-common.h | 24 +++++++++++++++++++++++- kernel/entry/common.c | 16 ++++++---------- 2 files changed, 29 insertions(+), 11 deletions(-) diff --git a/include/linux/entry-common.h b/include/linux/entry-common.h index a6e98b4ba8e92..da60980a2e7b6 100644 --- a/include/linux/entry-common.h +++ b/include/linux/entry-common.h @@ -101,6 +101,27 @@ static inline __must_check int arch_syscall_enter_tracehook(struct pt_regs *regs } #endif +/** + * enter_from_user_mode - Establish state when coming from user mode + * + * Syscall/interrupt entry disables interrupts, but user mode is traced as + * interrupts enabled. Also with NO_HZ_FULL RCU might be idle. + * + * 1) Tell lockdep that interrupts are disabled + * 2) Invoke context tracking if enabled to reactivate RCU + * 3) Trace interrupts off state + * + * Invoked from architecture specific syscall entry code with interrupts + * disabled. The calling code has to be non-instrumentable. When the + * function returns all state is correct and interrupts are still + * disabled. The subsequent functions can be instrumented. + * + * This is invoked when there is architecture specific functionality to be + * 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); + /** * syscall_enter_from_user_mode_prepare - Establish state and enable interrupts * @regs: Pointer to currents pt_regs @@ -110,7 +131,8 @@ static inline __must_check int arch_syscall_enter_tracehook(struct pt_regs *regs * function returns all state is correct, interrupts are enabled and the * subsequent functions can be instrumented. * - * This handles lockdep, RCU (context tracking) and tracing state. + * This handles lockdep, RCU (context tracking) and tracing state, i.e. + * the functionality provided by enter_from_user_mode(). * * This is invoked when there is extra architecture specific functionality * to be done between establishing state and handling user mode entry work. diff --git a/kernel/entry/common.c b/kernel/entry/common.c index dff07b4ce6ec9..17b1e032afe79 100644 --- a/kernel/entry/common.c +++ b/kernel/entry/common.c @@ -10,16 +10,7 @@ #define CREATE_TRACE_POINTS #include -/** - * __enter_from_user_mode - Establish state when coming from user mode - * - * Syscall/interrupt entry disables interrupts, but user mode is traced as - * interrupts enabled. Also with NO_HZ_FULL RCU might be idle. - * - * 1) Tell lockdep that interrupts are disabled - * 2) Invoke context tracking if enabled to reactivate RCU - * 3) Trace interrupts off state - */ +/* See comment for enter_from_user_mode() in entry-common.h */ static __always_inline void __enter_from_user_mode(struct pt_regs *regs) { arch_check_user_regs(regs); @@ -33,6 +24,11 @@ static __always_inline void __enter_from_user_mode(struct pt_regs *regs) 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())) {