Initial commit

arch/tile/include/asm/backtrace.h

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+/*
+ * Copyright 2010 Tilera Corporation. 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
+ *   as published by the Free Software Foundation, version 2.
+ *
+ *   This program is distributed in the hope that it will be useful, but
+ *   WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
+ *   NON INFRINGEMENT.  See the GNU General Public License for
+ *   more details.
+ */
+
+#ifndef _ASM_TILE_BACKTRACE_H
+#define _ASM_TILE_BACKTRACE_H
+
+#include <linux/types.h>
+
+/* Reads 'size' bytes from 'address' and writes the data to 'result'.
+ * Returns true if successful, else false (e.g. memory not readable).
+ */
+typedef bool (*BacktraceMemoryReader)(void *result,
+				      unsigned long address,
+				      unsigned int size,
+				      void *extra);
+
+typedef struct {
+	/* Current PC. */
+	unsigned long pc;
+
+	/* Current stack pointer value. */
+	unsigned long sp;
+
+	/* Current frame pointer value (i.e. caller's stack pointer) */
+	unsigned long fp;
+
+	/* Internal use only: caller's PC for first frame. */
+	unsigned long initial_frame_caller_pc;
+
+	/* Internal use only: callback to read memory. */
+	BacktraceMemoryReader read_memory_func;
+
+	/* Internal use only: arbitrary argument to read_memory_func. */
+	void *read_memory_func_extra;
+
+} BacktraceIterator;
+
+
+typedef enum {
+
+	/* We have no idea what the caller's pc is. */
+	PC_LOC_UNKNOWN,
+
+	/* The caller's pc is currently in lr. */
+	PC_LOC_IN_LR,
+
+	/* The caller's pc can be found by dereferencing the caller's sp. */
+	PC_LOC_ON_STACK
+
+} CallerPCLocation;
+
+
+typedef enum {
+
+	/* We have no idea what the caller's sp is. */
+	SP_LOC_UNKNOWN,
+
+	/* The caller's sp is currently in r52. */
+	SP_LOC_IN_R52,
+
+	/* The caller's sp can be found by adding a certain constant
+	 * to the current value of sp.
+	 */
+	SP_LOC_OFFSET
+
+} CallerSPLocation;
+
+
+/* Bit values ORed into CALLER_* values for info ops. */
+enum {
+	/* Setting the low bit on any of these values means the info op
+	 * applies only to one bundle ago.
+	 */
+	ONE_BUNDLE_AGO_FLAG = 1,
+
+	/* Setting this bit on a CALLER_SP_* value means the PC is in LR.
+	 * If not set, PC is on the stack.
+	 */
+	PC_IN_LR_FLAG = 2,
+
+	/* This many of the low bits of a CALLER_SP_* value are for the
+	 * flag bits above.
+	 */
+	NUM_INFO_OP_FLAGS = 2,
+
+	/* We cannot have one in the memory pipe so this is the maximum. */
+	MAX_INFO_OPS_PER_BUNDLE = 2
+};
+
+
+/* Internal constants used to define 'info' operands. */
+enum {
+	/* 0 and 1 are reserved, as are all negative numbers. */
+
+	CALLER_UNKNOWN_BASE = 2,
+
+	CALLER_SP_IN_R52_BASE = 4,
+
+	CALLER_SP_OFFSET_BASE = 8,
+};
+
+
+/* Current backtracer state describing where it thinks the caller is. */
+typedef struct {
+	/*
+	 * Public fields
+	 */
+
+	/* How do we find the caller's PC? */
+	CallerPCLocation pc_location : 8;
+
+	/* How do we find the caller's SP? */
+	CallerSPLocation sp_location : 8;
+
+	/* If sp_location == SP_LOC_OFFSET, then caller_sp == sp +
+	 * loc->sp_offset. Else this field is undefined.
+	 */
+	uint16_t sp_offset;
+
+	/* In the most recently visited bundle a terminating bundle? */
+	bool at_terminating_bundle;
+
+	/*
+	 * Private fields
+	 */
+
+	/* Will the forward scanner see someone clobbering sp
+	 * (i.e. changing it with something other than addi sp, sp, N?)
+	 */
+	bool sp_clobber_follows;
+
+	/* Operand to next "visible" info op (no more than one bundle past
+	 * the next terminating bundle), or -32768 if none.
+	 */
+	int16_t next_info_operand;
+
+	/* Is the info of in next_info_op in the very next bundle? */
+	bool is_next_info_operand_adjacent;
+
+} CallerLocation;
+
+extern void backtrace_init(BacktraceIterator *state,
+                          BacktraceMemoryReader read_memory_func,
+                          void *read_memory_func_extra,
+                          unsigned long pc, unsigned long lr,
+                          unsigned long sp, unsigned long r52);
+
+
+extern bool backtrace_next(BacktraceIterator *state);
+
+#endif /* _ASM_TILE_BACKTRACE_H */