v4.19.13 snapshot.
diff --git a/arch/sh/kernel/dwarf.c b/arch/sh/kernel/dwarf.c
new file mode 100644
index 0000000..bb511e2
--- /dev/null
+++ b/arch/sh/kernel/dwarf.c
@@ -0,0 +1,1208 @@
+/*
+ * 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(®->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(®->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, ®);
+ 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, ®);
+ current_insn += count;
+ break;
+ case DW_CFA_undefined:
+ count = dwarf_read_uleb128(current_insn, ®);
+ 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, ®);
+ 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, ®);
+ 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, ®);
+ 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 = _THIS_IP_;
+
+#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 __init dwarf_unwinder_cleanup(void)
+{
+ struct dwarf_fde *fde, *next_fde;
+ struct dwarf_cie *cie, *next_cie;
+
+ /*
+ * 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.
+ */
+ rbtree_postorder_for_each_entry_safe(fde, next_fde, &fde_root, node)
+ kfree(fde);
+
+ rbtree_postorder_for_each_entry_safe(cie, next_cie, &cie_root, node)
+ kfree(cie);
+
+ mempool_destroy(dwarf_reg_pool);
+ mempool_destroy(dwarf_frame_pool);
+ 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, NULL);
+
+ dwarf_reg_cachep = kmem_cache_create("dwarf_regs",
+ sizeof(struct dwarf_reg), 0,
+ SLAB_PANIC | SLAB_HWCACHE_ALIGN, NULL);
+
+ dwarf_frame_pool = mempool_create_slab_pool(DWARF_FRAME_MIN_REQ,
+ dwarf_frame_cachep);
+ if (!dwarf_frame_pool)
+ goto out;
+
+ dwarf_reg_pool = mempool_create_slab_pool(DWARF_REG_MIN_REQ,
+ 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);