3 files changed, 206 insertions, 0 deletions
diff --git a/arch/xtensa/oprofile/Makefile b/arch/xtensa/oprofile/Makefile
new file mode 100644
index 000000000000..69ffbe80f184
--- /dev/null
+++ b/arch/xtensa/oprofile/Makefile
@@ -0,0 +1,9 @@
+obj-$(CONFIG_OPROFILE) += oprofile.o
+
+DRIVER_OBJS = $(addprefix ../../../drivers/oprofile/, \
+		oprof.o cpu_buffer.o buffer_sync.o \
+		event_buffer.o oprofile_files.o \
+		oprofilefs.o oprofile_stats.o \
+		timer_int.o )
+
+oprofile-y := $(DRIVER_OBJS) init.o backtrace.o
diff --git a/arch/xtensa/oprofile/backtrace.c b/arch/xtensa/oprofile/backtrace.c
new file mode 100644
index 000000000000..66f32ee2c982
--- /dev/null
+++ b/arch/xtensa/oprofile/backtrace.c
@@ -0,0 +1,171 @@
+/**
+ * @file backtrace.c
+ *
+ * @remark Copyright 2008 Tensilica Inc.
+ * @remark Read the file COPYING
+ *
+ */
+
+#include <linux/oprofile.h>
+#include <linux/sched.h>
+#include <linux/mm.h>
+#include <asm/ptrace.h>
+#include <asm/uaccess.h>
+#include <asm/traps.h>
+
+/* Address of common_exception_return, used to check the
+ * transition from kernel to user space.
+ */
+extern int common_exception_return;
+
+/* A struct that maps to the part of the frame containing the a0 and
+ * a1 registers.
+ */
+struct frame_start {
+	unsigned long a0;
+	unsigned long a1;
+};
+
+static void xtensa_backtrace_user(struct pt_regs *regs, unsigned int depth)
+{
+	unsigned long windowstart = regs->windowstart;
+	unsigned long windowbase = regs->windowbase;
+	unsigned long a0 = regs->areg[0];
+	unsigned long a1 = regs->areg[1];
+	unsigned long pc = MAKE_PC_FROM_RA(a0, regs->pc);
+	int index;
+
+	/* First add the current PC to the trace. */
+	if (pc != 0 && pc <= TASK_SIZE)
+		oprofile_add_trace(pc);
+	else
+		return;
+
+	/* Two steps:
+	 *
+	 * 1. Look through the register window for the
+	 * previous PCs in the call trace.
+	 *
+	 * 2. Look on the stack.
+	 */
+
+	/* Step 1.  */
+	/* Rotate WINDOWSTART to move the bit corresponding to
+	 * the current window to the bit #0.
+	 */
+	windowstart = (windowstart << WSBITS | windowstart) >> windowbase;
+
+	/* Look for bits that are set, they correspond to
+	 * valid windows.
+	 */
+	for (index = WSBITS - 1; (index > 0) && depth; depth--, index--)
+		if (windowstart & (1 << index)) {
+			/* Read a0 and a1 from the
+			 * corresponding position in AREGs.
+			 */
+			a0 = regs->areg[index * 4];
+			a1 = regs->areg[index * 4 + 1];
+			/* Get the PC from a0 and a1. */
+			pc = MAKE_PC_FROM_RA(a0, pc);
+
+			/* Add the PC to the trace. */
+			if (pc != 0 && pc <= TASK_SIZE)
+				oprofile_add_trace(pc);
+			else
+				return;
+		}
+
+	/* Step 2. */
+	/* We are done with the register window, we need to
+	 * look through the stack.
+	 */
+	if (depth > 0) {
+		/* Start from the a1 register. */
+		/* a1 = regs->areg[1]; */
+		while (a0 != 0 && depth--) {
+
+			struct frame_start frame_start;
+			/* Get the location for a1, a0 for the
+			 * previous frame from the current a1.
+			 */
+			unsigned long *psp = (unsigned long *)a1;
+			psp -= 4;
+
+			/* Check if the region is OK to access. */
+			if (!access_ok(VERIFY_READ, psp, sizeof(frame_start)))
+				return;
+			/* Copy a1, a0 from user space stack frame. */
+			if (__copy_from_user_inatomic(&frame_start, psp,
+						sizeof(frame_start)))
+				return;
+
+			a0 = frame_start.a0;
+			a1 = frame_start.a1;
+			pc = MAKE_PC_FROM_RA(a0, pc);
+
+			if (pc != 0 && pc <= TASK_SIZE)
+				oprofile_add_trace(pc);
+			else
+				return;
+		}
+	}
+}
+
+static void xtensa_backtrace_kernel(struct pt_regs *regs, unsigned int depth)
+{
+	unsigned long pc = regs->pc;
+	unsigned long *psp;
+	unsigned long sp_start, sp_end;
+	unsigned long a0 = regs->areg[0];
+	unsigned long a1 = regs->areg[1];
+
+	sp_start = a1 & ~(THREAD_SIZE-1);
+	sp_end = sp_start + THREAD_SIZE;
+
+	/* Spill the register window to the stack first. */
+	spill_registers();
+
+	/* Read the stack frames one by one and create the PC
+	 * from the a0 and a1 registers saved there.
+	 */
+	while (a1 > sp_start && a1 < sp_end && depth--) {
+		pc = MAKE_PC_FROM_RA(a0, pc);
+
+		/* Add the PC to the trace. */
+		if (kernel_text_address(pc))
+			oprofile_add_trace(pc);
+
+		if (pc == (unsigned long) &common_exception_return) {
+			regs = (struct pt_regs *)a1;
+			if (user_mode(regs)) {
+				pc = regs->pc;
+				if (pc != 0 && pc <= TASK_SIZE)
+					oprofile_add_trace(pc);
+				else
+					return;
+				return xtensa_backtrace_user(regs, depth);
+			}
+			a0 = regs->areg[0];
+			a1 = regs->areg[1];
+			continue;
+		}
+
+		psp = (unsigned long *)a1;
+
+		a0 = *(psp - 4);
+		a1 = *(psp - 3);
+
+		if (a1 <= (unsigned long)psp)
+			return;
+
+	}
+	return;
+}
+
+void xtensa_backtrace(struct pt_regs * const regs, unsigned int depth)
+{
+	if (user_mode(regs))
+		xtensa_backtrace_user(regs, depth);
+	else
+		xtensa_backtrace_kernel(regs, depth);
+}
diff --git a/arch/xtensa/oprofile/init.c b/arch/xtensa/oprofile/init.c
new file mode 100644
index 000000000000..a67eea379766
--- /dev/null
+++ b/arch/xtensa/oprofile/init.c
@@ -0,0 +1,26 @@
+/**
+ * @file init.c
+ *
+ * @remark Copyright 2008 Tensilica Inc.
+ * @remark Read the file COPYING
+ *
+ */
+
+#include <linux/kernel.h>
+#include <linux/oprofile.h>
+#include <linux/errno.h>
+#include <linux/init.h>
+
+
+extern void xtensa_backtrace(struct pt_regs *const regs, unsigned int depth);
+
+int __init oprofile_arch_init(struct oprofile_operations *ops)
+{
+	ops->backtrace = xtensa_backtrace;
+	return -ENODEV;
+}
+
+
+void oprofile_arch_exit(void)
+{
+}