1 files changed, 114 insertions, 0 deletions
diff --git a/drivers/gator/gator_backtrace.c b/drivers/gator/gator_backtrace.c
new file mode 100644
index 00000000000..50783d69594
--- /dev/null
+++ b/drivers/gator/gator_backtrace.c
@@ -0,0 +1,114 @@
+/**
+ * Copyright (C) ARM Limited 2010-2012. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ */
+
+/*
+ * EABI backtrace stores {fp,lr} on the stack.
+ */
+struct frame_tail_eabi {
+	unsigned long fp; // points to prev_lr
+	unsigned long lr;
+};
+
+static void arm_backtrace_eabi(int cpu, int buftype, struct pt_regs * const regs, unsigned int depth)
+{
+#if defined(__arm__)
+	struct frame_tail_eabi *tail;
+	struct frame_tail_eabi *next;
+	struct frame_tail_eabi *ptrtail;
+	struct frame_tail_eabi buftail;
+	unsigned long fp = regs->ARM_fp;
+	unsigned long sp = regs->ARM_sp;
+	unsigned long lr = regs->ARM_lr;
+	int is_user_mode = user_mode(regs);
+
+	if (!is_user_mode) {
+		return;
+	}
+
+	/* entry preamble may not have executed */
+	gator_add_trace(cpu, buftype, lr);
+
+	/* check tail is valid */
+	if (fp == 0 || fp < sp) {
+		return;
+	}
+
+	tail = (struct frame_tail_eabi *)(fp - 4);
+
+	while (depth-- && tail && !((unsigned long) tail & 3)) {
+		/* Also check accessibility of one struct frame_tail beyond */
+		if (!access_ok(VERIFY_READ, tail, sizeof(struct frame_tail_eabi)))
+			return;
+		if (__copy_from_user_inatomic(&buftail, tail, sizeof(struct frame_tail_eabi)))
+			return;
+		ptrtail = &buftail;
+
+		lr = ptrtail[0].lr;
+		gator_add_trace(cpu, buftype, lr);
+
+		/* frame pointers should progress back up the stack, towards higher addresses */
+		next = (struct frame_tail_eabi *)(lr - 4);
+		if (tail >= next || lr == 0) {
+			fp = ptrtail[0].fp;
+			next = (struct frame_tail_eabi *)(fp - 4);
+			/* check tail is valid */
+			if (tail >= next || fp == 0) {
+				return;
+			}
+		}
+
+		tail = next;
+	}
+#endif
+}
+
+#if defined(__arm__)
+static DEFINE_PER_CPU(int, backtrace_buffer);
+static int report_trace(struct stackframe *frame, void *d)
+{
+	struct module *mod;
+	unsigned int *depth = d, addr = frame->pc, cookie = NO_COOKIE, cpu = smp_processor_id();
+
+	if (*depth) {
+		mod = __module_address(addr);
+		if (mod) {
+			cookie = get_cookie(cpu, per_cpu(backtrace_buffer, cpu), current, NULL, mod, true);
+			addr = addr - (unsigned long)mod->module_core;
+		}
+		marshal_backtrace(addr & ~1, cookie);
+		(*depth)--;
+	}
+
+	return *depth == 0;
+}
+#endif
+
+// Uncomment the following line to enable kernel stack unwinding within gator, note it can also be defined from the Makefile
+// #define GATOR_KERNEL_STACK_UNWINDING
+static void kernel_backtrace(int cpu, int buftype, struct pt_regs * const regs)
+{
+#if defined(__arm__)
+#ifdef GATOR_KERNEL_STACK_UNWINDING
+	int depth = gator_backtrace_depth;
+#else
+	int depth = 1;
+#endif
+	struct stackframe frame;
+	if (depth == 0)
+		depth = 1;
+	frame.fp = regs->ARM_fp;
+	frame.sp = regs->ARM_sp;
+	frame.lr = regs->ARM_lr;
+	frame.pc = regs->ARM_pc;
+	per_cpu(backtrace_buffer, cpu) = buftype;
+	walk_stackframe(&frame, report_trace, &depth);
+#else
+	marshal_backtrace(PC_REG & ~1, NO_COOKIE);
+#endif
+}