arch/x86/kernel/dumpstack_64.c

Source file repositories/reference/linux-study-clean/arch/x86/kernel/dumpstack_64.c

File Facts

System
Linux kernel
Corpus path
arch/x86/kernel/dumpstack_64.c
Extension
.c
Size
5492 bytes
Lines
222
Domain
Architecture Layer
Bucket
arch/x86
Inferred role
Architecture Layer: implementation source
Status
source implementation candidate

Why This File Exists

CPU and platform-specific kernel glue: boot entry, traps, syscall entry, interrupts, page tables, context switch, and low-level barriers.

Dependency Surface

Detected Declarations

Annotated Snippet

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(DB),
	EPAGERANGE(MCE),
	EPAGERANGE(VC),
	EPAGERANGE(VC2),
};

static __always_inline 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 __always_inline 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 points directly to the top most stack entry to avoid a -8
	 * adjustment in the stack switch hotpath. Adjust it back before
	 * calculating @begin.
	 */
	end++;
	begin = end - (IRQ_STACK_SIZE / sizeof(long));

	/*
	 * Due to the switching logic RSP can never be == @end because the
	 * final operation is 'popq %rsp' which means after that RSP points
	 * to the original stack and not to @end.
	 */
	if (stack < begin || stack >= end)
		return false;

Annotation

Implementation Notes