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ARM: 7473/1: deal with handlerless restarts without leaving the kernel

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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
This commit is contained in:
Al Viro 2012-07-19 17:48:21 +01:00 committed by Russell King
parent 0a267fa6a1
commit 81783786d5
2 changed files with 35 additions and 22 deletions
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7
arch/arm/kernel/entry-common.S
View File

@ -54,7 +54,11 @@ work_pending:
mov r0, sp @ 'regs'
mov r2, why @ 'syscall'
bl do_work_pending
b no_work_pending
tst r0, #1
beq no_work_pending
ldmia sp, {r0 - r6} @ have to reload r0 - r6
b local_restart @ ... and off we go
/*
* "slow" syscall return path. "why" tells us if this was a real syscall.
*/
@ -396,6 +400,7 @@ ENTRY(vector_swi)
eor scno, scno, #__NR_SYSCALL_BASE @ check OS number
#endif
local_restart:
ldr r10, [tsk, #TI_FLAGS] @ check for syscall tracing
stmdb sp!, {r4, r5} @ push fifth and sixth args

50
arch/arm/kernel/signal.c
View File

@ -569,12 +569,13 @@ handle_signal(unsigned long sig, struct k_sigaction *ka,
* the kernel can handle, and then we build all the user-level signal handling
* stack-frames in one go after that.
*/
static void do_signal(struct pt_regs *regs, int syscall)
static int do_signal(struct pt_regs *regs, int syscall)
{
unsigned int retval = 0, continue_addr = 0, restart_addr = 0;
struct k_sigaction ka;
siginfo_t info;
int signr;
int restart = 0;
/*
* If we were from a system call, check for system call restarting...
@ -589,10 +590,12 @@ static void do_signal(struct pt_regs *regs, int syscall)
* debugger will see the already changed PSW.
*/
switch (retval) {
case -ERESTART_RESTARTBLOCK:
restart++;
case -ERESTARTNOHAND:
case -ERESTARTSYS:
case -ERESTARTNOINTR:
case -ERESTART_RESTARTBLOCK:
restart++;
regs->ARM_r0 = regs->ARM_ORIG_r0;
regs->ARM_pc = restart_addr;
break;
@ -604,13 +607,15 @@ static void do_signal(struct pt_regs *regs, int syscall)
* point the debugger may change all our registers ...
*/
signr = get_signal_to_deliver(&info, &ka, regs, NULL);
/*
* Depending on the signal settings we may need to revert the
* decision to restart the system call. But skip this if a
* debugger has chosen to restart at a different PC.
*/
if (regs->ARM_pc != restart_addr)
restart = 0;
if (signr > 0) {
/*
* Depending on the signal settings we may need to revert the
* decision to restart the system call. But skip this if a
* debugger has chosen to restart at a different PC.
*/
if (regs->ARM_pc == restart_addr) {
if (unlikely(restart)) {
if (retval == -ERESTARTNOHAND ||
retval == -ERESTART_RESTARTBLOCK
|| (retval == -ERESTARTSYS
@ -618,28 +623,23 @@ static void do_signal(struct pt_regs *regs, int syscall)
regs->ARM_r0 = -EINTR;
regs->ARM_pc = continue_addr;
}
clear_thread_flag(TIF_SYSCALL_RESTARTSYS);
}
handle_signal(signr, &ka, &info, regs);
return;
return 0;
}
if (syscall) {
/*
* Handle restarting a different system call. As above,
* if a debugger has chosen to restart at a different PC,
* ignore the restart.
*/
if (retval == -ERESTART_RESTARTBLOCK
&& regs->ARM_pc == restart_addr)
if (unlikely(restart)) {
if (restart > 1)
set_thread_flag(TIF_SYSCALL_RESTARTSYS);
regs->ARM_pc = continue_addr;
}
restore_saved_sigmask();
return restart;
}
asmlinkage void
asmlinkage int
do_work_pending(struct pt_regs *regs, unsigned int thread_flags, int syscall)
{
do {
@ -647,10 +647,17 @@ do_work_pending(struct pt_regs *regs, unsigned int thread_flags, int syscall)
schedule();
} else {
if (unlikely(!user_mode(regs)))
return;
return 0;
local_irq_enable();
if (thread_flags & _TIF_SIGPENDING) {
do_signal(regs, syscall);
if (unlikely(do_signal(regs, syscall))) {
/*
* Restart without handlers.
* Deal with it without leaving
* the kernel space.
*/
return 1;
}
syscall = 0;
} else {
clear_thread_flag(TIF_NOTIFY_RESUME);
@ -660,4 +667,5 @@ do_work_pending(struct pt_regs *regs, unsigned int thread_flags, int syscall)
local_irq_disable();
thread_flags = current_thread_info()->flags;
} while (thread_flags & _TIF_WORK_MASK);
return 0;
}