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kernel-ark/arch/mips/kernel/kgdb.c
Jason Wessel f0a996eeed mips,kgdb: fix recursive page fault with CONFIG_KPROBES 
This fault was detected using the kgdb test suite on boot and it
crashes recursively due to the fact that CONFIG_KPROBES on mips adds
an extra die notifier in the page fault handler.  The crash signature
looks like this:

kgdbts:RUN bad memory access test
KGDB: re-enter exception: ALL breakpoints killed
Call Trace:
[<807b7548>] dump_stack+0x20/0x54
[<807b7548>] dump_stack+0x20/0x54

The fix for now is to have kgdb return immediately if the fault type
is DIE_PAGE_FAULT and allow the kprobe code to decide what is supposed
to happen.

Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: <stable@vger.kernel.org>
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
2012-10-12 06:37:34 -05:00

394 lines
11 KiB
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Raw Blame History

/*
* 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 */
};
struct dbg_reg_def_t dbg_reg_def[DBG_MAX_REG_NUM] =
{
{ "zero", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[0]) },
{ "at", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[1]) },
{ "v0", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[2]) },
{ "v1", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[3]) },
{ "a0", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[4]) },
{ "a1", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[5]) },
{ "a2", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[6]) },
{ "a3", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[7]) },
{ "t0", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[8]) },
{ "t1", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[9]) },
{ "t2", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[10]) },
{ "t3", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[11]) },
{ "t4", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[12]) },
{ "t5", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[13]) },
{ "t6", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[14]) },
{ "t7", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[15]) },
{ "s0", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[16]) },
{ "s1", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[17]) },
{ "s2", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[18]) },
{ "s3", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[19]) },
{ "s4", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[20]) },
{ "s5", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[21]) },
{ "s6", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[22]) },
{ "s7", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[23]) },
{ "t8", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[24]) },
{ "t9", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[25]) },
{ "k0", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[26]) },
{ "k1", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[27]) },
{ "gp", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[28]) },
{ "sp", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[29]) },
{ "s8", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[30]) },
{ "ra", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[31]) },
{ "sr", GDB_SIZEOF_REG, offsetof(struct pt_regs, cp0_status) },
{ "lo", GDB_SIZEOF_REG, offsetof(struct pt_regs, lo) },
{ "hi", GDB_SIZEOF_REG, offsetof(struct pt_regs, hi) },
{ "bad", GDB_SIZEOF_REG, offsetof(struct pt_regs, cp0_badvaddr) },
{ "cause", GDB_SIZEOF_REG, offsetof(struct pt_regs, cp0_cause) },
{ "pc", GDB_SIZEOF_REG, offsetof(struct pt_regs, cp0_epc) },
{ "f0", GDB_SIZEOF_REG, 0 },
{ "f1", GDB_SIZEOF_REG, 1 },
{ "f2", GDB_SIZEOF_REG, 2 },
{ "f3", GDB_SIZEOF_REG, 3 },
{ "f4", GDB_SIZEOF_REG, 4 },
{ "f5", GDB_SIZEOF_REG, 5 },
{ "f6", GDB_SIZEOF_REG, 6 },
{ "f7", GDB_SIZEOF_REG, 7 },
{ "f8", GDB_SIZEOF_REG, 8 },
{ "f9", GDB_SIZEOF_REG, 9 },
{ "f10", GDB_SIZEOF_REG, 10 },
{ "f11", GDB_SIZEOF_REG, 11 },
{ "f12", GDB_SIZEOF_REG, 12 },
{ "f13", GDB_SIZEOF_REG, 13 },
{ "f14", GDB_SIZEOF_REG, 14 },
{ "f15", GDB_SIZEOF_REG, 15 },
{ "f16", GDB_SIZEOF_REG, 16 },
{ "f17", GDB_SIZEOF_REG, 17 },
{ "f18", GDB_SIZEOF_REG, 18 },
{ "f19", GDB_SIZEOF_REG, 19 },
{ "f20", GDB_SIZEOF_REG, 20 },
{ "f21", GDB_SIZEOF_REG, 21 },
{ "f22", GDB_SIZEOF_REG, 22 },
{ "f23", GDB_SIZEOF_REG, 23 },
{ "f24", GDB_SIZEOF_REG, 24 },
{ "f25", GDB_SIZEOF_REG, 25 },
{ "f26", GDB_SIZEOF_REG, 26 },
{ "f27", GDB_SIZEOF_REG, 27 },
{ "f28", GDB_SIZEOF_REG, 28 },
{ "f29", GDB_SIZEOF_REG, 29 },
{ "f30", GDB_SIZEOF_REG, 30 },
{ "f31", GDB_SIZEOF_REG, 31 },
{ "fsr", GDB_SIZEOF_REG, 0 },
{ "fir", GDB_SIZEOF_REG, 0 },
};
int dbg_set_reg(int regno, void *mem, struct pt_regs *regs)
{
int fp_reg;
if (regno < 0 || regno >= DBG_MAX_REG_NUM)
return -EINVAL;
if (dbg_reg_def[regno].offset != -1 && regno < 38) {
memcpy((void *)regs + dbg_reg_def[regno].offset, mem,
dbg_reg_def[regno].size);
} else if (current && dbg_reg_def[regno].offset != -1 && regno < 72) {
/* FP registers 38 -> 69 */
if (!(regs->cp0_status & ST0_CU1))
return 0;
if (regno == 70) {
/* Process the fcr31/fsr (register 70) */
memcpy((void *)&current->thread.fpu.fcr31, mem,
dbg_reg_def[regno].size);
goto out_save;
} else if (regno == 71) {
/* Ignore the fir (register 71) */
goto out_save;
}
fp_reg = dbg_reg_def[regno].offset;
memcpy((void *)&current->thread.fpu.fpr[fp_reg], mem,
dbg_reg_def[regno].size);
out_save:
restore_fp(current);
}
return 0;
}
char *dbg_get_reg(int regno, void *mem, struct pt_regs *regs)
{
int fp_reg;
if (regno >= DBG_MAX_REG_NUM || regno < 0)
return NULL;
if (dbg_reg_def[regno].offset != -1 && regno < 38) {
/* First 38 registers */
memcpy(mem, (void *)regs + dbg_reg_def[regno].offset,
dbg_reg_def[regno].size);
} else if (current && dbg_reg_def[regno].offset != -1 && regno < 72) {
/* FP registers 38 -> 69 */
if (!(regs->cp0_status & ST0_CU1))
goto out;
save_fp(current);
if (regno == 70) {
/* Process the fcr31/fsr (register 70) */
memcpy(mem, (void *)&current->thread.fpu.fcr31,
dbg_reg_def[regno].size);
goto out;
} else if (regno == 71) {
/* Ignore the fir (register 71) */
memset(mem, 0, dbg_reg_def[regno].size);
goto out;
}
fp_reg = dbg_reg_def[regno].offset;
memcpy(mem, (void *)&current->thread.fpu.fpr[fp_reg],
dbg_reg_def[regno].size);
}
out:
return dbg_reg_def[regno].name;
}
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 */
}
/*
* 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;
#ifdef CONFIG_KPROBES
/*
* Return immediately if the kprobes fault notifier has set
* DIE_PAGE_FAULT.
*/
if (cmd == DIE_PAGE_FAULT)
return NOTIFY_DONE;
#endif /* CONFIG_KPROBES */
/* Userspace 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), cmd, 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;
}
#ifdef CONFIG_KGDB_LOW_LEVEL_TRAP
int kgdb_ll_trap(int cmd, const char *str,
struct pt_regs *regs, long err, int trap, int sig)
{
struct die_args args = {
.regs = regs,
.str = str,
.err = err,
.trapnr = trap,
.signr = sig,
};
if (!kgdb_io_module_registered)
return NOTIFY_DONE;
return kgdb_mips_notify(NULL, cmd, &args);
}
#endif /* CONFIG_KGDB_LOW_LEVEL_TRAP */
static struct notifier_block kgdb_notifier = {
.notifier_call = kgdb_mips_notify,
};
/*
* Handle the 'c' command
*/
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;
switch (remcom_in_buffer[0]) {
case 'c':
/* handle the optional parameter */
ptr = &remcom_in_buffer[1];
if (kgdb_hex2long(&ptr, &address))
regs->cp0_epc = address;
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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