Re: PPC KGDB changes and some help?

From: Tom Rini (trini_at_kernel.crashing.org)
Date: 01/23/04

  • Next message: Rafał 'rmrmg' Roszak: "Re: Linux 2.4.25-pre7" 
    Date:	Fri, 23 Jan 2004 15:46:05 -0700
To: "Amit S. Kale" <amitkale@emsyssoft.com>

    On Thu, Jan 22, 2004 at 11:05:55AM -0700, Tom Rini wrote:
    [snip]
    > First up:
    > We need to call flush_instruction_cache() on a 'c' or 's' command.
    > arch/ppc/kernel/ppc-stub.c | 19 ++++++-------------
    > 1 files changed, 6 insertions(+), 13 deletions(-)

    On tpo of this patch, there's the following:
    Put back some code to figure out what signal we're dealing with.

     arch/ppc/kernel/ppc-stub.c | 63 ++++++++++++++++++++++++++++++++++++++++++---
     1 files changed, 60 insertions(+), 3 deletions(-)
    --- 1.15/arch/ppc/kernel/ppc-stub.c Thu Jan 22 10:53:06 2004
    +++ edited/arch/ppc/kernel/ppc-stub.c Fri Jan 23 15:43:10 2004
    @@ -3,6 +3,7 @@
      *
      * PowerPC-specific bits to work with the common KGDB stub.
      *
    + * 1998 (c) Michael AK Tesch (tesch@cs.wisc.edu)
      * 2003 (c) TimeSys Corporation
      * 2004 (c) MontaVista Software, Inc.
      * This file is licensed under the terms of the GNU General Public License
    @@ -19,13 +20,69 @@
     #include <asm/processor.h>
     #include <asm/machdep.h>
     
    +/* Convert the hardware trap type code to a unix signal number. */
    +/*
    + * This table contains the mapping between PowerPC hardware trap types, and
    + * signals, which are primarily what GDB understands.
    + */
    +static struct hard_trap_info
    +{
    + unsigned int tt; /* Trap type code for powerpc */
    + unsigned char signo; /* Signal that we map this trap into */
    +} hard_trap_info[] = {
    +#if defined(CONFIG_40x)
    + { 0x100, SIGINT }, /* critical input interrupt */
    + { 0x200, SIGSEGV }, /* machine check */
    + { 0x300, SIGSEGV }, /* data storage */
    + { 0x400, SIGBUS }, /* instruction storage */
    + { 0x500, SIGINT }, /* interrupt */
    + { 0x600, SIGBUS }, /* alignment */
    + { 0x700, SIGILL }, /* program */
    + { 0x800, SIGILL }, /* reserved */
    + { 0x900, SIGILL }, /* reserved */
    + { 0xa00, SIGILL }, /* reserved */
    + { 0xb00, SIGILL }, /* reserved */
    + { 0xc00, SIGCHLD }, /* syscall */
    + { 0xd00, SIGILL }, /* reserved */
    + { 0xe00, SIGILL }, /* reserved */
    + { 0xf00, SIGILL }, /* reserved */
    + { 0x2000, SIGTRAP}, /* debug */
    +#else
    + { 0x200, SIGSEGV }, /* machine check */
    + { 0x300, SIGSEGV }, /* address error (store) */
    + { 0x400, SIGBUS }, /* instruction bus error */
    + { 0x500, SIGINT }, /* interrupt */
    + { 0x600, SIGBUS }, /* alingment */
    + { 0x700, SIGTRAP }, /* breakpoint trap */
    + { 0x800, SIGFPE }, /* fpu unavail */
    + { 0x900, SIGALRM }, /* decrementer */
    + { 0xa00, SIGILL }, /* reserved */
    + { 0xb00, SIGILL }, /* reserved */
    + { 0xc00, SIGCHLD }, /* syscall */
    + { 0xd00, SIGTRAP }, /* single-step/watch */
    + { 0xe00, SIGFPE }, /* fp assist */
    +#endif
    + { 0, 0} /* Must be last */
    +};
    +
    +static int computeSignal(unsigned int tt)
    +{
    + struct hard_trap_info *ht;
    +
    + for (ht = hard_trap_info; ht->tt && ht->signo; ht++)
    + if (ht->tt == tt)
    + return ht->signo;
    +
    + return SIGHUP; /* default for things we don't know about */
    +}
    +
     /*
      * Routines
      */
     static void
     kgdb_debugger(struct pt_regs *regs)
     {
    - (*linux_debug_hook) (0, 0, 0, regs);
    + (*linux_debug_hook) (0, computeSignal(regs->trap), 0, regs);
             return;
     }
     
    @@ -52,14 +109,14 @@
     int
     kgdb_iabr_match(struct pt_regs *regs)
     {
    - (*linux_debug_hook) (0, 0, 0, regs);
    + (*linux_debug_hook) (0, computeSignal(regs->trap), 0, regs);
             return 1;
     }
     
     int
     kgdb_dabr_match(struct pt_regs *regs)
     {
    - (*linux_debug_hook) (0, 0, 0, regs);
    + (*linux_debug_hook) (0, computeSignal(regs->trap), 0, regs);
             return 1;
     }
     

    Now, not being as well versed in all of the debugging infos that can be
    passed around, it sounds like this patch could be dropped in the future
    for a cleaner method using some of the dwarf2 bits being talked about.
    But I don't know, and clarification and pointers (if so) to how to do
    this would be appreciated. 

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