linux/arch/x86/kernel/dumpstack_32.c
Borislav Petkov 593309423c x86/32: Remove CONFIG_DOUBLEFAULT
Make the doublefault exception handler unconditional on 32-bit. Yes,
it is important to be able to catch #DF exceptions instead of silent
reboots. Yes, the code size increase is worth every byte. And one less
CONFIG symbol is just the cherry on top.

No functional changes.

Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Andy Lutomirski <luto@kernel.org>
Link: https://lkml.kernel.org/r/20200404083646.8897-1-bp@alien8.de
2020-04-14 14:24:05 +02:00

156 lines
3.5 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 1991, 1992 Linus Torvalds
* Copyright (C) 2000, 2001, 2002 Andi Kleen, SuSE Labs
*/
#include <linux/sched/debug.h>
#include <linux/kallsyms.h>
#include <linux/kprobes.h>
#include <linux/uaccess.h>
#include <linux/hardirq.h>
#include <linux/kdebug.h>
#include <linux/export.h>
#include <linux/ptrace.h>
#include <linux/kexec.h>
#include <linux/sysfs.h>
#include <linux/bug.h>
#include <linux/nmi.h>
#include <asm/stacktrace.h>
const char *stack_type_name(enum stack_type type)
{
if (type == STACK_TYPE_IRQ)
return "IRQ";
if (type == STACK_TYPE_SOFTIRQ)
return "SOFTIRQ";
if (type == STACK_TYPE_ENTRY)
return "ENTRY_TRAMPOLINE";
if (type == STACK_TYPE_EXCEPTION)
return "#DF";
return NULL;
}
static bool in_hardirq_stack(unsigned long *stack, struct stack_info *info)
{
unsigned long *begin = (unsigned long *)this_cpu_read(hardirq_stack_ptr);
unsigned long *end = begin + (THREAD_SIZE / sizeof(long));
/*
* This is a software stack, so 'end' can be a valid stack pointer.
* It just means the stack is empty.
*/
if (stack < begin || stack > end)
return false;
info->type = STACK_TYPE_IRQ;
info->begin = begin;
info->end = end;
/*
* See irq_32.c -- the next stack pointer is stored at the beginning of
* the stack.
*/
info->next_sp = (unsigned long *)*begin;
return true;
}
static bool in_softirq_stack(unsigned long *stack, struct stack_info *info)
{
unsigned long *begin = (unsigned long *)this_cpu_read(softirq_stack_ptr);
unsigned long *end = begin + (THREAD_SIZE / sizeof(long));
/*
* This is a software stack, so 'end' can be a valid stack pointer.
* It just means the stack is empty.
*/
if (stack < begin || stack > end)
return false;
info->type = STACK_TYPE_SOFTIRQ;
info->begin = begin;
info->end = end;
/*
* The next stack pointer is stored at the beginning of the stack.
* See irq_32.c.
*/
info->next_sp = (unsigned long *)*begin;
return true;
}
static bool in_doublefault_stack(unsigned long *stack, struct stack_info *info)
{
struct cpu_entry_area *cea = get_cpu_entry_area(raw_smp_processor_id());
struct doublefault_stack *ss = &cea->doublefault_stack;
void *begin = ss->stack;
void *end = begin + sizeof(ss->stack);
if ((void *)stack < begin || (void *)stack >= end)
return false;
info->type = STACK_TYPE_EXCEPTION;
info->begin = begin;
info->end = end;
info->next_sp = (unsigned long *)this_cpu_read(cpu_tss_rw.x86_tss.sp);
return true;
}
int get_stack_info(unsigned long *stack, struct task_struct *task,
struct stack_info *info, unsigned long *visit_mask)
{
if (!stack)
goto unknown;
task = task ? : current;
if (in_task_stack(stack, task, info))
goto recursion_check;
if (task != current)
goto unknown;
if (in_entry_stack(stack, info))
goto recursion_check;
if (in_hardirq_stack(stack, info))
goto recursion_check;
if (in_softirq_stack(stack, info))
goto recursion_check;
if (in_doublefault_stack(stack, info))
goto recursion_check;
goto unknown;
recursion_check:
/*
* Make sure we don't iterate through any given stack more than once.
* If it comes up a second time then there's something wrong going on:
* just break out and report an unknown stack type.
*/
if (visit_mask) {
if (*visit_mask & (1UL << info->type)) {
printk_deferred_once(KERN_WARNING "WARNING: stack recursion on stack type %d\n", info->type);
goto unknown;
}
*visit_mask |= 1UL << info->type;
}
return 0;
unknown:
info->type = STACK_TYPE_UNKNOWN;
return -EINVAL;
}