diff options
| author | Chris Metcalf <cmetcalf@mellanox.com> | 2016-07-14 23:48:14 +0300 |
|---|---|---|
| committer | Will Deacon <will.deacon@arm.com> | 2016-08-22 12:00:48 +0300 |
| commit | 421dd6fa6709ebee4f888ed89da5c103c77caee1 (patch) | |
| tree | 2ee670bc18f5fbe691906340c0a54b42f7f2635a /arch/arm64/kernel/signal.c | |
| parent | 0a7d87a7776e2616334473c4209e277b6ca300e5 (diff) | |
| download | linux-421dd6fa6709ebee4f888ed89da5c103c77caee1.tar.xz | |
arm64: factor work_pending state machine to C
Currently ret_fast_syscall, work_pending, and ret_to_user form an ad-hoc
state machine that can be difficult to reason about due to duplicated
code and a large number of branch targets.
This patch factors the common logic out into the existing
do_notify_resume function, converting the code to C in the process,
making the code more legible.
This patch tries to closely mirror the existing behaviour while using
the usual C control flow primitives. As local_irq_{disable,enable} may
be instrumented, we balance exception entry (where we will almost most
likely enable IRQs) with a call to trace_hardirqs_on just before the
return to userspace.
Signed-off-by: Chris Metcalf <cmetcalf@mellanox.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Diffstat (limited to 'arch/arm64/kernel/signal.c')
| -rw-r--r-- | arch/arm64/kernel/signal.c | 36 |
1 files changed, 26 insertions, 10 deletions
diff --git a/arch/arm64/kernel/signal.c b/arch/arm64/kernel/signal.c index a8eafdbc7cb8..404dd67080b9 100644 --- a/arch/arm64/kernel/signal.c +++ b/arch/arm64/kernel/signal.c @@ -402,15 +402,31 @@ static void do_signal(struct pt_regs *regs) asmlinkage void do_notify_resume(struct pt_regs *regs, unsigned int thread_flags) { - if (thread_flags & _TIF_SIGPENDING) - do_signal(regs); - - if (thread_flags & _TIF_NOTIFY_RESUME) { - clear_thread_flag(TIF_NOTIFY_RESUME); - tracehook_notify_resume(regs); - } - - if (thread_flags & _TIF_FOREIGN_FPSTATE) - fpsimd_restore_current_state(); + /* + * The assembly code enters us with IRQs off, but it hasn't + * informed the tracing code of that for efficiency reasons. + * Update the trace code with the current status. + */ + trace_hardirqs_off(); + do { + if (thread_flags & _TIF_NEED_RESCHED) { + schedule(); + } else { + local_irq_enable(); + + if (thread_flags & _TIF_SIGPENDING) + do_signal(regs); + + if (thread_flags & _TIF_NOTIFY_RESUME) { + clear_thread_flag(TIF_NOTIFY_RESUME); + tracehook_notify_resume(regs); + } + + if (thread_flags & _TIF_FOREIGN_FPSTATE) + fpsimd_restore_current_state(); + } + local_irq_disable(); + thread_flags = READ_ONCE(current_thread_info()->flags); + } while (thread_flags & _TIF_WORK_MASK); } |