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linux/arch/powerpc/kernel/kgdb.c
Jason Wessel ba797b2813 powerpc,kgdb: Introduce low level trap catching 
The only way the debugger can handle a trap in inside rcu_lock,
notify_die, or atomic_notifier_call_chain without a recursive fault is
to allow the kernel debugger to handle the exception first in
program_check_exception().

The other change here is to make sure that kgdb_handle_exception() is
called with correct parameters when catching an oops, because kdb
needs to know if the entry was an oops, single step, or breakpoint
exception.

[benh@kernel.crashing.org: move debugger_bpt instead of #ifdef]

CC: Paul Mackerras <paulus@samba.org>
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
2010-05-20 21:04:25 -05:00

411 lines
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/*
* PowerPC backend to the KGDB stub.
*
* 1998 (c) Michael AK Tesch (tesch@cs.wisc.edu)
* Copyright (C) 2003 Timesys Corporation.
* Copyright (C) 2004-2006 MontaVista Software, Inc.
* PPC64 Mods (C) 2005 Frank Rowand (frowand@mvista.com)
* PPC32 support restored by Vitaly Wool <vwool@ru.mvista.com> and
* Sergei Shtylyov <sshtylyov@ru.mvista.com>
* Copyright (C) 2007-2008 Wind River Systems, Inc.
*
* This file is licensed under the terms of the GNU General Public License
* version 2. This program as licensed "as is" without any warranty of any
* kind, whether express or implied.
*/
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/kgdb.h>
#include <linux/smp.h>
#include <linux/signal.h>
#include <linux/ptrace.h>
#include <linux/kdebug.h>
#include <asm/current.h>
#include <asm/processor.h>
#include <asm/machdep.h>
/*
* This table contains the mapping between PowerPC hardware trap types, and
* signals, which are primarily what GDB understands. GDB and the kernel
* don't always agree on values, so we use constants taken from gdb-6.2.
*/
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[] = {
{ 0x0100, 0x02 /* SIGINT */ }, /* system reset */
{ 0x0200, 0x0b /* SIGSEGV */ }, /* machine check */
{ 0x0300, 0x0b /* SIGSEGV */ }, /* data access */
{ 0x0400, 0x0b /* SIGSEGV */ }, /* instruction access */
{ 0x0500, 0x02 /* SIGINT */ }, /* external interrupt */
{ 0x0600, 0x0a /* SIGBUS */ }, /* alignment */
{ 0x0700, 0x05 /* SIGTRAP */ }, /* program check */
{ 0x0800, 0x08 /* SIGFPE */ }, /* fp unavailable */
{ 0x0900, 0x0e /* SIGALRM */ }, /* decrementer */
{ 0x0c00, 0x14 /* SIGCHLD */ }, /* system call */
#if defined(CONFIG_40x) || defined(CONFIG_BOOKE)
{ 0x2002, 0x05 /* SIGTRAP */ }, /* debug */
#if defined(CONFIG_FSL_BOOKE)
{ 0x2010, 0x08 /* SIGFPE */ }, /* spe unavailable */
{ 0x2020, 0x08 /* SIGFPE */ }, /* spe unavailable */
{ 0x2030, 0x08 /* SIGFPE */ }, /* spe fp data */
{ 0x2040, 0x08 /* SIGFPE */ }, /* spe fp data */
{ 0x2050, 0x08 /* SIGFPE */ }, /* spe fp round */
{ 0x2060, 0x0e /* SIGILL */ }, /* performance monitor */
{ 0x2900, 0x08 /* SIGFPE */ }, /* apu unavailable */
{ 0x3100, 0x0e /* SIGALRM */ }, /* fixed interval timer */
{ 0x3200, 0x02 /* SIGINT */ }, /* watchdog */
#else /* ! CONFIG_FSL_BOOKE */
{ 0x1000, 0x0e /* SIGALRM */ }, /* prog interval timer */
{ 0x1010, 0x0e /* SIGALRM */ }, /* fixed interval timer */
{ 0x1020, 0x02 /* SIGINT */ }, /* watchdog */
{ 0x2010, 0x08 /* SIGFPE */ }, /* fp unavailable */
{ 0x2020, 0x08 /* SIGFPE */ }, /* ap unavailable */
#endif
#else /* ! (defined(CONFIG_40x) || defined(CONFIG_BOOKE)) */
{ 0x0d00, 0x05 /* SIGTRAP */ }, /* single-step */
#if defined(CONFIG_8xx)
{ 0x1000, 0x04 /* SIGILL */ }, /* software emulation */
#else /* ! CONFIG_8xx */
{ 0x0f00, 0x04 /* SIGILL */ }, /* performance monitor */
{ 0x0f20, 0x08 /* SIGFPE */ }, /* altivec unavailable */
{ 0x1300, 0x05 /* SIGTRAP */ }, /* instruction address break */
#if defined(CONFIG_PPC64)
{ 0x1200, 0x05 /* SIGILL */ }, /* system error */
{ 0x1500, 0x04 /* SIGILL */ }, /* soft patch */
{ 0x1600, 0x04 /* SIGILL */ }, /* maintenance */
{ 0x1700, 0x08 /* SIGFPE */ }, /* altivec assist */
{ 0x1800, 0x04 /* SIGILL */ }, /* thermal */
#else /* ! CONFIG_PPC64 */
{ 0x1400, 0x02 /* SIGINT */ }, /* SMI */
{ 0x1600, 0x08 /* SIGFPE */ }, /* altivec assist */
{ 0x1700, 0x04 /* SIGILL */ }, /* TAU */
{ 0x2000, 0x05 /* SIGTRAP */ }, /* run mode */
#endif
#endif
#endif
{ 0x0000, 0x00 } /* 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 */
}
static int kgdb_call_nmi_hook(struct pt_regs *regs)
{
kgdb_nmicallback(raw_smp_processor_id(), regs);
return 0;
}
#ifdef CONFIG_SMP
void kgdb_roundup_cpus(unsigned long flags)
{
smp_send_debugger_break(MSG_ALL_BUT_SELF);
}
#endif
/* KGDB functions to use existing PowerPC64 hooks. */
static int kgdb_debugger(struct pt_regs *regs)
{
return !kgdb_handle_exception(1, computeSignal(TRAP(regs)),
DIE_OOPS, regs);
}
static int kgdb_handle_breakpoint(struct pt_regs *regs)
{
if (user_mode(regs))
return 0;
if (kgdb_handle_exception(1, SIGTRAP, 0, regs) != 0)
return 0;
if (*(u32 *) (regs->nip) == *(u32 *) (&arch_kgdb_ops.gdb_bpt_instr))
regs->nip += 4;
return 1;
}
static int kgdb_singlestep(struct pt_regs *regs)
{
struct thread_info *thread_info, *exception_thread_info;
if (user_mode(regs))
return 0;
/*
* On Book E and perhaps other processsors, singlestep is handled on
* the critical exception stack. This causes current_thread_info()
* to fail, since it it locates the thread_info by masking off
* the low bits of the current stack pointer. We work around
* this issue by copying the thread_info from the kernel stack
* before calling kgdb_handle_exception, and copying it back
* afterwards. On most processors the copy is avoided since
* exception_thread_info == thread_info.
*/
thread_info = (struct thread_info *)(regs->gpr[1] & ~(THREAD_SIZE-1));
exception_thread_info = current_thread_info();
if (thread_info != exception_thread_info)
memcpy(exception_thread_info, thread_info, sizeof *thread_info);
kgdb_handle_exception(0, SIGTRAP, 0, regs);
if (thread_info != exception_thread_info)
memcpy(thread_info, exception_thread_info, sizeof *thread_info);
return 1;
}
static int kgdb_iabr_match(struct pt_regs *regs)
{
if (user_mode(regs))
return 0;
if (kgdb_handle_exception(0, computeSignal(TRAP(regs)), 0, regs) != 0)
return 0;
return 1;
}
static int kgdb_dabr_match(struct pt_regs *regs)
{
if (user_mode(regs))
return 0;
if (kgdb_handle_exception(0, computeSignal(TRAP(regs)), 0, regs) != 0)
return 0;
return 1;
}
#define PACK64(ptr, src) do { *(ptr++) = (src); } while (0)
#define PACK32(ptr, src) do { \
u32 *ptr32; \
ptr32 = (u32 *)ptr; \
*(ptr32++) = (src); \
ptr = (unsigned long *)ptr32; \
} while (0)
void pt_regs_to_gdb_regs(unsigned long *gdb_regs, struct pt_regs *regs)
{
unsigned long *ptr = gdb_regs;
int reg;
memset(gdb_regs, 0, NUMREGBYTES);
for (reg = 0; reg < 32; reg++)
PACK64(ptr, regs->gpr[reg]);
#ifdef CONFIG_FSL_BOOKE
#ifdef CONFIG_SPE
for (reg = 0; reg < 32; reg++)
PACK64(ptr, current->thread.evr[reg]);
#else
ptr += 32;
#endif
#else
/* fp registers not used by kernel, leave zero */
ptr += 32 * 8 / sizeof(long);
#endif
PACK64(ptr, regs->nip);
PACK64(ptr, regs->msr);
PACK32(ptr, regs->ccr);
PACK64(ptr, regs->link);
PACK64(ptr, regs->ctr);
PACK32(ptr, regs->xer);
BUG_ON((unsigned long)ptr >
(unsigned long)(((void *)gdb_regs) + NUMREGBYTES));
}
void sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, struct task_struct *p)
{
struct pt_regs *regs = (struct pt_regs *)(p->thread.ksp +
STACK_FRAME_OVERHEAD);
unsigned long *ptr = gdb_regs;
int reg;
memset(gdb_regs, 0, NUMREGBYTES);
/* Regs GPR0-2 */
for (reg = 0; reg < 3; reg++)
PACK64(ptr, regs->gpr[reg]);
/* Regs GPR3-13 are caller saved, not in regs->gpr[] */
ptr += 11;
/* Regs GPR14-31 */
for (reg = 14; reg < 32; reg++)
PACK64(ptr, regs->gpr[reg]);
#ifdef CONFIG_FSL_BOOKE
#ifdef CONFIG_SPE
for (reg = 0; reg < 32; reg++)
PACK64(ptr, p->thread.evr[reg]);
#else
ptr += 32;
#endif
#else
/* fp registers not used by kernel, leave zero */
ptr += 32 * 8 / sizeof(long);
#endif
PACK64(ptr, regs->nip);
PACK64(ptr, regs->msr);
PACK32(ptr, regs->ccr);
PACK64(ptr, regs->link);
PACK64(ptr, regs->ctr);
PACK32(ptr, regs->xer);
BUG_ON((unsigned long)ptr >
(unsigned long)(((void *)gdb_regs) + NUMREGBYTES));
}
#define UNPACK64(dest, ptr) do { dest = *(ptr++); } while (0)
#define UNPACK32(dest, ptr) do { \
u32 *ptr32; \
ptr32 = (u32 *)ptr; \
dest = *(ptr32++); \
ptr = (unsigned long *)ptr32; \
} while (0)
void gdb_regs_to_pt_regs(unsigned long *gdb_regs, struct pt_regs *regs)
{
unsigned long *ptr = gdb_regs;
int reg;
for (reg = 0; reg < 32; reg++)
UNPACK64(regs->gpr[reg], ptr);
#ifdef CONFIG_FSL_BOOKE
#ifdef CONFIG_SPE
for (reg = 0; reg < 32; reg++)
UNPACK64(current->thread.evr[reg], ptr);
#else
ptr += 32;
#endif
#else
/* fp registers not used by kernel, leave zero */
ptr += 32 * 8 / sizeof(int);
#endif
UNPACK64(regs->nip, ptr);
UNPACK64(regs->msr, ptr);
UNPACK32(regs->ccr, ptr);
UNPACK64(regs->link, ptr);
UNPACK64(regs->ctr, ptr);
UNPACK32(regs->xer, ptr);
BUG_ON((unsigned long)ptr >
(unsigned long)(((void *)gdb_regs) + NUMREGBYTES));
}
void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long pc)
{
regs->nip = pc;
}
/*
* This function does PowerPC specific procesing for interfacing to gdb.
*/
int kgdb_arch_handle_exception(int vector, int signo, int err_code,
char *remcom_in_buffer, char *remcom_out_buffer,
struct pt_regs *linux_regs)
{
char *ptr = &remcom_in_buffer[1];
unsigned long addr;
switch (remcom_in_buffer[0]) {
/*
* sAA..AA Step one instruction from AA..AA
* This will return an error to gdb ..
*/
case 's':
case 'c':
/* handle the optional parameter */
if (kgdb_hex2long(&ptr, &addr))
linux_regs->nip = addr;
atomic_set(&kgdb_cpu_doing_single_step, -1);
/* set the trace bit if we're stepping */
if (remcom_in_buffer[0] == 's') {
#ifdef CONFIG_PPC_ADV_DEBUG_REGS
mtspr(SPRN_DBCR0,
mfspr(SPRN_DBCR0) | DBCR0_IC | DBCR0_IDM);
linux_regs->msr |= MSR_DE;
#else
linux_regs->msr |= MSR_SE;
#endif
kgdb_single_step = 1;
atomic_set(&kgdb_cpu_doing_single_step,
raw_smp_processor_id());
}
return 0;
}
return -1;
}
/*
* Global data
*/
struct kgdb_arch arch_kgdb_ops = {
.gdb_bpt_instr = {0x7d, 0x82, 0x10, 0x08},
};
static int kgdb_not_implemented(struct pt_regs *regs)
{
return 0;
}
static void *old__debugger_ipi;
static void *old__debugger;
static void *old__debugger_bpt;
static void *old__debugger_sstep;
static void *old__debugger_iabr_match;
static void *old__debugger_dabr_match;
static void *old__debugger_fault_handler;
int kgdb_arch_init(void)
{
old__debugger_ipi = __debugger_ipi;
old__debugger = __debugger;
old__debugger_bpt = __debugger_bpt;
old__debugger_sstep = __debugger_sstep;
old__debugger_iabr_match = __debugger_iabr_match;
old__debugger_dabr_match = __debugger_dabr_match;
old__debugger_fault_handler = __debugger_fault_handler;
__debugger_ipi = kgdb_call_nmi_hook;
__debugger = kgdb_debugger;
__debugger_bpt = kgdb_handle_breakpoint;
__debugger_sstep = kgdb_singlestep;
__debugger_iabr_match = kgdb_iabr_match;
__debugger_dabr_match = kgdb_dabr_match;
__debugger_fault_handler = kgdb_not_implemented;
return 0;
}
void kgdb_arch_exit(void)
{
__debugger_ipi = old__debugger_ipi;
__debugger = old__debugger;
__debugger_bpt = old__debugger_bpt;
__debugger_sstep = old__debugger_sstep;
__debugger_iabr_match = old__debugger_iabr_match;
__debugger_dabr_match = old__debugger_dabr_match;
__debugger_fault_handler = old__debugger_fault_handler;
}
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