Re: PPC KGDB changes and some help?

From: Tom Rini
Date: Mon Jan 26 2004 - 16:35:59 EST

On Wed, Jan 21, 2004 at 12:21:28PM -0700, Tom Rini wrote:

> On Wed, Jan 21, 2004 at 11:42:17AM -0700, Tom Rini wrote:
> > On Wed, Jan 21, 2004 at 10:23:12PM +0530, Amit S. Kale wrote:
> >
> > > Hi,
> > >
> > > Here it is: ppc kgdb from timesys kernel is available at
> > > http://kgdb.sourceforge.net/kgdb-2/linux-2.6.1-kgdb-2.1.0.tar.bz2
> > >
> > > This is my attempt at extracting kgdb from TimeSys kernel. It works well in
> > > TimeSys kernel, so blame me if above patch doesn't work.
> >
> > Okay, here's my first patch against this.
>
> And dependant upon this is a patch to fixup the rest of the common PPC
> code, as follows:

Relative to this, due to the PPC changes is the following:

- In kgdb_handle_exception, memset remcomOutBuffer twice, instead of
continiously throwing in NULLs around.
- Remove a KERN_CRIT from the printk while waiting for kgdb to connect
(it's not needed there).
- Switch the initial packet from an 'S' packet (followed by a p for the
thread ID) to a 'T' packet.

This is tested on PPC and i386 (lightly).

include/asm-i386/kgdb.h | 4 ++
include/asm-ppc/kgdb.h | 3 +
include/asm-x86_64/kgdb.h | 4 ++
kernel/kgdbstub.c | 70 ++++++++++++++++++++++------------------------
4 files changed, 45 insertions(+), 36 deletions(-)

--- 1.1/include/asm-i386/kgdb.h Wed Jan 21 10:13:15 2004
+++ edited/include/asm-i386/kgdb.h Mon Jan 26 12:15:22 2004
@@ -43,6 +43,10 @@
_GS /* 15 */
};

+#define PC_REGNUM _PC /* Program Counter */
+#define SP_REGNUM _ESP /* Stack Pointer */
+#define PTRACE_PC eip /* Program Counter, in ptrace regs. */
+
#define BREAKPOINT() asm(" int $3");
#define BREAK_INSTR_SIZE 1

--- 1.5/include/asm-ppc/kgdb.h Wed Jan 21 12:21:23 2004
+++ edited/include/asm-ppc/kgdb.h Mon Jan 26 12:16:39 2004
@@ -19,6 +19,9 @@
#define NUMREGBYTES (MAXREG * sizeof(int))
#define BUFMAX ((NUMREGBYTES * 2) + 512)
#define OUTBUFMAX ((NUMREGBYTES * 2) + 512)
+#define PC_REGNUM 64
+#define SP_REGNUM 1
+#define PTRACE_PC nip /* Program Counter, in ptrace regs. */
#define BREAKPOINT() asm(".long 0x7d821008") /* twge r2, r2 */

/* Things specific to the gen550 backend. */
--- 1.1/include/asm-x86_64/kgdb.h Wed Jan 21 10:13:16 2004
+++ edited/include/asm-x86_64/kgdb.h Mon Jan 26 12:16:15 2004
@@ -44,6 +44,10 @@
_PS,
_LASTREG=_PS };

+#define PC_REGNUM _PC /* Program Counter */
+#define SP_REGNUM _RSP /* Stack Pointer */
+#define PTRACE_PC rip /* Program Counter, in ptrace regs. */
+
/* Number of bytes of registers. */
#define NUMREGBYTES (_LASTREG*8)

--- 1.2/kernel/kgdbstub.c Wed Jan 21 12:21:23 2004
+++ edited/kernel/kgdbstub.c Mon Jan 26 12:17:02 2004
@@ -615,6 +615,9 @@
* need one here */
procindebug[smp_processor_id()] = 1;

+ /* Clear the out buffer. */
+ memset(remcomOutBuffer, 0, sizeof(remcomOutBuffer));
+
/* Master processor is completely in the debugger */
if (kgdb_ops->post_master_code)
kgdb_ops->post_master_code(linux_regs, exVector, err_code);
@@ -624,9 +627,7 @@
if(remcomInBuffer[0] == 'H' && remcomInBuffer[1] =='c') {
remove_all_break();
atomic_set(&kgdb_killed_or_detached, 0);
- remcomOutBuffer[0] = 'O';
- remcomOutBuffer[1] = 'K';
- remcomOutBuffer[2] = 0;
+ strcpy(remcomOutBuffer, "OK");
}
else
return 1;
@@ -634,13 +635,25 @@
else {

/* reply to host that an exception has occurred */
- remcomOutBuffer[0] = 'S';
- remcomOutBuffer[1] = hexchars[signo >> 4];
- remcomOutBuffer[2] = hexchars[signo % 16];
- remcomOutBuffer[3] = 'p';
-
+ ptr = remcomOutBuffer;
+ *ptr++ = 'T';
+ *ptr++ = hexchars[(signo >> 4) % 16];
+ *ptr++ = hexchars[signo % 16];
+ *ptr++ = hexchars[(PC_REGNUM >> 4) % 16];
+ *ptr++ = hexchars[PC_REGNUM % 16];
+ *ptr++ = ':';
+ ptr = kgdb_mem2hex((char *)&linux_regs->PTRACE_PC, ptr, 4, 0);
+ *ptr++ = ';';
+ *ptr++ = hexchars[SP_REGNUM >> 4];
+ *ptr++ = hexchars[SP_REGNUM & 0xf];
+ *ptr++ = ':';
+ ptr = kgdb_mem2hex(((char *)linux_regs) + SP_REGNUM * 4, ptr,
+ 4, 0);
+ *ptr++ = ';';
+ ptr += strlen(strcpy(ptr, "thread:"));
int_to_threadref(&thref, shadow_pid(current->pid));
- *pack_threadid(remcomOutBuffer + 4, &thref) = 0;
+ ptr = pack_threadid(ptr, &thref);
+ *ptr++ = ';';
}
putpacket(remcomOutBuffer, 0);
kgdb_connected = 1;
@@ -651,8 +664,10 @@
while (1) {
int bpt_type = 0;
error = 0;
- remcomOutBuffer[0] = 0;
- remcomOutBuffer[1] = 0;
+
+ /* Clear the out buffer. */
+ memset(remcomOutBuffer, 0, sizeof(remcomOutBuffer));
+
getpacket(remcomInBuffer);

#if KGDB_DEBUG
@@ -666,7 +681,6 @@
remcomOutBuffer[0] = 'S';
remcomOutBuffer[1] = hexchars[signo >> 4];
remcomOutBuffer[2] = hexchars[signo % 16];
- remcomOutBuffer[3] = 0;
break;

case 'g': /* return the value of the CPU registers */
@@ -764,9 +778,7 @@
* continue.
*/
case 'D':
- remcomOutBuffer[0] = 'O';
- remcomOutBuffer[1] = 'K';
- remcomOutBuffer[2] = '\0';
+ strcpy(remcomOutBuffer, "OK");
remove_all_break();
putpacket(remcomOutBuffer, 0);
kgdb_connected = 0;
@@ -804,19 +816,16 @@
i++;
}
}
- *(--ptr) = '\0';
break;

case 'C':
/* Current thread id */
- remcomOutBuffer[0] = 'Q';
- remcomOutBuffer[1] = 'C';
+ strcpy(remcomOutBuffer, "QC");

threadid = shadow_pid(current->pid);

int_to_threadref(&thref, threadid);
pack_threadid(remcomOutBuffer + 2, &thref);
- remcomOutBuffer[18] = '\0';
break;

case 'E':
@@ -829,7 +838,6 @@
case 'T':
if (memcmp(remcomInBuffer+1, "ThreadExtraInfo,",16))
{
- remcomOutBuffer[0] = 0;
strcpy(remcomOutBuffer, "E05");
break;
}
@@ -872,14 +880,11 @@
thread = getthread(linux_regs, threadid);
if (!thread && threadid > 0) {
remcomOutBuffer[0] = 'E';
- remcomOutBuffer[1] = '\0';
break;
}
kgdb_usethread = thread;
kgdb_usethreadid = threadid;
- remcomOutBuffer[0] = 'O';
- remcomOutBuffer[1] = 'K';
- remcomOutBuffer[2] = '\0';
+ strcpy(remcomOutBuffer, "OK");
break;

case 'c':
@@ -892,14 +897,11 @@
thread = getthread(linux_regs, threadid);
if (!thread && threadid > 0) {
remcomOutBuffer[0] = 'E';
- remcomOutBuffer[1] = '\0';
break;
}
kgdb_contthread = thread;
}
- remcomOutBuffer[0] = 'O';
- remcomOutBuffer[1] = 'K';
- remcomOutBuffer[2] = '\0';
+ strcpy(remcomOutBuffer, "OK");
break;
}
break;
@@ -909,14 +911,10 @@
ptr = &remcomInBuffer[1];
kgdb_hexToLong(&ptr, &threadid);
thread = getthread(linux_regs, threadid);
- if (thread) {
- remcomOutBuffer[0] = 'O';
- remcomOutBuffer[1] = 'K';
- remcomOutBuffer[2] = '\0';
- } else {
+ if (thread)
+ strcpy(remcomOutBuffer, "OK");
+ else
remcomOutBuffer[0] = 'E';
- remcomOutBuffer[1] = '\0';
- }
break;
case 'z':
case 'Z':
@@ -1127,7 +1125,7 @@
*/
printk(KERN_CRIT "Waiting for connection from remote gdb... ");
breakpoint() ;
- printk(KERN_CRIT "Connected.\n");
+ printk("Connected.\n");
}

#ifdef CONFIG_KGDB_CONSOLE

--
Tom Rini
http://gate.crashing.org/~trini/
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