1 files changed, 193 insertions, 0 deletions

diff --git a/arch/tile/include/asm/backtrace.h b/arch/tile/include/asm/backtrace.h
new file mode 100644
index 00000000000..6970bfcad54
--- /dev/null
+++ b/arch/tile/include/asm/backtrace.h
@@ -0,0 +1,193 @@
+/*
+ * 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 _TILE_BACKTRACE_H
+#define _TILE_BACKTRACE_H
+
+
+
+#include <linux/types.h>
+
+#include <arch/chip.h>
+
+#if CHIP_VA_WIDTH() > 32
+typedef unsigned long long VirtualAddress;
+#else
+typedef unsigned int VirtualAddress;
+#endif
+
+
+/** 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,
+                                      VirtualAddress address,
+                                      unsigned int size,
+                                      void *extra);
+
+typedef struct {
+        /** Current PC. */
+        VirtualAddress pc;
+
+        /** Current stack pointer value. */
+        VirtualAddress sp;
+
+        /** Current frame pointer value (i.e. caller's stack pointer) */
+        VirtualAddress fp;
+
+        /** Internal use only: caller's PC for first frame. */
+        VirtualAddress 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;
+
+
+/** Initializes a backtracer to start from the given location.
+ *
+ * If the frame pointer cannot be determined it is set to -1.
+ *
+ * @param state The state to be filled in.
+ * @param read_memory_func A callback that reads memory. If NULL, a default
+ *        value is provided.
+ * @param read_memory_func_extra An arbitrary argument to read_memory_func.
+ * @param pc The current PC.
+ * @param lr The current value of the 'lr' register.
+ * @param sp The current value of the 'sp' register.
+ * @param r52 The current value of the 'r52' register.
+ */
+extern void backtrace_init(BacktraceIterator *state,
+                           BacktraceMemoryReader read_memory_func,
+                           void *read_memory_func_extra,
+                           VirtualAddress pc, VirtualAddress lr,
+                           VirtualAddress sp, VirtualAddress r52);
+
+
+/** Advances the backtracing state to the calling frame, returning
+ * true iff successful.
+ */
+extern bool backtrace_next(BacktraceIterator *state);
+
+
+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;
+
+
+
+
+#endif /* _TILE_BACKTRACE_H */