From 369842658a36bcea28ecb643ba4bdb53919330dd Mon Sep 17 00:00:00 2001 From: Mikael Pettersson Date: Sat, 15 Aug 2009 12:58:11 +0100 Subject: 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 Signed-off-by: Russell King --- arch/arm/include/asm/thread_info.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'arch/arm/include/asm/thread_info.h') diff --git a/arch/arm/include/asm/thread_info.h b/arch/arm/include/asm/thread_info.h index 73394e50cbca..e20d80539b42 100644 --- a/arch/arm/include/asm/thread_info.h +++ b/arch/arm/include/asm/thread_info.h @@ -140,6 +140,7 @@ extern void vfp_sync_state(struct thread_info *thread); #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) @@ -147,6 +148,7 @@ extern void vfp_sync_state(struct thread_info *thread); #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 -- cgit v1.2.3