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linux-sg2042
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powerpc: fix double syscall restarts 

Make sigreturn zero regs->trap, make do_signal() do the same on all
paths.  As it is, signal interrupting e.g. read() from fd 512 (==
ERESTARTSYS) with another signal getting unblocked when the first
handler finishes will lead to restart one insn earlier than it ought
to.  Same for multiple signals with in-kernel handlers interrupting
that sucker at the same time.  Same for multiple signals of any kind
interrupting that sucker on 64bit...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Acked-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Al Viro 2010-09-20 21:48:57 +01:00 committed by Linus Torvalds
parent b68e9d4581
commit 9a81c16b52
3 changed files with 4 additions and 3 deletions
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2
arch/powerpc/kernel/signal.c
View File

@ -138,6 +138,7 @@ static int do_signal_pending(sigset_t *oldset, struct pt_regs *regs)
ti->local_flags &= ~_TLF_RESTORE_SIGMASK;
sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
}
regs->trap = 0;
return 0; /* no signals delivered */
}
@ -164,6 +165,7 @@ static int do_signal_pending(sigset_t *oldset, struct pt_regs *regs)
ret = handle_rt_signal64(signr, &ka, &info, oldset, regs);
}
regs->trap = 0;
if (ret) {
spin_lock_irq(&current->sighand->siglock);
sigorsets(&current->blocked, &current->blocked,

3
arch/powerpc/kernel/signal_32.c
View File

@ -511,6 +511,7 @@ static long restore_user_regs(struct pt_regs *regs,
if (!sig)
save_r2 = (unsigned int)regs->gpr[2];
err = restore_general_regs(regs, sr);
regs->trap = 0;
err |= __get_user(msr, &sr->mc_gregs[PT_MSR]);
if (!sig)
regs->gpr[2] = (unsigned long) save_r2;
@ -884,7 +885,6 @@ int handle_rt_signal32(unsigned long sig, struct k_sigaction *ka,
regs->nip = (unsigned long) ka->sa.sa_handler;
/* enter the signal handler in big-endian mode */
regs->msr &= ~MSR_LE;
regs->trap = 0;
return 1;
badframe:
@ -1228,7 +1228,6 @@ int handle_signal32(unsigned long sig, struct k_sigaction *ka,
regs->nip = (unsigned long) ka->sa.sa_handler;
/* enter the signal handler in big-endian mode */
regs->msr &= ~MSR_LE;
regs->trap = 0;
return 1;

2
arch/powerpc/kernel/signal_64.c
View File

@ -178,7 +178,7 @@ static long restore_sigcontext(struct pt_regs *regs, sigset_t *set, int sig,
err |= __get_user(regs->xer, &sc->gp_regs[PT_XER]);
err |= __get_user(regs->ccr, &sc->gp_regs[PT_CCR]);
/* skip SOFTE */
err |= __get_user(regs->trap, &sc->gp_regs[PT_TRAP]);
regs->trap = 0;
err |= __get_user(regs->dar, &sc->gp_regs[PT_DAR]);
err |= __get_user(regs->dsisr, &sc->gp_regs[PT_DSISR]);
err |= __get_user(regs->result, &sc->gp_regs[PT_RESULT]);