Linux-libre 4.3.2-gnu

1 files changed, 33 insertions, 21 deletions

diff --git a/arch/powerpc/include/asm/syscall.h b/arch/powerpc/include/asm/syscall.h
index ff21b7a2f..ab9f3f0a8 100644
--- a/arch/powerpc/include/asm/syscall.h
+++ b/arch/powerpc/include/asm/syscall.h
@@ -22,10 +22,15 @@
 extern const unsigned long sys_call_table[];
 #endif /* CONFIG_FTRACE_SYSCALLS */
 
-static inline long syscall_get_nr(struct task_struct *task,
-				  struct pt_regs *regs)
+static inline int syscall_get_nr(struct task_struct *task, struct pt_regs *regs)
 {
-	return TRAP(regs) == 0xc00 ? regs->gpr[0] : -1L;
+	/*
+	 * Note that we are returning an int here. That means 0xffffffff, ie.
+	 * 32-bit negative 1, will be interpreted as -1 on a 64-bit kernel.
+	 * This is important for seccomp so that compat tasks can set r0 = -1
+	 * to reject the syscall.
+	 */
+	return TRAP(regs) == 0xc00 ? regs->gpr[0] : -1;
 }
 
 static inline void syscall_rollback(struct task_struct *task,
@@ -34,12 +39,6 @@ static inline void syscall_rollback(struct task_struct *task,
 	regs->gpr[3] = regs->orig_gpr3;
 }
 
-static inline long syscall_get_error(struct task_struct *task,
-				     struct pt_regs *regs)
-{
-	return (regs->ccr & 0x10000000) ? -regs->gpr[3] : 0;
-}
-
 static inline long syscall_get_return_value(struct task_struct *task,
 					    struct pt_regs *regs)
 {
@@ -50,9 +49,15 @@ static inline void syscall_set_return_value(struct task_struct *task,
 					    struct pt_regs *regs,
 					    int error, long val)
 {
+	/*
+	 * In the general case it's not obvious that we must deal with CCR
+	 * here, as the syscall exit path will also do that for us. However
+	 * there are some places, eg. the signal code, which check ccr to
+	 * decide if the value in r3 is actually an error.
+	 */
 	if (error) {
 		regs->ccr |= 0x10000000L;
-		regs->gpr[3] = -error;
+		regs->gpr[3] = error;
 	} else {
 		regs->ccr &= ~0x10000000L;
 		regs->gpr[3] = val;
@@ -64,19 +69,22 @@ static inline void syscall_get_arguments(struct task_struct *task,
 					 unsigned int i, unsigned int n,
 					 unsigned long *args)
 {
+	unsigned long val, mask = -1UL;
+
 	BUG_ON(i + n > 6);
-#ifdef CONFIG_PPC64
-	if (test_tsk_thread_flag(task, TIF_32BIT)) {
-		/*
-		 * Zero-extend 32-bit argument values.  The high bits are
-		 * garbage ignored by the actual syscall dispatch.
-		 */
-		while (n-- > 0)
-			args[n] = (u32) regs->gpr[3 + i + n];
-		return;
-	}
+
+#ifdef CONFIG_COMPAT
+	if (test_tsk_thread_flag(task, TIF_32BIT))
+		mask = 0xffffffff;
 #endif
-	memcpy(args, &regs->gpr[3 + i], n * sizeof(args[0]));
+	while (n--) {
+		if (n == 0 && i == 0)
+			val = regs->orig_gpr3;
+		else
+			val = regs->gpr[3 + i + n];
+
+		args[n] = val & mask;
+	}
 }
 
 static inline void syscall_set_arguments(struct task_struct *task,
@@ -86,6 +94,10 @@ static inline void syscall_set_arguments(struct task_struct *task,
 {
 	BUG_ON(i + n > 6);
 	memcpy(&regs->gpr[3 + i], args, n * sizeof(args[0]));
+
+	/* Also copy the first argument into orig_gpr3 */
+	if (i == 0 && n > 0)
+		regs->orig_gpr3 = args[0];
 }
 
 static inline int syscall_get_arch(void)