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Commit 9a81c16b authored by Al Viro's avatar Al Viro Committed by Linus Torvalds
Browse files

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: default avatarAl Viro <viro@zeniv.linux.org.uk>
Acked-by: default avatarPaul Mackerras <paulus@samba.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent b68e9d45

arch/powerpc/kernel/signal.c

+2 −0
Original line number Diff line number Diff line
@@ -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,

arch/powerpc/kernel/signal_32.c

+1 −2
Original line number Diff line number Diff line
@@ -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;

arch/powerpc/kernel/signal_64.c

+1 −1
Original line number Diff line number Diff line
@@ -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]);