From: kettenis <kettenis@openbsd.org>
Date: Sun, 16 Apr 2023 10:14:59 +0000 (+0000)
Subject: Clear BTYPE bits when setting up a signal handler and when handling a
X-Git-Url: http://artulab.com/gitweb/?a=commitdiff_plain;h=98a8a58a8f51400acf32a042cfa61b62c11317b4;p=openbsd

Clear BTYPE bits when setting up a signal handler and when handling a
PT_CONTINUE ptrace(2) request.  Otherwise we would trap if userland was
interrupted at a point where it is doing an indirect branch that has set
the bits but before it has executed the BTI instruction at the branch
target.

The PT_SETREGS request may need similar treatment, at least when the
PC is changed.  But Linux doesn't do this and debuggers might want full
control over the BTYPE bits.  So leave this alone for now.

ok guenther@
---

diff --git a/sys/arch/arm64/arm64/process_machdep.c b/sys/arch/arm64/arm64/process_machdep.c
index 8703a9178ae..26671a70093 100644
--- a/sys/arch/arm64/arm64/process_machdep.c
+++ b/sys/arch/arm64/arm64/process_machdep.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: process_machdep.c,v 1.6 2022/01/01 18:52:36 kettenis Exp $ */
+/* $OpenBSD: process_machdep.c,v 1.7 2023/04/16 10:14:59 kettenis Exp $ */
 /*
  * Copyright (c) 2014 Patrick Wildt <patrick@blueri.se>
  *
@@ -128,7 +128,10 @@ int
 process_set_pc(struct proc *p, caddr_t addr)
 {
 	struct trapframe *tf = p->p_addr->u_pcb.pcb_tf;
+
 	tf->tf_elr = (uint64_t)addr;
+	tf->tf_spsr &= ~PSR_BTYPE;
+
 	return (0);
 }
 
diff --git a/sys/arch/arm64/arm64/sig_machdep.c b/sys/arch/arm64/arm64/sig_machdep.c
index 69006f72827..e0368ff2635 100644
--- a/sys/arch/arm64/arm64/sig_machdep.c
+++ b/sys/arch/arm64/arm64/sig_machdep.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: sig_machdep.c,v 1.8 2021/10/06 15:46:03 claudio Exp $ */
+/*	$OpenBSD: sig_machdep.c,v 1.9 2023/04/16 10:14:59 kettenis Exp $ */
 
 /*
  * Copyright (c) 1990 The Regents of the University of California.
@@ -157,6 +157,7 @@ sendsig(sig_t catcher, int sig, sigset_t mask, const siginfo_t *ksip,
 	tf->tf_sp = (register_t)fp;
 
 	tf->tf_elr = p->p_p->ps_sigcode;
+	tf->tf_spsr &= ~PSR_BTYPE;
 
 	return 0;
 }
diff --git a/sys/arch/arm64/include/armreg.h b/sys/arch/arm64/include/armreg.h
index bffe8cccacf..7c5be0c6da9 100644
--- a/sys/arch/arm64/include/armreg.h
+++ b/sys/arch/arm64/include/armreg.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: armreg.h,v 1.27 2023/03/27 19:02:48 kettenis Exp $ */
+/* $OpenBSD: armreg.h,v 1.28 2023/04/16 10:14:59 kettenis Exp $ */
 /*-
  * Copyright (c) 2013, 2014 Andrew Turner
  * Copyright (c) 2015 The FreeBSD Foundation
@@ -673,6 +673,7 @@
 #define	PSR_I		0x00000080
 #define	PSR_A		0x00000100
 #define	PSR_D		0x00000200
+#define	PSR_BTYPE	0x00000c00
 #define	PSR_SSBS	0x00001000
 #define	PSR_IL		0x00100000
 #define	PSR_SS		0x00200000