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/oprofile/backtrace.c | 127 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 127 insertions(+)
 create mode 100644 arch/x86/oprofile/backtrace.c

(limited to 'arch/x86/oprofile/backtrace.c')

diff --git a/arch/x86/oprofile/backtrace.c b/arch/x86/oprofile/backtrace.c
new file mode 100644
index 000000000..4e664bdb5
--- /dev/null
+++ b/arch/x86/oprofile/backtrace.c
@@ -0,0 +1,127 @@
+/**
+ * @file backtrace.c
+ *
+ * @remark Copyright 2002 OProfile authors
+ * @remark Read the file COPYING
+ *
+ * @author John Levon
+ * @author David Smith
+ */
+
+#include <linux/oprofile.h>
+#include <linux/sched.h>
+#include <linux/mm.h>
+#include <linux/compat.h>
+#include <linux/uaccess.h>
+
+#include <asm/ptrace.h>
+#include <asm/stacktrace.h>
+
+static int backtrace_stack(void *data, char *name)
+{
+	/* Yes, we want all stacks */
+	return 0;
+}
+
+static void backtrace_address(void *data, unsigned long addr, int reliable)
+{
+	unsigned int *depth = data;
+
+	if ((*depth)--)
+		oprofile_add_trace(addr);
+}
+
+static struct stacktrace_ops backtrace_ops = {
+	.stack		= backtrace_stack,
+	.address	= backtrace_address,
+	.walk_stack	= print_context_stack,
+};
+
+#ifdef CONFIG_COMPAT
+static struct stack_frame_ia32 *
+dump_user_backtrace_32(struct stack_frame_ia32 *head)
+{
+	/* Also check accessibility of one struct frame_head beyond: */
+	struct stack_frame_ia32 bufhead[2];
+	struct stack_frame_ia32 *fp;
+	unsigned long bytes;
+
+	bytes = copy_from_user_nmi(bufhead, head, sizeof(bufhead));
+	if (bytes != 0)
+		return NULL;
+
+	fp = (struct stack_frame_ia32 *) compat_ptr(bufhead[0].next_frame);
+
+	oprofile_add_trace(bufhead[0].return_address);
+
+	/* frame pointers should strictly progress back up the stack
+	* (towards higher addresses) */
+	if (head >= fp)
+		return NULL;
+
+	return fp;
+}
+
+static inline int
+x86_backtrace_32(struct pt_regs * const regs, unsigned int depth)
+{
+	struct stack_frame_ia32 *head;
+
+	/* User process is IA32 */
+	if (!current || !test_thread_flag(TIF_IA32))
+		return 0;
+
+	head = (struct stack_frame_ia32 *) regs->bp;
+	while (depth-- && head)
+		head = dump_user_backtrace_32(head);
+
+	return 1;
+}
+
+#else
+static inline int
+x86_backtrace_32(struct pt_regs * const regs, unsigned int depth)
+{
+	return 0;
+}
+#endif /* CONFIG_COMPAT */
+
+static struct stack_frame *dump_user_backtrace(struct stack_frame *head)
+{
+	/* Also check accessibility of one struct frame_head beyond: */
+	struct stack_frame bufhead[2];
+	unsigned long bytes;
+
+	bytes = copy_from_user_nmi(bufhead, head, sizeof(bufhead));
+	if (bytes != 0)
+		return NULL;
+
+	oprofile_add_trace(bufhead[0].return_address);
+
+	/* frame pointers should strictly progress back up the stack
+	 * (towards higher addresses) */
+	if (head >= bufhead[0].next_frame)
+		return NULL;
+
+	return bufhead[0].next_frame;
+}
+
+void
+x86_backtrace(struct pt_regs * const regs, unsigned int depth)
+{
+	struct stack_frame *head = (struct stack_frame *)frame_pointer(regs);
+
+	if (!user_mode(regs)) {
+		unsigned long stack = kernel_stack_pointer(regs);
+		if (depth)
+			dump_trace(NULL, regs, (unsigned long *)stack, 0,
+				   &backtrace_ops, &depth);
+		return;
+	}
+
+	if (x86_backtrace_32(regs, depth))
+		return;
+
+	while (depth-- && head)
+		head = dump_user_backtrace(head);
+}
-- 
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