Export a breakpoint() function to userland for arm and arm64.

Enable ptrace() tests using breakpoint() on these architectures.

Reviewed by:	andrew
Differential Revision:	https://reviews.freebsd.org/D15191

3 files changed, 28 insertions, 10 deletions

diff --git a/sys/arm/include/cpufunc.h b/sys/arm/include/cpufunc.h
index 83304e2e545b..1f2e94db70c0 100644
--- a/sys/arm/include/cpufunc.h
+++ b/sys/arm/include/cpufunc.h
@@ -54,7 +54,7 @@
 static __inline void
 breakpoint(void)
 {
-	__asm(".word      0xe7ffffff");
+	__asm("udf        0xffff");
 }
 
 struct cpu_functions {
@@ -495,6 +495,19 @@ extern u_int	arm_cache_level;
 extern u_int	arm_cache_loc;
 extern u_int	arm_cache_type[14];
 
+#else	/* !_KERNEL */
+
+static __inline void
+breakpoint(void)
+{
+
+	/*
+	 * This matches the instruction used by GDB for software
+	 * breakpoints.
+	 */
+	__asm("udf        0xfdee");
+}
+
 #endif	/* _KERNEL */
 #endif	/* _MACHINE_CPUFUNC_H_ */
 
diff --git a/sys/arm64/include/cpufunc.h b/sys/arm64/include/cpufunc.h
index b73e24fc5b88..c3e2a36e04d2 100644
--- a/sys/arm64/include/cpufunc.h
+++ b/sys/arm64/include/cpufunc.h
@@ -29,12 +29,6 @@
 #ifndef _MACHINE_CPUFUNC_H_
 #define	_MACHINE_CPUFUNC_H_
 
-#ifdef _KERNEL
-
-#include <machine/armreg.h>
-
-void pan_enable(void);
-
 static __inline void
 breakpoint(void)
 {
@@ -42,6 +36,12 @@ breakpoint(void)
 	__asm("brk #0");
 }
 
+#ifdef _KERNEL
+
+#include <machine/armreg.h>
+
+void pan_enable(void);
+
 static __inline register_t
 dbg_disable(void)
 {
diff --git a/tests/sys/kern/ptrace_test.c b/tests/sys/kern/ptrace_test.c
index a205f225fcf2..9589bb62922a 100644
--- a/tests/sys/kern/ptrace_test.c
+++ b/tests/sys/kern/ptrace_test.c
@@ -54,8 +54,9 @@ __FBSDID("$FreeBSD$");
 /*
  * Architectures with a user-visible breakpoint().
  */
-#if defined(__amd64__) || defined(__i386__) || defined(__mips__) ||	\
-    defined(__riscv) || defined(__sparc64__)
+#if defined(__aarch64__) || defined(__amd64__) || defined(__arm__) ||	\
+    defined(__i386__) || defined(__mips__) || defined(__riscv) ||	\
+    defined(__sparc64__)
 #define	HAVE_BREAKPOINT
 #endif
 
@@ -63,8 +64,12 @@ __FBSDID("$FreeBSD$");
  * Adjust PC to skip over a breakpoint when stopped for a breakpoint trap.
  */
 #ifdef HAVE_BREAKPOINT
-#if defined(__amd64__) || defined(__i386__)
+#if defined(__aarch64__)
+#define	SKIP_BREAK(reg)	((reg)->elr += 4)
+#elif defined(__amd64__) || defined(__i386__)
 #define	SKIP_BREAK(reg)
+#elif defined(__arm__)
+#define	SKIP_BREAK(reg)	((reg)->r_pc += 4)
 #elif defined(__mips__)
 #define	SKIP_BREAK(reg)	((reg)->r_regs[PC] += 4)
 #elif defined(__riscv)