Re: PPC KGDB changes and some help?

From: Amit S. Kale
Date: Tue Jan 27 2004 - 04:01:27 EST

On Tuesday 27 Jan 2004 3:02 am, Tom Rini wrote:
> 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.

Good.

> - Remove a KERN_CRIT from the printk while waiting for kgdb to connect
> (it's not needed there).

It's needed for kgdb over ethernet. At present the ethernet comes up really
late. At that point syslogd has taken over printing of kernel messages,
KERN_CRIT ensures that a user sees that message regardless of the syslogd
configuratio.

> - Switch the initial packet from an 'S' packet (followed by a p for the
> thread ID) to a 'T' packet.

That's also good.

>
> 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/
>
> ** Sent via the linuxppc-dev mail list. See http://lists.linuxppc.org/

--
Amit Kale
EmSysSoft (http://www.emsyssoft.com)
KGDB: Linux Kernel Source Level Debugger (http://kgdb.sourceforge.net)

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