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git-svn-id: svn://svn.openwrt.org/openwrt/trunk@22719 3c298f89-4303-0410-b956-a3cf2f4a3e73
355 lines
11 KiB
Diff
355 lines
11 KiB
Diff
From: Mikael Pettersson <mikpe@it.uu.se>
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Date: Sat, 15 Aug 2009 11:58:11 +0000 (+0100)
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Subject: ARM: 5677/1: ARM support for TIF_RESTORE_SIGMASK/pselect6/ppoll/epoll_pwait
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X-Git-Tag: next-20090817~86^2~1^6
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X-Git-Url: http://git.kernel.org/?p=linux%2Fkernel%2Fgit%2Fnext%2Flinux-next.git;a=commitdiff_plain;h=369842658a36bcea28ecb643ba4bdb53919330dd
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ARM: 5677/1: ARM support for TIF_RESTORE_SIGMASK/pselect6/ppoll/epoll_pwait
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This patch adds support for TIF_RESTORE_SIGMASK to ARM's
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signal handling, which allows to hook up the pselect6, ppoll,
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and epoll_pwait syscalls on ARM.
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Tested here with eabi userspace and a test program with a
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deliberate race between a child's exit and the parent's
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sigprocmask/select sequence. Using sys_pselect6() instead
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of sigprocmask/select reliably prevents the race.
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The other arch's support for TIF_RESTORE_SIGMASK has evolved
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over time:
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In 2.6.16:
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- add TIF_RESTORE_SIGMASK which parallels TIF_SIGPENDING
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- test both when checking for pending signal [changed later]
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- reimplement sys_sigsuspend() to use current->saved_sigmask,
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TIF_RESTORE_SIGMASK [changed later], and -ERESTARTNOHAND;
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ditto for sys_rt_sigsuspend(), but drop private code and
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use common code via __ARCH_WANT_SYS_RT_SIGSUSPEND;
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- there are now no "extra" calls to do_signal() so its oldset
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parameter is always ¤t->blocked so need not be passed,
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also its return value is changed to void
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- change handle_signal() to return 0/-errno
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- change do_signal() to honor TIF_RESTORE_SIGMASK:
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+ get oldset from current->saved_sigmask if TIF_RESTORE_SIGMASK
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is set
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+ if handle_signal() was successful then clear TIF_RESTORE_SIGMASK
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+ if no signal was delivered and TIF_RESTORE_SIGMASK is set then
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clear it and restore the sigmask
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- hook up sys_pselect6() and sys_ppoll()
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In 2.6.19:
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- hook up sys_epoll_pwait()
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In 2.6.26:
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- allow archs to override how TIF_RESTORE_SIGMASK is implemented;
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default set_restore_sigmask() sets both TIF_RESTORE_SIGMASK and
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TIF_SIGPENDING; archs need now just test TIF_SIGPENDING again
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when checking for pending signal work; some archs now implement
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TIF_RESTORE_SIGMASK as a secondary/non-atomic thread flag bit
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- call set_restore_sigmask() in sys_sigsuspend() instead of setting
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TIF_RESTORE_SIGMASK
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In 2.6.29-rc:
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- kill sys_pselect7() which no arch wanted
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So for 2.6.31-rc6/ARM this patch does the following:
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- Add TIF_RESTORE_SIGMASK. Use the generic set_restore_sigmask()
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which sets both TIF_SIGPENDING and TIF_RESTORE_SIGMASK, so
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TIF_RESTORE_SIGMASK need not claim one of the scarce low thread
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flags, and existing TIF_SIGPENDING and _TIF_WORK_MASK tests need
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not be extended for TIF_RESTORE_SIGMASK.
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- sys_sigsuspend() is reimplemented to use current->saved_sigmask
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and set_restore_sigmask(), making it identical to most other archs
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- The private code for sys_rt_sigsuspend() is removed, instead
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generic code supplies it via __ARCH_WANT_SYS_RT_SIGSUSPEND.
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- sys_sigsuspend() and sys_rt_sigsuspend() no longer need a pt_regs
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parameter, so their assembly code wrappers are removed.
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- handle_signal() is changed to return 0 on success or -errno.
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- The oldset parameter to do_signal() is now redundant and removed,
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and the return value is now also redundant and changed to void.
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- do_signal() is changed to honor TIF_RESTORE_SIGMASK:
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+ get oldset from current->saved_sigmask if TIF_RESTORE_SIGMASK
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is set
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+ if handle_signal() was successful then clear TIF_RESTORE_SIGMASK
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+ if no signal was delivered and TIF_RESTORE_SIGMASK is set then
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clear it and restore the sigmask
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- Hook up sys_pselect6, sys_ppoll, and sys_epoll_pwait.
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Signed-off-by: Mikael Pettersson <mikpe@it.uu.se>
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Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
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---
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--- a/arch/arm/include/asm/thread_info.h
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+++ b/arch/arm/include/asm/thread_info.h
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@@ -141,6 +141,7 @@
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#define TIF_USING_IWMMXT 17
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#define TIF_MEMDIE 18
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#define TIF_FREEZE 19
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+#define TIF_RESTORE_SIGMASK 20
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#define _TIF_SIGPENDING (1 << TIF_SIGPENDING)
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#define _TIF_NEED_RESCHED (1 << TIF_NEED_RESCHED)
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@@ -148,6 +149,7 @@
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#define _TIF_POLLING_NRFLAG (1 << TIF_POLLING_NRFLAG)
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#define _TIF_USING_IWMMXT (1 << TIF_USING_IWMMXT)
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#define _TIF_FREEZE (1 << TIF_FREEZE)
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+#define _TIF_RESTORE_SIGMASK (1 << TIF_RESTORE_SIGMASK)
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/*
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* Change these and you break ASM code in entry-common.S
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--- a/arch/arm/include/asm/unistd.h
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+++ b/arch/arm/include/asm/unistd.h
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@@ -360,8 +360,8 @@
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#define __NR_readlinkat (__NR_SYSCALL_BASE+332)
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#define __NR_fchmodat (__NR_SYSCALL_BASE+333)
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#define __NR_faccessat (__NR_SYSCALL_BASE+334)
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- /* 335 for pselect6 */
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- /* 336 for ppoll */
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+#define __NR_pselect6 (__NR_SYSCALL_BASE+335)
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+#define __NR_ppoll (__NR_SYSCALL_BASE+336)
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#define __NR_unshare (__NR_SYSCALL_BASE+337)
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#define __NR_set_robust_list (__NR_SYSCALL_BASE+338)
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#define __NR_get_robust_list (__NR_SYSCALL_BASE+339)
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@@ -372,7 +372,7 @@
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#define __NR_vmsplice (__NR_SYSCALL_BASE+343)
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#define __NR_move_pages (__NR_SYSCALL_BASE+344)
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#define __NR_getcpu (__NR_SYSCALL_BASE+345)
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- /* 346 for epoll_pwait */
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+#define __NR_epoll_pwait (__NR_SYSCALL_BASE+346)
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#define __NR_kexec_load (__NR_SYSCALL_BASE+347)
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#define __NR_utimensat (__NR_SYSCALL_BASE+348)
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#define __NR_signalfd (__NR_SYSCALL_BASE+349)
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@@ -432,6 +432,7 @@
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#define __ARCH_WANT_SYS_SIGPENDING
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#define __ARCH_WANT_SYS_SIGPROCMASK
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#define __ARCH_WANT_SYS_RT_SIGACTION
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+#define __ARCH_WANT_SYS_RT_SIGSUSPEND
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#if !defined(CONFIG_AEABI) || defined(CONFIG_OABI_COMPAT)
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#define __ARCH_WANT_SYS_TIME
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--- a/arch/arm/kernel/calls.S
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+++ b/arch/arm/kernel/calls.S
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@@ -81,7 +81,7 @@
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CALL(sys_ni_syscall) /* was sys_ssetmask */
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/* 70 */ CALL(sys_setreuid16)
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CALL(sys_setregid16)
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- CALL(sys_sigsuspend_wrapper)
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+ CALL(sys_sigsuspend)
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CALL(sys_sigpending)
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CALL(sys_sethostname)
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/* 75 */ CALL(sys_setrlimit)
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@@ -188,7 +188,7 @@
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CALL(sys_rt_sigpending)
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CALL(sys_rt_sigtimedwait)
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CALL(sys_rt_sigqueueinfo)
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- CALL(sys_rt_sigsuspend_wrapper)
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+ CALL(sys_rt_sigsuspend)
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/* 180 */ CALL(ABI(sys_pread64, sys_oabi_pread64))
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CALL(ABI(sys_pwrite64, sys_oabi_pwrite64))
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CALL(sys_chown16)
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@@ -344,8 +344,8 @@
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CALL(sys_readlinkat)
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CALL(sys_fchmodat)
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CALL(sys_faccessat)
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-/* 335 */ CALL(sys_ni_syscall) /* eventually pselect6 */
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- CALL(sys_ni_syscall) /* eventually ppoll */
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+/* 335 */ CALL(sys_pselect6)
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+ CALL(sys_ppoll)
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CALL(sys_unshare)
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CALL(sys_set_robust_list)
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CALL(sys_get_robust_list)
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@@ -355,7 +355,7 @@
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CALL(sys_vmsplice)
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CALL(sys_move_pages)
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/* 345 */ CALL(sys_getcpu)
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- CALL(sys_ni_syscall) /* eventually epoll_pwait */
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+ CALL(sys_epoll_pwait)
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CALL(sys_kexec_load)
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CALL(sys_utimensat)
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CALL(sys_signalfd)
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--- a/arch/arm/kernel/entry-common.S
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+++ b/arch/arm/kernel/entry-common.S
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@@ -373,16 +373,6 @@
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b sys_clone
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ENDPROC(sys_clone_wrapper)
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-sys_sigsuspend_wrapper:
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- add r3, sp, #S_OFF
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- b sys_sigsuspend
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-ENDPROC(sys_sigsuspend_wrapper)
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-
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-sys_rt_sigsuspend_wrapper:
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- add r2, sp, #S_OFF
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- b sys_rt_sigsuspend
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-ENDPROC(sys_rt_sigsuspend_wrapper)
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-
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sys_sigreturn_wrapper:
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add r0, sp, #S_OFF
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b sys_sigreturn
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--- a/arch/arm/kernel/signal.c
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+++ b/arch/arm/kernel/signal.c
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@@ -47,57 +47,22 @@
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MOV_R7_NR_RT_SIGRETURN, SWI_SYS_RT_SIGRETURN, SWI_THUMB_RT_SIGRETURN,
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};
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-static int do_signal(sigset_t *oldset, struct pt_regs * regs, int syscall);
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-
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/*
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* atomically swap in the new signal mask, and wait for a signal.
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*/
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-asmlinkage int sys_sigsuspend(int restart, unsigned long oldmask, old_sigset_t mask, struct pt_regs *regs)
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+asmlinkage int sys_sigsuspend(int restart, unsigned long oldmask, old_sigset_t mask)
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{
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- sigset_t saveset;
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-
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mask &= _BLOCKABLE;
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spin_lock_irq(¤t->sighand->siglock);
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- saveset = current->blocked;
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+ current->saved_sigmask = current->blocked;
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siginitset(¤t->blocked, mask);
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recalc_sigpending();
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spin_unlock_irq(¤t->sighand->siglock);
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- regs->ARM_r0 = -EINTR;
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-
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- while (1) {
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- current->state = TASK_INTERRUPTIBLE;
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- schedule();
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- if (do_signal(&saveset, regs, 0))
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- return regs->ARM_r0;
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- }
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-}
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-
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-asmlinkage int
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-sys_rt_sigsuspend(sigset_t __user *unewset, size_t sigsetsize, struct pt_regs *regs)
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-{
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- sigset_t saveset, newset;
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-
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- /* XXX: Don't preclude handling different sized sigset_t's. */
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- if (sigsetsize != sizeof(sigset_t))
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- return -EINVAL;
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-
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- if (copy_from_user(&newset, unewset, sizeof(newset)))
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- return -EFAULT;
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- sigdelsetmask(&newset, ~_BLOCKABLE);
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-
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- spin_lock_irq(¤t->sighand->siglock);
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- saveset = current->blocked;
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- current->blocked = newset;
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- recalc_sigpending();
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- spin_unlock_irq(¤t->sighand->siglock);
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- regs->ARM_r0 = -EINTR;
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- while (1) {
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- current->state = TASK_INTERRUPTIBLE;
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- schedule();
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- if (do_signal(&saveset, regs, 0))
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- return regs->ARM_r0;
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- }
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+ current->state = TASK_INTERRUPTIBLE;
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+ schedule();
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+ set_restore_sigmask();
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+ return -ERESTARTNOHAND;
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}
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asmlinkage int
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@@ -545,7 +510,7 @@
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/*
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* OK, we're invoking a handler
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*/
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-static void
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+static int
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handle_signal(unsigned long sig, struct k_sigaction *ka,
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siginfo_t *info, sigset_t *oldset,
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struct pt_regs * regs, int syscall)
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@@ -596,7 +561,7 @@
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if (ret != 0) {
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force_sigsegv(sig, tsk);
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- return;
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+ return ret;
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}
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/*
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@@ -610,6 +575,7 @@
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recalc_sigpending();
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spin_unlock_irq(&tsk->sighand->siglock);
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+ return 0;
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}
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/*
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@@ -621,11 +587,12 @@
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* the kernel can handle, and then we build all the user-level signal handling
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* stack-frames in one go after that.
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*/
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-static int do_signal(sigset_t *oldset, struct pt_regs *regs, int syscall)
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+static void do_signal(struct pt_regs *regs, int syscall)
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{
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struct k_sigaction ka;
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siginfo_t info;
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int signr;
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+ sigset_t *oldset;
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/*
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* We want the common case to go fast, which
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@@ -634,18 +601,32 @@
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* if so.
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*/
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if (!user_mode(regs))
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- return 0;
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+ return;
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if (try_to_freeze())
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goto no_signal;
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single_step_clear(current);
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+ if (test_thread_flag(TIF_RESTORE_SIGMASK))
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+ oldset = ¤t->saved_sigmask;
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+ else
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+ oldset = ¤t->blocked;
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+
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signr = get_signal_to_deliver(&info, &ka, regs, NULL);
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if (signr > 0) {
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- handle_signal(signr, &ka, &info, oldset, regs, syscall);
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+ if (handle_signal(signr, &ka, &info, oldset, regs, syscall) == 0) {
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+ /*
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+ * A signal was successfully delivered; the saved
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+ * sigmask will have been stored in the signal frame,
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+ * and will be restored by sigreturn, so we can simply
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+ * clear the TIF_RESTORE_SIGMASK flag.
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+ */
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+ if (test_thread_flag(TIF_RESTORE_SIGMASK))
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+ clear_thread_flag(TIF_RESTORE_SIGMASK);
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+ }
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single_step_set(current);
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- return 1;
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+ return;
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}
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no_signal:
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@@ -697,14 +678,21 @@
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regs->ARM_r0 == -ERESTARTNOINTR) {
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setup_syscall_restart(regs);
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}
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+
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+ /* If there's no signal to deliver, we just put the saved sigmask
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+ * back.
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+ */
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+ if (test_thread_flag(TIF_RESTORE_SIGMASK)) {
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+ clear_thread_flag(TIF_RESTORE_SIGMASK);
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+ sigprocmask(SIG_SETMASK, ¤t->saved_sigmask, NULL);
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+ }
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}
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single_step_set(current);
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- return 0;
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}
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asmlinkage void
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do_notify_resume(struct pt_regs *regs, unsigned int thread_flags, int syscall)
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{
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if (thread_flags & _TIF_SIGPENDING)
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- do_signal(¤t->blocked, regs, syscall);
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+ do_signal(regs, syscall);
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}
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