NetBSD Problem Report #52867

From martin@duskware.de  Wed Dec 27 19:29:50 2017
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From: martin@NetBSD.org
Reply-To: martin@NetBSD.org
To: gnats-bugs@NetBSD.org
Subject: arm sofware breakpoint asm is slightly off
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>Number:         52867
>Category:       port-arm
>Synopsis:       arm sofware breakpoint asm is slightly off
>Confidential:   no
>Severity:       critical
>Priority:       high
>Responsible:    port-arm-maintainer
>State:          feedback
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Wed Dec 27 19:30:01 +0000 2017
>Closed-Date:    
>Last-Modified:  Mon Jun 04 11:33:15 +0000 2018
>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:/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

>Release-Note:

>Audit-Trail:
From: "Christos Zoulas" <christos@netbsd.org>
To: gnats-bugs@gnats.NetBSD.org
Cc: 
Subject: PR/52867 CVS commit: src/sys/arch/arm/include
Date: Wed, 27 Dec 2017 14:35:05 -0500

 Module Name:	src
 Committed By:	christos
 Date:		Wed Dec 27 19:35:05 UTC 2017

 Modified Files:
 	src/sys/arch/arm/include: ptrace.h

 Log Message:
 PR/52867: Martin Husemann: arm sofware breakpoint asm is slightly off

 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.


 To generate a diff of this commit:
 cvs rdiff -u -r1.11 -r1.12 src/sys/arch/arm/include/ptrace.h

 Please note that diffs are not public domain; they are subject to the
 copyright notices on the relevant files.

State-Changed-From-To: open->feedback
State-Changed-By: maya@NetBSD.org
State-Changed-When: Mon, 04 Jun 2018 11:33:15 +0000
State-Changed-Why:
Is this good now? (if so, we need pullups)


>Unformatted:

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