From 57f0f512b273f60d52568b8c6b77e17f5636edc0 Mon Sep 17 00:00:00 2001
From: André Fabian Silva Delgado <emulatorman@parabola.nu>
Date: Wed, 5 Aug 2015 17:04:01 -0300
Subject: Initial import

---
 arch/x86/kernel/stacktrace.c | 146 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 146 insertions(+)
 create mode 100644 arch/x86/kernel/stacktrace.c

(limited to 'arch/x86/kernel/stacktrace.c')

diff --git a/arch/x86/kernel/stacktrace.c b/arch/x86/kernel/stacktrace.c
new file mode 100644
index 000000000..fdd0c6430
--- /dev/null
+++ b/arch/x86/kernel/stacktrace.c
@@ -0,0 +1,146 @@
+/*
+ * Stack trace management functions
+ *
+ *  Copyright (C) 2006-2009 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
+ */
+#include <linux/sched.h>
+#include <linux/stacktrace.h>
+#include <linux/module.h>
+#include <linux/uaccess.h>
+#include <asm/stacktrace.h>
+
+static int save_stack_stack(void *data, char *name)
+{
+	return 0;
+}
+
+static void
+__save_stack_address(void *data, unsigned long addr, bool reliable, bool nosched)
+{
+	struct stack_trace *trace = data;
+#ifdef CONFIG_FRAME_POINTER
+	if (!reliable)
+		return;
+#endif
+	if (nosched && in_sched_functions(addr))
+		return;
+	if (trace->skip > 0) {
+		trace->skip--;
+		return;
+	}
+	if (trace->nr_entries < trace->max_entries)
+		trace->entries[trace->nr_entries++] = addr;
+}
+
+static void save_stack_address(void *data, unsigned long addr, int reliable)
+{
+	return __save_stack_address(data, addr, reliable, false);
+}
+
+static void
+save_stack_address_nosched(void *data, unsigned long addr, int reliable)
+{
+	return __save_stack_address(data, addr, reliable, true);
+}
+
+static const struct stacktrace_ops save_stack_ops = {
+	.stack		= save_stack_stack,
+	.address	= save_stack_address,
+	.walk_stack	= print_context_stack,
+};
+
+static const struct stacktrace_ops save_stack_ops_nosched = {
+	.stack		= save_stack_stack,
+	.address	= save_stack_address_nosched,
+	.walk_stack	= print_context_stack,
+};
+
+/*
+ * Save stack-backtrace addresses into a stack_trace buffer.
+ */
+void save_stack_trace(struct stack_trace *trace)
+{
+	dump_trace(current, NULL, NULL, 0, &save_stack_ops, trace);
+	if (trace->nr_entries < trace->max_entries)
+		trace->entries[trace->nr_entries++] = ULONG_MAX;
+}
+EXPORT_SYMBOL_GPL(save_stack_trace);
+
+void save_stack_trace_regs(struct pt_regs *regs, struct stack_trace *trace)
+{
+	dump_trace(current, regs, NULL, 0, &save_stack_ops, trace);
+	if (trace->nr_entries < trace->max_entries)
+		trace->entries[trace->nr_entries++] = ULONG_MAX;
+}
+
+void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
+{
+	dump_trace(tsk, NULL, NULL, 0, &save_stack_ops_nosched, trace);
+	if (trace->nr_entries < trace->max_entries)
+		trace->entries[trace->nr_entries++] = ULONG_MAX;
+}
+EXPORT_SYMBOL_GPL(save_stack_trace_tsk);
+
+/* Userspace stacktrace - based on kernel/trace/trace_sysprof.c */
+
+struct stack_frame_user {
+	const void __user	*next_fp;
+	unsigned long		ret_addr;
+};
+
+static int
+copy_stack_frame(const void __user *fp, struct stack_frame_user *frame)
+{
+	int ret;
+
+	if (!access_ok(VERIFY_READ, fp, sizeof(*frame)))
+		return 0;
+
+	ret = 1;
+	pagefault_disable();
+	if (__copy_from_user_inatomic(frame, fp, sizeof(*frame)))
+		ret = 0;
+	pagefault_enable();
+
+	return ret;
+}
+
+static inline void __save_stack_trace_user(struct stack_trace *trace)
+{
+	const struct pt_regs *regs = task_pt_regs(current);
+	const void __user *fp = (const void __user *)regs->bp;
+
+	if (trace->nr_entries < trace->max_entries)
+		trace->entries[trace->nr_entries++] = regs->ip;
+
+	while (trace->nr_entries < trace->max_entries) {
+		struct stack_frame_user frame;
+
+		frame.next_fp = NULL;
+		frame.ret_addr = 0;
+		if (!copy_stack_frame(fp, &frame))
+			break;
+		if ((unsigned long)fp < regs->sp)
+			break;
+		if (frame.ret_addr) {
+			trace->entries[trace->nr_entries++] =
+				frame.ret_addr;
+		}
+		if (fp == frame.next_fp)
+			break;
+		fp = frame.next_fp;
+	}
+}
+
+void save_stack_trace_user(struct stack_trace *trace)
+{
+	/*
+	 * Trace user stack if we are not a kernel thread
+	 */
+	if (current->mm) {
+		__save_stack_trace_user(trace);
+	}
+	if (trace->nr_entries < trace->max_entries)
+		trace->entries[trace->nr_entries++] = ULONG_MAX;
+}
+
-- 
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