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// 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/cpu_entry_area.h>
#include <asm/stacktrace.h>
static const char * const exception_stack_names[] = {
[ ESTACK_DF ] = "#DF",
[ ESTACK_NMI ] = "NMI",
[ ESTACK_DB2 ] = "#DB2",
[ ESTACK_DB1 ] = "#DB1",
[ ESTACK_DB ] = "#DB",
[ ESTACK_MCE ] = "#MC",
};
const char *stack_type_name(enum stack_type type)
{
BUILD_BUG_ON(N_EXCEPTION_STACKS != 6);
if (type == STACK_TYPE_IRQ)
return "IRQ";
if (type == STACK_TYPE_ENTRY) {
/*
* On 64-bit, we have a generic entry stack that we
* use for all the kernel entry points, including
* SYSENTER.
*/
return "ENTRY_TRAMPOLINE";
}
if (type >= STACK_TYPE_EXCEPTION && type <= STACK_TYPE_EXCEPTION_LAST)
return exception_stack_names[type - STACK_TYPE_EXCEPTION];
return NULL;
}
/**
* struct estack_pages - Page descriptor for exception stacks
* @offs: Offset from the start of the exception stack area
* @size: Size of the exception stack
* @type: Type to store in the stack_info struct
*/
struct estack_pages {
u32 offs;
u16 size;
u16 type;
};
#define EPAGERANGE(st) \
[PFN_DOWN(CEA_ESTACK_OFFS(st)) ... \
PFN_DOWN(CEA_ESTACK_OFFS(st) + CEA_ESTACK_SIZE(st) - 1)] = { \
.offs = CEA_ESTACK_OFFS(st), \
.size = CEA_ESTACK_SIZE(st), \
.type = STACK_TYPE_EXCEPTION + ESTACK_ ##st, }
/*
* Array of exception stack page descriptors. If the stack is larger than
* PAGE_SIZE, all pages covering a particular stack will have the same
* info. The guard pages including the not mapped DB2 stack are zeroed
* out.
*/
static const
struct estack_pages estack_pages[CEA_ESTACK_PAGES] ____cacheline_aligned = {
EPAGERANGE(DF),
EPAGERANGE(NMI),
EPAGERANGE(DB1),
EPAGERANGE(DB),
EPAGERANGE(MCE),
};
static bool in_exception_stack(unsigned long *stack, struct stack_info *info)
{
unsigned long begin, end, stk = (unsigned long)stack;
const struct estack_pages *ep;
struct pt_regs *regs;
unsigned int k;
BUILD_BUG_ON(N_EXCEPTION_STACKS != 6);
begin = (unsigned long)__this_cpu_read(cea_exception_stacks);
/*
* Handle the case where stack trace is collected _before_
* cea_exception_stacks had been initialized.
*/
if (!begin)
return false;
end = begin + sizeof(struct cea_exception_stacks);
/* Bail if @stack is outside the exception stack area. */
if (stk < begin || stk >= end)
return false;
/* Calc page offset from start of exception stacks */
k = (stk - begin) >> PAGE_SHIFT;
/* Lookup the page descriptor */
ep = &estack_pages[k];
/* Guard page? */
if (!ep->size)
return false;
begin += (unsigned long)ep->offs;
end = begin + (unsigned long)ep->size;
regs = (struct pt_regs *)end - 1;
info->type = ep->type;
info->begin = (unsigned long *)begin;
info->end = (unsigned long *)end;
info->next_sp = (unsigned long *)regs->sp;
return true;
}
static bool in_irq_stack(unsigned long *stack, struct stack_info *info)
{
unsigned long *end = (unsigned long *)this_cpu_read(hardirq_stack_ptr);
unsigned long *begin = end - (IRQ_STACK_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;
/*
* The next stack pointer is the first thing pushed by the entry code
* after switching to the irq stack.
*/
info->next_sp = (unsigned long *)*(end - 1);
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_exception_stack(stack, info))
goto recursion_check;
if (in_irq_stack(stack, info))
goto recursion_check;
if (in_entry_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)) {
if (task == current)
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;
}
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