[uml-devel] UML: Fix gdbserver "Couldn't write debug register" error

[uml-devel] UML: Fix gdbserver "Couldn't write debug register" error

[Vincent Bernat]

[-- Attachment #1: Type: text/plain, Size: 298 bytes --]

Hi!

Using gdbserver  inside an UML  instance displays "Couldn't  write 
debug
register". I have discovered this  patch from Barry Friedman which 
works
fine for me:
  
http://www.mail-archive.com/user-mode-linux-devel@lists.sourceforge.net/msg06753.html

Here is a rebased version of this patch:


[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #2: uml_ptrace64_fix.patch --]
[-- Type: text/x-diff; name=uml_ptrace64_fix.patch, Size: 924 bytes --]

diff --git a/arch/x86/um/ptrace_64.c b/arch/x86/um/ptrace_64.c
index 3b52bf0..583070c 100644
--- a/arch/x86/um/ptrace_64.c
+++ b/arch/x86/um/ptrace_64.c
@@ -120,7 +120,7 @@ int poke_user(struct task_struct *child, long addr, long data)
 	else if ((addr >= offsetof(struct user, u_debugreg[0])) &&
 		(addr <= offsetof(struct user, u_debugreg[7]))) {
 		addr -= offsetof(struct user, u_debugreg[0]);
-		addr = addr >> 2;
+		addr = addr >> 3;
 		if ((addr == 4) || (addr == 5))
 			return -EIO;
 		child->thread.arch.debugregs[addr] = data;
@@ -187,7 +187,7 @@ int peek_user(struct task_struct *child, long addr, long data)
 	else if ((addr >= offsetof(struct user, u_debugreg[0])) &&
 		(addr <= offsetof(struct user, u_debugreg[7]))) {
 		addr -= offsetof(struct user, u_debugreg[0]);
-		addr = addr >> 2;
+		addr = addr >> 3;
 		tmp = child->thread.arch.debugregs[addr];
 	}
 	return put_user(tmp, (unsigned long *) data);

[-- Attachment #3: Type: text/plain, Size: 395 bytes --]

------------------------------------------------------------------------------
Live Security Virtual Conference
Exclusive live event will cover all the ways today's security and 
threat landscape has changed and how IT managers can respond. Discussions 
will include endpoint security, mobile security and the latest in malware 
threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/

[-- Attachment #4: Type: text/plain, Size: 194 bytes --]

_______________________________________________
User-mode-linux-devel mailing list
User-mode-linux-devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/user-mode-linux-devel