[PATCH] arm: add support for TIF_NOTIFY_SIGNAL
Russell King - ARM Linux admin
linux at armlinux.org.uk
Thu Nov 12 10:32:13 EST 2020
On Tue, Nov 03, 2020 at 08:11:49AM -0700, Jens Axboe wrote:
> On 10/29/20 11:42 AM, Russell King - ARM Linux admin wrote:
> > On Thu, Oct 29, 2020 at 11:20:07AM -0600, Jens Axboe wrote:
> >> On 10/29/20 11:17 AM, Russell King - ARM Linux admin wrote:
> >>> On Thu, Oct 29, 2020 at 11:15:37AM -0600, Jens Axboe wrote:
> >>>> How about this?
> >>>>
> >>>> commit c03932936d8f99ff7c1c6c7d984e7a457284396c
> >>>> Author: Jens Axboe <axboe at kernel.dk>
> >>>> Date: Fri Oct 9 16:00:49 2020 -0600
> >>>>
> >>>> arm: add support for TIF_NOTIFY_SIGNAL
> >>>>
> >>>> Wire up TIF_NOTIFY_SIGNAL handling for arm.
> >>>>
> >>>> Cc: linux-arm-kernel at lists.infradead.org
> >>>> Signed-off-by: Jens Axboe <axboe at kernel.dk>
> >>>>
> >>>> diff --git a/arch/arm/include/asm/thread_info.h b/arch/arm/include/asm/thread_info.h
> >>>> index 536b6b979f63..eb7ce2747eb0 100644
> >>>> --- a/arch/arm/include/asm/thread_info.h
> >>>> +++ b/arch/arm/include/asm/thread_info.h
> >>>> @@ -126,6 +126,8 @@ extern int vfp_restore_user_hwstate(struct user_vfp *,
> >>>> * thread information flags:
> >>>> * TIF_USEDFPU - FPU was used by this task this quantum (SMP)
> >>>> * TIF_POLLING_NRFLAG - true if poll_idle() is polling TIF_NEED_RESCHED
> >>>> + *
> >>>> + * Any bit in the range of 0..15 will cause do_work_pending() to be invoked.
> >>>> */
> >>>> #define TIF_SIGPENDING 0 /* signal pending */
> >>>> #define TIF_NEED_RESCHED 1 /* rescheduling necessary */
> >>>> @@ -135,6 +137,7 @@ extern int vfp_restore_user_hwstate(struct user_vfp *,
> >>>> #define TIF_SYSCALL_AUDIT 5 /* syscall auditing active */
> >>>> #define TIF_SYSCALL_TRACEPOINT 6 /* syscall tracepoint instrumentation */
> >>>> #define TIF_SECCOMP 7 /* seccomp syscall filtering active */
> >>>> +#define TIF_NOTIFY_SIGNAL 8 /* signal notifications exist */
> >>>>
> >>>> #define TIF_USING_IWMMXT 17
> >>>> #define TIF_MEMDIE 18 /* is terminating due to OOM killer */
> >>>> @@ -148,6 +151,7 @@ extern int vfp_restore_user_hwstate(struct user_vfp *,
> >>>> #define _TIF_SYSCALL_AUDIT (1 << TIF_SYSCALL_AUDIT)
> >>>> #define _TIF_SYSCALL_TRACEPOINT (1 << TIF_SYSCALL_TRACEPOINT)
> >>>> #define _TIF_SECCOMP (1 << TIF_SECCOMP)
> >>>> +#define _TIF_NOTIFY_SIGNAL (1 << TIF_NOTIFY_SIGNAL)
> >>>> #define _TIF_USING_IWMMXT (1 << TIF_USING_IWMMXT)
> >>>>
> >>>> /* Checks for any syscall work in entry-common.S */
> >>>> @@ -158,7 +162,8 @@ extern int vfp_restore_user_hwstate(struct user_vfp *,
> >>>> * Change these and you break ASM code in entry-common.S
> >>>> */
> >>>> #define _TIF_WORK_MASK (_TIF_NEED_RESCHED | _TIF_SIGPENDING | \
> >>>> - _TIF_NOTIFY_RESUME | _TIF_UPROBE)
> >>>> + _TIF_NOTIFY_RESUME | _TIF_UPROBE | \
> >>>> + _TIF_NOTIFY_SIGNAL)
> >>>>
> >>>> #endif /* __KERNEL__ */
> >>>> #endif /* __ASM_ARM_THREAD_INFO_H */
> >>>> diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S
> >>>> index 271cb8a1eba1..77d16390a524 100644
> >>>> --- a/arch/arm/kernel/entry-common.S
> >>>> +++ b/arch/arm/kernel/entry-common.S
> >>>> @@ -53,7 +53,7 @@ __ret_fast_syscall:
> >>>> cmp r2, #TASK_SIZE
> >>>> blne addr_limit_check_failed
> >>>> ldr r1, [tsk, #TI_FLAGS] @ re-check for syscall tracing
> >>>> - tst r1, #_TIF_SYSCALL_WORK | _TIF_WORK_MASK
> >>>> + movs r1, r1, lsl #16
> >>>> bne fast_work_pending
> >>>>
> >>>>
> >>>> @@ -90,7 +90,7 @@ __ret_fast_syscall:
> >>>> cmp r2, #TASK_SIZE
> >>>> blne addr_limit_check_failed
> >>>> ldr r1, [tsk, #TI_FLAGS] @ re-check for syscall tracing
> >>>> - tst r1, #_TIF_SYSCALL_WORK | _TIF_WORK_MASK
> >>>> + movs r1, r1, lsl #16
> >>>> beq no_work_pending
> >>>> UNWIND(.fnend )
> >>>> ENDPROC(ret_fast_syscall)
> >>>> @@ -131,7 +131,7 @@ ENTRY(ret_to_user_from_irq)
> >>>> cmp r2, #TASK_SIZE
> >>>> blne addr_limit_check_failed
> >>>> ldr r1, [tsk, #TI_FLAGS]
> >>>> - tst r1, #_TIF_WORK_MASK
> >>>> + movs r1, r1, lsl #16
> >>>> bne slow_work_pending
> >>>> no_work_pending:
> >>>> asm_trace_hardirqs_on save = 0
> >>>> diff --git a/arch/arm/kernel/entry-v7m.S b/arch/arm/kernel/entry-v7m.S
> >>>> index de1f20624be1..d0e898608d30 100644
> >>>> --- a/arch/arm/kernel/entry-v7m.S
> >>>> +++ b/arch/arm/kernel/entry-v7m.S
> >>>> @@ -59,7 +59,7 @@ __irq_entry:
> >>>>
> >>>> get_thread_info tsk
> >>>> ldr r2, [tsk, #TI_FLAGS]
> >>>> - tst r2, #_TIF_WORK_MASK
> >>>> + movs r2, r2, lsl #16
> >>>> beq 2f @ no work pending
> >>>> mov r0, #V7M_SCB_ICSR_PENDSVSET
> >>>> str r0, [r1, V7M_SCB_ICSR] @ raise PendSV
> >>>> diff --git a/arch/arm/kernel/signal.c b/arch/arm/kernel/signal.c
> >>>> index 585edbfccf6d..9d2e916121be 100644
> >>>> --- a/arch/arm/kernel/signal.c
> >>>> +++ b/arch/arm/kernel/signal.c
> >>>> @@ -655,7 +655,7 @@ do_work_pending(struct pt_regs *regs, unsigned int thread_flags, int syscall)
> >>>> if (unlikely(!user_mode(regs)))
> >>>> return 0;
> >>>> local_irq_enable();
> >>>> - if (thread_flags & _TIF_SIGPENDING) {
> >>>> + if (thread_flags & (_TIF_SIGPENDING | _TIF_NOTIFY_SIGNAL)) {
> >>>> int restart = do_signal(regs, syscall);
> >>>> if (unlikely(restart)) {
> >>>> /*
> >>>>
> >>>
> >>> Looks perfect to me, thanks! I assume the pre-requisits for this are
> >>> already in mainline or linux-next?
> >>
> >> Great! Thanks for your expedient attention and help.
> >>
> >> The bits using this are queued in tip for 5.11, so not in mainline yet,
> >> but should be in linux-next tomorrow I guess. But it was done such that
> >> arch patches could be queued up independently, so we didn't have weird
> >> cross dependencies.
> >
> > Okay, I'll wait a few days and see about temporarily dumping it in
> > my for-next branch so it gets a spin through kernelci next week.
> > I'm not anticipating any breakage, so (if I remember) I'll give you
> > a reviewed-by next week once it seems good. As I say, if I remember.
>
> Russell, did you have a chance to run it through the machinery?
I threw the patch on top of my for-next branch, and let the various
autobuilders chew on it for a few days. I haven't had any reports
back, not even of any breakage through me adding it to my tree.
I guess that's a positive indication.
--
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
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