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author | Sven Schnelle <svens@linux.ibm.com> | 2020-12-01 15:27:55 +0100 |
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committer | Thomas Gleixner <tglx@linutronix.de> | 2020-12-02 15:07:58 +0100 |
commit | c6156e1da633f241e132eaea3b676d674376d770 (patch) | |
tree | c3d78a19a518c4e3358f1949306be1494b55d793 | |
parent | 310de1a678b2184c078c593dae343cb79c807f8d (diff) | |
download | linux-c6156e1da633f241e132eaea3b676d674376d770.tar.gz linux-c6156e1da633f241e132eaea3b676d674376d770.tar.bz2 linux-c6156e1da633f241e132eaea3b676d674376d770.zip |
entry: Add syscall_exit_to_user_mode_work()
This is the same as syscall_exit_to_user_mode() but without calling
exit_to_user_mode(). This can be used if there is an architectural reason
to avoid the combo function, e.g. restarting a syscall without returning to
userspace. Before returning to user space the caller has to invoke
exit_to_user_mode().
[ tglx: Amended comments ]
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20201201142755.31931-6-svens@linux.ibm.com
-rw-r--r-- | include/linux/entry-common.h | 20 | ||||
-rw-r--r-- | kernel/entry/common.c | 14 |
2 files changed, 32 insertions, 2 deletions
diff --git a/include/linux/entry-common.h b/include/linux/entry-common.h index e370be8121aa..7c581a4c3797 100644 --- a/include/linux/entry-common.h +++ b/include/linux/entry-common.h @@ -316,10 +316,26 @@ static inline void arch_syscall_exit_tracehook(struct pt_regs *regs, bool step) * is not suitable as the last step before returning to userspace. Must be * invoked with interrupts disabled and the caller must be * non-instrumentable. + * The caller has to invoke syscall_exit_to_user_mode_work() before this. */ void exit_to_user_mode(void); /** + * 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(). + */ +void syscall_exit_to_user_mode_work(struct pt_regs *regs); + +/** * syscall_exit_to_user_mode - Handle work before returning to user mode * @regs: Pointer to currents pt_regs * @@ -343,6 +359,10 @@ void exit_to_user_mode(void); * * 3) Final transition (lockdep, tracing, context tracking, RCU), i.e. the * functionality in exit_to_user_mode(). + * + * This is a combination of syscall_exit_to_user_mode_work() (1,2) and + * exit_to_user_mode(). This function is preferred unless there is a + * compelling architectural reason to use the seperate functions. */ void syscall_exit_to_user_mode(struct pt_regs *regs); diff --git a/kernel/entry/common.c b/kernel/entry/common.c index 48d30ce2e00e..d6b73937dab3 100644 --- a/kernel/entry/common.c +++ b/kernel/entry/common.c @@ -282,12 +282,22 @@ static void syscall_exit_to_user_mode_prepare(struct pt_regs *regs) syscall_exit_work(regs, work); } -__visible noinstr void syscall_exit_to_user_mode(struct pt_regs *regs) +static __always_inline void __syscall_exit_to_user_mode_work(struct pt_regs *regs) { - instrumentation_begin(); 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); instrumentation_end(); __exit_to_user_mode(); } |