Linux-2.6.33.2/arch/x86/kernel/kgdb.c
/*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation; either version 2, or (at your option) any
* later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
*/
/*
* Copyright (C) 2004 Amit S. Kale <amitkale@linsyssoft.com>
* Copyright (C) 2000-2001 VERITAS Software Corporation.
* Copyright (C) 2002 Andi Kleen, SuSE Labs
* Copyright (C) 2004 LinSysSoft Technologies Pvt. Ltd.
* Copyright (C) 2007 MontaVista Software, Inc.
* Copyright (C) 2007-2008 Jason Wessel, Wind River Systems, Inc.
*/
/****************************************************************************
* Contributor: Lake Stevens Instrument Division$
* Written by: Glenn Engel $
* Updated by: Amit Kale<akale@veritas.com>
* Updated by: Tom Rini <trini@kernel.crashing.org>
* Updated by: Jason Wessel <jason.wessel@windriver.com>
* Modified for 386 by Jim Kingdon, Cygnus Support.
* Origianl kgdb, compatibility with 2.1.xx kernel by
* David Grothe <dave@gcom.com>
* Integrated into 2.2.5 kernel by Tigran Aivazian <tigran@sco.com>
* X86_64 changes from Andi Kleen's patch merged by Jim Houston
*/
#include <linux/spinlock.h>
#include <linux/kdebug.h>
#include <linux/string.h>
#include <linux/kernel.h>
#include <linux/ptrace.h>
#include <linux/sched.h>
#include <linux/delay.h>
#include <linux/kgdb.h>
#include <linux/init.h>
#include <linux/smp.h>
#include <linux/nmi.h>
#include <linux/hw_breakpoint.h>
#include <asm/debugreg.h>
#include <asm/apicdef.h>
#include <asm/system.h>
#include <asm/apic.h>
/*
* Put the error code here just in case the user cares:
*/
static int gdb_x86errcode;
/*
* Likewise, the vector number here (since GDB only gets the signal
* number through the usual means, and that's not very specific):
*/
static int gdb_x86vector = -1;
/**
* pt_regs_to_gdb_regs - Convert ptrace regs to GDB regs
* @gdb_regs: A pointer to hold the registers in the order GDB wants.
* @regs: The &struct pt_regs of the current process.
*
* Convert the pt_regs in @regs into the format for registers that
* GDB expects, stored in @gdb_regs.
*/
void pt_regs_to_gdb_regs(unsigned long *gdb_regs, struct pt_regs *regs)
{
#ifndef CONFIG_X86_32
u32 *gdb_regs32 = (u32 *)gdb_regs;
#endif
gdb_regs[GDB_AX] = regs->ax;
gdb_regs[GDB_BX] = regs->bx;
gdb_regs[GDB_CX] = regs->cx;
gdb_regs[GDB_DX] = regs->dx;
gdb_regs[GDB_SI] = regs->si;
gdb_regs[GDB_DI] = regs->di;
gdb_regs[GDB_BP] = regs->bp;
gdb_regs[GDB_PC] = regs->ip;
#ifdef CONFIG_X86_32
gdb_regs[GDB_PS] = regs->flags;
gdb_regs[GDB_DS] = regs->ds;
gdb_regs[GDB_ES] = regs->es;
gdb_regs[GDB_CS] = regs->cs;
gdb_regs[GDB_FS] = 0xFFFF;
gdb_regs[GDB_GS] = 0xFFFF;
if (user_mode_vm(regs)) {
gdb_regs[GDB_SS] = regs->ss;
gdb_regs[GDB_SP] = regs->sp;
} else {
gdb_regs[GDB_SS] = __KERNEL_DS;
gdb_regs[GDB_SP] = kernel_stack_pointer(regs);
}
#else
gdb_regs[GDB_R8] = regs->r8;
gdb_regs[GDB_R9] = regs->r9;
gdb_regs[GDB_R10] = regs->r10;
gdb_regs[GDB_R11] = regs->r11;
gdb_regs[GDB_R12] = regs->r12;
gdb_regs[GDB_R13] = regs->r13;
gdb_regs[GDB_R14] = regs->r14;
gdb_regs[GDB_R15] = regs->r15;
gdb_regs32[GDB_PS] = regs->flags;
gdb_regs32[GDB_CS] = regs->cs;
gdb_regs32[GDB_SS] = regs->ss;
gdb_regs[GDB_SP] = kernel_stack_pointer(regs);
#endif
}
/**
* sleeping_thread_to_gdb_regs - Convert ptrace regs to GDB regs
* @gdb_regs: A pointer to hold the registers in the order GDB wants.
* @p: The &struct task_struct of the desired process.
*
* Convert the register values of the sleeping process in @p to
* the format that GDB expects.
* This function is called when kgdb does not have access to the
* &struct pt_regs and therefore it should fill the gdb registers
* @gdb_regs with what has been saved in &struct thread_struct
* thread field during switch_to.
*/
void sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, struct task_struct *p)
{
#ifndef CONFIG_X86_32
u32 *gdb_regs32 = (u32 *)gdb_regs;
#endif
gdb_regs[GDB_AX] = 0;
gdb_regs[GDB_BX] = 0;
gdb_regs[GDB_CX] = 0;
gdb_regs[GDB_DX] = 0;
gdb_regs[GDB_SI] = 0;
gdb_regs[GDB_DI] = 0;
gdb_regs[GDB_BP] = *(unsigned long *)p->thread.sp;
#ifdef CONFIG_X86_32
gdb_regs[GDB_DS] = __KERNEL_DS;
gdb_regs[GDB_ES] = __KERNEL_DS;
gdb_regs[GDB_PS] = 0;
gdb_regs[GDB_CS] = __KERNEL_CS;
gdb_regs[GDB_PC] = p->thread.ip;
gdb_regs[GDB_SS] = __KERNEL_DS;
gdb_regs[GDB_FS] = 0xFFFF;
gdb_regs[GDB_GS] = 0xFFFF;
#else
gdb_regs32[GDB_PS] = *(unsigned long *)(p->thread.sp + 8);
gdb_regs32[GDB_CS] = __KERNEL_CS;
gdb_regs32[GDB_SS] = __KERNEL_DS;
gdb_regs[GDB_PC] = 0;
gdb_regs[GDB_R8] = 0;
gdb_regs[GDB_R9] = 0;
gdb_regs[GDB_R10] = 0;
gdb_regs[GDB_R11] = 0;
gdb_regs[GDB_R12] = 0;
gdb_regs[GDB_R13] = 0;
gdb_regs[GDB_R14] = 0;
gdb_regs[GDB_R15] = 0;
#endif
gdb_regs[GDB_SP] = p->thread.sp;
}
/**
* gdb_regs_to_pt_regs - Convert GDB regs to ptrace regs.
* @gdb_regs: A pointer to hold the registers we've received from GDB.
* @regs: A pointer to a &struct pt_regs to hold these values in.
*
* Convert the GDB regs in @gdb_regs into the pt_regs, and store them
* in @regs.
*/
void gdb_regs_to_pt_regs(unsigned long *gdb_regs, struct pt_regs *regs)
{
#ifndef CONFIG_X86_32
u32 *gdb_regs32 = (u32 *)gdb_regs;
#endif
regs->ax = gdb_regs[GDB_AX];
regs->bx = gdb_regs[GDB_BX];
regs->cx = gdb_regs[GDB_CX];
regs->dx = gdb_regs[GDB_DX];
regs->si = gdb_regs[GDB_SI];
regs->di = gdb_regs[GDB_DI];
regs->bp = gdb_regs[GDB_BP];
regs->ip = gdb_regs[GDB_PC];
#ifdef CONFIG_X86_32
regs->flags = gdb_regs[GDB_PS];
regs->ds = gdb_regs[GDB_DS];
regs->es = gdb_regs[GDB_ES];
regs->cs = gdb_regs[GDB_CS];
#else
regs->r8 = gdb_regs[GDB_R8];
regs->r9 = gdb_regs[GDB_R9];
regs->r10 = gdb_regs[GDB_R10];
regs->r11 = gdb_regs[GDB_R11];
regs->r12 = gdb_regs[GDB_R12];
regs->r13 = gdb_regs[GDB_R13];
regs->r14 = gdb_regs[GDB_R14];
regs->r15 = gdb_regs[GDB_R15];
regs->flags = gdb_regs32[GDB_PS];
regs->cs = gdb_regs32[GDB_CS];
regs->ss = gdb_regs32[GDB_SS];
#endif
}
static struct hw_breakpoint {
unsigned enabled;
unsigned long addr;
int len;
int type;
struct perf_event **pev;
} breakinfo[4];
static void kgdb_correct_hw_break(void)
{
int breakno;
for (breakno = 0; breakno < 4; breakno++) {
struct perf_event *bp;
struct arch_hw_breakpoint *info;
int val;
int cpu = raw_smp_processor_id();
if (!breakinfo[breakno].enabled)
continue;
bp = *per_cpu_ptr(breakinfo[breakno].pev, cpu);
info = counter_arch_bp(bp);
if (bp->attr.disabled != 1)
continue;
bp->attr.bp_addr = breakinfo[breakno].addr;
bp->attr.bp_len = breakinfo[breakno].len;
bp->attr.bp_type = breakinfo[breakno].type;
info->address = breakinfo[breakno].addr;
info->len = breakinfo[breakno].len;
info->type = breakinfo[breakno].type;
val = arch_install_hw_breakpoint(bp);
if (!val)
bp->attr.disabled = 0;
}
hw_breakpoint_restore();
}
static int hw_break_reserve_slot(int breakno)
{
int cpu;
int cnt = 0;
struct perf_event **pevent;
for_each_online_cpu(cpu) {
cnt++;
pevent = per_cpu_ptr(breakinfo[breakno].pev, cpu);
if (dbg_reserve_bp_slot(*pevent))
goto fail;
}
return 0;
fail:
for_each_online_cpu(cpu) {
cnt--;
if (!cnt)
break;
pevent = per_cpu_ptr(breakinfo[breakno].pev, cpu);
dbg_release_bp_slot(*pevent);
}
return -1;
}
static int hw_break_release_slot(int breakno)
{
struct perf_event **pevent;
int cpu;
for_each_online_cpu(cpu) {
pevent = per_cpu_ptr(breakinfo[breakno].pev, cpu);
if (dbg_release_bp_slot(*pevent))
/*
* The debugger is responisble for handing the retry on
* remove failure.
*/
return -1;
}
return 0;
}
static int
kgdb_remove_hw_break(unsigned long addr, int len, enum kgdb_bptype bptype)
{
int i;
for (i = 0; i < 4; i++)
if (breakinfo[i].addr == addr && breakinfo[i].enabled)
break;
if (i == 4)
return -1;
if (hw_break_release_slot(i)) {
printk(KERN_ERR "Cannot remove hw breakpoint at %lx\n", addr);
return -1;
}
breakinfo[i].enabled = 0;
return 0;
}
static void kgdb_remove_all_hw_break(void)
{
int i;
int cpu = raw_smp_processor_id();
struct perf_event *bp;
for (i = 0; i < 4; i++) {
if (!breakinfo[i].enabled)
continue;
bp = *per_cpu_ptr(breakinfo[i].pev, cpu);
if (bp->attr.disabled == 1)
continue;
arch_uninstall_hw_breakpoint(bp);
bp->attr.disabled = 1;
}
}
static int
kgdb_set_hw_break(unsigned long addr, int len, enum kgdb_bptype bptype)
{
int i;
for (i = 0; i < 4; i++)
if (!breakinfo[i].enabled)
break;
if (i == 4)
return -1;
switch (bptype) {
case BP_HARDWARE_BREAKPOINT:
len = 1;
breakinfo[i].type = X86_BREAKPOINT_EXECUTE;
break;
case BP_WRITE_WATCHPOINT:
breakinfo[i].type = X86_BREAKPOINT_WRITE;
break;
case BP_ACCESS_WATCHPOINT:
breakinfo[i].type = X86_BREAKPOINT_RW;
break;
default:
return -1;
}
switch (len) {
case 1:
breakinfo[i].len = X86_BREAKPOINT_LEN_1;
break;
case 2:
breakinfo[i].len = X86_BREAKPOINT_LEN_2;
break;
case 4:
breakinfo[i].len = X86_BREAKPOINT_LEN_4;
break;
#ifdef CONFIG_X86_64
case 8:
breakinfo[i].len = X86_BREAKPOINT_LEN_8;
break;
#endif
default:
return -1;
}
breakinfo[i].addr = addr;
if (hw_break_reserve_slot(i)) {
breakinfo[i].addr = 0;
return -1;
}
breakinfo[i].enabled = 1;
return 0;
}
/**
* kgdb_disable_hw_debug - Disable hardware debugging while we in kgdb.
* @regs: Current &struct pt_regs.
*
* This function will be called if the particular architecture must
* disable hardware debugging while it is processing gdb packets or
* handling exception.
*/
void kgdb_disable_hw_debug(struct pt_regs *regs)
{
int i;
int cpu = raw_smp_processor_id();
struct perf_event *bp;
/* Disable hardware debugging while we are in kgdb: */
set_debugreg(0UL, 7);
for (i = 0; i < 4; i++) {
if (!breakinfo[i].enabled)
continue;
bp = *per_cpu_ptr(breakinfo[i].pev, cpu);
if (bp->attr.disabled == 1)
continue;
arch_uninstall_hw_breakpoint(bp);
bp->attr.disabled = 1;
}
}
/**
* kgdb_post_primary_code - Save error vector/code numbers.
* @regs: Original pt_regs.
* @e_vector: Original error vector.
* @err_code: Original error code.
*
* This is needed on architectures which support SMP and KGDB.
* This function is called after all the slave cpus have been put
* to a know spin state and the primary CPU has control over KGDB.
*/
void kgdb_post_primary_code(struct pt_regs *regs, int e_vector, int err_code)
{
/* primary processor is completely in the debugger */
gdb_x86vector = e_vector;
gdb_x86errcode = err_code;
}
#ifdef CONFIG_SMP
/**
* kgdb_roundup_cpus - Get other CPUs into a holding pattern
* @flags: Current IRQ state
*
* On SMP systems, we need to get the attention of the other CPUs
* and get them be in a known state. This should do what is needed
* to get the other CPUs to call kgdb_wait(). Note that on some arches,
* the NMI approach is not used for rounding up all the CPUs. For example,
* in case of MIPS, smp_call_function() is used to roundup CPUs. In
* this case, we have to make sure that interrupts are enabled before
* calling smp_call_function(). The argument to this function is
* the flags that will be used when restoring the interrupts. There is
* local_irq_save() call before kgdb_roundup_cpus().
*
* On non-SMP systems, this is not called.
*/
void kgdb_roundup_cpus(unsigned long flags)
{
apic->send_IPI_allbutself(APIC_DM_NMI);
}
#endif
/**
* kgdb_arch_handle_exception - Handle architecture specific GDB packets.
* @vector: The error vector of the exception that happened.
* @signo: The signal number of the exception that happened.
* @err_code: The error code of the exception that happened.
* @remcom_in_buffer: The buffer of the packet we have read.
* @remcom_out_buffer: The buffer of %BUFMAX bytes to write a packet into.
* @regs: The &struct pt_regs of the current process.
*
* This function MUST handle the 'c' and 's' command packets,
* as well packets to set / remove a hardware breakpoint, if used.
* If there are additional packets which the hardware needs to handle,
* they are handled here. The code should return -1 if it wants to
* process more packets, and a %0 or %1 if it wants to exit from the
* kgdb callback.
*/
int kgdb_arch_handle_exception(int e_vector, int signo, int err_code,
char *remcomInBuffer, char *remcomOutBuffer,
struct pt_regs *linux_regs)
{
unsigned long addr;
char *ptr;
int newPC;
switch (remcomInBuffer[0]) {
case 'c':
case 's':
/* try to read optional parameter, pc unchanged if no parm */
ptr = &remcomInBuffer[1];
if (kgdb_hex2long(&ptr, &addr))
linux_regs->ip = addr;
case 'D':
case 'k':
newPC = linux_regs->ip;
/* clear the trace bit */
linux_regs->flags &= ~X86_EFLAGS_TF;
atomic_set(&kgdb_cpu_doing_single_step, -1);
/* set the trace bit if we're stepping */
if (remcomInBuffer[0] == 's') {
linux_regs->flags |= X86_EFLAGS_TF;
atomic_set(&kgdb_cpu_doing_single_step,
raw_smp_processor_id());
}
kgdb_correct_hw_break();
return 0;
}
/* this means that we do not want to exit from the handler: */
return -1;
}
static inline int
single_step_cont(struct pt_regs *regs, struct die_args *args)
{
/*
* Single step exception from kernel space to user space so
* eat the exception and continue the process:
*/
printk(KERN_ERR "KGDB: trap/step from kernel to user space, "
"resuming...\n");
kgdb_arch_handle_exception(args->trapnr, args->signr,
args->err, "c", "", regs);
/*
* Reset the BS bit in dr6 (pointed by args->err) to
* denote completion of processing
*/
(*(unsigned long *)ERR_PTR(args->err)) &= ~DR_STEP;
return NOTIFY_STOP;
}
static int was_in_debug_nmi[NR_CPUS];
static int __kgdb_notify(struct die_args *args, unsigned long cmd)
{
struct pt_regs *regs = args->regs;
switch (cmd) {
case DIE_NMI:
if (atomic_read(&kgdb_active) != -1) {
/* KGDB CPU roundup */
kgdb_nmicallback(raw_smp_processor_id(), regs);
was_in_debug_nmi[raw_smp_processor_id()] = 1;
touch_nmi_watchdog();
return NOTIFY_STOP;
}
return NOTIFY_DONE;
case DIE_NMI_IPI:
/* Just ignore, we will handle the roundup on DIE_NMI. */
return NOTIFY_DONE;
case DIE_NMIUNKNOWN:
if (was_in_debug_nmi[raw_smp_processor_id()]) {
was_in_debug_nmi[raw_smp_processor_id()] = 0;
return NOTIFY_STOP;
}
return NOTIFY_DONE;
case DIE_NMIWATCHDOG:
if (atomic_read(&kgdb_active) != -1) {
/* KGDB CPU roundup: */
kgdb_nmicallback(raw_smp_processor_id(), regs);
return NOTIFY_STOP;
}
/* Enter debugger: */
break;
case DIE_DEBUG:
if (atomic_read(&kgdb_cpu_doing_single_step) != -1) {
if (user_mode(regs))
return single_step_cont(regs, args);
break;
} else if (test_thread_flag(TIF_SINGLESTEP))
/* This means a user thread is single stepping
* a system call which should be ignored
*/
return NOTIFY_DONE;
/* fall through */
default:
if (user_mode(regs))
return NOTIFY_DONE;
}
if (kgdb_handle_exception(args->trapnr, args->signr, args->err, regs))
return NOTIFY_DONE;
/* Must touch watchdog before return to normal operation */
touch_nmi_watchdog();
return NOTIFY_STOP;
}
static int
kgdb_notify(struct notifier_block *self, unsigned long cmd, void *ptr)
{
unsigned long flags;
int ret;
local_irq_save(flags);
ret = __kgdb_notify(ptr, cmd);
local_irq_restore(flags);
return ret;
}
static struct notifier_block kgdb_notifier = {
.notifier_call = kgdb_notify,
/*
* Lowest-prio notifier priority, we want to be notified last:
*/
.priority = -INT_MAX,
};
/**
* kgdb_arch_init - Perform any architecture specific initalization.
*
* This function will handle the initalization of any architecture
* specific callbacks.
*/
int kgdb_arch_init(void)
{
int i, cpu;
int ret;
struct perf_event_attr attr;
struct perf_event **pevent;
ret = register_die_notifier(&kgdb_notifier);
if (ret != 0)
return ret;
/*
* Pre-allocate the hw breakpoint structions in the non-atomic
* portion of kgdb because this operation requires mutexs to
* complete.
*/
attr.bp_addr = (unsigned long)kgdb_arch_init;
attr.type = PERF_TYPE_BREAKPOINT;
attr.bp_len = HW_BREAKPOINT_LEN_1;
attr.bp_type = HW_BREAKPOINT_W;
attr.disabled = 1;
for (i = 0; i < 4; i++) {
breakinfo[i].pev = register_wide_hw_breakpoint(&attr, NULL);
if (IS_ERR(breakinfo[i].pev)) {
printk(KERN_ERR "kgdb: Could not allocate hw breakpoints\n");
breakinfo[i].pev = NULL;
kgdb_arch_exit();
return -1;
}
for_each_online_cpu(cpu) {
pevent = per_cpu_ptr(breakinfo[i].pev, cpu);
pevent[0]->hw.sample_period = 1;
if (pevent[0]->destroy != NULL) {
pevent[0]->destroy = NULL;
release_bp_slot(*pevent);
}
}
}
return ret;
}
/**
* 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)
{
int i;
for (i = 0; i < 4; i++) {
if (breakinfo[i].pev) {
unregister_wide_hw_breakpoint(breakinfo[i].pev);
breakinfo[i].pev = NULL;
}
}
unregister_die_notifier(&kgdb_notifier);
}
/**
*
* kgdb_skipexception - Bail out of KGDB when we've been triggered.
* @exception: Exception vector number
* @regs: Current &struct pt_regs.
*
* On some architectures we need to skip a breakpoint exception when
* it occurs after a breakpoint has been removed.
*
* Skip an int3 exception when it occurs after a breakpoint has been
* removed. Backtrack eip by 1 since the int3 would have caused it to
* increment by 1.
*/
int kgdb_skipexception(int exception, struct pt_regs *regs)
{
if (exception == 3 && kgdb_isremovedbreak(regs->ip - 1)) {
regs->ip -= 1;
return 1;
}
return 0;
}
unsigned long kgdb_arch_pc(int exception, struct pt_regs *regs)
{
if (exception == 3)
return instruction_pointer(regs) - 1;
return instruction_pointer(regs);
}
struct kgdb_arch arch_kgdb_ops = {
/* Breakpoint instruction: */
.gdb_bpt_instr = { 0xcc },
.flags = KGDB_HW_BREAKPOINT,
.set_hw_breakpoint = kgdb_set_hw_break,
.remove_hw_breakpoint = kgdb_remove_hw_break,
.remove_all_hw_break = kgdb_remove_all_hw_break,
.correct_hw_break = kgdb_correct_hw_break,
};