1 files changed, 163 insertions, 244 deletions

diff --git a/arch/x86/kernel/dumpstack_64.c b/arch/x86/kernel/dumpstack_64.c
index addb207dab92..6c5defd6569a 100644
--- a/arch/x86/kernel/dumpstack_64.c
+++ b/arch/x86/kernel/dumpstack_64.c
@@ -1,302 +1,221 @@
+// 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/module.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>
 
-
-#define N_EXCEPTION_STACKS_END \
-		(N_EXCEPTION_STACKS + DEBUG_STKSZ/EXCEPTION_STKSZ - 2)
-
-static char x86_stack_ids[][8] = {
-		[ DEBUG_STACK-1			]	= "#DB",
-		[ NMI_STACK-1			]	= "NMI",
-		[ DOUBLEFAULT_STACK-1		]	= "#DF",
-		[ STACKFAULT_STACK-1		]	= "#SS",
-		[ MCE_STACK-1			]	= "#MC",
-#if DEBUG_STKSZ > EXCEPTION_STKSZ
-		[ N_EXCEPTION_STACKS ...
-		  N_EXCEPTION_STACKS_END	]	= "#DB[?]"
-#endif
+static const char * const exception_stack_names[] = {
+		[ ESTACK_DF	]	= "#DF",
+		[ ESTACK_NMI	]	= "NMI",
+		[ ESTACK_DB	]	= "#DB",
+		[ ESTACK_MCE	]	= "#MC",
+		[ ESTACK_VC	]	= "#VC",
+		[ ESTACK_VC2	]	= "#VC2",
 };
 
-static unsigned long *in_exception_stack(unsigned cpu, unsigned long stack,
-					 unsigned *usedp, char **idp)
+const char *stack_type_name(enum stack_type type)
 {
-	unsigned k;
+	BUILD_BUG_ON(N_EXCEPTION_STACKS != 6);
 
-	/*
-	 * Iterate over all exception stacks, and figure out whether
-	 * 'stack' is in one of them:
-	 */
-	for (k = 0; k < N_EXCEPTION_STACKS; k++) {
-		unsigned long end = per_cpu(orig_ist, cpu).ist[k];
-		/*
-		 * Is 'stack' above this exception frame's end?
-		 * If yes then skip to the next frame.
-		 */
-		if (stack >= end)
-			continue;
-		/*
-		 * Is 'stack' above this exception frame's start address?
-		 * If yes then we found the right frame.
-		 */
-		if (stack >= end - EXCEPTION_STKSZ) {
-			/*
-			 * Make sure we only iterate through an exception
-			 * stack once. If it comes up for the second time
-			 * then there's something wrong going on - just
-			 * break out and return NULL:
-			 */
-			if (*usedp & (1U << k))
-				break;
-			*usedp |= 1U << k;
-			*idp = x86_stack_ids[k];
-			return (unsigned long *)end;
-		}
+	if (type == STACK_TYPE_TASK)
+		return "TASK";
+
+	if (type == STACK_TYPE_IRQ)
+		return "IRQ";
+
+	if (type == STACK_TYPE_SOFTIRQ)
+		return "SOFTIRQ";
+
+	if (type == STACK_TYPE_ENTRY) {
 		/*
-		 * If this is a debug stack, and if it has a larger size than
-		 * the usual exception stacks, then 'stack' might still
-		 * be within the lower portion of the debug stack:
+		 * On 64-bit, we have a generic entry stack that we
+		 * use for all the kernel entry points, including
+		 * SYSENTER.
 		 */
-#if DEBUG_STKSZ > EXCEPTION_STKSZ
-		if (k == DEBUG_STACK - 1 && stack >= end - DEBUG_STKSZ) {
-			unsigned j = N_EXCEPTION_STACKS - 1;
-
-			/*
-			 * Black magic. A large debug stack is composed of
-			 * multiple exception stack entries, which we
-			 * iterate through now. Dont look:
-			 */
-			do {
-				++j;
-				end -= EXCEPTION_STKSZ;
-				x86_stack_ids[j][4] = '1' +
-						(j - N_EXCEPTION_STACKS);
-			} while (stack < end - EXCEPTION_STKSZ);
-			if (*usedp & (1U << j))
-				break;
-			*usedp |= 1U << j;
-			*idp = x86_stack_ids[j];
-			return (unsigned long *)end;
-		}
-#endif
+		return "ENTRY_TRAMPOLINE";
 	}
+
+	if (type >= STACK_TYPE_EXCEPTION && type <= STACK_TYPE_EXCEPTION_LAST)
+		return exception_stack_names[type - STACK_TYPE_EXCEPTION];
+
 	return NULL;
 }
 
-static inline int
-in_irq_stack(unsigned long *stack, unsigned long *irq_stack,
-	     unsigned long *irq_stack_end)
-{
-	return (stack >= irq_stack && stack < irq_stack_end);
-}
+/**
+ * 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, }
 
 /*
- * x86-64 can have up to three kernel stacks:
- * process stack
- * interrupt stack
- * severe exception (double fault, nmi, stack fault, debug, mce) hardware stack
+ * 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),
+};
 
-void dump_trace(struct task_struct *task, struct pt_regs *regs,
-		unsigned long *stack, unsigned long bp,
-		const struct stacktrace_ops *ops, void *data)
+static __always_inline bool in_exception_stack(unsigned long *stack, struct stack_info *info)
 {
-	const unsigned cpu = get_cpu();
-	unsigned long *irq_stack_end =
-		(unsigned long *)per_cpu(irq_stack_ptr, cpu);
-	unsigned used = 0;
-	struct thread_info *tinfo;
-	int graph = 0;
-	unsigned long dummy;
-
-	if (!task)
-		task = current;
-
-	if (!stack) {
-		if (regs)
-			stack = (unsigned long *)regs->sp;
-		else if (task != current)
-			stack = (unsigned long *)task->thread.sp;
-		else
-			stack = &dummy;
-	}
+	unsigned long begin, end, stk = (unsigned long)stack;
+	const struct estack_pages *ep;
+	struct pt_regs *regs;
+	unsigned int k;
 
-	if (!bp)
-		bp = stack_frame(task, regs);
-	/*
-	 * Print function call entries in all stacks, starting at the
-	 * current stack address. If the stacks consist of nested
-	 * exceptions
-	 */
-	tinfo = task_thread_info(task);
-	for (;;) {
-		char *id;
-		unsigned long *estack_end;
-		estack_end = in_exception_stack(cpu, (unsigned long)stack,
-						&used, &id);
-
-		if (estack_end) {
-			if (ops->stack(data, id) < 0)
-				break;
-
-			bp = ops->walk_stack(tinfo, stack, bp, ops,
-					     data, estack_end, &graph);
-			ops->stack(data, "<EOE>");
-			/*
-			 * We link to the next stack via the
-			 * second-to-last pointer (index -2 to end) in the
-			 * exception stack:
-			 */
-			stack = (unsigned long *) estack_end[-2];
-			continue;
-		}
-		if (irq_stack_end) {
-			unsigned long *irq_stack;
-			irq_stack = irq_stack_end -
-				(IRQ_STACK_SIZE - 64) / sizeof(*irq_stack);
-
-			if (in_irq_stack(stack, irq_stack, irq_stack_end)) {
-				if (ops->stack(data, "IRQ") < 0)
-					break;
-				bp = ops->walk_stack(tinfo, stack, bp,
-					ops, data, irq_stack_end, &graph);
-				/*
-				 * We link to the next stack (which would be
-				 * the process stack normally) the last
-				 * pointer (index -1 to end) in the IRQ stack:
-				 */
-				stack = (unsigned long *) (irq_stack_end[-1]);
-				irq_stack_end = NULL;
-				ops->stack(data, "EOI");
-				continue;
-			}
-		}
-		break;
-	}
+	BUILD_BUG_ON(N_EXCEPTION_STACKS != 6);
 
+	begin = (unsigned long)__this_cpu_read(cea_exception_stacks);
 	/*
-	 * This handles the process stack:
+	 * Handle the case where stack trace is collected _before_
+	 * cea_exception_stacks had been initialized.
 	 */
-	bp = ops->walk_stack(tinfo, stack, bp, ops, data, NULL, &graph);
-	put_cpu();
+	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;
 }
-EXPORT_SYMBOL(dump_trace);
 
-void
-show_stack_log_lvl(struct task_struct *task, struct pt_regs *regs,
-		   unsigned long *sp, unsigned long bp, char *log_lvl)
+static __always_inline bool in_irq_stack(unsigned long *stack, struct stack_info *info)
 {
-	unsigned long *irq_stack_end;
-	unsigned long *irq_stack;
-	unsigned long *stack;
-	int cpu;
-	int i;
+	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));
 
-	preempt_disable();
-	cpu = smp_processor_id();
+	/*
+	 * 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;
 
-	irq_stack_end	= (unsigned long *)(per_cpu(irq_stack_ptr, cpu));
-	irq_stack	= (unsigned long *)(per_cpu(irq_stack_ptr, cpu) - IRQ_STACK_SIZE);
+	info->type	= STACK_TYPE_IRQ;
+	info->begin	= begin;
+	info->end	= end;
 
 	/*
-	 * Debugging aid: "show_stack(NULL, NULL);" prints the
-	 * back trace for this cpu:
+	 * The next stack pointer is stored at the top of the irq stack
+	 * before switching to the irq stack. Actual stack entries are all
+	 * below that.
 	 */
-	if (sp == NULL) {
-		if (task)
-			sp = (unsigned long *)task->thread.sp;
-		else
-			sp = (unsigned long *)&sp;
-	}
+	info->next_sp = (unsigned long *)*(end - 1);
 
-	stack = sp;
-	for (i = 0; i < kstack_depth_to_print; i++) {
-		if (stack >= irq_stack && stack <= irq_stack_end) {
-			if (stack == irq_stack_end) {
-				stack = (unsigned long *) (irq_stack_end[-1]);
-				pr_cont(" <EOI> ");
-			}
-		} else {
-		if (((long) stack & (THREAD_SIZE-1)) == 0)
-			break;
-		}
-		if (i && ((i % STACKSLOTS_PER_LINE) == 0))
-			pr_cont("\n");
-		pr_cont(" %016lx", *stack++);
-		touch_nmi_watchdog();
-	}
-	preempt_enable();
+	return true;
+}
 
-	pr_cont("\n");
-	show_trace_log_lvl(task, regs, sp, bp, log_lvl);
+bool noinstr get_stack_info_noinstr(unsigned long *stack, struct task_struct *task,
+				    struct stack_info *info)
+{
+	if (in_task_stack(stack, task, info))
+		return true;
+
+	if (task != current)
+		return false;
+
+	if (in_exception_stack(stack, info))
+		return true;
+
+	if (in_irq_stack(stack, info))
+		return true;
+
+	if (in_entry_stack(stack, info))
+		return true;
+
+	return false;
 }
 
-void show_regs(struct pt_regs *regs)
+int get_stack_info(unsigned long *stack, struct task_struct *task,
+		   struct stack_info *info, unsigned long *visit_mask)
 {
-	int i;
-	unsigned long sp;
+	task = task ? : current;
 
-	sp = regs->sp;
-	show_regs_print_info(KERN_DEFAULT);
-	__show_regs(regs, 1);
+	if (!stack)
+		goto unknown;
+
+	if (!get_stack_info_noinstr(stack, task, info))
+		goto unknown;
 
 	/*
-	 * When in-kernel, we also print out the stack and code at the
-	 * time of the fault..
+	 * 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 (!user_mode(regs)) {
-		unsigned int code_prologue = code_bytes * 43 / 64;
-		unsigned int code_len = code_bytes;
-		unsigned char c;
-		u8 *ip;
-
-		printk(KERN_DEFAULT "Stack:\n");
-		show_stack_log_lvl(NULL, regs, (unsigned long *)sp,
-				   0, KERN_DEFAULT);
-
-		printk(KERN_DEFAULT "Code: ");
-
-		ip = (u8 *)regs->ip - code_prologue;
-		if (ip < (u8 *)PAGE_OFFSET || probe_kernel_address(ip, c)) {
-			/* try starting at IP */
-			ip = (u8 *)regs->ip;
-			code_len = code_len - code_prologue + 1;
-		}
-		for (i = 0; i < code_len; i++, ip++) {
-			if (ip < (u8 *)PAGE_OFFSET ||
-					probe_kernel_address(ip, c)) {
-				pr_cont(" Bad RIP value.");
-				break;
-			}
-			if (ip == (u8 *)regs->ip)
-				pr_cont("<%02x> ", c);
-			else
-				pr_cont("%02x ", c);
+	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;
 	}
-	pr_cont("\n");
-}
-
-int is_valid_bugaddr(unsigned long ip)
-{
-	unsigned short ud2;
 
-	if (__copy_from_user(&ud2, (const void __user *) ip, sizeof(ud2)))
-		return 0;
+	return 0;
 
-	return ud2 == 0x0b0f;
+unknown:
+	info->type = STACK_TYPE_UNKNOWN;
+	return -EINVAL;
 }