[PATCH] Fix PTRACE_CONT after single-step into signal delivery

The previous single-step patch ("make single-step into signal delivery
stop in handler") took things a little too far. 

It left TF set in the sigcontext on the stack, so a PTRACE_CONT after
stopping at the handler entry will step instead of resume.  This
additional patch fixes it. 
Signed-off-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

arch/i386/kernel/signal.c

@@ -270,6 +270,7 @@ setup_sigcontext(struct sigcontext __user *sc, struct _fpstate __user *fpstate,
 		 struct pt_regs *regs, unsigned long mask)
 {
 	int tmp, err = 0;
+	unsigned long eflags;
 
 	tmp = 0;
 	__asm__("movl %%gs,%0" : "=r"(tmp): "0"(tmp));
@@ -291,7 +292,11 @@ setup_sigcontext(struct sigcontext __user *sc, struct _fpstate __user *fpstate,
 	err |= __put_user(current->thread.error_code, &sc->err);
 	err |= __put_user(regs->eip, &sc->eip);
 	err |= __put_user(regs->xcs, (unsigned int __user *)&sc->cs);
-	err |= __put_user(regs->eflags, &sc->eflags);
+	eflags = regs->eflags;
+	if (current->ptrace & PT_PTRACED) {
+		eflags &= ~TF_MASK;
+	}
+	err |= __put_user(eflags, &sc->eflags);
 	err |= __put_user(regs->esp, &sc->esp_at_signal);
 	err |= __put_user(regs->xss, (unsigned int __user *)&sc->ss);
 

arch/x86_64/ia32/ia32_signal.c

@@ -349,6 +349,7 @@ ia32_setup_sigcontext(struct sigcontext_ia32 __user *sc, struct _fpstate_ia32 __
 		 struct pt_regs *regs, unsigned int mask)
 {
 	int tmp, err = 0;
+	u32 eflags;
 
 	tmp = 0;
 	__asm__("movl %%gs,%0" : "=r"(tmp): "0"(tmp));
@@ -373,7 +374,11 @@ ia32_setup_sigcontext(struct sigcontext_ia32 __user *sc, struct _fpstate_ia32 __
 	err |= __put_user(current->thread.trap_no, &sc->trapno);
 	err |= __put_user(current->thread.error_code, &sc->err);
 	err |= __put_user((u32)regs->rip, &sc->eip);
-	err |= __put_user((u32)regs->eflags, &sc->eflags);
+	eflags = regs->eflags;
+	if (current->ptrace & PT_PTRACED) {
+		eflags &= ~TF_MASK;
+	}
+	err |= __put_user((u32)eflags, &sc->eflags);
 	err |= __put_user((u32)regs->rsp, &sc->esp_at_signal);
 
 	tmp = save_i387_ia32(current, fpstate, regs, 0);

arch/x86_64/kernel/signal.c

@@ -181,6 +181,7 @@ static inline int
 setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs, unsigned long mask, struct task_struct *me)
 {
 	int err = 0;
+	unsigned long eflags;
 
 	err |= __put_user(0, &sc->gs);
 	err |= __put_user(0, &sc->fs);
@@ -204,7 +205,11 @@ setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs, unsigned lo
 	err |= __put_user(me->thread.trap_no, &sc->trapno);
 	err |= __put_user(me->thread.error_code, &sc->err);
 	err |= __put_user(regs->rip, &sc->rip);
-	err |= __put_user(regs->eflags, &sc->eflags);
+	eflags = regs->eflags;
+	if (current->ptrace & PT_PTRACED) {
+		eflags &= ~TF_MASK;
+	}
+	err |= __put_user(eflags, &sc->eflags);
 	err |= __put_user(mask, &sc->oldmask);
 	err |= __put_user(me->thread.cr2, &sc->cr2);