1 files changed, 22 insertions, 27 deletions

diff --git a/arch/arm64/kernel/signal.c b/arch/arm64/kernel/signal.c
index 8807ba2..abd7563 100644
--- a/arch/arm64/kernel/signal.c
+++ b/arch/arm64/kernel/signal.c
@@ -41,6 +41,8 @@
 struct rt_sigframe {
 	struct siginfo info;
 	struct ucontext uc;
+	u64 fp;
+	u64 lr;
 };
 
 static int preserve_fpsimd_context(struct fpsimd_context __user *ctx)
@@ -175,6 +177,10 @@ static int setup_sigframe(struct rt_sigframe __user *sf,
 	struct aux_context __user *aux =
 		(struct aux_context __user *)sf->uc.uc_mcontext.__reserved;
 
+	/* set up the stack frame for unwinding */
+	__put_user_error(regs->regs[29], &sf->fp, err);
+	__put_user_error(regs->regs[30], &sf->lr, err);
+
 	for (i = 0; i < 31; i++)
 		__put_user_error(regs->regs[i], &sf->uc.uc_mcontext.regs[i],
 				 err);
@@ -196,11 +202,11 @@ static int setup_sigframe(struct rt_sigframe __user *sf,
 	return err;
 }
 
-static void __user *get_sigframe(struct k_sigaction *ka, struct pt_regs *regs,
-				 int framesize)
+static struct rt_sigframe __user *get_sigframe(struct k_sigaction *ka,
+					       struct pt_regs *regs)
 {
 	unsigned long sp, sp_top;
-	void __user *frame;
+	struct rt_sigframe __user *frame;
 
 	sp = sp_top = regs->sp;
 
@@ -210,11 +216,8 @@ static void __user *get_sigframe(struct k_sigaction *ka, struct pt_regs *regs,
 	if ((ka->sa.sa_flags & SA_ONSTACK) && !sas_ss_flags(sp))
 		sp = sp_top = current->sas_ss_sp + current->sas_ss_size;
 
-	/* room for stack frame (FP, LR) */
-	sp -= 16;
-
-	sp = (sp - framesize) & ~15;
-	frame = (void __user *)sp;
+	sp = (sp - sizeof(struct rt_sigframe)) & ~15;
+	frame = (struct rt_sigframe __user *)sp;
 
 	/*
 	 * Check that we can actually write to the signal frame.
@@ -225,20 +228,14 @@ static void __user *get_sigframe(struct k_sigaction *ka, struct pt_regs *regs,
 	return frame;
 }
 
-static int setup_return(struct pt_regs *regs, struct k_sigaction *ka,
-			void __user *frame, int usig)
+static void setup_return(struct pt_regs *regs, struct k_sigaction *ka,
+			 void __user *frame, int usig)
 {
-	int err = 0;
 	__sigrestore_t sigtramp;
-	unsigned long __user *sp = (unsigned long __user *)regs->sp;
-
-	/* set up the stack frame */
-	__put_user_error(regs->regs[29], sp - 2, err);
-	__put_user_error(regs->regs[30], sp - 1, err);
 
 	regs->regs[0] = usig;
-	regs->regs[29] = regs->sp - 16;
 	regs->sp = (unsigned long)frame;
+	regs->regs[29] = regs->sp + offsetof(struct rt_sigframe, fp);
 	regs->pc = (unsigned long)ka->sa.sa_handler;
 
 	if (ka->sa.sa_flags & SA_RESTORER)
@@ -247,8 +244,6 @@ static int setup_return(struct pt_regs *regs, struct k_sigaction *ka,
 		sigtramp = VDSO_SYMBOL(current->mm->context.vdso, sigtramp);
 
 	regs->regs[30] = (unsigned long)sigtramp;
-
-	return err;
 }
 
 static int setup_rt_frame(int usig, struct k_sigaction *ka, siginfo_t *info,
@@ -258,7 +253,7 @@ static int setup_rt_frame(int usig, struct k_sigaction *ka, siginfo_t *info,
 	stack_t stack;
 	int err = 0;
 
-	frame = get_sigframe(ka, regs, sizeof(*frame));
+	frame = get_sigframe(ka, regs);
 	if (!frame)
 		return 1;
 
@@ -272,13 +267,13 @@ static int setup_rt_frame(int usig, struct k_sigaction *ka, siginfo_t *info,
 	err |= __copy_to_user(&frame->uc.uc_stack, &stack, sizeof(stack));
 
 	err |= setup_sigframe(frame, regs, set);
-	if (err == 0)
-		err = setup_return(regs, ka, frame, usig);
-
-	if (err == 0 && ka->sa.sa_flags & SA_SIGINFO) {
-		err |= copy_siginfo_to_user(&frame->info, info);
-		regs->regs[1] = (unsigned long)&frame->info;
-		regs->regs[2] = (unsigned long)&frame->uc;
+	if (err == 0) {
+		setup_return(regs, ka, frame, usig);
+		if (ka->sa.sa_flags & SA_SIGINFO) {
+			err |= copy_siginfo_to_user(&frame->info, info);
+			regs->regs[1] = (unsigned long)&frame->info;
+			regs->regs[2] = (unsigned long)&frame->uc;
+		}
 	}
 
 	return err;