Merge branch 'master' of master.kernel.org:/pub/scm/linux/kernel/git/torvalds/linux-2.6 into common/serial-rework

Conflicts:
	arch/sh/kernel/cpu/sh2/setup-sh7619.c
	arch/sh/kernel/cpu/sh2a/setup-mxg.c
	arch/sh/kernel/cpu/sh2a/setup-sh7201.c
	arch/sh/kernel/cpu/sh2a/setup-sh7203.c
	arch/sh/kernel/cpu/sh2a/setup-sh7206.c
	arch/sh/kernel/cpu/sh3/setup-sh7705.c
	arch/sh/kernel/cpu/sh3/setup-sh770x.c
	arch/sh/kernel/cpu/sh3/setup-sh7710.c
	arch/sh/kernel/cpu/sh3/setup-sh7720.c
	arch/sh/kernel/cpu/sh4/setup-sh4-202.c
	arch/sh/kernel/cpu/sh4/setup-sh7750.c
	arch/sh/kernel/cpu/sh4/setup-sh7760.c
	arch/sh/kernel/cpu/sh4a/setup-sh7343.c
	arch/sh/kernel/cpu/sh4a/setup-sh7366.c
	arch/sh/kernel/cpu/sh4a/setup-sh7722.c
	arch/sh/kernel/cpu/sh4a/setup-sh7723.c
	arch/sh/kernel/cpu/sh4a/setup-sh7724.c
	arch/sh/kernel/cpu/sh4a/setup-sh7763.c
	arch/sh/kernel/cpu/sh4a/setup-sh7770.c
	arch/sh/kernel/cpu/sh4a/setup-sh7780.c
	arch/sh/kernel/cpu/sh4a/setup-sh7785.c
	arch/sh/kernel/cpu/sh4a/setup-sh7786.c
	arch/sh/kernel/cpu/sh4a/setup-shx3.c
	arch/sh/kernel/cpu/sh5/setup-sh5.c
	drivers/serial/sh-sci.c
	drivers/serial/sh-sci.h
	include/linux/serial_sci.h

1 files changed, 1220 insertions, 0 deletions

diff --git a/arch/sh/kernel/dwarf.c b/arch/sh/kernel/dwarf.c
new file mode 100644
index 000000000000..49c09c7d5b77
--- /dev/null
+++ b/arch/sh/kernel/dwarf.c
@@ -0,0 +1,1220 @@
+/*
+ * Copyright (C) 2009 Matt Fleming <matt@console-pimps.org>
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * This is an implementation of a DWARF unwinder. Its main purpose is
+ * for generating stacktrace information. Based on the DWARF 3
+ * specification from http://www.dwarfstd.org.
+ *
+ * TODO:
+ *      - DWARF64 doesn't work.
+ *      - Registers with DWARF_VAL_OFFSET rules aren't handled properly.
+ */
+
+/* #define DEBUG */
+#include <linux/kernel.h>
+#include <linux/io.h>
+#include <linux/list.h>
+#include <linux/mempool.h>
+#include <linux/mm.h>
+#include <linux/elf.h>
+#include <linux/ftrace.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <asm/dwarf.h>
+#include <asm/unwinder.h>
+#include <asm/sections.h>
+#include <asm/unaligned.h>
+#include <asm/stacktrace.h>
+
+/* Reserve enough memory for two stack frames */
+#define DWARF_FRAME_MIN_REQ     2
+/* ... with 4 registers per frame. */
+#define DWARF_REG_MIN_REQ       (DWARF_FRAME_MIN_REQ * 4)
+
+static struct kmem_cache *dwarf_frame_cachep;
+static mempool_t *dwarf_frame_pool;
+
+static struct kmem_cache *dwarf_reg_cachep;
+static mempool_t *dwarf_reg_pool;
+
+static struct rb_root cie_root;
+static DEFINE_SPINLOCK(dwarf_cie_lock);
+
+static struct rb_root fde_root;
+static DEFINE_SPINLOCK(dwarf_fde_lock);
+
+static struct dwarf_cie *cached_cie;
+
+static unsigned int dwarf_unwinder_ready;
+
+/**
+ *      dwarf_frame_alloc_reg - allocate memory for a DWARF register
+ *      @frame: the DWARF frame whose list of registers we insert on
+ *      @reg_num: the register number
+ *
+ *      Allocate space for, and initialise, a dwarf reg from
+ *      dwarf_reg_pool and insert it onto the (unsorted) linked-list of
+ *      dwarf registers for @frame.
+ *
+ *      Return the initialised DWARF reg.
+ */
+static struct dwarf_reg *dwarf_frame_alloc_reg(struct dwarf_frame *frame,
+                                               unsigned int reg_num)
+{
+        struct dwarf_reg *reg;
+
+        reg = mempool_alloc(dwarf_reg_pool, GFP_ATOMIC);
+        if (!reg) {
+                printk(KERN_WARNING "Unable to allocate a DWARF register\n");
+                /*
+                 * Let's just bomb hard here, we have no way to
+                 * gracefully recover.
+                 */
+                UNWINDER_BUG();
+        }
+
+        reg->number = reg_num;
+        reg->addr = 0;
+        reg->flags = 0;
+
+        list_add(&reg->link, &frame->reg_list);
+
+        return reg;
+}
+
+static void dwarf_frame_free_regs(struct dwarf_frame *frame)
+{
+        struct dwarf_reg *reg, *n;
+
+        list_for_each_entry_safe(reg, n, &frame->reg_list, link) {
+                list_del(&reg->link);
+                mempool_free(reg, dwarf_reg_pool);
+        }
+}
+
+/**
+ *      dwarf_frame_reg - return a DWARF register
+ *      @frame: the DWARF frame to search in for @reg_num
+ *      @reg_num: the register number to search for
+ *
+ *      Lookup and return the dwarf reg @reg_num for this frame. Return
+ *      NULL if @reg_num is an register invalid number.
+ */
+static struct dwarf_reg *dwarf_frame_reg(struct dwarf_frame *frame,
+                                         unsigned int reg_num)
+{
+        struct dwarf_reg *reg;
+
+        list_for_each_entry(reg, &frame->reg_list, link) {
+                if (reg->number == reg_num)
+                        return reg;
+        }
+
+        return NULL;
+}
+
+/**
+ *      dwarf_read_addr - read dwarf data
+ *      @src: source address of data
+ *      @dst: destination address to store the data to
+ *
+ *      Read 'n' bytes from @src, where 'n' is the size of an address on
+ *      the native machine. We return the number of bytes read, which
+ *      should always be 'n'. We also have to be careful when reading
+ *      from @src and writing to @dst, because they can be arbitrarily
+ *      aligned. Return 'n' - the number of bytes read.
+ */
+static inline int dwarf_read_addr(unsigned long *src, unsigned long *dst)
+{
+        u32 val = get_unaligned(src);
+        put_unaligned(val, dst);
+        return sizeof(unsigned long *);
+}
+
+/**
+ *      dwarf_read_uleb128 - read unsigned LEB128 data
+ *      @addr: the address where the ULEB128 data is stored
+ *      @ret: address to store the result
+ *
+ *      Decode an unsigned LEB128 encoded datum. The algorithm is taken
+ *      from Appendix C of the DWARF 3 spec. For information on the
+ *      encodings refer to section "7.6 - Variable Length Data". Return
+ *      the number of bytes read.
+ */
+static inline unsigned long dwarf_read_uleb128(char *addr, unsigned int *ret)
+{
+        unsigned int result;
+        unsigned char byte;
+        int shift, count;
+
+        result = 0;
+        shift = 0;
+        count = 0;
+
+        while (1) {
+                byte = __raw_readb(addr);
+                addr++;
+                count++;
+
+                result |= (byte & 0x7f) << shift;
+                shift += 7;
+
+                if (!(byte & 0x80))
+                        break;
+        }
+
+        *ret = result;
+
+        return count;
+}
+
+/**
+ *      dwarf_read_leb128 - read signed LEB128 data
+ *      @addr: the address of the LEB128 encoded data
+ *      @ret: address to store the result
+ *
+ *      Decode signed LEB128 data. The algorithm is taken from Appendix
+ *      C of the DWARF 3 spec. Return the number of bytes read.
+ */
+static inline unsigned long dwarf_read_leb128(char *addr, int *ret)
+{
+        unsigned char byte;
+        int result, shift;
+        int num_bits;
+        int count;
+
+        result = 0;
+        shift = 0;
+        count = 0;
+
+        while (1) {
+                byte = __raw_readb(addr);
+                addr++;
+                result |= (byte & 0x7f) << shift;
+                shift += 7;
+                count++;
+
+                if (!(byte & 0x80))
+                        break;
+        }
+
+        /* The number of bits in a signed integer. */
+        num_bits = 8 * sizeof(result);
+
+        if ((shift < num_bits) && (byte & 0x40))
+                result |= (-1 << shift);
+
+        *ret = result;
+
+        return count;
+}
+
+/**
+ *      dwarf_read_encoded_value - return the decoded value at @addr
+ *      @addr: the address of the encoded value
+ *      @val: where to write the decoded value
+ *      @encoding: the encoding with which we can decode @addr
+ *
+ *      GCC emits encoded address in the .eh_frame FDE entries. Decode
+ *      the value at @addr using @encoding. The decoded value is written
+ *      to @val and the number of bytes read is returned.
+ */
+static int dwarf_read_encoded_value(char *addr, unsigned long *val,
+                                    char encoding)
+{
+        unsigned long decoded_addr = 0;
+        int count = 0;
+
+        switch (encoding & 0x70) {
+        case DW_EH_PE_absptr:
+                break;
+        case DW_EH_PE_pcrel:
+                decoded_addr = (unsigned long)addr;
+                break;
+        default:
+                pr_debug("encoding=0x%x\n", (encoding & 0x70));
+                UNWINDER_BUG();
+        }
+
+        if ((encoding & 0x07) == 0x00)
+                encoding |= DW_EH_PE_udata4;
+
+        switch (encoding & 0x0f) {
+        case DW_EH_PE_sdata4:
+        case DW_EH_PE_udata4:
+                count += 4;
+                decoded_addr += get_unaligned((u32 *)addr);
+                __raw_writel(decoded_addr, val);
+                break;
+        default:
+                pr_debug("encoding=0x%x\n", encoding);
+                UNWINDER_BUG();
+        }
+
+        return count;
+}
+
+/**
+ *      dwarf_entry_len - return the length of an FDE or CIE
+ *      @addr: the address of the entry
+ *      @len: the length of the entry
+ *
+ *      Read the initial_length field of the entry and store the size of
+ *      the entry in @len. We return the number of bytes read. Return a
+ *      count of 0 on error.
+ */
+static inline int dwarf_entry_len(char *addr, unsigned long *len)
+{
+        u32 initial_len;
+        int count;
+
+        initial_len = get_unaligned((u32 *)addr);
+        count = 4;
+
+        /*
+         * An initial length field value in the range DW_LEN_EXT_LO -
+         * DW_LEN_EXT_HI indicates an extension, and should not be
+         * interpreted as a length. The only extension that we currently
+         * understand is the use of DWARF64 addresses.
+         */
+        if (initial_len >= DW_EXT_LO && initial_len <= DW_EXT_HI) {
+                /*
+                 * The 64-bit length field immediately follows the
+                 * compulsory 32-bit length field.
+                 */
+                if (initial_len == DW_EXT_DWARF64) {
+                        *len = get_unaligned((u64 *)addr + 4);
+                        count = 12;
+                } else {
+                        printk(KERN_WARNING "Unknown DWARF extension\n");
+                        count = 0;
+                }
+        } else
+                *len = initial_len;
+
+        return count;
+}
+
+/**
+ *      dwarf_lookup_cie - locate the cie
+ *      @cie_ptr: pointer to help with lookup
+ */
+static struct dwarf_cie *dwarf_lookup_cie(unsigned long cie_ptr)
+{
+        struct rb_node **rb_node = &cie_root.rb_node;
+        struct dwarf_cie *cie = NULL;
+        unsigned long flags;
+
+        spin_lock_irqsave(&dwarf_cie_lock, flags);
+
+        /*
+         * We've cached the last CIE we looked up because chances are
+         * that the FDE wants this CIE.
+         */
+        if (cached_cie && cached_cie->cie_pointer == cie_ptr) {
+                cie = cached_cie;
+                goto out;
+        }
+
+        while (*rb_node) {
+                struct dwarf_cie *cie_tmp;
+
+                cie_tmp = rb_entry(*rb_node, struct dwarf_cie, node);
+                BUG_ON(!cie_tmp);
+
+                if (cie_ptr == cie_tmp->cie_pointer) {
+                        cie = cie_tmp;
+                        cached_cie = cie_tmp;
+                        goto out;
+                } else {
+                        if (cie_ptr < cie_tmp->cie_pointer)
+                                rb_node = &(*rb_node)->rb_left;
+                        else
+                                rb_node = &(*rb_node)->rb_right;
+                }
+        }
+
+out:
+        spin_unlock_irqrestore(&dwarf_cie_lock, flags);
+        return cie;
+}
+
+/**
+ *      dwarf_lookup_fde - locate the FDE that covers pc
+ *      @pc: the program counter
+ */
+struct dwarf_fde *dwarf_lookup_fde(unsigned long pc)
+{
+        struct rb_node **rb_node = &fde_root.rb_node;
+        struct dwarf_fde *fde = NULL;
+        unsigned long flags;
+
+        spin_lock_irqsave(&dwarf_fde_lock, flags);
+
+        while (*rb_node) {
+                struct dwarf_fde *fde_tmp;
+                unsigned long tmp_start, tmp_end;
+
+                fde_tmp = rb_entry(*rb_node, struct dwarf_fde, node);
+                BUG_ON(!fde_tmp);
+
+                tmp_start = fde_tmp->initial_location;
+                tmp_end = fde_tmp->initial_location + fde_tmp->address_range;
+
+                if (pc < tmp_start) {
+                        rb_node = &(*rb_node)->rb_left;
+                } else {
+                        if (pc < tmp_end) {
+                                fde = fde_tmp;
+                                goto out;
+                        } else
+                                rb_node = &(*rb_node)->rb_right;
+                }
+        }
+
+out:
+        spin_unlock_irqrestore(&dwarf_fde_lock, flags);
+
+        return fde;
+}
+
+/**
+ *      dwarf_cfa_execute_insns - execute instructions to calculate a CFA
+ *      @insn_start: address of the first instruction
+ *      @insn_end: address of the last instruction
+ *      @cie: the CIE for this function
+ *      @fde: the FDE for this function
+ *      @frame: the instructions calculate the CFA for this frame
+ *      @pc: the program counter of the address we're interested in
+ *
+ *      Execute the Call Frame instruction sequence starting at
+ *      @insn_start and ending at @insn_end. The instructions describe
+ *      how to calculate the Canonical Frame Address of a stackframe.
+ *      Store the results in @frame.
+ */
+static int dwarf_cfa_execute_insns(unsigned char *insn_start,
+                                   unsigned char *insn_end,
+                                   struct dwarf_cie *cie,
+                                   struct dwarf_fde *fde,
+                                   struct dwarf_frame *frame,
+                                   unsigned long pc)
+{
+        unsigned char insn;
+        unsigned char *current_insn;
+        unsigned int count, delta, reg, expr_len, offset;
+        struct dwarf_reg *regp;
+
+        current_insn = insn_start;
+
+        while (current_insn < insn_end && frame->pc <= pc) {
+                insn = __raw_readb(current_insn++);
+
+                /*
+                 * Firstly, handle the opcodes that embed their operands
+                 * in the instructions.
+                 */
+                switch (DW_CFA_opcode(insn)) {
+                case DW_CFA_advance_loc:
+                        delta = DW_CFA_operand(insn);
+                        delta *= cie->code_alignment_factor;
+                        frame->pc += delta;
+                        continue;
+                        /* NOTREACHED */
+                case DW_CFA_offset:
+                        reg = DW_CFA_operand(insn);
+                        count = dwarf_read_uleb128(current_insn, &offset);
+                        current_insn += count;
+                        offset *= cie->data_alignment_factor;
+                        regp = dwarf_frame_alloc_reg(frame, reg);
+                        regp->addr = offset;
+                        regp->flags |= DWARF_REG_OFFSET;
+                        continue;
+                        /* NOTREACHED */
+                case DW_CFA_restore:
+                        reg = DW_CFA_operand(insn);
+                        continue;
+                        /* NOTREACHED */
+                }
+
+                /*
+                 * Secondly, handle the opcodes that don't embed their
+                 * operands in the instruction.
+                 */
+                switch (insn) {
+                case DW_CFA_nop:
+                        continue;
+                case DW_CFA_advance_loc1:
+                        delta = *current_insn++;
+                        frame->pc += delta * cie->code_alignment_factor;
+                        break;
+                case DW_CFA_advance_loc2:
+                        delta = get_unaligned((u16 *)current_insn);
+                        current_insn += 2;
+                        frame->pc += delta * cie->code_alignment_factor;
+                        break;
+                case DW_CFA_advance_loc4:
+                        delta = get_unaligned((u32 *)current_insn);
+                        current_insn += 4;
+                        frame->pc += delta * cie->code_alignment_factor;
+                        break;
+                case DW_CFA_offset_extended:
+                        count = dwarf_read_uleb128(current_insn, &reg);
+                        current_insn += count;
+                        count = dwarf_read_uleb128(current_insn, &offset);
+                        current_insn += count;
+                        offset *= cie->data_alignment_factor;
+                        break;
+                case DW_CFA_restore_extended:
+                        count = dwarf_read_uleb128(current_insn, &reg);
+                        current_insn += count;
+                        break;
+                case DW_CFA_undefined:
+                        count = dwarf_read_uleb128(current_insn, &reg);
+                        current_insn += count;
+                        regp = dwarf_frame_alloc_reg(frame, reg);
+                        regp->flags |= DWARF_UNDEFINED;
+                        break;
+                case DW_CFA_def_cfa:
+                        count = dwarf_read_uleb128(current_insn,
+                                                   &frame->cfa_register);
+                        current_insn += count;
+                        count = dwarf_read_uleb128(current_insn,
+                                                   &frame->cfa_offset);
+                        current_insn += count;
+
+                        frame->flags |= DWARF_FRAME_CFA_REG_OFFSET;
+                        break;
+                case DW_CFA_def_cfa_register:
+                        count = dwarf_read_uleb128(current_insn,
+                                                   &frame->cfa_register);
+                        current_insn += count;
+                        frame->flags |= DWARF_FRAME_CFA_REG_OFFSET;
+                        break;
+                case DW_CFA_def_cfa_offset:
+                        count = dwarf_read_uleb128(current_insn, &offset);
+                        current_insn += count;
+                        frame->cfa_offset = offset;
+                        break;
+                case DW_CFA_def_cfa_expression:
+                        count = dwarf_read_uleb128(current_insn, &expr_len);
+                        current_insn += count;
+
+                        frame->cfa_expr = current_insn;
+                        frame->cfa_expr_len = expr_len;
+                        current_insn += expr_len;
+
+                        frame->flags |= DWARF_FRAME_CFA_REG_EXP;
+                        break;
+                case DW_CFA_offset_extended_sf:
+                        count = dwarf_read_uleb128(current_insn, &reg);
+                        current_insn += count;
+                        count = dwarf_read_leb128(current_insn, &offset);
+                        current_insn += count;
+                        offset *= cie->data_alignment_factor;
+                        regp = dwarf_frame_alloc_reg(frame, reg);
+                        regp->flags |= DWARF_REG_OFFSET;
+                        regp->addr = offset;
+                        break;
+                case DW_CFA_val_offset:
+                        count = dwarf_read_uleb128(current_insn, &reg);
+                        current_insn += count;
+                        count = dwarf_read_leb128(current_insn, &offset);
+                        offset *= cie->data_alignment_factor;
+                        regp = dwarf_frame_alloc_reg(frame, reg);
+                        regp->flags |= DWARF_VAL_OFFSET;
+                        regp->addr = offset;
+                        break;
+                case DW_CFA_GNU_args_size:
+                        count = dwarf_read_uleb128(current_insn, &offset);
+                        current_insn += count;
+                        break;
+                case DW_CFA_GNU_negative_offset_extended:
+                        count = dwarf_read_uleb128(current_insn, &reg);
+                        current_insn += count;
+                        count = dwarf_read_uleb128(current_insn, &offset);
+                        offset *= cie->data_alignment_factor;
+
+                        regp = dwarf_frame_alloc_reg(frame, reg);
+                        regp->flags |= DWARF_REG_OFFSET;
+                        regp->addr = -offset;
+                        break;
+                default:
+                        pr_debug("unhandled DWARF instruction 0x%x\n", insn);
+                        UNWINDER_BUG();
+                        break;
+                }
+        }
+
+        return 0;
+}
+
+/**
+ *      dwarf_free_frame - free the memory allocated for @frame
+ *      @frame: the frame to free
+ */
+void dwarf_free_frame(struct dwarf_frame *frame)
+{
+        dwarf_frame_free_regs(frame);
+        mempool_free(frame, dwarf_frame_pool);
+}
+
+extern void ret_from_irq(void);
+
+/**
+ *      dwarf_unwind_stack - unwind the stack
+ *
+ *      @pc: address of the function to unwind
+ *      @prev: struct dwarf_frame of the previous stackframe on the callstack
+ *
+ *      Return a struct dwarf_frame representing the most recent frame
+ *      on the callstack. Each of the lower (older) stack frames are
+ *      linked via the "prev" member.
+ */
+struct dwarf_frame *dwarf_unwind_stack(unsigned long pc,
+                                       struct dwarf_frame *prev)
+{
+        struct dwarf_frame *frame;
+        struct dwarf_cie *cie;
+        struct dwarf_fde *fde;
+        struct dwarf_reg *reg;
+        unsigned long addr;
+
+        /*
+         * If we've been called in to before initialization has
+         * completed, bail out immediately.
+         */
+        if (!dwarf_unwinder_ready)
+                return NULL;
+
+        /*
+         * If we're starting at the top of the stack we need get the
+         * contents of a physical register to get the CFA in order to
+         * begin the virtual unwinding of the stack.
+         *
+         * NOTE: the return address is guaranteed to be setup by the
+         * time this function makes its first function call.
+         */
+        if (!pc || !prev)
+                pc = (unsigned long)current_text_addr();
+
+#ifdef CONFIG_FUNCTION_GRAPH_TRACER
+        /*
+         * If our stack has been patched by the function graph tracer
+         * then we might see the address of return_to_handler() where we
+         * expected to find the real return address.
+         */
+        if (pc == (unsigned long)&return_to_handler) {
+                int index = current->curr_ret_stack;
+
+                /*
+                 * We currently have no way of tracking how many
+                 * return_to_handler()'s we've seen. If there is more
+                 * than one patched return address on our stack,
+                 * complain loudly.
+                 */
+                WARN_ON(index > 0);
+
+                pc = current->ret_stack[index].ret;
+        }
+#endif
+
+        frame = mempool_alloc(dwarf_frame_pool, GFP_ATOMIC);
+        if (!frame) {
+                printk(KERN_ERR "Unable to allocate a dwarf frame\n");
+                UNWINDER_BUG();
+        }
+
+        INIT_LIST_HEAD(&frame->reg_list);
+        frame->flags = 0;
+        frame->prev = prev;
+        frame->return_addr = 0;
+
+        fde = dwarf_lookup_fde(pc);
+        if (!fde) {
+                /*
+                 * This is our normal exit path. There are two reasons
+                 * why we might exit here,
+                 *
+                 *      a) pc has no asscociated DWARF frame info and so
+                 *      we don't know how to unwind this frame. This is
+                 *      usually the case when we're trying to unwind a
+                 *      frame that was called from some assembly code
+                 *      that has no DWARF info, e.g. syscalls.
+                 *
+                 *      b) the DEBUG info for pc is bogus. There's
+                 *      really no way to distinguish this case from the
+                 *      case above, which sucks because we could print a
+                 *      warning here.
+                 */
+                goto bail;
+        }
+
+        cie = dwarf_lookup_cie(fde->cie_pointer);
+
+        frame->pc = fde->initial_location;
+
+        /* CIE initial instructions */
+        dwarf_cfa_execute_insns(cie->initial_instructions,
+                                cie->instructions_end, cie, fde,
+                                frame, pc);
+
+        /* FDE instructions */
+        dwarf_cfa_execute_insns(fde->instructions, fde->end, cie,
+                                fde, frame, pc);
+
+        /* Calculate the CFA */
+        switch (frame->flags) {
+        case DWARF_FRAME_CFA_REG_OFFSET:
+                if (prev) {
+                        reg = dwarf_frame_reg(prev, frame->cfa_register);
+                        UNWINDER_BUG_ON(!reg);
+                        UNWINDER_BUG_ON(reg->flags != DWARF_REG_OFFSET);
+
+                        addr = prev->cfa + reg->addr;
+                        frame->cfa = __raw_readl(addr);
+
+                } else {
+                        /*
+                         * Again, we're starting from the top of the
+                         * stack. We need to physically read
+                         * the contents of a register in order to get
+                         * the Canonical Frame Address for this
+                         * function.
+                         */
+                        frame->cfa = dwarf_read_arch_reg(frame->cfa_register);
+                }
+
+                frame->cfa += frame->cfa_offset;
+                break;
+        default:
+                UNWINDER_BUG();
+        }
+
+        reg = dwarf_frame_reg(frame, DWARF_ARCH_RA_REG);
+
+        /*
+         * If we haven't seen the return address register or the return
+         * address column is undefined then we must assume that this is
+         * the end of the callstack.
+         */
+        if (!reg || reg->flags == DWARF_UNDEFINED)
+                goto bail;
+
+        UNWINDER_BUG_ON(reg->flags != DWARF_REG_OFFSET);
+
+        addr = frame->cfa + reg->addr;
+        frame->return_addr = __raw_readl(addr);
+
+        /*
+         * Ah, the joys of unwinding through interrupts.
+         *
+         * Interrupts are tricky - the DWARF info needs to be _really_
+         * accurate and unfortunately I'm seeing a lot of bogus DWARF
+         * info. For example, I've seen interrupts occur in epilogues
+         * just after the frame pointer (r14) had been restored. The
+         * problem was that the DWARF info claimed that the CFA could be
+         * reached by using the value of the frame pointer before it was
+         * restored.
+         *
+         * So until the compiler can be trusted to produce reliable
+         * DWARF info when it really matters, let's stop unwinding once
+         * we've calculated the function that was interrupted.
+         */
+        if (prev && prev->pc == (unsigned long)ret_from_irq)
+                frame->return_addr = 0;
+
+        return frame;
+
+bail:
+        dwarf_free_frame(frame);
+        return NULL;
+}
+
+static int dwarf_parse_cie(void *entry, void *p, unsigned long len,
+                           unsigned char *end, struct module *mod)
+{
+        struct rb_node **rb_node = &cie_root.rb_node;
+        struct rb_node *parent = *rb_node;
+        struct dwarf_cie *cie;
+        unsigned long flags;
+        int count;
+
+        cie = kzalloc(sizeof(*cie), GFP_KERNEL);
+        if (!cie)
+                return -ENOMEM;
+
+        cie->length = len;
+
+        /*
+         * Record the offset into the .eh_frame section
+         * for this CIE. It allows this CIE to be
+         * quickly and easily looked up from the
+         * corresponding FDE.
+         */
+        cie->cie_pointer = (unsigned long)entry;
+
+        cie->version = *(char *)p++;
+        UNWINDER_BUG_ON(cie->version != 1);
+
+        cie->augmentation = p;
+        p += strlen(cie->augmentation) + 1;
+
+        count = dwarf_read_uleb128(p, &cie->code_alignment_factor);
+        p += count;
+
+        count = dwarf_read_leb128(p, &cie->data_alignment_factor);
+        p += count;
+
+        /*
+         * Which column in the rule table contains the
+         * return address?
+         */
+        if (cie->version == 1) {
+                cie->return_address_reg = __raw_readb(p);
+                p++;
+        } else {
+                count = dwarf_read_uleb128(p, &cie->return_address_reg);
+                p += count;
+        }
+
+        if (cie->augmentation[0] == 'z') {
+                unsigned int length, count;
+                cie->flags |= DWARF_CIE_Z_AUGMENTATION;
+
+                count = dwarf_read_uleb128(p, &length);
+                p += count;
+
+                UNWINDER_BUG_ON((unsigned char *)p > end);
+
+                cie->initial_instructions = p + length;
+                cie->augmentation++;
+        }
+
+        while (*cie->augmentation) {
+                /*
+                 * "L" indicates a byte showing how the
+                 * LSDA pointer is encoded. Skip it.
+                 */
+                if (*cie->augmentation == 'L') {
+                        p++;
+                        cie->augmentation++;
+                } else if (*cie->augmentation == 'R') {
+                        /*
+                         * "R" indicates a byte showing
+                         * how FDE addresses are
+                         * encoded.
+                         */
+                        cie->encoding = *(char *)p++;
+                        cie->augmentation++;
+                } else if (*cie->augmentation == 'P') {
+                        /*
+                         * "R" indicates a personality
+                         * routine in the CIE
+                         * augmentation.
+                         */
+                        UNWINDER_BUG();
+                } else if (*cie->augmentation == 'S') {
+                        UNWINDER_BUG();
+                } else {
+                        /*
+                         * Unknown augmentation. Assume
+                         * 'z' augmentation.
+                         */
+                        p = cie->initial_instructions;
+                        UNWINDER_BUG_ON(!p);
+                        break;
+                }
+        }
+
+        cie->initial_instructions = p;
+        cie->instructions_end = end;
+
+        /* Add to list */
+        spin_lock_irqsave(&dwarf_cie_lock, flags);
+
+        while (*rb_node) {
+                struct dwarf_cie *cie_tmp;
+
+                cie_tmp = rb_entry(*rb_node, struct dwarf_cie, node);
+
+                parent = *rb_node;
+
+                if (cie->cie_pointer < cie_tmp->cie_pointer)
+                        rb_node = &parent->rb_left;
+                else if (cie->cie_pointer >= cie_tmp->cie_pointer)
+                        rb_node = &parent->rb_right;
+                else
+                        WARN_ON(1);
+        }
+
+        rb_link_node(&cie->node, parent, rb_node);
+        rb_insert_color(&cie->node, &cie_root);
+
+#ifdef CONFIG_MODULES
+        if (mod != NULL)
+                list_add_tail(&cie->link, &mod->arch.cie_list);
+#endif
+
+        spin_unlock_irqrestore(&dwarf_cie_lock, flags);
+
+        return 0;
+}
+
+static int dwarf_parse_fde(void *entry, u32 entry_type,
+                           void *start, unsigned long len,
+                           unsigned char *end, struct module *mod)
+{
+        struct rb_node **rb_node = &fde_root.rb_node;
+        struct rb_node *parent = *rb_node;
+        struct dwarf_fde *fde;
+        struct dwarf_cie *cie;
+        unsigned long flags;
+        int count;
+        void *p = start;
+
+        fde = kzalloc(sizeof(*fde), GFP_KERNEL);
+        if (!fde)
+                return -ENOMEM;
+
+        fde->length = len;
+
+        /*
+         * In a .eh_frame section the CIE pointer is the
+         * delta between the address within the FDE
+         */
+        fde->cie_pointer = (unsigned long)(p - entry_type - 4);
+
+        cie = dwarf_lookup_cie(fde->cie_pointer);
+        fde->cie = cie;
+
+        if (cie->encoding)
+                count = dwarf_read_encoded_value(p, &fde->initial_location,
+                                                 cie->encoding);
+        else
+                count = dwarf_read_addr(p, &fde->initial_location);
+
+        p += count;
+
+        if (cie->encoding)
+                count = dwarf_read_encoded_value(p, &fde->address_range,
+                                                 cie->encoding & 0x0f);
+        else
+                count = dwarf_read_addr(p, &fde->address_range);
+
+        p += count;
+
+        if (fde->cie->flags & DWARF_CIE_Z_AUGMENTATION) {
+                unsigned int length;
+                count = dwarf_read_uleb128(p, &length);
+                p += count + length;
+        }
+
+        /* Call frame instructions. */
+        fde->instructions = p;
+        fde->end = end;
+
+        /* Add to list. */
+        spin_lock_irqsave(&dwarf_fde_lock, flags);
+
+        while (*rb_node) {
+                struct dwarf_fde *fde_tmp;
+                unsigned long tmp_start, tmp_end;
+                unsigned long start, end;
+
+                fde_tmp = rb_entry(*rb_node, struct dwarf_fde, node);
+
+                start = fde->initial_location;
+                end = fde->initial_location + fde->address_range;
+
+                tmp_start = fde_tmp->initial_location;
+                tmp_end = fde_tmp->initial_location + fde_tmp->address_range;
+
+                parent = *rb_node;
+
+                if (start < tmp_start)
+                        rb_node = &parent->rb_left;
+                else if (start >= tmp_end)
+                        rb_node = &parent->rb_right;
+                else
+                        WARN_ON(1);
+        }
+
+        rb_link_node(&fde->node, parent, rb_node);
+        rb_insert_color(&fde->node, &fde_root);
+
+#ifdef CONFIG_MODULES
+        if (mod != NULL)
+                list_add_tail(&fde->link, &mod->arch.fde_list);
+#endif
+
+        spin_unlock_irqrestore(&dwarf_fde_lock, flags);
+
+        return 0;
+}
+
+static void dwarf_unwinder_dump(struct task_struct *task,
+                                struct pt_regs *regs,
+                                unsigned long *sp,
+                                const struct stacktrace_ops *ops,
+                                void *data)
+{
+        struct dwarf_frame *frame, *_frame;
+        unsigned long return_addr;
+
+        _frame = NULL;
+        return_addr = 0;
+
+        while (1) {
+                frame = dwarf_unwind_stack(return_addr, _frame);
+
+                if (_frame)
+                        dwarf_free_frame(_frame);
+
+                _frame = frame;
+
+                if (!frame || !frame->return_addr)
+                        break;
+
+                return_addr = frame->return_addr;
+                ops->address(data, return_addr, 1);
+        }
+
+        if (frame)
+                dwarf_free_frame(frame);
+}
+
+static struct unwinder dwarf_unwinder = {
+        .name = "dwarf-unwinder",
+        .dump = dwarf_unwinder_dump,
+        .rating = 150,
+};
+
+static void dwarf_unwinder_cleanup(void)
+{
+        struct rb_node **fde_rb_node = &fde_root.rb_node;
+        struct rb_node **cie_rb_node = &cie_root.rb_node;
+
+        /*
+         * Deallocate all the memory allocated for the DWARF unwinder.
+         * Traverse all the FDE/CIE lists and remove and free all the
+         * memory associated with those data structures.
+         */
+        while (*fde_rb_node) {
+                struct dwarf_fde *fde;
+
+                fde = rb_entry(*fde_rb_node, struct dwarf_fde, node);
+                rb_erase(*fde_rb_node, &fde_root);
+                kfree(fde);
+        }
+
+        while (*cie_rb_node) {
+                struct dwarf_cie *cie;
+
+                cie = rb_entry(*cie_rb_node, struct dwarf_cie, node);
+                rb_erase(*cie_rb_node, &cie_root);
+                kfree(cie);
+        }
+
+        kmem_cache_destroy(dwarf_reg_cachep);
+        kmem_cache_destroy(dwarf_frame_cachep);
+}
+
+/**
+ *      dwarf_parse_section - parse DWARF section
+ *      @eh_frame_start: start address of the .eh_frame section
+ *      @eh_frame_end: end address of the .eh_frame section
+ *      @mod: the kernel module containing the .eh_frame section
+ *
+ *      Parse the information in a .eh_frame section.
+ */
+static int dwarf_parse_section(char *eh_frame_start, char *eh_frame_end,
+                               struct module *mod)
+{
+        u32 entry_type;
+        void *p, *entry;
+        int count, err = 0;
+        unsigned long len = 0;
+        unsigned int c_entries, f_entries;
+        unsigned char *end;
+
+        c_entries = 0;
+        f_entries = 0;
+        entry = eh_frame_start;
+
+        while ((char *)entry < eh_frame_end) {
+                p = entry;
+
+                count = dwarf_entry_len(p, &len);
+                if (count == 0) {
+                        /*
+                         * We read a bogus length field value. There is
+                         * nothing we can do here apart from disabling
+                         * the DWARF unwinder. We can't even skip this
+                         * entry and move to the next one because 'len'
+                         * tells us where our next entry is.
+                         */
+                        err = -EINVAL;
+                        goto out;
+                } else
+                        p += count;
+
+                /* initial length does not include itself */
+                end = p + len;
+
+                entry_type = get_unaligned((u32 *)p);
+                p += 4;
+
+                if (entry_type == DW_EH_FRAME_CIE) {
+                        err = dwarf_parse_cie(entry, p, len, end, mod);
+                        if (err < 0)
+                                goto out;
+                        else
+                                c_entries++;
+                } else {
+                        err = dwarf_parse_fde(entry, entry_type, p, len,
+                                              end, mod);
+                        if (err < 0)
+                                goto out;
+                        else
+                                f_entries++;
+                }
+
+                entry = (char *)entry + len + 4;
+        }
+
+        printk(KERN_INFO "DWARF unwinder initialised: read %u CIEs, %u FDEs\n",
+               c_entries, f_entries);
+
+        return 0;
+
+out:
+        return err;
+}
+
+#ifdef CONFIG_MODULES
+int module_dwarf_finalize(const Elf_Ehdr *hdr, const Elf_Shdr *sechdrs,
+                          struct module *me)
+{
+        unsigned int i, err;
+        unsigned long start, end;
+        char *secstrings = (void *)hdr + sechdrs[hdr->e_shstrndx].sh_offset;
+
+        start = end = 0;
+
+        for (i = 1; i < hdr->e_shnum; i++) {
+                /* Alloc bit cleared means "ignore it." */
+                if ((sechdrs[i].sh_flags & SHF_ALLOC)
+                    && !strcmp(secstrings+sechdrs[i].sh_name, ".eh_frame")) {
+                        start = sechdrs[i].sh_addr;
+                        end = start + sechdrs[i].sh_size;
+                        break;
+                }
+        }
+
+        /* Did we find the .eh_frame section? */
+        if (i != hdr->e_shnum) {
+                INIT_LIST_HEAD(&me->arch.cie_list);
+                INIT_LIST_HEAD(&me->arch.fde_list);
+                err = dwarf_parse_section((char *)start, (char *)end, me);
+                if (err) {
+                        printk(KERN_WARNING "%s: failed to parse DWARF info\n",
+                               me->name);
+                        return err;
+                }
+        }
+
+        return 0;
+}
+
+/**
+ *      module_dwarf_cleanup - remove FDE/CIEs associated with @mod
+ *      @mod: the module that is being unloaded
+ *
+ *      Remove any FDEs and CIEs from the global lists that came from
+ *      @mod's .eh_frame section because @mod is being unloaded.
+ */
+void module_dwarf_cleanup(struct module *mod)
+{
+        struct dwarf_fde *fde, *ftmp;
+        struct dwarf_cie *cie, *ctmp;
+        unsigned long flags;
+
+        spin_lock_irqsave(&dwarf_cie_lock, flags);
+
+        list_for_each_entry_safe(cie, ctmp, &mod->arch.cie_list, link) {
+                list_del(&cie->link);
+                rb_erase(&cie->node, &cie_root);
+                kfree(cie);
+        }
+
+        spin_unlock_irqrestore(&dwarf_cie_lock, flags);
+
+        spin_lock_irqsave(&dwarf_fde_lock, flags);
+
+        list_for_each_entry_safe(fde, ftmp, &mod->arch.fde_list, link) {
+                list_del(&fde->link);
+                rb_erase(&fde->node, &fde_root);
+                kfree(fde);
+        }
+
+        spin_unlock_irqrestore(&dwarf_fde_lock, flags);
+}
+#endif /* CONFIG_MODULES */
+
+/**
+ *      dwarf_unwinder_init - initialise the dwarf unwinder
+ *
+ *      Build the data structures describing the .dwarf_frame section to
+ *      make it easier to lookup CIE and FDE entries. Because the
+ *      .eh_frame section is packed as tightly as possible it is not
+ *      easy to lookup the FDE for a given PC, so we build a list of FDE
+ *      and CIE entries that make it easier.
+ */
+static int __init dwarf_unwinder_init(void)
+{
+        int err = -ENOMEM;
+
+        dwarf_frame_cachep = kmem_cache_create("dwarf_frames",
+                        sizeof(struct dwarf_frame), 0,
+                        SLAB_PANIC | SLAB_HWCACHE_ALIGN | SLAB_NOTRACK, NULL);
+
+        dwarf_reg_cachep = kmem_cache_create("dwarf_regs",
+                        sizeof(struct dwarf_reg), 0,
+                        SLAB_PANIC | SLAB_HWCACHE_ALIGN | SLAB_NOTRACK, NULL);
+
+        dwarf_frame_pool = mempool_create(DWARF_FRAME_MIN_REQ,
+                                          mempool_alloc_slab,
+                                          mempool_free_slab,
+                                          dwarf_frame_cachep);
+        if (!dwarf_frame_pool)
+                goto out;
+
+        dwarf_reg_pool = mempool_create(DWARF_REG_MIN_REQ,
+                                         mempool_alloc_slab,
+                                         mempool_free_slab,
+                                         dwarf_reg_cachep);
+        if (!dwarf_reg_pool)
+                goto out;
+
+        err = dwarf_parse_section(__start_eh_frame, __stop_eh_frame, NULL);
+        if (err)
+                goto out;
+
+        err = unwinder_register(&dwarf_unwinder);
+        if (err)
+                goto out;
+
+        dwarf_unwinder_ready = 1;
+
+        return 0;
+
+out:
+        printk(KERN_ERR "Failed to initialise DWARF unwinder: %d\n", err);
+        dwarf_unwinder_cleanup();
+        return err;
+}
+early_initcall(dwarf_unwinder_init);