[PATCH 1/2] Support TIF_RESTORE_SIGMASK on x86_64

From: David Woodhouse
Date: Mon Jul 03 2006 - 05:40:30 EST

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@xxxxxxxxxxxxx>

diff --git a/arch/x86_64/ia32/ia32_signal.c b/arch/x86_64/ia32/ia32_signal.c
index 25e5ca2..549de43 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 *
}

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 @@ #if DEBUG_SIG
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
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 @@ #if DEBUG_SIG
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 2816117..7f58bc9 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_s
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 @@ #ifdef DEBUG_SIG
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 @@ #ifdef CONFIG_IA32_EMULATION
#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 @@ #endif
* 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, sigs
* 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, sigs
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 @@ #endif
}

/* 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 cef7a7d..00f2d38 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 2029b00..790c512 100644
--- a/include/asm-x86_64/thread_info.h
+++ b/include/asm-x86_64/thread_info.h
@@ -114,6 +114,7 @@ #define TIF_SINGLESTEP 4 /* reenable si
#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 @@ #define _TIF_NEED_RESCHED (1<<TIF_NEED_R
#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 94387c9..c9db37d 100644
--- a/include/asm-x86_64/unistd.h
+++ b/include/asm-x86_64/unistd.h
@@ -658,6 +658,7 @@ #define __ARCH_WANT_SYS_OLDUMOUNT
#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



--
dwmw2

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