diff options
| author | Chris Metcalf <cmetcalf@mellanox.com> | 2016-07-14 16:48:14 -0400 |
|---|---|---|
| committer | Will Deacon <will.deacon@arm.com> | 2016-08-22 10:00:48 +0100 |
| commit | 421dd6fa6709ebee4f888ed89da5c103c77caee1 (patch) | |
| tree | 2ee670bc18f5fbe691906340c0a54b42f7f2635a /arch/arm64/kernel/entry.S | |
| parent | 0a7d87a7776e2616334473c4209e277b6ca300e5 (diff) | |
| download | linux-421dd6fa6709ebee4f888ed89da5c103c77caee1.tar.gz linux-421dd6fa6709ebee4f888ed89da5c103c77caee1.tar.bz2 linux-421dd6fa6709ebee4f888ed89da5c103c77caee1.zip | |
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/entry.S')
| -rw-r--r-- | arch/arm64/kernel/entry.S | 12 |
1 files changed, 4 insertions, 8 deletions
diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index 441420ca7d08..6a64182822e5 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -707,18 +707,13 @@ ret_fast_syscall_trace: * Ok, we need to do extra processing, enter the slow path. */ work_pending: - tbnz x1, #TIF_NEED_RESCHED, work_resched - /* TIF_SIGPENDING, TIF_NOTIFY_RESUME or TIF_FOREIGN_FPSTATE case */ mov x0, sp // 'regs' - enable_irq // enable interrupts for do_notify_resume() bl do_notify_resume - b ret_to_user -work_resched: #ifdef CONFIG_TRACE_IRQFLAGS - bl trace_hardirqs_off // the IRQs are off here, inform the tracing code + bl trace_hardirqs_on // enabled while in userspace #endif - bl schedule - + ldr x1, [tsk, #TI_FLAGS] // re-check for single-step + b finish_ret_to_user /* * "slow" syscall return path. */ @@ -727,6 +722,7 @@ ret_to_user: ldr x1, [tsk, #TI_FLAGS] and x2, x1, #_TIF_WORK_MASK cbnz x2, work_pending +finish_ret_to_user: enable_step_tsk x1, x2 kernel_exit 0 ENDPROC(ret_to_user) |