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// SPDX-License-Identifier: GPL-2.0
#include <linux/bug.h>
#include <linux/io.h>
#include <linux/types.h>
#include <linux/kdebug.h>
#include <linux/signal.h>
#include <linux/sched.h>
#include <linux/sched/debug.h>
#include <linux/sched/task_stack.h>
#include <linux/uaccess.h>
#include <linux/hardirq.h>
#include <linux/kernel.h>
#include <linux/kexec.h>
#include <linux/sched/signal.h>
#include <linux/extable.h>
#include <linux/module.h> /* print_modules */
#include <asm/unwinder.h>
#include <asm/traps.h>
static DEFINE_SPINLOCK(die_lock);
void die(const char *str, struct pt_regs *regs, long err)
{
static int die_counter;
oops_enter();
spin_lock_irq(&die_lock);
console_verbose();
bust_spinlocks(1);
printk("%s: %04lx [#%d]\n", str, err & 0xffff, ++die_counter);
print_modules();
show_regs(regs);
printk("Process: %s (pid: %d, stack limit = %p)\n", current->comm,
task_pid_nr(current), task_stack_page(current) + 1);
if (!user_mode(regs) || in_interrupt())
dump_mem("Stack: ", regs->regs[15], THREAD_SIZE +
(unsigned long)task_stack_page(current));
notify_die(DIE_OOPS, str, regs, err, 255, SIGSEGV);
bust_spinlocks(0);
add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
spin_unlock_irq(&die_lock);
oops_exit();
if (kexec_should_crash(current))
crash_kexec(regs);
if (in_interrupt())
panic("Fatal exception in interrupt");
if (panic_on_oops)
panic("Fatal exception");
do_exit(SIGSEGV);
}
void die_if_kernel(const char *str, struct pt_regs *regs, long err)
{
if (!user_mode(regs))
die(str, regs, err);
}
/*
* try and fix up kernelspace address errors
* - userspace errors just cause EFAULT to be returned, resulting in SEGV
* - kernel/userspace interfaces cause a jump to an appropriate handler
* - other kernel errors are bad
*/
void die_if_no_fixup(const char *str, struct pt_regs *regs, long err)
{
if (!user_mode(regs)) {
const struct exception_table_entry *fixup;
fixup = search_exception_tables(regs->pc);
if (fixup) {
regs->pc = fixup->fixup;
return;
}
die(str, regs, err);
}
}
#ifdef CONFIG_GENERIC_BUG
static void handle_BUG(struct pt_regs *regs)
{
const struct bug_entry *bug;
unsigned long bugaddr = regs->pc;
enum bug_trap_type tt;
if (!is_valid_bugaddr(bugaddr))
goto invalid;
bug = find_bug(bugaddr);
/* Switch unwinders when unwind_stack() is called */
if (bug->flags & BUGFLAG_UNWINDER)
unwinder_faulted = 1;
tt = report_bug(bugaddr, regs);
if (tt == BUG_TRAP_TYPE_WARN) {
regs->pc += instruction_size(bugaddr);
return;
}
invalid:
die("Kernel BUG", regs, TRAPA_BUG_OPCODE & 0xff);
}
int is_valid_bugaddr(unsigned long addr)
{
insn_size_t opcode;
if (addr < PAGE_OFFSET)
return 0;
if (probe_kernel_address((insn_size_t *)addr, opcode))
return 0;
if (opcode == TRAPA_BUG_OPCODE)
return 1;
return 0;
}
#endif
/*
* Generic trap handler.
*/
BUILD_TRAP_HANDLER(debug)
{
TRAP_HANDLER_DECL;
/* Rewind */
regs->pc -= instruction_size(__raw_readw(regs->pc - 4));
if (notify_die(DIE_TRAP, "debug trap", regs, 0, vec & 0xff,
SIGTRAP) == NOTIFY_STOP)
return;
force_sig(SIGTRAP, current);
}
/*
* Special handler for BUG() traps.
*/
BUILD_TRAP_HANDLER(bug)
{
TRAP_HANDLER_DECL;
/* Rewind */
regs->pc -= instruction_size(__raw_readw(regs->pc - 4));
if (notify_die(DIE_TRAP, "bug trap", regs, 0, TRAPA_BUG_OPCODE & 0xff,
SIGTRAP) == NOTIFY_STOP)
return;
#ifdef CONFIG_GENERIC_BUG
if (__kernel_text_address(instruction_pointer(regs))) {
insn_size_t insn = *(insn_size_t *)instruction_pointer(regs);
if (insn == TRAPA_BUG_OPCODE)
handle_BUG(regs);
return;
}
#endif
force_sig(SIGTRAP, current);
}
BUILD_TRAP_HANDLER(nmi)
{
unsigned int cpu = smp_processor_id();
TRAP_HANDLER_DECL;
nmi_enter();
nmi_count(cpu)++;
switch (notify_die(DIE_NMI, "NMI", regs, 0, vec & 0xff, SIGINT)) {
case NOTIFY_OK:
case NOTIFY_STOP:
break;
case NOTIFY_BAD:
die("Fatal Non-Maskable Interrupt", regs, SIGINT);
default:
printk(KERN_ALERT "Got NMI, but nobody cared. Ignoring...\n");
break;
}
nmi_exit();
}
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