port-arm/52867: arm sofware breakpoint asm is slightly off

[martin%NetBSD.org@localhost]

>Number:         52867
>Category:       port-arm
>Synopsis:       arm sofware breakpoint asm is slightly off
>Confidential:   no
>Severity:       critical
>Priority:       high
>Responsible:    port-arm-maintainer
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Wed Dec 27 19:30:01 +0000 2017
>Originator:     Martin Husemann
>Release:        NetBSD 8.99.9
>Organization:
The NetBSD Foundation, Inc.
>Environment:
System: NetBSD space-truckin.duskware.de 8.99.9 NetBSD 8.99.9 (SUNXI) #10: Tue Dec 26 13:50:30 CET 2017 martin%night-owl.duskware.de@localhost:/usr/src/sys/arch/evbarm/compile/SUNXI evbarm
Architecture: earmv7hfeb
Machine: evbarm
>Description:

ARM uses an undefined instruction to emulate a software breakpoint.
However, the ptrace.h instruction on the one hand, and gdb/the kernel
disagree on the exact value.

This causes PTRACE_BREAKPOINT_ASM to generate a SIGILL instead of a SIGTRAP.

>How-To-Repeat:
code inspection

>Fix:
Index: ptrace.h
===================================================================
RCS file: /cvsroot/src/sys/arch/arm/include/ptrace.h,v
retrieving revision 1.11
diff -u -r1.11 ptrace.h
--- ptrace.h	12 Apr 2017 18:17:59 -0000	1.11
+++ ptrace.h	27 Dec 2017 19:26:21 -0000
@@ -64,7 +64,12 @@
 #define PTRACE_REG_SP(_r)		(_r)->r_sp
 #define PTRACE_REG_INTRV(_r)		(_r)->r[0]
 
-#define PTRACE_BREAKPOINT	((const uint8_t[]) { 0xe7, 0xff, 0xff, 0xfe })
-#define PTRACE_BREAKPOINT_INSN	0xe7fffffe
+#ifdef __ARMEB__
+#define PTRACE_BREAKPOINT	((const uint8_t[]) { 0xfe, 0xde, 0xff, 0xe7 })
+#define PTRACE_BREAKPOINT_INSN	0xfedeffe7
+#else
+#define PTRACE_BREAKPOINT	((const uint8_t[]) { 0xe7, 0xff, 0xde, 0xfe })
+#define PTRACE_BREAKPOINT_INSN	0xe7ffdefe
+#endif
 #define PTRACE_BREAKPOINT_ASM	__asm __volatile (".word " ___STRING(PTRACE_BREAKPOINT_INSN) )
 #define PTRACE_BREAKPOINT_SIZE	4