[Cbe-oss-dev] [PATCH 14/21] powerpc: Make syscall restart code more common
Christoph Hellwig
hch at lst.de
Mon Jun 4 17:06:06 EST 2007
On Mon, Jun 04, 2007 at 03:15:49PM +1000, Benjamin Herrenschmidt wrote:
> This patch moves the code in signal_32.c and signal_64.c for handling
> syscall restart into a common signal.c file and converge around a single
> implementation that is based on the 32 bits one, using trap, ccr
> and r3 rather than the special "result" field for deciding what to do.
>
> The "result" field is now pretty much deprecated. We still set it for
> the sake of whatever might rely on it in userland but we no longer use
> it's content.
>
> This, along with a previous patch that enables ptracers to write to
> "trap" and "orig_r3" should allow gdb to properly handle syscall
> restarting.
>
> Signed-off-by: Benjamin Herrenschmidt <benh at kernel.crashing.org>
> ---
>
> This is basically my initial patch as modified by Christoph Hellwig
> (hch, care to send a SOB ? :-)
Signed-off-by: Christoph Hellwig <hch at lst.de>
>
>
> arch/powerpc/kernel/Makefile | 3 +
> arch/powerpc/kernel/signal.c | 64 ++++++++++++++++++++++++++++++++++++++++
> arch/powerpc/kernel/signal.h | 16 ++++++++++
> arch/powerpc/kernel/signal_32.c | 28 ++---------------
> arch/powerpc/kernel/signal_64.c | 59 ++++--------------------------------
> 5 files changed, 93 insertions(+), 77 deletions(-)
>
> Index: linux-cell/arch/powerpc/kernel/signal_32.c
> ===================================================================
> --- linux-cell.orig/arch/powerpc/kernel/signal_32.c 2007-05-30 16:45:57.000000000 +1000
> +++ linux-cell/arch/powerpc/kernel/signal_32.c 2007-06-04 11:45:43.000000000 +1000
> @@ -51,6 +51,8 @@
> #include <asm/pgtable.h>
> #endif
>
> +#include "signal.h"
> +
> #undef DEBUG_SIG
>
> #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
> @@ -1156,30 +1158,8 @@ int do_signal(sigset_t *oldset, struct p
> #ifdef CONFIG_PPC32
> no_signal:
> #endif
> - if (TRAP(regs) == 0x0C00 /* System Call! */
> - && regs->ccr & 0x10000000 /* error signalled */
> - && ((ret = regs->gpr[3]) == ERESTARTSYS
> - || ret == ERESTARTNOHAND || ret == ERESTARTNOINTR
> - || ret == ERESTART_RESTARTBLOCK)) {
> -
> - if (signr > 0
> - && (ret == ERESTARTNOHAND || ret == ERESTART_RESTARTBLOCK
> - || (ret == ERESTARTSYS
> - && !(ka.sa.sa_flags & SA_RESTART)))) {
> - /* make the system call return an EINTR error */
> - regs->result = -EINTR;
> - regs->gpr[3] = EINTR;
> - /* note that the cr0.SO bit is already set */
> - } else {
> - regs->nip -= 4; /* Back up & retry system call */
> - regs->result = 0;
> - regs->trap = 0;
> - if (ret == ERESTART_RESTARTBLOCK)
> - regs->gpr[0] = __NR_restart_syscall;
> - else
> - regs->gpr[3] = regs->orig_gpr3;
> - }
> - }
> + /* Is there any syscall restart business here ? */
> + check_syscall_restart(regs, &ka, signr > 0);
>
> if (signr == 0) {
> /* No signal to deliver -- put the saved sigmask back */
> Index: linux-cell/arch/powerpc/kernel/signal_64.c
> ===================================================================
> --- linux-cell.orig/arch/powerpc/kernel/signal_64.c 2007-05-30 16:45:57.000000000 +1000
> +++ linux-cell/arch/powerpc/kernel/signal_64.c 2007-06-04 11:45:43.000000000 +1000
> @@ -34,6 +34,8 @@
> #include <asm/syscalls.h>
> #include <asm/vdso.h>
>
> +#include "signal.h"
> +
> #define DEBUG_SIG 0
>
> #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
> @@ -463,41 +465,6 @@ static int handle_signal(unsigned long s
> return ret;
> }
>
> -static inline void syscall_restart(struct pt_regs *regs, struct k_sigaction *ka)
> -{
> - switch ((int)regs->result) {
> - case -ERESTART_RESTARTBLOCK:
> - case -ERESTARTNOHAND:
> - /* ERESTARTNOHAND means that the syscall should only be
> - * restarted if there was no handler for the signal, and since
> - * we only get here if there is a handler, we dont restart.
> - */
> - regs->result = -EINTR;
> - regs->gpr[3] = EINTR;
> - regs->ccr |= 0x10000000;
> - break;
> - case -ERESTARTSYS:
> - /* ERESTARTSYS means to restart the syscall if there is no
> - * handler or the handler was registered with SA_RESTART
> - */
> - if (!(ka->sa.sa_flags & SA_RESTART)) {
> - regs->result = -EINTR;
> - regs->gpr[3] = EINTR;
> - regs->ccr |= 0x10000000;
> - break;
> - }
> - /* fallthrough */
> - case -ERESTARTNOINTR:
> - /* ERESTARTNOINTR means that the syscall should be
> - * called again after the signal handler returns.
> - */
> - regs->gpr[3] = regs->orig_gpr3;
> - regs->nip -= 4;
> - regs->result = 0;
> - break;
> - }
> -}
> -
> /*
> * Note that 'init' is a special process: it doesn't get signals it doesn't
> * want to handle. Thus you cannot kill init even with a SIGKILL even by
> @@ -522,13 +489,13 @@ int do_signal(sigset_t *oldset, struct p
> oldset = ¤t->blocked;
>
> signr = get_signal_to_deliver(&info, &ka, regs, NULL);
> +
> + /* Is there any syscall restart business here ? */
> + check_syscall_restart(regs, &ka, signr > 0);
> +
> if (signr > 0) {
> int ret;
>
> - /* Whee! Actually deliver the signal. */
> - if (TRAP(regs) == 0x0C00)
> - syscall_restart(regs, &ka);
> -
> /*
> * Reenable the DABR before delivering the signal to
> * user space. The DABR will have been cleared if it
> @@ -537,6 +504,7 @@ int do_signal(sigset_t *oldset, struct p
> if (current->thread.dabr)
> set_dabr(current->thread.dabr);
>
> + /* Whee! Actually deliver the signal. */
> ret = handle_signal(signr, &ka, &info, oldset, regs);
>
> /* If a signal was successfully delivered, the saved sigmask is in
> @@ -547,19 +515,6 @@ int do_signal(sigset_t *oldset, struct p
> return ret;
> }
>
> - if (TRAP(regs) == 0x0C00) { /* System Call! */
> - if ((int)regs->result == -ERESTARTNOHAND ||
> - (int)regs->result == -ERESTARTSYS ||
> - (int)regs->result == -ERESTARTNOINTR) {
> - regs->gpr[3] = regs->orig_gpr3;
> - regs->nip -= 4; /* Back up & retry system call */
> - regs->result = 0;
> - } else if ((int)regs->result == -ERESTART_RESTARTBLOCK) {
> - regs->gpr[0] = __NR_restart_syscall;
> - regs->nip -= 4;
> - regs->result = 0;
> - }
> - }
> /* No signal to deliver -- put the saved sigmask back */
> if (test_thread_flag(TIF_RESTORE_SIGMASK)) {
> clear_thread_flag(TIF_RESTORE_SIGMASK);
> Index: linux-cell/arch/powerpc/kernel/Makefile
> ===================================================================
> --- linux-cell.orig/arch/powerpc/kernel/Makefile 2007-06-04 11:16:01.000000000 +1000
> +++ linux-cell/arch/powerpc/kernel/Makefile 2007-06-04 11:16:16.000000000 +1000
> @@ -12,7 +12,8 @@ endif
>
> obj-y := semaphore.o cputable.o ptrace.o syscalls.o \
> irq.o align.o signal_32.o pmc.o vdso.o \
> - init_task.o process.o systbl.o idle.o
> + init_task.o process.o systbl.o idle.o \
> + signal.o
> obj-y += vdso32/
> obj-$(CONFIG_PPC64) += setup_64.o binfmt_elf32.o sys_ppc32.o \
> signal_64.o ptrace32.o \
> Index: linux-cell/arch/powerpc/kernel/signal.c
> ===================================================================
> --- /dev/null 1970-01-01 00:00:00.000000000 +0000
> +++ linux-cell/arch/powerpc/kernel/signal.c 2007-06-04 11:45:50.000000000 +1000
> @@ -0,0 +1,64 @@
> +/*
> + * Common signal handling code for both 32 and 64 bits
> + *
> + * Copyright (c) 2007 Benjamin Herrenschmidt, IBM Coproration
> + * Extracted from signal_32.c and signal_64.c
> + *
> + * This file is subject to the terms and conditions of the GNU General
> + * Public License. See the file README.legal in the main directory of
> + * this archive for more details.
> + */
> +
> +#include <linux/ptrace.h>
> +#include <linux/signal.h>
> +
> +void check_syscall_restart(struct pt_regs *regs, struct k_sigaction *ka,
> + int has_handler)
> +{
> + unsigned long ret = regs->gpr[3];
> + int restart = 1;
> +
> + /* syscall ? */
> + if (TRAP(regs) != 0x0C00)
> + return;
> +
> + /* error signalled ? */
> + if (!(regs->ccr & 0x10000000))
> + return;
> +
> + switch (ret) {
> + case ERESTART_RESTARTBLOCK:
> + case ERESTARTNOHAND:
> + /* ERESTARTNOHAND means that the syscall should only be
> + * restarted if there was no handler for the signal, and since
> + * we only get here if there is a handler, we dont restart.
> + */
> + restart = !has_handler;
> + break;
> + case ERESTARTSYS:
> + /* ERESTARTSYS means to restart the syscall if there is no
> + * handler or the handler was registered with SA_RESTART
> + */
> + restart = !has_handler || (ka->sa.sa_flags & SA_RESTART) != 0;
> + break;
> + case ERESTARTNOINTR:
> + /* ERESTARTNOINTR means that the syscall should be
> + * called again after the signal handler returns.
> + */
> + break;
> + default:
> + return;
> + }
> + if (restart) {
> + if (ret == ERESTART_RESTARTBLOCK)
> + regs->gpr[0] = __NR_restart_syscall;
> + else
> + regs->gpr[3] = regs->orig_gpr3;
> + regs->nip -= 4;
> + regs->result = 0;
> + } else {
> + regs->result = -EINTR;
> + regs->gpr[3] = EINTR;
> + regs->ccr |= 0x10000000;
> + }
> +}
> Index: linux-cell/arch/powerpc/kernel/signal.h
> ===================================================================
> --- /dev/null 1970-01-01 00:00:00.000000000 +0000
> +++ linux-cell/arch/powerpc/kernel/signal.h 2007-06-04 11:45:41.000000000 +1000
> @@ -0,0 +1,16 @@
> +/*
> + * Copyright (c) 2007 Benjamin Herrenschmidt, IBM Coproration
> + * Extracted from signal_32.c and signal_64.c
> + *
> + * This file is subject to the terms and conditions of the GNU General
> + * Public License. See the file README.legal in the main directory of
> + * this archive for more details.
> + */
> +
> +#ifndef _POWERPC_ARCH_SIGNAL_H
> +#define _POWERPC_ARCH_SIGNAL_H
> +
> +extern void check_syscall_restart(struct pt_regs *regs, struct k_sigaction *ka,
> + int has_handler);
> +
> +#endif /* _POWERPC_ARCH_SIGNAL_H */
---end quoted text---
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