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kernel-fxtec-pro1x/arch/mips/kernel/kgdb.c
Jason Wessel dcc7871128 kgdb: core changes to support kdb 
These are the minimum changes to the kgdb core in order to enable an
API to connect a new front end (kdb) to the debug core.

This patch introduces the dbg_kdb_mode variable controls where the
user level I/O is routed.  It will be routed to the gdbstub (kgdb) or
to the kdb front end which is a simple shell available over the kgdboc
connection.

You can switch back and forth between kdb or the gdb stub mode of
operation dynamically.  From gdb stub mode you can blindly type
"$3#33", or from the kdb mode you can enter "kgdb" to switch to the
gdb stub.

The logic in the debug core depends on kdb to look for the typical gdb
connection sequences and return immediately with KGDB_PASS_EVENT if a
gdb serial command sequence is detected.  That should allow a
reasonably seamless transition between kdb -> gdb without leaving the
kernel exception state.  The two gdb serial queries that kdb is
responsible for detecting are the "?" and "qSupported" packets.

CC: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
Acked-by: Martin Hicks <mort@sgi.com>
2010-05-20 21:04:21 -05:00

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/*
* Originally written by Glenn Engel, Lake Stevens Instrument Division
*
* Contributed by HP Systems
*
* Modified for Linux/MIPS (and MIPS in general) by Andreas Busse
* Send complaints, suggestions etc. to <andy@waldorf-gmbh.de>
*
* Copyright (C) 1995 Andreas Busse
*
* Copyright (C) 2003 MontaVista Software Inc.
* Author: Jun Sun, jsun@mvista.com or jsun@junsun.net
*
* Copyright (C) 2004-2005 MontaVista Software Inc.
* Author: Manish Lachwani, mlachwani@mvista.com or manish@koffee-break.com
*
* Copyright (C) 2007-2008 Wind River Systems, Inc.
* Author/Maintainer: Jason Wessel, jason.wessel@windriver.com
*
* This file is licensed under the terms of the GNU General Public License
* version 2. This program is licensed "as is" without any warranty of any
* kind, whether express or implied.
*/
#include <linux/ptrace.h> /* for linux pt_regs struct */
#include <linux/kgdb.h>
#include <linux/kdebug.h>
#include <linux/sched.h>
#include <linux/smp.h>
#include <asm/inst.h>
#include <asm/fpu.h>
#include <asm/cacheflush.h>
#include <asm/processor.h>
#include <asm/sigcontext.h>
static struct hard_trap_info {
unsigned char tt; /* Trap type code for MIPS R3xxx and R4xxx */
unsigned char signo; /* Signal that we map this trap into */
} hard_trap_info[] = {
{ 6, SIGBUS }, /* instruction bus error */
{ 7, SIGBUS }, /* data bus error */
{ 9, SIGTRAP }, /* break */
/* { 11, SIGILL }, */ /* CPU unusable */
{ 12, SIGFPE }, /* overflow */
{ 13, SIGTRAP }, /* trap */
{ 14, SIGSEGV }, /* virtual instruction cache coherency */
{ 15, SIGFPE }, /* floating point exception */
{ 23, SIGSEGV }, /* watch */
{ 31, SIGSEGV }, /* virtual data cache coherency */
{ 0, 0} /* Must be last */
};
void arch_kgdb_breakpoint(void)
{
__asm__ __volatile__(
".globl breakinst\n\t"
".set\tnoreorder\n\t"
"nop\n"
"breakinst:\tbreak\n\t"
"nop\n\t"
".set\treorder");
}
static void kgdb_call_nmi_hook(void *ignored)
{
kgdb_nmicallback(raw_smp_processor_id(), NULL);
}
void kgdb_roundup_cpus(unsigned long flags)
{
local_irq_enable();
smp_call_function(kgdb_call_nmi_hook, NULL, 0);
local_irq_disable();
}
static int compute_signal(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 */
}
void pt_regs_to_gdb_regs(unsigned long *gdb_regs, struct pt_regs *regs)
{
int reg;
#if (KGDB_GDB_REG_SIZE == 32)
u32 *ptr = (u32 *)gdb_regs;
#else
u64 *ptr = (u64 *)gdb_regs;
#endif
for (reg = 0; reg < 32; reg++)
*(ptr++) = regs->regs[reg];
*(ptr++) = regs->cp0_status;
*(ptr++) = regs->lo;
*(ptr++) = regs->hi;
*(ptr++) = regs->cp0_badvaddr;
*(ptr++) = regs->cp0_cause;
*(ptr++) = regs->cp0_epc;
/* FP REGS */
if (!(current && (regs->cp0_status & ST0_CU1)))
return;
save_fp(current);
for (reg = 0; reg < 32; reg++)
*(ptr++) = current->thread.fpu.fpr[reg];
}
void gdb_regs_to_pt_regs(unsigned long *gdb_regs, struct pt_regs *regs)
{
int reg;
#if (KGDB_GDB_REG_SIZE == 32)
const u32 *ptr = (u32 *)gdb_regs;
#else
const u64 *ptr = (u64 *)gdb_regs;
#endif
for (reg = 0; reg < 32; reg++)
regs->regs[reg] = *(ptr++);
regs->cp0_status = *(ptr++);
regs->lo = *(ptr++);
regs->hi = *(ptr++);
regs->cp0_badvaddr = *(ptr++);
regs->cp0_cause = *(ptr++);
regs->cp0_epc = *(ptr++);
/* FP REGS from current */
if (!(current && (regs->cp0_status & ST0_CU1)))
return;
for (reg = 0; reg < 32; reg++)
current->thread.fpu.fpr[reg] = *(ptr++);
restore_fp(current);
}
/*
* Similar to regs_to_gdb_regs() except that process is sleeping and so
* we may not be able to get all the info.
*/
void sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, struct task_struct *p)
{
int reg;
struct thread_info *ti = task_thread_info(p);
unsigned long ksp = (unsigned long)ti + THREAD_SIZE - 32;
struct pt_regs *regs = (struct pt_regs *)ksp - 1;
#if (KGDB_GDB_REG_SIZE == 32)
u32 *ptr = (u32 *)gdb_regs;
#else
u64 *ptr = (u64 *)gdb_regs;
#endif
for (reg = 0; reg < 16; reg++)
*(ptr++) = regs->regs[reg];
/* S0 - S7 */
for (reg = 16; reg < 24; reg++)
*(ptr++) = regs->regs[reg];
for (reg = 24; reg < 28; reg++)
*(ptr++) = 0;
/* GP, SP, FP, RA */
for (reg = 28; reg < 32; reg++)
*(ptr++) = regs->regs[reg];
*(ptr++) = regs->cp0_status;
*(ptr++) = regs->lo;
*(ptr++) = regs->hi;
*(ptr++) = regs->cp0_badvaddr;
*(ptr++) = regs->cp0_cause;
*(ptr++) = regs->cp0_epc;
}
void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long pc)
{
regs->cp0_epc = pc;
}
/*
* Calls linux_debug_hook before the kernel dies. If KGDB is enabled,
* then try to fall into the debugger
*/
static int kgdb_mips_notify(struct notifier_block *self, unsigned long cmd,
void *ptr)
{
struct die_args *args = (struct die_args *)ptr;
struct pt_regs *regs = args->regs;
int trap = (regs->cp0_cause & 0x7c) >> 2;
/* Userpace events, ignore. */
if (user_mode(regs))
return NOTIFY_DONE;
if (atomic_read(&kgdb_active) != -1)
kgdb_nmicallback(smp_processor_id(), regs);
if (kgdb_handle_exception(trap, compute_signal(trap), 0, regs))
return NOTIFY_DONE;
if (atomic_read(&kgdb_setting_breakpoint))
if ((trap == 9) && (regs->cp0_epc == (unsigned long)breakinst))
regs->cp0_epc += 4;
/* In SMP mode, __flush_cache_all does IPI */
local_irq_enable();
__flush_cache_all();
return NOTIFY_STOP;
}
static struct notifier_block kgdb_notifier = {
.notifier_call = kgdb_mips_notify,
};
/*
* Handle the 's' and 'c' commands
*/
int kgdb_arch_handle_exception(int vector, int signo, int err_code,
char *remcom_in_buffer, char *remcom_out_buffer,
struct pt_regs *regs)
{
char *ptr;
unsigned long address;
int cpu = smp_processor_id();
switch (remcom_in_buffer[0]) {
case 's':
case 'c':
/* handle the optional parameter */
ptr = &remcom_in_buffer[1];
if (kgdb_hex2long(&ptr, &address))
regs->cp0_epc = address;
atomic_set(&kgdb_cpu_doing_single_step, -1);
if (remcom_in_buffer[0] == 's')
atomic_set(&kgdb_cpu_doing_single_step, cpu);
return 0;
}
return -1;
}
struct kgdb_arch arch_kgdb_ops;
/*
* We use kgdb_early_setup so that functions we need to call now don't
* cause trouble when called again later.
*/
int kgdb_arch_init(void)
{
union mips_instruction insn = {
.r_format = {
.opcode = spec_op,
.func = break_op,
}
};
memcpy(arch_kgdb_ops.gdb_bpt_instr, insn.byte, BREAK_INSTR_SIZE);
register_die_notifier(&kgdb_notifier);
return 0;
}
/*
* kgdb_arch_exit - Perform any architecture specific uninitalization.
*
* This function will handle the uninitalization of any architecture
* specific callbacks, for dynamic registration and unregistration.
*/
void kgdb_arch_exit(void)
{
unregister_die_notifier(&kgdb_notifier);
}
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