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1224 lines
28 KiB
1224 lines
28 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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/* |
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* Kernel Debug Core |
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* |
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* Maintainer: Jason Wessel <[email protected]> |
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* |
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* Copyright (C) 2000-2001 VERITAS Software Corporation. |
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* Copyright (C) 2002-2004 Timesys Corporation |
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* Copyright (C) 2003-2004 Amit S. Kale <[email protected]> |
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* Copyright (C) 2004 Pavel Machek <[email protected]> |
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* Copyright (C) 2004-2006 Tom Rini <[email protected]> |
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* Copyright (C) 2004-2006 LinSysSoft Technologies Pvt. Ltd. |
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* Copyright (C) 2005-2009 Wind River Systems, Inc. |
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* Copyright (C) 2007 MontaVista Software, Inc. |
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* Copyright (C) 2008 Red Hat, Inc., Ingo Molnar <[email protected]> |
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* |
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* Contributors at various stages not listed above: |
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* Jason Wessel ( [email protected] ) |
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* George Anzinger <[email protected]> |
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* Anurekh Saxena ([email protected]) |
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* Lake Stevens Instrument Division (Glenn Engel) |
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* Jim Kingdon, Cygnus Support. |
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* |
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* Original KGDB stub: David Grothe <[email protected]>, |
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* Tigran Aivazian <[email protected]> |
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*/ |
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|
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#define pr_fmt(fmt) "KGDB: " fmt |
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|
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#include <linux/pid_namespace.h> |
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#include <linux/clocksource.h> |
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#include <linux/serial_core.h> |
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#include <linux/interrupt.h> |
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#include <linux/spinlock.h> |
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#include <linux/console.h> |
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#include <linux/threads.h> |
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#include <linux/uaccess.h> |
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#include <linux/kernel.h> |
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#include <linux/module.h> |
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#include <linux/ptrace.h> |
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#include <linux/string.h> |
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#include <linux/delay.h> |
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#include <linux/sched.h> |
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#include <linux/sysrq.h> |
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#include <linux/reboot.h> |
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#include <linux/init.h> |
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#include <linux/kgdb.h> |
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#include <linux/kdb.h> |
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#include <linux/nmi.h> |
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#include <linux/pid.h> |
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#include <linux/smp.h> |
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#include <linux/mm.h> |
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#include <linux/vmacache.h> |
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#include <linux/rcupdate.h> |
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#include <linux/irq.h> |
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|
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#include <asm/cacheflush.h> |
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#include <asm/byteorder.h> |
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#include <linux/atomic.h> |
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|
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#include "debug_core.h" |
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|
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static int kgdb_break_asap; |
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struct debuggerinfo_struct kgdb_info[NR_CPUS]; |
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|
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/* kgdb_connected - Is a host GDB connected to us? */ |
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int kgdb_connected; |
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EXPORT_SYMBOL_GPL(kgdb_connected); |
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|
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/* All the KGDB handlers are installed */ |
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int kgdb_io_module_registered; |
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|
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/* Guard for recursive entry */ |
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static int exception_level; |
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struct kgdb_io *dbg_io_ops; |
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static DEFINE_SPINLOCK(kgdb_registration_lock); |
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|
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/* Action for the reboot notifier, a global allow kdb to change it */ |
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static int kgdbreboot; |
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/* kgdb console driver is loaded */ |
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static int kgdb_con_registered; |
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/* determine if kgdb console output should be used */ |
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static int kgdb_use_con; |
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/* Flag for alternate operations for early debugging */ |
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bool dbg_is_early = true; |
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/* Next cpu to become the master debug core */ |
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int dbg_switch_cpu; |
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|
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/* Use kdb or gdbserver mode */ |
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int dbg_kdb_mode = 1; |
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module_param(kgdb_use_con, int, 0644); |
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module_param(kgdbreboot, int, 0644); |
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/* |
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* Holds information about breakpoints in a kernel. These breakpoints are |
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* added and removed by gdb. |
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*/ |
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static struct kgdb_bkpt kgdb_break[KGDB_MAX_BREAKPOINTS] = { |
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[0 ... KGDB_MAX_BREAKPOINTS-1] = { .state = BP_UNDEFINED } |
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}; |
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|
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/* |
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* The CPU# of the active CPU, or -1 if none: |
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*/ |
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atomic_t kgdb_active = ATOMIC_INIT(-1); |
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EXPORT_SYMBOL_GPL(kgdb_active); |
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static DEFINE_RAW_SPINLOCK(dbg_master_lock); |
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static DEFINE_RAW_SPINLOCK(dbg_slave_lock); |
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|
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/* |
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* We use NR_CPUs not PERCPU, in case kgdb is used to debug early |
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* bootup code (which might not have percpu set up yet): |
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*/ |
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static atomic_t masters_in_kgdb; |
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static atomic_t slaves_in_kgdb; |
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atomic_t kgdb_setting_breakpoint; |
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|
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struct task_struct *kgdb_usethread; |
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struct task_struct *kgdb_contthread; |
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|
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int kgdb_single_step; |
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static pid_t kgdb_sstep_pid; |
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|
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/* to keep track of the CPU which is doing the single stepping*/ |
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atomic_t kgdb_cpu_doing_single_step = ATOMIC_INIT(-1); |
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|
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/* |
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* If you are debugging a problem where roundup (the collection of |
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* all other CPUs) is a problem [this should be extremely rare], |
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* then use the nokgdbroundup option to avoid roundup. In that case |
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* the other CPUs might interfere with your debugging context, so |
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* use this with care: |
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*/ |
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static int kgdb_do_roundup = 1; |
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|
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static int __init opt_nokgdbroundup(char *str) |
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{ |
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kgdb_do_roundup = 0; |
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return 0; |
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} |
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early_param("nokgdbroundup", opt_nokgdbroundup); |
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|
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/* |
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* Finally, some KGDB code :-) |
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*/ |
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|
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/* |
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* Weak aliases for breakpoint management, |
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* can be overridden by architectures when needed: |
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*/ |
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int __weak kgdb_arch_set_breakpoint(struct kgdb_bkpt *bpt) |
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{ |
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int err; |
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err = copy_from_kernel_nofault(bpt->saved_instr, (char *)bpt->bpt_addr, |
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BREAK_INSTR_SIZE); |
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if (err) |
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return err; |
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err = copy_to_kernel_nofault((char *)bpt->bpt_addr, |
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arch_kgdb_ops.gdb_bpt_instr, BREAK_INSTR_SIZE); |
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return err; |
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} |
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NOKPROBE_SYMBOL(kgdb_arch_set_breakpoint); |
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int __weak kgdb_arch_remove_breakpoint(struct kgdb_bkpt *bpt) |
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{ |
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return copy_to_kernel_nofault((char *)bpt->bpt_addr, |
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(char *)bpt->saved_instr, BREAK_INSTR_SIZE); |
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} |
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NOKPROBE_SYMBOL(kgdb_arch_remove_breakpoint); |
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int __weak kgdb_validate_break_address(unsigned long addr) |
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{ |
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struct kgdb_bkpt tmp; |
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int err; |
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if (kgdb_within_blocklist(addr)) |
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return -EINVAL; |
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|
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/* Validate setting the breakpoint and then removing it. If the |
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* remove fails, the kernel needs to emit a bad message because we |
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* are deep trouble not being able to put things back the way we |
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* found them. |
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*/ |
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tmp.bpt_addr = addr; |
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err = kgdb_arch_set_breakpoint(&tmp); |
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if (err) |
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return err; |
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err = kgdb_arch_remove_breakpoint(&tmp); |
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if (err) |
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pr_err("Critical breakpoint error, kernel memory destroyed at: %lx\n", |
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addr); |
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return err; |
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} |
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unsigned long __weak kgdb_arch_pc(int exception, struct pt_regs *regs) |
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{ |
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return instruction_pointer(regs); |
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} |
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NOKPROBE_SYMBOL(kgdb_arch_pc); |
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|
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int __weak kgdb_arch_init(void) |
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{ |
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return 0; |
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} |
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int __weak kgdb_skipexception(int exception, struct pt_regs *regs) |
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{ |
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return 0; |
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} |
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NOKPROBE_SYMBOL(kgdb_skipexception); |
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#ifdef CONFIG_SMP |
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/* |
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* Default (weak) implementation for kgdb_roundup_cpus |
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*/ |
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void __weak kgdb_call_nmi_hook(void *ignored) |
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{ |
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/* |
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* NOTE: get_irq_regs() is supposed to get the registers from |
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* before the IPI interrupt happened and so is supposed to |
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* show where the processor was. In some situations it's |
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* possible we might be called without an IPI, so it might be |
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* safer to figure out how to make kgdb_breakpoint() work |
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* properly here. |
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*/ |
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kgdb_nmicallback(raw_smp_processor_id(), get_irq_regs()); |
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} |
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NOKPROBE_SYMBOL(kgdb_call_nmi_hook); |
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static DEFINE_PER_CPU(call_single_data_t, kgdb_roundup_csd) = |
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CSD_INIT(kgdb_call_nmi_hook, NULL); |
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void __weak kgdb_roundup_cpus(void) |
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{ |
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call_single_data_t *csd; |
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int this_cpu = raw_smp_processor_id(); |
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int cpu; |
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int ret; |
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for_each_online_cpu(cpu) { |
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/* No need to roundup ourselves */ |
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if (cpu == this_cpu) |
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continue; |
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csd = &per_cpu(kgdb_roundup_csd, cpu); |
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|
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/* |
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* If it didn't round up last time, don't try again |
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* since smp_call_function_single_async() will block. |
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* |
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* If rounding_up is false then we know that the |
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* previous call must have at least started and that |
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* means smp_call_function_single_async() won't block. |
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*/ |
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if (kgdb_info[cpu].rounding_up) |
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continue; |
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kgdb_info[cpu].rounding_up = true; |
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ret = smp_call_function_single_async(cpu, csd); |
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if (ret) |
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kgdb_info[cpu].rounding_up = false; |
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} |
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} |
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NOKPROBE_SYMBOL(kgdb_roundup_cpus); |
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#endif |
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/* |
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* Some architectures need cache flushes when we set/clear a |
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* breakpoint: |
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*/ |
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static void kgdb_flush_swbreak_addr(unsigned long addr) |
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{ |
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if (!CACHE_FLUSH_IS_SAFE) |
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return; |
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if (current->mm) { |
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int i; |
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for (i = 0; i < VMACACHE_SIZE; i++) { |
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if (!current->vmacache.vmas[i]) |
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continue; |
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flush_cache_range(current->vmacache.vmas[i], |
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addr, addr + BREAK_INSTR_SIZE); |
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} |
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} |
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|
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/* Force flush instruction cache if it was outside the mm */ |
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flush_icache_range(addr, addr + BREAK_INSTR_SIZE); |
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} |
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NOKPROBE_SYMBOL(kgdb_flush_swbreak_addr); |
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/* |
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* SW breakpoint management: |
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*/ |
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int dbg_activate_sw_breakpoints(void) |
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{ |
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int error; |
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int ret = 0; |
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int i; |
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for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { |
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if (kgdb_break[i].state != BP_SET) |
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continue; |
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error = kgdb_arch_set_breakpoint(&kgdb_break[i]); |
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if (error) { |
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ret = error; |
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pr_info("BP install failed: %lx\n", |
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kgdb_break[i].bpt_addr); |
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continue; |
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} |
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kgdb_flush_swbreak_addr(kgdb_break[i].bpt_addr); |
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kgdb_break[i].state = BP_ACTIVE; |
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} |
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return ret; |
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} |
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NOKPROBE_SYMBOL(dbg_activate_sw_breakpoints); |
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int dbg_set_sw_break(unsigned long addr) |
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{ |
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int err = kgdb_validate_break_address(addr); |
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int breakno = -1; |
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int i; |
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if (err) |
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return err; |
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for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { |
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if ((kgdb_break[i].state == BP_SET) && |
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(kgdb_break[i].bpt_addr == addr)) |
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return -EEXIST; |
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} |
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for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { |
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if (kgdb_break[i].state == BP_REMOVED && |
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kgdb_break[i].bpt_addr == addr) { |
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breakno = i; |
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break; |
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} |
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} |
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if (breakno == -1) { |
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for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { |
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if (kgdb_break[i].state == BP_UNDEFINED) { |
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breakno = i; |
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break; |
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} |
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} |
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} |
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if (breakno == -1) |
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return -E2BIG; |
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kgdb_break[breakno].state = BP_SET; |
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kgdb_break[breakno].type = BP_BREAKPOINT; |
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kgdb_break[breakno].bpt_addr = addr; |
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return 0; |
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} |
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int dbg_deactivate_sw_breakpoints(void) |
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{ |
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int error; |
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int ret = 0; |
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int i; |
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for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { |
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if (kgdb_break[i].state != BP_ACTIVE) |
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continue; |
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error = kgdb_arch_remove_breakpoint(&kgdb_break[i]); |
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if (error) { |
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pr_info("BP remove failed: %lx\n", |
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kgdb_break[i].bpt_addr); |
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ret = error; |
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} |
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kgdb_flush_swbreak_addr(kgdb_break[i].bpt_addr); |
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kgdb_break[i].state = BP_SET; |
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} |
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return ret; |
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} |
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NOKPROBE_SYMBOL(dbg_deactivate_sw_breakpoints); |
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int dbg_remove_sw_break(unsigned long addr) |
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{ |
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int i; |
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for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { |
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if ((kgdb_break[i].state == BP_SET) && |
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(kgdb_break[i].bpt_addr == addr)) { |
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kgdb_break[i].state = BP_REMOVED; |
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return 0; |
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} |
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} |
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return -ENOENT; |
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} |
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|
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int kgdb_isremovedbreak(unsigned long addr) |
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{ |
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int i; |
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|
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for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { |
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if ((kgdb_break[i].state == BP_REMOVED) && |
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(kgdb_break[i].bpt_addr == addr)) |
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return 1; |
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} |
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return 0; |
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} |
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int kgdb_has_hit_break(unsigned long addr) |
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{ |
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int i; |
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for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { |
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if (kgdb_break[i].state == BP_ACTIVE && |
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kgdb_break[i].bpt_addr == addr) |
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return 1; |
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} |
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return 0; |
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} |
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int dbg_remove_all_break(void) |
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{ |
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int error; |
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int i; |
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|
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/* Clear memory breakpoints. */ |
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for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { |
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if (kgdb_break[i].state != BP_ACTIVE) |
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goto setundefined; |
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error = kgdb_arch_remove_breakpoint(&kgdb_break[i]); |
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if (error) |
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pr_err("breakpoint remove failed: %lx\n", |
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kgdb_break[i].bpt_addr); |
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setundefined: |
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kgdb_break[i].state = BP_UNDEFINED; |
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} |
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|
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/* Clear hardware breakpoints. */ |
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if (arch_kgdb_ops.remove_all_hw_break) |
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arch_kgdb_ops.remove_all_hw_break(); |
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|
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return 0; |
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} |
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|
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void kgdb_free_init_mem(void) |
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{ |
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int i; |
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|
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/* Clear init memory breakpoints. */ |
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for (i = 0; i < KGDB_MAX_BREAKPOINTS; i++) { |
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if (init_section_contains((void *)kgdb_break[i].bpt_addr, 0)) |
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kgdb_break[i].state = BP_UNDEFINED; |
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} |
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} |
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|
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#ifdef CONFIG_KGDB_KDB |
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void kdb_dump_stack_on_cpu(int cpu) |
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{ |
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if (cpu == raw_smp_processor_id() || !IS_ENABLED(CONFIG_SMP)) { |
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dump_stack(); |
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return; |
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} |
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|
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if (!(kgdb_info[cpu].exception_state & DCPU_IS_SLAVE)) { |
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kdb_printf("ERROR: Task on cpu %d didn't stop in the debugger\n", |
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cpu); |
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return; |
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} |
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|
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/* |
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* In general, architectures don't support dumping the stack of a |
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* "running" process that's not the current one. From the point of |
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* view of the Linux, kernel processes that are looping in the kgdb |
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* slave loop are still "running". There's also no API (that actually |
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* works across all architectures) that can do a stack crawl based |
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* on registers passed as a parameter. |
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* |
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* Solve this conundrum by asking slave CPUs to do the backtrace |
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* themselves. |
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*/ |
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kgdb_info[cpu].exception_state |= DCPU_WANT_BT; |
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while (kgdb_info[cpu].exception_state & DCPU_WANT_BT) |
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cpu_relax(); |
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} |
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#endif |
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|
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/* |
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* Return true if there is a valid kgdb I/O module. Also if no |
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* debugger is attached a message can be printed to the console about |
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* waiting for the debugger to attach. |
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* |
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* The print_wait argument is only to be true when called from inside |
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* the core kgdb_handle_exception, because it will wait for the |
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* debugger to attach. |
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*/ |
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static int kgdb_io_ready(int print_wait) |
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{ |
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if (!dbg_io_ops) |
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return 0; |
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if (kgdb_connected) |
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return 1; |
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if (atomic_read(&kgdb_setting_breakpoint)) |
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return 1; |
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if (print_wait) { |
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#ifdef CONFIG_KGDB_KDB |
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if (!dbg_kdb_mode) |
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pr_crit("waiting... or $3#33 for KDB\n"); |
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#else |
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pr_crit("Waiting for remote debugger\n"); |
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#endif |
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} |
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return 1; |
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} |
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NOKPROBE_SYMBOL(kgdb_io_ready); |
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|
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static int kgdb_reenter_check(struct kgdb_state *ks) |
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{ |
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unsigned long addr; |
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|
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if (atomic_read(&kgdb_active) != raw_smp_processor_id()) |
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return 0; |
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|
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/* Panic on recursive debugger calls: */ |
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exception_level++; |
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addr = kgdb_arch_pc(ks->ex_vector, ks->linux_regs); |
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dbg_deactivate_sw_breakpoints(); |
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|
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/* |
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* If the break point removed ok at the place exception |
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* occurred, try to recover and print a warning to the end |
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* user because the user planted a breakpoint in a place that |
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* KGDB needs in order to function. |
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*/ |
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if (dbg_remove_sw_break(addr) == 0) { |
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exception_level = 0; |
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kgdb_skipexception(ks->ex_vector, ks->linux_regs); |
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dbg_activate_sw_breakpoints(); |
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pr_crit("re-enter error: breakpoint removed %lx\n", addr); |
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WARN_ON_ONCE(1); |
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|
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return 1; |
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} |
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dbg_remove_all_break(); |
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kgdb_skipexception(ks->ex_vector, ks->linux_regs); |
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|
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if (exception_level > 1) { |
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dump_stack(); |
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kgdb_io_module_registered = false; |
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panic("Recursive entry to debugger"); |
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} |
|
|
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pr_crit("re-enter exception: ALL breakpoints killed\n"); |
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#ifdef CONFIG_KGDB_KDB |
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/* Allow kdb to debug itself one level */ |
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return 0; |
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#endif |
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dump_stack(); |
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panic("Recursive entry to debugger"); |
|
|
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return 1; |
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} |
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NOKPROBE_SYMBOL(kgdb_reenter_check); |
|
|
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static void dbg_touch_watchdogs(void) |
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{ |
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touch_softlockup_watchdog_sync(); |
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clocksource_touch_watchdog(); |
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rcu_cpu_stall_reset(); |
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} |
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NOKPROBE_SYMBOL(dbg_touch_watchdogs); |
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|
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static int kgdb_cpu_enter(struct kgdb_state *ks, struct pt_regs *regs, |
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int exception_state) |
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{ |
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unsigned long flags; |
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int sstep_tries = 100; |
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int error; |
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int cpu; |
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int trace_on = 0; |
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int online_cpus = num_online_cpus(); |
|
u64 time_left; |
|
|
|
kgdb_info[ks->cpu].enter_kgdb++; |
|
kgdb_info[ks->cpu].exception_state |= exception_state; |
|
|
|
if (exception_state == DCPU_WANT_MASTER) |
|
atomic_inc(&masters_in_kgdb); |
|
else |
|
atomic_inc(&slaves_in_kgdb); |
|
|
|
if (arch_kgdb_ops.disable_hw_break) |
|
arch_kgdb_ops.disable_hw_break(regs); |
|
|
|
acquirelock: |
|
rcu_read_lock(); |
|
/* |
|
* Interrupts will be restored by the 'trap return' code, except when |
|
* single stepping. |
|
*/ |
|
local_irq_save(flags); |
|
|
|
cpu = ks->cpu; |
|
kgdb_info[cpu].debuggerinfo = regs; |
|
kgdb_info[cpu].task = current; |
|
kgdb_info[cpu].ret_state = 0; |
|
kgdb_info[cpu].irq_depth = hardirq_count() >> HARDIRQ_SHIFT; |
|
|
|
/* Make sure the above info reaches the primary CPU */ |
|
smp_mb(); |
|
|
|
if (exception_level == 1) { |
|
if (raw_spin_trylock(&dbg_master_lock)) |
|
atomic_xchg(&kgdb_active, cpu); |
|
goto cpu_master_loop; |
|
} |
|
|
|
/* |
|
* CPU will loop if it is a slave or request to become a kgdb |
|
* master cpu and acquire the kgdb_active lock: |
|
*/ |
|
while (1) { |
|
cpu_loop: |
|
if (kgdb_info[cpu].exception_state & DCPU_NEXT_MASTER) { |
|
kgdb_info[cpu].exception_state &= ~DCPU_NEXT_MASTER; |
|
goto cpu_master_loop; |
|
} else if (kgdb_info[cpu].exception_state & DCPU_WANT_MASTER) { |
|
if (raw_spin_trylock(&dbg_master_lock)) { |
|
atomic_xchg(&kgdb_active, cpu); |
|
break; |
|
} |
|
} else if (kgdb_info[cpu].exception_state & DCPU_WANT_BT) { |
|
dump_stack(); |
|
kgdb_info[cpu].exception_state &= ~DCPU_WANT_BT; |
|
} else if (kgdb_info[cpu].exception_state & DCPU_IS_SLAVE) { |
|
if (!raw_spin_is_locked(&dbg_slave_lock)) |
|
goto return_normal; |
|
} else { |
|
return_normal: |
|
/* Return to normal operation by executing any |
|
* hw breakpoint fixup. |
|
*/ |
|
if (arch_kgdb_ops.correct_hw_break) |
|
arch_kgdb_ops.correct_hw_break(); |
|
if (trace_on) |
|
tracing_on(); |
|
kgdb_info[cpu].debuggerinfo = NULL; |
|
kgdb_info[cpu].task = NULL; |
|
kgdb_info[cpu].exception_state &= |
|
~(DCPU_WANT_MASTER | DCPU_IS_SLAVE); |
|
kgdb_info[cpu].enter_kgdb--; |
|
smp_mb__before_atomic(); |
|
atomic_dec(&slaves_in_kgdb); |
|
dbg_touch_watchdogs(); |
|
local_irq_restore(flags); |
|
rcu_read_unlock(); |
|
return 0; |
|
} |
|
cpu_relax(); |
|
} |
|
|
|
/* |
|
* For single stepping, try to only enter on the processor |
|
* that was single stepping. To guard against a deadlock, the |
|
* kernel will only try for the value of sstep_tries before |
|
* giving up and continuing on. |
|
*/ |
|
if (atomic_read(&kgdb_cpu_doing_single_step) != -1 && |
|
(kgdb_info[cpu].task && |
|
kgdb_info[cpu].task->pid != kgdb_sstep_pid) && --sstep_tries) { |
|
atomic_set(&kgdb_active, -1); |
|
raw_spin_unlock(&dbg_master_lock); |
|
dbg_touch_watchdogs(); |
|
local_irq_restore(flags); |
|
rcu_read_unlock(); |
|
|
|
goto acquirelock; |
|
} |
|
|
|
if (!kgdb_io_ready(1)) { |
|
kgdb_info[cpu].ret_state = 1; |
|
goto kgdb_restore; /* No I/O connection, resume the system */ |
|
} |
|
|
|
/* |
|
* Don't enter if we have hit a removed breakpoint. |
|
*/ |
|
if (kgdb_skipexception(ks->ex_vector, ks->linux_regs)) |
|
goto kgdb_restore; |
|
|
|
atomic_inc(&ignore_console_lock_warning); |
|
|
|
/* Call the I/O driver's pre_exception routine */ |
|
if (dbg_io_ops->pre_exception) |
|
dbg_io_ops->pre_exception(); |
|
|
|
/* |
|
* Get the passive CPU lock which will hold all the non-primary |
|
* CPU in a spin state while the debugger is active |
|
*/ |
|
if (!kgdb_single_step) |
|
raw_spin_lock(&dbg_slave_lock); |
|
|
|
#ifdef CONFIG_SMP |
|
/* If send_ready set, slaves are already waiting */ |
|
if (ks->send_ready) |
|
atomic_set(ks->send_ready, 1); |
|
|
|
/* Signal the other CPUs to enter kgdb_wait() */ |
|
else if ((!kgdb_single_step) && kgdb_do_roundup) |
|
kgdb_roundup_cpus(); |
|
#endif |
|
|
|
/* |
|
* Wait for the other CPUs to be notified and be waiting for us: |
|
*/ |
|
time_left = MSEC_PER_SEC; |
|
while (kgdb_do_roundup && --time_left && |
|
(atomic_read(&masters_in_kgdb) + atomic_read(&slaves_in_kgdb)) != |
|
online_cpus) |
|
udelay(1000); |
|
if (!time_left) |
|
pr_crit("Timed out waiting for secondary CPUs.\n"); |
|
|
|
/* |
|
* At this point the primary processor is completely |
|
* in the debugger and all secondary CPUs are quiescent |
|
*/ |
|
dbg_deactivate_sw_breakpoints(); |
|
kgdb_single_step = 0; |
|
kgdb_contthread = current; |
|
exception_level = 0; |
|
trace_on = tracing_is_on(); |
|
if (trace_on) |
|
tracing_off(); |
|
|
|
while (1) { |
|
cpu_master_loop: |
|
if (dbg_kdb_mode) { |
|
kgdb_connected = 1; |
|
error = kdb_stub(ks); |
|
if (error == -1) |
|
continue; |
|
kgdb_connected = 0; |
|
} else { |
|
error = gdb_serial_stub(ks); |
|
} |
|
|
|
if (error == DBG_PASS_EVENT) { |
|
dbg_kdb_mode = !dbg_kdb_mode; |
|
} else if (error == DBG_SWITCH_CPU_EVENT) { |
|
kgdb_info[dbg_switch_cpu].exception_state |= |
|
DCPU_NEXT_MASTER; |
|
goto cpu_loop; |
|
} else { |
|
kgdb_info[cpu].ret_state = error; |
|
break; |
|
} |
|
} |
|
|
|
dbg_activate_sw_breakpoints(); |
|
|
|
/* Call the I/O driver's post_exception routine */ |
|
if (dbg_io_ops->post_exception) |
|
dbg_io_ops->post_exception(); |
|
|
|
atomic_dec(&ignore_console_lock_warning); |
|
|
|
if (!kgdb_single_step) { |
|
raw_spin_unlock(&dbg_slave_lock); |
|
/* Wait till all the CPUs have quit from the debugger. */ |
|
while (kgdb_do_roundup && atomic_read(&slaves_in_kgdb)) |
|
cpu_relax(); |
|
} |
|
|
|
kgdb_restore: |
|
if (atomic_read(&kgdb_cpu_doing_single_step) != -1) { |
|
int sstep_cpu = atomic_read(&kgdb_cpu_doing_single_step); |
|
if (kgdb_info[sstep_cpu].task) |
|
kgdb_sstep_pid = kgdb_info[sstep_cpu].task->pid; |
|
else |
|
kgdb_sstep_pid = 0; |
|
} |
|
if (arch_kgdb_ops.correct_hw_break) |
|
arch_kgdb_ops.correct_hw_break(); |
|
if (trace_on) |
|
tracing_on(); |
|
|
|
kgdb_info[cpu].debuggerinfo = NULL; |
|
kgdb_info[cpu].task = NULL; |
|
kgdb_info[cpu].exception_state &= |
|
~(DCPU_WANT_MASTER | DCPU_IS_SLAVE); |
|
kgdb_info[cpu].enter_kgdb--; |
|
smp_mb__before_atomic(); |
|
atomic_dec(&masters_in_kgdb); |
|
/* Free kgdb_active */ |
|
atomic_set(&kgdb_active, -1); |
|
raw_spin_unlock(&dbg_master_lock); |
|
dbg_touch_watchdogs(); |
|
local_irq_restore(flags); |
|
rcu_read_unlock(); |
|
|
|
return kgdb_info[cpu].ret_state; |
|
} |
|
NOKPROBE_SYMBOL(kgdb_cpu_enter); |
|
|
|
/* |
|
* kgdb_handle_exception() - main entry point from a kernel exception |
|
* |
|
* Locking hierarchy: |
|
* interface locks, if any (begin_session) |
|
* kgdb lock (kgdb_active) |
|
*/ |
|
int |
|
kgdb_handle_exception(int evector, int signo, int ecode, struct pt_regs *regs) |
|
{ |
|
struct kgdb_state kgdb_var; |
|
struct kgdb_state *ks = &kgdb_var; |
|
int ret = 0; |
|
|
|
if (arch_kgdb_ops.enable_nmi) |
|
arch_kgdb_ops.enable_nmi(0); |
|
/* |
|
* Avoid entering the debugger if we were triggered due to an oops |
|
* but panic_timeout indicates the system should automatically |
|
* reboot on panic. We don't want to get stuck waiting for input |
|
* on such systems, especially if its "just" an oops. |
|
*/ |
|
if (signo != SIGTRAP && panic_timeout) |
|
return 1; |
|
|
|
memset(ks, 0, sizeof(struct kgdb_state)); |
|
ks->cpu = raw_smp_processor_id(); |
|
ks->ex_vector = evector; |
|
ks->signo = signo; |
|
ks->err_code = ecode; |
|
ks->linux_regs = regs; |
|
|
|
if (kgdb_reenter_check(ks)) |
|
goto out; /* Ouch, double exception ! */ |
|
if (kgdb_info[ks->cpu].enter_kgdb != 0) |
|
goto out; |
|
|
|
ret = kgdb_cpu_enter(ks, regs, DCPU_WANT_MASTER); |
|
out: |
|
if (arch_kgdb_ops.enable_nmi) |
|
arch_kgdb_ops.enable_nmi(1); |
|
return ret; |
|
} |
|
NOKPROBE_SYMBOL(kgdb_handle_exception); |
|
|
|
/* |
|
* GDB places a breakpoint at this function to know dynamically loaded objects. |
|
*/ |
|
static int module_event(struct notifier_block *self, unsigned long val, |
|
void *data) |
|
{ |
|
return 0; |
|
} |
|
|
|
static struct notifier_block dbg_module_load_nb = { |
|
.notifier_call = module_event, |
|
}; |
|
|
|
int kgdb_nmicallback(int cpu, void *regs) |
|
{ |
|
#ifdef CONFIG_SMP |
|
struct kgdb_state kgdb_var; |
|
struct kgdb_state *ks = &kgdb_var; |
|
|
|
kgdb_info[cpu].rounding_up = false; |
|
|
|
memset(ks, 0, sizeof(struct kgdb_state)); |
|
ks->cpu = cpu; |
|
ks->linux_regs = regs; |
|
|
|
if (kgdb_info[ks->cpu].enter_kgdb == 0 && |
|
raw_spin_is_locked(&dbg_master_lock)) { |
|
kgdb_cpu_enter(ks, regs, DCPU_IS_SLAVE); |
|
return 0; |
|
} |
|
#endif |
|
return 1; |
|
} |
|
NOKPROBE_SYMBOL(kgdb_nmicallback); |
|
|
|
int kgdb_nmicallin(int cpu, int trapnr, void *regs, int err_code, |
|
atomic_t *send_ready) |
|
{ |
|
#ifdef CONFIG_SMP |
|
if (!kgdb_io_ready(0) || !send_ready) |
|
return 1; |
|
|
|
if (kgdb_info[cpu].enter_kgdb == 0) { |
|
struct kgdb_state kgdb_var; |
|
struct kgdb_state *ks = &kgdb_var; |
|
|
|
memset(ks, 0, sizeof(struct kgdb_state)); |
|
ks->cpu = cpu; |
|
ks->ex_vector = trapnr; |
|
ks->signo = SIGTRAP; |
|
ks->err_code = err_code; |
|
ks->linux_regs = regs; |
|
ks->send_ready = send_ready; |
|
kgdb_cpu_enter(ks, regs, DCPU_WANT_MASTER); |
|
return 0; |
|
} |
|
#endif |
|
return 1; |
|
} |
|
NOKPROBE_SYMBOL(kgdb_nmicallin); |
|
|
|
static void kgdb_console_write(struct console *co, const char *s, |
|
unsigned count) |
|
{ |
|
unsigned long flags; |
|
|
|
/* If we're debugging, or KGDB has not connected, don't try |
|
* and print. */ |
|
if (!kgdb_connected || atomic_read(&kgdb_active) != -1 || dbg_kdb_mode) |
|
return; |
|
|
|
local_irq_save(flags); |
|
gdbstub_msg_write(s, count); |
|
local_irq_restore(flags); |
|
} |
|
|
|
static struct console kgdbcons = { |
|
.name = "kgdb", |
|
.write = kgdb_console_write, |
|
.flags = CON_PRINTBUFFER | CON_ENABLED, |
|
.index = -1, |
|
}; |
|
|
|
static int __init opt_kgdb_con(char *str) |
|
{ |
|
kgdb_use_con = 1; |
|
|
|
if (kgdb_io_module_registered && !kgdb_con_registered) { |
|
register_console(&kgdbcons); |
|
kgdb_con_registered = 1; |
|
} |
|
|
|
return 0; |
|
} |
|
|
|
early_param("kgdbcon", opt_kgdb_con); |
|
|
|
#ifdef CONFIG_MAGIC_SYSRQ |
|
static void sysrq_handle_dbg(int key) |
|
{ |
|
if (!dbg_io_ops) { |
|
pr_crit("ERROR: No KGDB I/O module available\n"); |
|
return; |
|
} |
|
if (!kgdb_connected) { |
|
#ifdef CONFIG_KGDB_KDB |
|
if (!dbg_kdb_mode) |
|
pr_crit("KGDB or $3#33 for KDB\n"); |
|
#else |
|
pr_crit("Entering KGDB\n"); |
|
#endif |
|
} |
|
|
|
kgdb_breakpoint(); |
|
} |
|
|
|
static const struct sysrq_key_op sysrq_dbg_op = { |
|
.handler = sysrq_handle_dbg, |
|
.help_msg = "debug(g)", |
|
.action_msg = "DEBUG", |
|
}; |
|
#endif |
|
|
|
void kgdb_panic(const char *msg) |
|
{ |
|
if (!kgdb_io_module_registered) |
|
return; |
|
|
|
/* |
|
* We don't want to get stuck waiting for input from user if |
|
* "panic_timeout" indicates the system should automatically |
|
* reboot on panic. |
|
*/ |
|
if (panic_timeout) |
|
return; |
|
|
|
if (dbg_kdb_mode) |
|
kdb_printf("PANIC: %s\n", msg); |
|
|
|
kgdb_breakpoint(); |
|
} |
|
|
|
static void kgdb_initial_breakpoint(void) |
|
{ |
|
kgdb_break_asap = 0; |
|
|
|
pr_crit("Waiting for connection from remote gdb...\n"); |
|
kgdb_breakpoint(); |
|
} |
|
|
|
void __weak kgdb_arch_late(void) |
|
{ |
|
} |
|
|
|
void __init dbg_late_init(void) |
|
{ |
|
dbg_is_early = false; |
|
if (kgdb_io_module_registered) |
|
kgdb_arch_late(); |
|
kdb_init(KDB_INIT_FULL); |
|
|
|
if (kgdb_io_module_registered && kgdb_break_asap) |
|
kgdb_initial_breakpoint(); |
|
} |
|
|
|
static int |
|
dbg_notify_reboot(struct notifier_block *this, unsigned long code, void *x) |
|
{ |
|
/* |
|
* Take the following action on reboot notify depending on value: |
|
* 1 == Enter debugger |
|
* 0 == [the default] detach debug client |
|
* -1 == Do nothing... and use this until the board resets |
|
*/ |
|
switch (kgdbreboot) { |
|
case 1: |
|
kgdb_breakpoint(); |
|
goto done; |
|
case -1: |
|
goto done; |
|
} |
|
if (!dbg_kdb_mode) |
|
gdbstub_exit(code); |
|
done: |
|
return NOTIFY_DONE; |
|
} |
|
|
|
static struct notifier_block dbg_reboot_notifier = { |
|
.notifier_call = dbg_notify_reboot, |
|
.next = NULL, |
|
.priority = INT_MAX, |
|
}; |
|
|
|
static void kgdb_register_callbacks(void) |
|
{ |
|
if (!kgdb_io_module_registered) { |
|
kgdb_io_module_registered = 1; |
|
kgdb_arch_init(); |
|
if (!dbg_is_early) |
|
kgdb_arch_late(); |
|
register_module_notifier(&dbg_module_load_nb); |
|
register_reboot_notifier(&dbg_reboot_notifier); |
|
#ifdef CONFIG_MAGIC_SYSRQ |
|
register_sysrq_key('g', &sysrq_dbg_op); |
|
#endif |
|
if (kgdb_use_con && !kgdb_con_registered) { |
|
register_console(&kgdbcons); |
|
kgdb_con_registered = 1; |
|
} |
|
} |
|
} |
|
|
|
static void kgdb_unregister_callbacks(void) |
|
{ |
|
/* |
|
* When this routine is called KGDB should unregister from |
|
* handlers and clean up, making sure it is not handling any |
|
* break exceptions at the time. |
|
*/ |
|
if (kgdb_io_module_registered) { |
|
kgdb_io_module_registered = 0; |
|
unregister_reboot_notifier(&dbg_reboot_notifier); |
|
unregister_module_notifier(&dbg_module_load_nb); |
|
kgdb_arch_exit(); |
|
#ifdef CONFIG_MAGIC_SYSRQ |
|
unregister_sysrq_key('g', &sysrq_dbg_op); |
|
#endif |
|
if (kgdb_con_registered) { |
|
unregister_console(&kgdbcons); |
|
kgdb_con_registered = 0; |
|
} |
|
} |
|
} |
|
|
|
/** |
|
* kgdb_register_io_module - register KGDB IO module |
|
* @new_dbg_io_ops: the io ops vector |
|
* |
|
* Register it with the KGDB core. |
|
*/ |
|
int kgdb_register_io_module(struct kgdb_io *new_dbg_io_ops) |
|
{ |
|
struct kgdb_io *old_dbg_io_ops; |
|
int err; |
|
|
|
spin_lock(&kgdb_registration_lock); |
|
|
|
old_dbg_io_ops = dbg_io_ops; |
|
if (old_dbg_io_ops) { |
|
if (!old_dbg_io_ops->deinit) { |
|
spin_unlock(&kgdb_registration_lock); |
|
|
|
pr_err("KGDB I/O driver %s can't replace %s.\n", |
|
new_dbg_io_ops->name, old_dbg_io_ops->name); |
|
return -EBUSY; |
|
} |
|
pr_info("Replacing I/O driver %s with %s\n", |
|
old_dbg_io_ops->name, new_dbg_io_ops->name); |
|
} |
|
|
|
if (new_dbg_io_ops->init) { |
|
err = new_dbg_io_ops->init(); |
|
if (err) { |
|
spin_unlock(&kgdb_registration_lock); |
|
return err; |
|
} |
|
} |
|
|
|
dbg_io_ops = new_dbg_io_ops; |
|
|
|
spin_unlock(&kgdb_registration_lock); |
|
|
|
if (old_dbg_io_ops) { |
|
old_dbg_io_ops->deinit(); |
|
return 0; |
|
} |
|
|
|
pr_info("Registered I/O driver %s\n", new_dbg_io_ops->name); |
|
|
|
/* Arm KGDB now. */ |
|
kgdb_register_callbacks(); |
|
|
|
if (kgdb_break_asap && |
|
(!dbg_is_early || IS_ENABLED(CONFIG_ARCH_HAS_EARLY_DEBUG))) |
|
kgdb_initial_breakpoint(); |
|
|
|
return 0; |
|
} |
|
EXPORT_SYMBOL_GPL(kgdb_register_io_module); |
|
|
|
/** |
|
* kgdb_unregister_io_module - unregister KGDB IO module |
|
* @old_dbg_io_ops: the io ops vector |
|
* |
|
* Unregister it with the KGDB core. |
|
*/ |
|
void kgdb_unregister_io_module(struct kgdb_io *old_dbg_io_ops) |
|
{ |
|
BUG_ON(kgdb_connected); |
|
|
|
/* |
|
* KGDB is no longer able to communicate out, so |
|
* unregister our callbacks and reset state. |
|
*/ |
|
kgdb_unregister_callbacks(); |
|
|
|
spin_lock(&kgdb_registration_lock); |
|
|
|
WARN_ON_ONCE(dbg_io_ops != old_dbg_io_ops); |
|
dbg_io_ops = NULL; |
|
|
|
spin_unlock(&kgdb_registration_lock); |
|
|
|
if (old_dbg_io_ops->deinit) |
|
old_dbg_io_ops->deinit(); |
|
|
|
pr_info("Unregistered I/O driver %s, debugger disabled\n", |
|
old_dbg_io_ops->name); |
|
} |
|
EXPORT_SYMBOL_GPL(kgdb_unregister_io_module); |
|
|
|
int dbg_io_get_char(void) |
|
{ |
|
int ret = dbg_io_ops->read_char(); |
|
if (ret == NO_POLL_CHAR) |
|
return -1; |
|
if (!dbg_kdb_mode) |
|
return ret; |
|
if (ret == 127) |
|
return 8; |
|
return ret; |
|
} |
|
|
|
/** |
|
* kgdb_breakpoint - generate breakpoint exception |
|
* |
|
* This function will generate a breakpoint exception. It is used at the |
|
* beginning of a program to sync up with a debugger and can be used |
|
* otherwise as a quick means to stop program execution and "break" into |
|
* the debugger. |
|
*/ |
|
noinline void kgdb_breakpoint(void) |
|
{ |
|
atomic_inc(&kgdb_setting_breakpoint); |
|
wmb(); /* Sync point before breakpoint */ |
|
arch_kgdb_breakpoint(); |
|
wmb(); /* Sync point after breakpoint */ |
|
atomic_dec(&kgdb_setting_breakpoint); |
|
} |
|
EXPORT_SYMBOL_GPL(kgdb_breakpoint); |
|
|
|
static int __init opt_kgdb_wait(char *str) |
|
{ |
|
kgdb_break_asap = 1; |
|
|
|
kdb_init(KDB_INIT_EARLY); |
|
if (kgdb_io_module_registered && |
|
IS_ENABLED(CONFIG_ARCH_HAS_EARLY_DEBUG)) |
|
kgdb_initial_breakpoint(); |
|
|
|
return 0; |
|
} |
|
|
|
early_param("kgdbwait", opt_kgdb_wait);
|
|
|