1 files changed, 112 insertions, 95 deletions

diff --git a/arch/x86/kernel/dumpstack_32.c b/arch/x86/kernel/dumpstack_32.c
index f2a1770ca176..722fd712e1cf 100644
--- a/arch/x86/kernel/dumpstack_32.c
+++ b/arch/x86/kernel/dumpstack_32.c
@@ -1,13 +1,15 @@
+// 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>
@@ -16,123 +18,138 @@
 
 #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";
 
-void dump_trace(struct task_struct *task, struct pt_regs *regs,
-		unsigned long *stack, unsigned long bp,
-		const struct stacktrace_ops *ops, void *data)
+	if (type == STACK_TYPE_EXCEPTION)
+		return "#DF";
+
+	return NULL;
+}
+
+static bool in_hardirq_stack(unsigned long *stack, struct stack_info *info)
 {
-	int graph = 0;
+	unsigned long *begin = (unsigned long *)this_cpu_read(hardirq_stack_ptr);
+	unsigned long *end   = begin + (THREAD_SIZE / sizeof(long));
 
-	if (!task)
-		task = current;
+	/*
+	 * 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;
 
-	if (!stack) {
-		unsigned long dummy;
+	info->type	= STACK_TYPE_IRQ;
+	info->begin	= begin;
+	info->end	= end;
 
-		stack = &dummy;
-		if (task && task != current)
-			stack = (unsigned long *)task->thread.sp;
-	}
+	/*
+	 * See irq_32.c -- the next stack pointer is stored at the beginning of
+	 * the stack.
+	 */
+	info->next_sp	= (unsigned long *)*begin;
 
-	if (!bp)
-		bp = stack_frame(task, regs);
+	return true;
+}
 
-	for (;;) {
-		struct thread_info *context;
+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));
 
-		context = (struct thread_info *)
-			((unsigned long)stack & (~(THREAD_SIZE - 1)));
-		bp = ops->walk_stack(context, stack, bp, ops, data, NULL, &graph);
+	/*
+	 * 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;
 
-		stack = (unsigned long *)context->previous_esp;
-		if (!stack)
-			break;
-		if (ops->stack(data, "IRQ") < 0)
-			break;
-		touch_nmi_watchdog();
-	}
+	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;
 }
-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 bool in_doublefault_stack(unsigned long *stack, struct stack_info *info)
 {
-	unsigned long *stack;
-	int i;
-
-	if (sp == NULL) {
-		if (task)
-			sp = (unsigned long *)task->thread.sp;
-		else
-			sp = (unsigned long *)&sp;
-	}
+	struct cpu_entry_area *cea = get_cpu_entry_area(raw_smp_processor_id());
+	struct doublefault_stack *ss = &cea->doublefault_stack;
 
-	stack = sp;
-	for (i = 0; i < kstack_depth_to_print; i++) {
-		if (kstack_end(stack))
-			break;
-		if (i && ((i % STACKSLOTS_PER_LINE) == 0))
-			pr_cont("\n");
-		pr_cont(" %08lx", *stack++);
-		touch_nmi_watchdog();
-	}
-	pr_cont("\n");
-	show_trace_log_lvl(task, regs, sp, bp, log_lvl);
+	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;
 }
 
 
-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;
+	if (!stack)
+		goto unknown;
+
+	task = task ? : current;
+
+	if (in_task_stack(stack, task, info))
+		goto recursion_check;
 
-	show_regs_print_info(KERN_EMERG);
-	__show_regs(regs, !user_mode_vm(regs));
+	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:
 	/*
-	 * 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_vm(regs)) {
-		unsigned int code_prologue = code_bytes * 43 / 64;
-		unsigned int code_len = code_bytes;
-		unsigned char c;
-		u8 *ip;
-
-		pr_emerg("Stack:\n");
-		show_stack_log_lvl(NULL, regs, &regs->sp, 0, KERN_EMERG);
-
-		pr_emerg("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 EIP 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)) {
+			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 (ip < PAGE_OFFSET)
-		return 0;
-	if (probe_kernel_address((unsigned short *)ip, ud2))
-		return 0;
+	return 0;
 
-	return ud2 == 0x0b0f;
+unknown:
+	info->type = STACK_TYPE_UNKNOWN;
+	return -EINVAL;
 }