diff options
| -rw-r--r-- | target/linux/generic/patches-2.6.31/965-arm_restore_sigmask_v2.patch | 354 |
1 files changed, 354 insertions, 0 deletions
diff --git a/target/linux/generic/patches-2.6.31/965-arm_restore_sigmask_v2.patch b/target/linux/generic/patches-2.6.31/965-arm_restore_sigmask_v2.patch new file mode 100644 index 0000000000..b622529dec --- /dev/null +++ b/target/linux/generic/patches-2.6.31/965-arm_restore_sigmask_v2.patch @@ -0,0 +1,354 @@ +From: Mikael Pettersson <mikpe@it.uu.se> +Date: Sat, 15 Aug 2009 11:58:11 +0000 (+0100) +Subject: ARM: 5677/1: ARM support for TIF_RESTORE_SIGMASK/pselect6/ppoll/epoll_pwait +X-Git-Tag: next-20090817~86^2~1^6 +X-Git-Url: http://git.kernel.org/?p=linux%2Fkernel%2Fgit%2Fnext%2Flinux-next.git;a=commitdiff_plain;h=369842658a36bcea28ecb643ba4bdb53919330dd + +ARM: 5677/1: ARM support for TIF_RESTORE_SIGMASK/pselect6/ppoll/epoll_pwait + +This patch adds support for TIF_RESTORE_SIGMASK to ARM's +signal handling, which allows to hook up the pselect6, ppoll, +and epoll_pwait syscalls on ARM. + +Tested here with eabi userspace and a test program with a +deliberate race between a child's exit and the parent's +sigprocmask/select sequence. Using sys_pselect6() instead +of sigprocmask/select reliably prevents the race. + +The other arch's support for TIF_RESTORE_SIGMASK has evolved +over time: + +In 2.6.16: +- add TIF_RESTORE_SIGMASK which parallels TIF_SIGPENDING +- test both when checking for pending signal [changed later] +- reimplement sys_sigsuspend() to use current->saved_sigmask, + TIF_RESTORE_SIGMASK [changed later], and -ERESTARTNOHAND; + ditto for sys_rt_sigsuspend(), but drop private code and + use common code via __ARCH_WANT_SYS_RT_SIGSUSPEND; +- there are now no "extra" calls to do_signal() so its oldset + parameter is always ¤t->blocked so need not be passed, + also its return value is changed to void +- change handle_signal() to return 0/-errno +- change do_signal() to honor TIF_RESTORE_SIGMASK: + + get oldset from current->saved_sigmask if TIF_RESTORE_SIGMASK + is set + + if handle_signal() was successful then clear TIF_RESTORE_SIGMASK + + if no signal was delivered and TIF_RESTORE_SIGMASK is set then + clear it and restore the sigmask +- hook up sys_pselect6() and sys_ppoll() + +In 2.6.19: +- hook up sys_epoll_pwait() + +In 2.6.26: +- allow archs to override how TIF_RESTORE_SIGMASK is implemented; + default set_restore_sigmask() sets both TIF_RESTORE_SIGMASK and + TIF_SIGPENDING; archs need now just test TIF_SIGPENDING again + when checking for pending signal work; some archs now implement + TIF_RESTORE_SIGMASK as a secondary/non-atomic thread flag bit +- call set_restore_sigmask() in sys_sigsuspend() instead of setting + TIF_RESTORE_SIGMASK + +In 2.6.29-rc: +- kill sys_pselect7() which no arch wanted + +So for 2.6.31-rc6/ARM this patch does the following: +- Add TIF_RESTORE_SIGMASK. Use the generic set_restore_sigmask() + which sets both TIF_SIGPENDING and TIF_RESTORE_SIGMASK, so + TIF_RESTORE_SIGMASK need not claim one of the scarce low thread + flags, and existing TIF_SIGPENDING and _TIF_WORK_MASK tests need + not be extended for TIF_RESTORE_SIGMASK. +- sys_sigsuspend() is reimplemented to use current->saved_sigmask + and set_restore_sigmask(), making it identical to most other archs +- The private code for sys_rt_sigsuspend() is removed, instead + generic code supplies it via __ARCH_WANT_SYS_RT_SIGSUSPEND. +- sys_sigsuspend() and sys_rt_sigsuspend() no longer need a pt_regs + parameter, so their assembly code wrappers are removed. +- handle_signal() is changed to return 0 on success or -errno. +- The oldset parameter to do_signal() is now redundant and removed, + and the return value is now also redundant and changed to void. +- do_signal() is changed to honor TIF_RESTORE_SIGMASK: + + get oldset from current->saved_sigmask if TIF_RESTORE_SIGMASK + is set + + if handle_signal() was successful then clear TIF_RESTORE_SIGMASK + + if no signal was delivered and TIF_RESTORE_SIGMASK is set then + clear it and restore the sigmask +- Hook up sys_pselect6, sys_ppoll, and sys_epoll_pwait. + +Signed-off-by: Mikael Pettersson <mikpe@it.uu.se> +Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk> +--- + +--- a/arch/arm/include/asm/thread_info.h ++++ b/arch/arm/include/asm/thread_info.h +@@ -141,6 +141,7 @@ + #define TIF_USING_IWMMXT 17 + #define TIF_MEMDIE 18 + #define TIF_FREEZE 19 ++#define TIF_RESTORE_SIGMASK 20 + + #define _TIF_SIGPENDING (1 << TIF_SIGPENDING) + #define _TIF_NEED_RESCHED (1 << TIF_NEED_RESCHED) +@@ -148,6 +149,7 @@ + #define _TIF_POLLING_NRFLAG (1 << TIF_POLLING_NRFLAG) + #define _TIF_USING_IWMMXT (1 << TIF_USING_IWMMXT) + #define _TIF_FREEZE (1 << TIF_FREEZE) ++#define _TIF_RESTORE_SIGMASK (1 << TIF_RESTORE_SIGMASK) + + /* + * Change these and you break ASM code in entry-common.S +--- a/arch/arm/include/asm/unistd.h ++++ b/arch/arm/include/asm/unistd.h +@@ -360,8 +360,8 @@ + #define __NR_readlinkat (__NR_SYSCALL_BASE+332) + #define __NR_fchmodat (__NR_SYSCALL_BASE+333) + #define __NR_faccessat (__NR_SYSCALL_BASE+334) +- /* 335 for pselect6 */ +- /* 336 for ppoll */ ++#define __NR_pselect6 (__NR_SYSCALL_BASE+335) ++#define __NR_ppoll (__NR_SYSCALL_BASE+336) + #define __NR_unshare (__NR_SYSCALL_BASE+337) + #define __NR_set_robust_list (__NR_SYSCALL_BASE+338) + #define __NR_get_robust_list (__NR_SYSCALL_BASE+339) +@@ -372,7 +372,7 @@ + #define __NR_vmsplice (__NR_SYSCALL_BASE+343) + #define __NR_move_pages (__NR_SYSCALL_BASE+344) + #define __NR_getcpu (__NR_SYSCALL_BASE+345) +- /* 346 for epoll_pwait */ ++#define __NR_epoll_pwait (__NR_SYSCALL_BASE+346) + #define __NR_kexec_load (__NR_SYSCALL_BASE+347) + #define __NR_utimensat (__NR_SYSCALL_BASE+348) + #define __NR_signalfd (__NR_SYSCALL_BASE+349) +@@ -432,6 +432,7 @@ + #define __ARCH_WANT_SYS_SIGPENDING + #define __ARCH_WANT_SYS_SIGPROCMASK + #define __ARCH_WANT_SYS_RT_SIGACTION ++#define __ARCH_WANT_SYS_RT_SIGSUSPEND + + #if !defined(CONFIG_AEABI) || defined(CONFIG_OABI_COMPAT) + #define __ARCH_WANT_SYS_TIME +--- a/arch/arm/kernel/calls.S ++++ b/arch/arm/kernel/calls.S +@@ -81,7 +81,7 @@ + CALL(sys_ni_syscall) /* was sys_ssetmask */ + /* 70 */ CALL(sys_setreuid16) + CALL(sys_setregid16) +- CALL(sys_sigsuspend_wrapper) ++ CALL(sys_sigsuspend) + CALL(sys_sigpending) + CALL(sys_sethostname) + /* 75 */ CALL(sys_setrlimit) +@@ -188,7 +188,7 @@ + CALL(sys_rt_sigpending) + CALL(sys_rt_sigtimedwait) + CALL(sys_rt_sigqueueinfo) +- CALL(sys_rt_sigsuspend_wrapper) ++ CALL(sys_rt_sigsuspend) + /* 180 */ CALL(ABI(sys_pread64, sys_oabi_pread64)) + CALL(ABI(sys_pwrite64, sys_oabi_pwrite64)) + CALL(sys_chown16) +@@ -344,8 +344,8 @@ + CALL(sys_readlinkat) + CALL(sys_fchmodat) + CALL(sys_faccessat) +-/* 335 */ CALL(sys_ni_syscall) /* eventually pselect6 */ +- CALL(sys_ni_syscall) /* eventually ppoll */ ++/* 335 */ CALL(sys_pselect6) ++ CALL(sys_ppoll) + CALL(sys_unshare) + CALL(sys_set_robust_list) + CALL(sys_get_robust_list) +@@ -355,7 +355,7 @@ + CALL(sys_vmsplice) + CALL(sys_move_pages) + /* 345 */ CALL(sys_getcpu) +- CALL(sys_ni_syscall) /* eventually epoll_pwait */ ++ CALL(sys_epoll_pwait) + CALL(sys_kexec_load) + CALL(sys_utimensat) + CALL(sys_signalfd) +--- a/arch/arm/kernel/entry-common.S ++++ b/arch/arm/kernel/entry-common.S +@@ -373,16 +373,6 @@ + b sys_clone + ENDPROC(sys_clone_wrapper) + +-sys_sigsuspend_wrapper: +- add r3, sp, #S_OFF +- b sys_sigsuspend +-ENDPROC(sys_sigsuspend_wrapper) +- +-sys_rt_sigsuspend_wrapper: +- add r2, sp, #S_OFF +- b sys_rt_sigsuspend +-ENDPROC(sys_rt_sigsuspend_wrapper) +- + sys_sigreturn_wrapper: + add r0, sp, #S_OFF + b sys_sigreturn +--- a/arch/arm/kernel/signal.c ++++ b/arch/arm/kernel/signal.c +@@ -47,57 +47,22 @@ + MOV_R7_NR_RT_SIGRETURN, SWI_SYS_RT_SIGRETURN, SWI_THUMB_RT_SIGRETURN, + }; + +-static int do_signal(sigset_t *oldset, struct pt_regs * regs, int syscall); +- + /* + * atomically swap in the new signal mask, and wait for a signal. + */ +-asmlinkage int sys_sigsuspend(int restart, unsigned long oldmask, old_sigset_t mask, struct pt_regs *regs) ++asmlinkage int sys_sigsuspend(int restart, unsigned long oldmask, old_sigset_t mask) + { +- sigset_t saveset; +- + mask &= _BLOCKABLE; + spin_lock_irq(¤t->sighand->siglock); +- saveset = current->blocked; ++ current->saved_sigmask = current->blocked; + siginitset(¤t->blocked, mask); + recalc_sigpending(); + spin_unlock_irq(¤t->sighand->siglock); +- regs->ARM_r0 = -EINTR; +- +- while (1) { +- current->state = TASK_INTERRUPTIBLE; +- schedule(); +- if (do_signal(&saveset, regs, 0)) +- return regs->ARM_r0; +- } +-} +- +-asmlinkage int +-sys_rt_sigsuspend(sigset_t __user *unewset, size_t sigsetsize, struct pt_regs *regs) +-{ +- sigset_t saveset, newset; +- +- /* XXX: Don't preclude handling different sized sigset_t's. */ +- if (sigsetsize != sizeof(sigset_t)) +- return -EINVAL; +- +- if (copy_from_user(&newset, unewset, sizeof(newset))) +- return -EFAULT; +- sigdelsetmask(&newset, ~_BLOCKABLE); +- +- spin_lock_irq(¤t->sighand->siglock); +- saveset = current->blocked; +- current->blocked = newset; +- recalc_sigpending(); +- spin_unlock_irq(¤t->sighand->siglock); +- regs->ARM_r0 = -EINTR; + +- while (1) { +- current->state = TASK_INTERRUPTIBLE; +- schedule(); +- if (do_signal(&saveset, regs, 0)) +- return regs->ARM_r0; +- } ++ current->state = TASK_INTERRUPTIBLE; ++ schedule(); ++ set_restore_sigmask(); ++ return -ERESTARTNOHAND; + } + + asmlinkage int +@@ -545,7 +510,7 @@ + /* + * OK, we're invoking a handler + */ +-static void ++static int + handle_signal(unsigned long sig, struct k_sigaction *ka, + siginfo_t *info, sigset_t *oldset, + struct pt_regs * regs, int syscall) +@@ -596,7 +561,7 @@ + + if (ret != 0) { + force_sigsegv(sig, tsk); +- return; ++ return ret; + } + + /* +@@ -610,6 +575,7 @@ + recalc_sigpending(); + spin_unlock_irq(&tsk->sighand->siglock); + ++ return 0; + } + + /* +@@ -621,11 +587,12 @@ + * the kernel can handle, and then we build all the user-level signal handling + * stack-frames in one go after that. + */ +-static int do_signal(sigset_t *oldset, struct pt_regs *regs, int syscall) ++static void do_signal(struct pt_regs *regs, int syscall) + { + struct k_sigaction ka; + siginfo_t info; + int signr; ++ sigset_t *oldset; + + /* + * We want the common case to go fast, which +@@ -634,18 +601,32 @@ + * if so. + */ + if (!user_mode(regs)) +- return 0; ++ return; + + if (try_to_freeze()) + goto no_signal; + + single_step_clear(current); + ++ if (test_thread_flag(TIF_RESTORE_SIGMASK)) ++ oldset = ¤t->saved_sigmask; ++ else ++ oldset = ¤t->blocked; ++ + signr = get_signal_to_deliver(&info, &ka, regs, NULL); + if (signr > 0) { +- handle_signal(signr, &ka, &info, oldset, regs, syscall); ++ if (handle_signal(signr, &ka, &info, oldset, regs, syscall) == 0) { ++ /* ++ * A signal was successfully delivered; the saved ++ * sigmask will have been stored in the signal frame, ++ * and will be restored by sigreturn, so we can simply ++ * clear the TIF_RESTORE_SIGMASK flag. ++ */ ++ if (test_thread_flag(TIF_RESTORE_SIGMASK)) ++ clear_thread_flag(TIF_RESTORE_SIGMASK); ++ } + single_step_set(current); +- return 1; ++ return; + } + + no_signal: +@@ -697,14 +678,21 @@ + regs->ARM_r0 == -ERESTARTNOINTR) { + setup_syscall_restart(regs); + } ++ ++ /* If there's no signal to deliver, we just put the saved sigmask ++ * back. ++ */ ++ if (test_thread_flag(TIF_RESTORE_SIGMASK)) { ++ clear_thread_flag(TIF_RESTORE_SIGMASK); ++ sigprocmask(SIG_SETMASK, ¤t->saved_sigmask, NULL); ++ } + } + single_step_set(current); +- return 0; + } + + asmlinkage void + do_notify_resume(struct pt_regs *regs, unsigned int thread_flags, int syscall) + { + if (thread_flags & _TIF_SIGPENDING) +- do_signal(¤t->blocked, regs, syscall); ++ do_signal(regs, syscall); + } |