[PATCH] Add TIF_RESTORE_SIGMASK

We need TIF_RESTORE_SIGMASK in order to support ppoll() and pselect()
system calls. This patch originally came from Andi, and was based
heavily on David Howells' implementation of same on i386. I fixed a typo
which was causing do_signal() to use the wrong signal mask.

Signed-off-by: David Woodhouse <dwmw2@infradead.org>
Signed-off-by: Andi Kleen <ak@suse.de>

5 files changed, 49 insertions, 68 deletions

diff --git a/arch/x86_64/ia32/ia32_signal.c b/arch/x86_64/ia32/ia32_signal.c
index 25e5ca22204c..549de439fb2d 100644
--- a/arch/x86_64/ia32/ia32_signal.c
+++ b/arch/x86_64/ia32/ia32_signal.c
@@ -113,25 +113,19 @@ int copy_siginfo_from_user32(siginfo_t *to, compat_siginfo_t __user *from)
 }
 
 asmlinkage long
-sys32_sigsuspend(int history0, int history1, old_sigset_t mask,
-                 struct pt_regs *regs)
+sys32_sigsuspend(int history0, int history1, old_sigset_t mask)
 {
-        sigset_t saveset;
-
         mask &= _BLOCKABLE;
         spin_lock_irq(&current->sighand->siglock);
-        saveset = current->blocked;
+        current->saved_sigmask = current->blocked;
         siginitset(&current->blocked, mask);
         recalc_sigpending();
         spin_unlock_irq(&current->sighand->siglock);
 
-        regs->rax = -EINTR;
-        while (1) {
-                current->state = TASK_INTERRUPTIBLE;
-                schedule();
-                if (do_signal(regs, &saveset))
-                        return -EINTR;
-        }
+        current->state = TASK_INTERRUPTIBLE;
+        schedule();
+        set_thread_flag(TIF_RESTORE_SIGMASK);
+        return -ERESTARTNOHAND;
 }
 
 asmlinkage long
@@ -508,11 +502,11 @@ int ia32_setup_frame(int sig, struct k_sigaction *ka,
                 current->comm, current->pid, frame, regs->rip, frame->pretcode);
 #endif
 
-        return 1;
+        return 0;
 
 give_sigsegv:
         force_sigsegv(sig, current);
-        return 0;
+        return -EFAULT;
 }
 
 int ia32_setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
@@ -595,7 +589,7 @@ int ia32_setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
         regs->ss = __USER32_DS; 
 
         set_fs(USER_DS);
-    regs->eflags &= ~TF_MASK;
+        regs->eflags &= ~TF_MASK;
     if (test_thread_flag(TIF_SINGLESTEP))
         ptrace_notify(SIGTRAP);
 
@@ -604,9 +598,9 @@ int ia32_setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
                 current->comm, current->pid, frame, regs->rip, frame->pretcode);
 #endif
 
-        return 1;
+        return 0;
 
 give_sigsegv:
         force_sigsegv(sig, current);
-        return 0;
+        return -EFAULT;
 }
diff --git a/arch/x86_64/kernel/signal.c b/arch/x86_64/kernel/signal.c
index 28161170fb0a..7f58bc9a056d 100644
--- a/arch/x86_64/kernel/signal.c
+++ b/arch/x86_64/kernel/signal.c
@@ -38,37 +38,6 @@ int ia32_setup_frame(int sig, struct k_sigaction *ka,
             sigset_t *set, struct pt_regs * regs); 
 
 asmlinkage long
-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(&current->sighand->siglock);
-        saveset = current->blocked;
-        current->blocked = newset;
-        recalc_sigpending();
-        spin_unlock_irq(&current->sighand->siglock);
-#ifdef DEBUG_SIG
-        printk("rt_sigsuspend savset(%lx) newset(%lx) regs(%p) rip(%lx)\n",
-                saveset, newset, regs, regs->rip);
-#endif 
-        regs->rax = -EINTR;
-        while (1) {
-                current->state = TASK_INTERRUPTIBLE;
-                schedule();
-                if (do_signal(regs, &saveset))
-                        return -EINTR;
-        }
-}
-
-asmlinkage long
 sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss,
                 struct pt_regs *regs)
 {
@@ -341,11 +310,11 @@ static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
                 current->comm, current->pid, frame, regs->rip, frame->pretcode);
 #endif
 
-        return 1;
+        return 0;
 
 give_sigsegv:
         force_sigsegv(sig, current);
-        return 0;
+        return -EFAULT;
 }
 
 /*
@@ -408,7 +377,7 @@ handle_signal(unsigned long sig, siginfo_t *info, struct k_sigaction *ka,
 #endif
         ret = setup_rt_frame(sig, ka, info, oldset, regs);
 
-        if (ret) {
+        if (ret == 0) {
                 spin_lock_irq(&current->sighand->siglock);
                 sigorsets(&current->blocked,&current->blocked,&ka->sa.sa_mask);
                 if (!(ka->sa.sa_flags & SA_NODEFER))
@@ -425,11 +394,12 @@ handle_signal(unsigned long sig, siginfo_t *info, struct k_sigaction *ka,
  * want to handle. Thus you cannot kill init even with a SIGKILL even by
  * mistake.
  */
-int do_signal(struct pt_regs *regs, sigset_t *oldset)
+static void do_signal(struct pt_regs *regs)
 {
         struct k_sigaction ka;
         siginfo_t info;
         int signr;
+        sigset_t *oldset;
 
         /*
          * We want the common case to go fast, which
@@ -438,9 +408,11 @@ int do_signal(struct pt_regs *regs, sigset_t *oldset)
          * if so.
          */
         if (!user_mode(regs))
-                return 1;
+                return;
 
-        if (!oldset)
+        if (test_thread_flag(TIF_RESTORE_SIGMASK))
+                oldset = &current->saved_sigmask;
+        else
                 oldset = &current->blocked;
 
         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
@@ -454,30 +426,46 @@ int do_signal(struct pt_regs *regs, sigset_t *oldset)
                         set_debugreg(current->thread.debugreg7, 7);
 
                 /* Whee!  Actually deliver the signal.  */
-                return handle_signal(signr, &info, &ka, oldset, regs);
+                if (handle_signal(signr, &info, &ka, oldset, regs) == 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 */
+                        clear_thread_flag(TIF_RESTORE_SIGMASK);
+                }
+                return;
         }
 
         /* Did we come from a system call? */
         if ((long)regs->orig_rax >= 0) {
                 /* Restart the system call - no handlers present */
                 long res = regs->rax;
-                if (res == -ERESTARTNOHAND ||
-                    res == -ERESTARTSYS ||
-                    res == -ERESTARTNOINTR) {
+                switch (res) {
+                case -ERESTARTNOHAND:
+                case -ERESTARTSYS:
+                case -ERESTARTNOINTR:
                         regs->rax = regs->orig_rax;
                         regs->rip -= 2;
-                }
-                if (regs->rax == (unsigned long)-ERESTART_RESTARTBLOCK) {
+                        break;
+                case -ERESTART_RESTARTBLOCK:
                         regs->rax = test_thread_flag(TIF_IA32) ?
                                         __NR_ia32_restart_syscall :
                                         __NR_restart_syscall;
                         regs->rip -= 2;
+                        break;
                 }
         }
-        return 0;
+
+        /* 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, &current->saved_sigmask, NULL);
+        }
 }
 
-void do_notify_resume(struct pt_regs *regs, sigset_t *oldset, __u32 thread_info_flags)
+void
+do_notify_resume(struct pt_regs *regs, void *unused, __u32 thread_info_flags)
 {
 #ifdef DEBUG_SIG
         printk("do_notify_resume flags:%x rip:%lx rsp:%lx caller:%lx pending:%lx\n",
@@ -491,8 +479,8 @@ void do_notify_resume(struct pt_regs *regs, sigset_t *oldset, __u32 thread_info_
         }
 
         /* deal with pending signal delivery */
-        if (thread_info_flags & _TIF_SIGPENDING)
-                do_signal(regs,oldset);
+        if (thread_info_flags & (_TIF_SIGPENDING|_TIF_RESTORE_SIGMASK))
+                do_signal(regs);
 }
 
 void signal_fault(struct pt_regs *regs, void __user *frame, char *where)
diff --git a/include/asm-x86_64/signal.h b/include/asm-x86_64/signal.h
index 3ede2a61973a..4581f978b299 100644
--- a/include/asm-x86_64/signal.h
+++ b/include/asm-x86_64/signal.h
@@ -24,10 +24,6 @@ typedef struct {
 } sigset_t;
 
 
-struct pt_regs; 
-asmlinkage int do_signal(struct pt_regs *regs, sigset_t *oldset);
-
-
 #else
 /* Here we must cater to libcs that poke about in kernel headers.  */
 
diff --git a/include/asm-x86_64/thread_info.h b/include/asm-x86_64/thread_info.h
index 2029b00351f3..790c512a4369 100644
--- a/include/asm-x86_64/thread_info.h
+++ b/include/asm-x86_64/thread_info.h
@@ -114,6 +114,7 @@ static inline struct thread_info *stack_thread_info(void)
 #define TIF_IRET                5       /* force IRET */
 #define TIF_SYSCALL_AUDIT       7       /* syscall auditing active */
 #define TIF_SECCOMP             8       /* secure computing */
+#define TIF_RESTORE_SIGMASK     9       /* restore signal mask in do_signal */
 /* 16 free */
 #define TIF_IA32                17      /* 32bit process */ 
 #define TIF_FORK                18      /* ret_from_fork */
@@ -128,6 +129,7 @@ static inline struct thread_info *stack_thread_info(void)
 #define _TIF_IRET               (1<<TIF_IRET)
 #define _TIF_SYSCALL_AUDIT      (1<<TIF_SYSCALL_AUDIT)
 #define _TIF_SECCOMP            (1<<TIF_SECCOMP)
+#define _TIF_RESTORE_SIGMASK    (1<<TIF_RESTORE_SIGMASK)
 #define _TIF_IA32               (1<<TIF_IA32)
 #define _TIF_FORK               (1<<TIF_FORK)
 #define _TIF_ABI_PENDING        (1<<TIF_ABI_PENDING)
diff --git a/include/asm-x86_64/unistd.h b/include/asm-x86_64/unistd.h
index 80fd48e84bbb..f266de294003 100644
--- a/include/asm-x86_64/unistd.h
+++ b/include/asm-x86_64/unistd.h
@@ -658,6 +658,7 @@ do { \
 #define __ARCH_WANT_SYS_SIGPENDING
 #define __ARCH_WANT_SYS_SIGPROCMASK
 #define __ARCH_WANT_SYS_RT_SIGACTION
+#define __ARCH_WANT_SYS_RT_SIGSUSPEND
 #define __ARCH_WANT_SYS_TIME
 #define __ARCH_WANT_COMPAT_SYS_TIME