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x86: kgdb support

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simplified and streamlined kgdb support on x86, both 32-bit and 64-bit,
based on patch from:

  Subject: kgdb: core-lite
  From: Jason Wessel <jason.wessel@windriver.com>

[ and countless other authors - see the patch for details. ]

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
Signed-off-by: Jan Kiszka <jan.kiszka@web.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Ingo Molnar 2008-04-17 20:05:37 +02:00
parent f2d937f3bf
commit 82da3ff89d
4 changed files with 500 additions and 0 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

1
arch/x86/Kconfig
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@ -23,6 +23,7 @@ config X86
select HAVE_KPROBES
select HAVE_KRETPROBES
select HAVE_KVM if ((X86_32 && !X86_VOYAGER && !X86_VISWS && !X86_NUMAQ) || X86_64)
select HAVE_ARCH_KGDB
config GENERIC_LOCKBREAK

1
arch/x86/kernel/Makefile
View file

@ -66,6 +66,7 @@ obj-$(CONFIG_MODULES) += module_$(BITS).o
obj-$(CONFIG_ACPI_SRAT) += srat_32.o
obj-$(CONFIG_EFI) += efi.o efi_$(BITS).o efi_stub_$(BITS).o
obj-$(CONFIG_DOUBLEFAULT) += doublefault_32.o
obj-$(CONFIG_KGDB) += kgdb.o
obj-$(CONFIG_VM86) += vm86_32.o
obj-$(CONFIG_EARLY_PRINTK) += early_printk.o

417
arch/x86/kernel/kgdb.c Normal file
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@ -0,0 +1,417 @@
/*
* 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 <asm/apicdef.h>
#include <asm/system.h>
#ifdef CONFIG_X86_32
# include <mach_ipi.h>
#else
# include <asm/mach_apic.h>
#endif
/*
* 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)
{
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_PS] = regs->flags;
gdb_regs[GDB_PC] = regs->ip;
#ifdef CONFIG_X86_32
gdb_regs[GDB_DS] = regs->ds;
gdb_regs[GDB_ES] = regs->es;
gdb_regs[GDB_CS] = regs->cs;
gdb_regs[GDB_SS] = __KERNEL_DS;
gdb_regs[GDB_FS] = 0xFFFF;
gdb_regs[GDB_GS] = 0xFFFF;
#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;
#endif
gdb_regs[GDB_SP] = regs->sp;
}
/**
* 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)
{
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_regs[GDB_PS] = *(unsigned long *)(p->thread.sp + 8);
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)
{
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->flags = gdb_regs[GDB_PS];
regs->ip = gdb_regs[GDB_PC];
#ifdef CONFIG_X86_32
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];
#endif
}
/**
* 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)
{
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;
newPC = linux_regs->ip;
/* clear the trace bit */
linux_regs->flags &= ~TF_MASK;
atomic_set(&kgdb_cpu_doing_single_step, -1);
/* set the trace bit if we're stepping */
if (remcomInBuffer[0] == 's') {
linux_regs->flags |= TF_MASK;
kgdb_single_step = 1;
if (kgdb_contthread) {
atomic_set(&kgdb_cpu_doing_single_step,
raw_smp_processor_id());
}
}
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);
return NOTIFY_STOP;
}
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);
return NOTIFY_STOP;
}
return NOTIFY_DONE;
case DIE_NMI_IPI:
if (atomic_read(&kgdb_active) != -1) {
/* KGDB CPU roundup: */
if (kgdb_nmicallback(raw_smp_processor_id(), regs))
return NOTIFY_DONE;
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) ==
raw_smp_processor_id() &&
user_mode(regs))
return single_step_cont(regs, args);
/* fall through */
default:
if (user_mode(regs))
return NOTIFY_DONE;
}
if (kgdb_handle_exception(args->trapnr, args->signr, args->err, regs))
return NOTIFY_DONE;
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)
{
return register_die_notifier(&kgdb_notifier);
}
/**
* 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);
}
/**
*
* 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 },
};

81
include/asm-x86/kgdb.h Normal file
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@ -0,0 +1,81 @@
#ifndef _ASM_KGDB_H_
#define _ASM_KGDB_H_
/*
* Copyright (C) 2001-2004 Amit S. Kale
* Copyright (C) 2008 Wind River Systems, Inc.
*/
/*
* BUFMAX defines the maximum number of characters in inbound/outbound
* buffers at least NUMREGBYTES*2 are needed for register packets
* Longer buffer is needed to list all threads
*/
#define BUFMAX 1024
/*
* Note that this register image is in a different order than
* the register image that Linux produces at interrupt time.
*
* Linux's register image is defined by struct pt_regs in ptrace.h.
* Just why GDB uses a different order is a historical mystery.
*/
#ifdef CONFIG_X86_32
enum regnames {
GDB_AX, /* 0 */
GDB_CX, /* 1 */
GDB_DX, /* 2 */
GDB_BX, /* 3 */
GDB_SP, /* 4 */
GDB_BP, /* 5 */
GDB_SI, /* 6 */
GDB_DI, /* 7 */
GDB_PC, /* 8 also known as eip */
GDB_PS, /* 9 also known as eflags */
GDB_CS, /* 10 */
GDB_SS, /* 11 */
GDB_DS, /* 12 */
GDB_ES, /* 13 */
GDB_FS, /* 14 */
GDB_GS, /* 15 */
};
#else /* ! CONFIG_X86_32 */
enum regnames {
GDB_AX, /* 0 */
GDB_DX, /* 1 */
GDB_CX, /* 2 */
GDB_BX, /* 3 */
GDB_SI, /* 4 */
GDB_DI, /* 5 */
GDB_BP, /* 6 */
GDB_SP, /* 7 */
GDB_R8, /* 8 */
GDB_R9, /* 9 */
GDB_R10, /* 10 */
GDB_R11, /* 11 */
GDB_R12, /* 12 */
GDB_R13, /* 13 */
GDB_R14, /* 14 */
GDB_R15, /* 15 */
GDB_PC, /* 16 */
GDB_PS, /* 17 */
};
#endif /* CONFIG_X86_32 */
/*
* Number of bytes of registers:
*/
#ifdef CONFIG_X86_32
# define NUMREGBYTES 64
#else
# define NUMREGBYTES ((GDB_PS+1)*8)
#endif
static inline void arch_kgdb_breakpoint(void)
{
asm(" int $3");
}
#define BREAK_INSTR_SIZE 1
#define CACHE_FLUSH_IS_SAFE 1
#endif /* _ASM_KGDB_H_ */