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Message-Id: <E1P0QOT-0008TU-0m@ZenIV.linux.org.uk>
Date: Tue, 28 Sep 2010 03:58:13 +0100
From: Al Viro <viro@....linux.org.uk>
To: hans-christian.egtvedt@...el.com
Cc: torvalds@...ux-foundation.org, linux-kernel@...r.kernel.org,
linux-arch@...r.kernel.org
Subject: [PATCH 6/6] avr32: deal with syscall restarts
Currently we both have signals arriving at sigreturn trigger syscall restart
when the original handler hadn't been in the syscall at all *and* have
multiple pending signals trigger the sitation when %pc is shifted back by
more than one insn.
a) take handling of reschedule, signals and keychains into a new helper -
work_pending(). All looping is done there now; asm glue calls that if
we have anything for it to do.
b) do_signal() gets explicit "may restart" flag as an argument; after
the first call during that loop it gets unconditional 0.
c) sigreturn() sets a thread flag - TIF_NORESTART. It is included into
the "work_pending() has something to do" mask. work_pending() clears
it, clearing its may_restart flag if it had done so.
Signed-off-by: Al Viro <viro@...iv.linux.org.uk>
---
arch/avr32/include/asm/thread_info.h | 3 ++
arch/avr32/kernel/entry-avr32b.S | 45 ++++------------------------
arch/avr32/kernel/signal.c | 55 ++++++++++++++++++++++++----------
3 files changed, 48 insertions(+), 55 deletions(-)
diff --git a/arch/avr32/include/asm/thread_info.h b/arch/avr32/include/asm/thread_info.h
index 7a9c03d..1e8fa49 100644
--- a/arch/avr32/include/asm/thread_info.h
+++ b/arch/avr32/include/asm/thread_info.h
@@ -85,6 +85,7 @@ static inline struct thread_info *current_thread_info(void)
#define TIF_RESTORE_SIGMASK 7 /* restore signal mask in do_signal */
#define TIF_CPU_GOING_TO_SLEEP 8 /* CPU is entering sleep 0 mode */
#define TIF_NOTIFY_RESUME 9 /* callback before returning to user */
+#define TIF_NORESTART 10
#define TIF_FREEZE 29
#define TIF_DEBUG 30 /* debugging enabled */
#define TIF_USERSPACE 31 /* true if FS sets userspace */
@@ -98,6 +99,7 @@ static inline struct thread_info *current_thread_info(void)
#define _TIF_RESTORE_SIGMASK (1 << TIF_RESTORE_SIGMASK)
#define _TIF_CPU_GOING_TO_SLEEP (1 << TIF_CPU_GOING_TO_SLEEP)
#define _TIF_NOTIFY_RESUME (1 << TIF_NOTIFY_RESUME)
+#define _TIF_NORESTART (1 << TIF_NORESTART)
#define _TIF_FREEZE (1 << TIF_FREEZE)
/* Note: The masks below must never span more than 16 bits! */
@@ -106,6 +108,7 @@ static inline struct thread_info *current_thread_info(void)
#define _TIF_WORK_MASK \
((1 << TIF_SIGPENDING) \
| _TIF_NOTIFY_RESUME \
+ | _TIF_NORESTART \
| (1 << TIF_NEED_RESCHED) \
| (1 << TIF_POLLING_NRFLAG) \
| (1 << TIF_BREAKPOINT) \
diff --git a/arch/avr32/kernel/entry-avr32b.S b/arch/avr32/kernel/entry-avr32b.S
index 5e6beb2..bb455b7 100644
--- a/arch/avr32/kernel/entry-avr32b.S
+++ b/arch/avr32/kernel/entry-avr32b.S
@@ -271,28 +271,11 @@ syscall_exit_work:
unmask_interrupts
call syscall_trace
mask_interrupts
- ld.w r1, r0[TI_flags]
-
-1: bld r1, TIF_NEED_RESCHED
- brcc 2f
- unmask_interrupts
- call schedule
- mask_interrupts
- ld.w r1, r0[TI_flags]
- rjmp 1b
-
-2: mov r2, _TIF_SIGPENDING | _TIF_RESTORE_SIGMASK | _TIF_NOTIFY_RESUME
- tst r1, r2
- breq 3f
- unmask_interrupts
mov r12, sp
mov r11, r0
- call do_notify_resume
- mask_interrupts
- ld.w r1, r0[TI_flags]
- rjmp 1b
-
-3: bld r1, TIF_BREAKPOINT
+ mov r10, 1
+ call work_pending
+ bld r12, TIF_BREAKPOINT
brcc syscall_exit_cont
rjmp enter_monitor_mode
@@ -576,29 +559,13 @@ irq_exit_work:
mtsr SYSREG_SR, r8
sub pc, -2
get_thread_info r0
- ld.w r1, r0[TI_flags]
fault_exit_work:
- bld r1, TIF_NEED_RESCHED
- brcc 1f
- unmask_interrupts
- call schedule
- mask_interrupts
- ld.w r1, r0[TI_flags]
- rjmp fault_exit_work
-
-1: mov r2, _TIF_SIGPENDING | _TIF_RESTORE_SIGMASK | _TIF_NOTIFY_RESUME
- tst r1, r2
- breq 2f
- unmask_interrupts
mov r12, sp
mov r11, r0
- call do_notify_resume
- mask_interrupts
- ld.w r1, r0[TI_flags]
- rjmp fault_exit_work
-
-2: bld r1, TIF_BREAKPOINT
+ mov r10, 0
+ call work_pending
+ bld r12, TIF_BREAKPOINT
brcc fault_resume_user
rjmp enter_monitor_mode
diff --git a/arch/avr32/kernel/signal.c b/arch/avr32/kernel/signal.c
index 8e8f6ba..c4c76f5 100644
--- a/arch/avr32/kernel/signal.c
+++ b/arch/avr32/kernel/signal.c
@@ -45,6 +45,8 @@ restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc)
/* Always make any pending restarted system calls return -EINTR */
current_thread_info()->restart_block.fn = do_no_restart_syscall;
+ set_thread_flag(TIF_NORESTART);
+
#define COPY(x) err |= __get_user(regs->x, &sc->x)
COPY(sr);
COPY(pc);
@@ -264,7 +266,7 @@ fail:
* doesn't want to handle. Thus you cannot kill init even with a
* SIGKILL even by mistake.
*/
-static void do_signal(struct pt_regs *regs, int syscall)
+static void do_signal(struct pt_regs *regs, int may_restart)
{
siginfo_t info;
int signr;
@@ -285,7 +287,7 @@ static void do_signal(struct pt_regs *regs, int syscall)
oldset = ¤t->blocked;
signr = get_signal_to_deliver(&info, &ka, regs, NULL);
- if (syscall) {
+ if (may_restart) {
switch (regs->r12) {
case -ERESTART_RESTARTBLOCK:
case -ERESTARTNOHAND:
@@ -317,20 +319,41 @@ static void do_signal(struct pt_regs *regs, int syscall)
handle_signal(signr, &ka, &info, oldset, regs);
}
-asmlinkage void do_notify_resume(struct pt_regs *regs, struct thread_info *ti)
+asmlinkage int work_pending(struct pt_regs *regs, struct thread_info *ti, int may_restart)
{
- int syscall = 0;
-
- if ((sysreg_read(SR) & MODE_MASK) == MODE_SUPERVISOR)
- syscall = 1;
-
- if (ti->flags & (_TIF_SIGPENDING | _TIF_RESTORE_SIGMASK))
- do_signal(regs, syscall);
-
- if (ti->flags & _TIF_NOTIFY_RESUME) {
- clear_thread_flag(TIF_NOTIFY_RESUME);
- tracehook_notify_resume(regs);
- if (current->replacement_session_keyring)
- key_replace_session_keyring();
+ int flags = ti->flags;
+ if (unlikely(flags & _TIF_NORESTART)) {
+ ti->flags &= ~_TIF_NORESTART;
+ may_restart = 0;
+ }
+ while (1) {
+ if (flags & _TIF_NEED_RESCHED) {
+ local_irq_enable();
+ schedule();
+ local_irq_disable();
+ flags = ti->flags;
+ continue;
+ }
+ if (flags & _TIF_SIGPENDING) {
+ local_irq_enable();
+ if ((sysreg_read(SR) & MODE_MASK) != MODE_SUPERVISOR)
+ may_restart = 0;
+ do_signal(regs, may_restart);
+ may_restart = 0;
+ local_irq_disable();
+ flags = ti->flags;
+ continue;
+ }
+ if (flags & _TIF_NOTIFY_RESUME) {
+ ti->flags &= ~_TIF_NOTIFY_RESUME;
+ local_irq_enable();
+ tracehook_notify_resume(regs);
+ if (current->replacement_session_keyring)
+ key_replace_session_keyring();
+ local_irq_disable();
+ flags = ti->flags;
+ continue;
+ }
+ return flags;
}
}
--
1.5.6.5
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