Fedora kernel-2.6.17-1.2142_FC4 patched with stable patch-2.6.17.4-vs2.0.2-rc26.diff

[linux-2.6.git] / arch / x86_64 / kernel / signal.c

diff --git a/arch/x86_64/kernel/signal.c b/arch/x86_64/kernel/signal.c
index 429c026..e5f5ce7 100644 (file)
--- a/arch/x86_64/kernel/signal.c
+++ b/arch/x86_64/kernel/signal.c
@@ -34,9 +34,9 @@
 
 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
 
-void ia32_setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
+int ia32_setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
                sigset_t *set, struct pt_regs * regs); 
-void ia32_setup_frame(int sig, struct k_sigaction *ka,
+int ia32_setup_frame(int sig, struct k_sigaction *ka,
             sigset_t *set, struct pt_regs * regs); 
 
 asmlinkage long
@@ -110,6 +110,15 @@ restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc, unsigned
        COPY(r14);
        COPY(r15);
 
+       /* Kernel saves and restores only the CS segment register on signals,
+        * which is the bare minimum needed to allow mixed 32/64-bit code.
+        * App's signal handler can save/restore other segments if needed. */
+       {
+               unsigned cs;
+               err |= __get_user(cs, &sc->cs);
+               regs->cs = cs | 3;      /* Force into user mode */
+       }
+
        {
                unsigned int tmpflags;
                err |= __get_user(tmpflags, &sc->eflags);
@@ -187,6 +196,7 @@ setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs, unsigned lo
 {
        int err = 0;
 
+       err |= __put_user(regs->cs, &sc->cs);
        err |= __put_user(0, &sc->gs);
        err |= __put_user(0, &sc->fs);
 
@@ -238,7 +248,7 @@ get_stack(struct k_sigaction *ka, struct pt_regs *regs, unsigned long size)
        return (void __user *)round_down(rsp - size, 16); 
 }
 
-static void setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
+static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
                           sigset_t *set, struct pt_regs * regs)
 {
        struct rt_sigframe __user *frame;
@@ -318,7 +328,14 @@ static void setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 
        regs->rsp = (unsigned long)frame;
 
+       /* Set up the CS register to run signal handlers in 64-bit mode,
+          even if the handler happens to be interrupting 32-bit code. */
+       regs->cs = __USER_CS;
+
+       /* This, by contrast, has nothing to do with segment registers -
+          see include/asm-x86_64/uaccess.h for details. */
        set_fs(USER_DS);
+
        regs->eflags &= ~TF_MASK;
        if (test_thread_flag(TIF_SINGLESTEP))
                ptrace_notify(SIGTRAP);
@@ -327,20 +344,23 @@ static void setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
                current->comm, current->pid, frame, regs->rip, frame->pretcode);
 #endif
 
-       return;
+       return 1;
 
 give_sigsegv:
        force_sigsegv(sig, current);
+       return 0;
 }
 
 /*
  * OK, we're invoking a handler
  */    
 
-static void
+static int
 handle_signal(unsigned long sig, siginfo_t *info, struct k_sigaction *ka,
                sigset_t *oldset, struct pt_regs *regs)
 {
+       int ret;
+
 #ifdef DEBUG_SIG
        printk("handle_signal pid:%d sig:%lu rip:%lx rsp:%lx regs=%p\n",
                current->pid, sig,
@@ -384,20 +404,23 @@ handle_signal(unsigned long sig, siginfo_t *info, struct k_sigaction *ka,
 #ifdef CONFIG_IA32_EMULATION
        if (test_thread_flag(TIF_IA32)) {
                if (ka->sa.sa_flags & SA_SIGINFO)
-                       ia32_setup_rt_frame(sig, ka, info, oldset, regs);
+                       ret = ia32_setup_rt_frame(sig, ka, info, oldset, regs);
                else
-                       ia32_setup_frame(sig, ka, oldset, regs);
+                       ret = ia32_setup_frame(sig, ka, oldset, regs);
        } else 
 #endif
-       setup_rt_frame(sig, ka, info, oldset, regs);
+       ret = setup_rt_frame(sig, ka, info, oldset, regs);
 
-       if (!(ka->sa.sa_flags & SA_NODEFER)) {
+       if (ret) {
                spin_lock_irq(&current->sighand->siglock);
                sigorsets(&current->blocked,&current->blocked,&ka->sa.sa_mask);
-               sigaddset(&current->blocked,sig);
+               if (!(ka->sa.sa_flags & SA_NODEFER))
+                       sigaddset(&current->blocked,sig);
                recalc_sigpending();
                spin_unlock_irq(&current->sighand->siglock);
        }
+
+       return ret;
 }
 
 /*
@@ -417,12 +440,9 @@ int do_signal(struct pt_regs *regs, sigset_t *oldset)
         * kernel mode. Just return without doing anything
         * if so.
         */
-       if ((regs->cs & 3) != 3)
+       if (!user_mode(regs))
                return 1;
 
-       if (try_to_freeze(0))
-               goto no_signal;
-
        if (!oldset)
                oldset = &current->blocked;
 
@@ -434,14 +454,12 @@ int do_signal(struct pt_regs *regs, sigset_t *oldset)
                 * inside the kernel.
                 */
                if (current->thread.debugreg7)
-                       asm volatile("movq %0,%%db7"    : : "r" (current->thread.debugreg7));
+                       set_debugreg(current->thread.debugreg7, 7);
 
                /* Whee!  Actually deliver the signal.  */
-               handle_signal(signr, &info, &ka, oldset, regs);
-               return 1;
+               return handle_signal(signr, &info, &ka, oldset, regs);
        }
 
- no_signal:
        /* Did we come from a system call? */
        if ((long)regs->orig_rax >= 0) {
                /* Restart the system call - no handlers present */