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@@ -0,0 +1,901 @@
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+/*
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+ * Copyright (C) 2009 Matt Fleming <matt@console-pimps.org>
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+ *
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+ * This file is subject to the terms and conditions of the GNU General Public
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+ * License. See the file "COPYING" in the main directory of this archive
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+ * for more details.
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+ *
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+ * This is an implementation of a DWARF unwinder. Its main purpose is
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+ * for generating stacktrace information. Based on the DWARF 3
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+ * specification from http://www.dwarfstd.org.
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+ *
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+ * TODO:
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+ * - DWARF64 doesn't work.
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+ */
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+
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+/* #define DEBUG */
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+#include <linux/kernel.h>
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+#include <linux/io.h>
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+#include <linux/list.h>
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+#include <linux/mm.h>
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+#include <asm/dwarf.h>
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+#include <asm/unwinder.h>
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+#include <asm/sections.h>
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+#include <asm/unaligned.h>
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+#include <asm/dwarf.h>
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+#include <asm/stacktrace.h>
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+
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+static LIST_HEAD(dwarf_cie_list);
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+DEFINE_SPINLOCK(dwarf_cie_lock);
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+
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+static LIST_HEAD(dwarf_fde_list);
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+DEFINE_SPINLOCK(dwarf_fde_lock);
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+
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+static struct dwarf_cie *cached_cie;
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+
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+/*
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+ * Figure out whether we need to allocate some dwarf registers. If dwarf
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+ * registers have already been allocated then we may need to realloc
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+ * them. "reg" is a register number that we need to be able to access
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+ * after this call.
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+ *
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+ * Register numbers start at zero, therefore we need to allocate space
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+ * for "reg" + 1 registers.
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+ */
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+static void dwarf_frame_alloc_regs(struct dwarf_frame *frame,
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+ unsigned int reg)
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+{
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+ struct dwarf_reg *regs;
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+ unsigned int num_regs = reg + 1;
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+ size_t new_size;
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+ size_t old_size;
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+
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+ new_size = num_regs * sizeof(*regs);
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+ old_size = frame->num_regs * sizeof(*regs);
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+
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+ /* Fast path: don't allocate any regs if we've already got enough. */
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+ if (frame->num_regs >= num_regs)
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+ return;
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+
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+ regs = kzalloc(new_size, GFP_KERNEL);
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+ if (!regs) {
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+ printk(KERN_WARNING "Unable to allocate DWARF registers\n");
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+ /*
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+ * Let's just bomb hard here, we have no way to
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+ * gracefully recover.
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+ */
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+ BUG();
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+ }
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+
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+ if (frame->regs) {
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+ memcpy(regs, frame->regs, old_size);
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+ kfree(frame->regs);
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+ }
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+
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+ frame->regs = regs;
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+ frame->num_regs = num_regs;
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+}
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+
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+/**
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+ * dwarf_read_addr - read dwarf data
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+ * @src: source address of data
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+ * @dst: destination address to store the data to
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+ *
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+ * Read 'n' bytes from @src, where 'n' is the size of an address on
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+ * the native machine. We return the number of bytes read, which
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+ * should always be 'n'. We also have to be careful when reading
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+ * from @src and writing to @dst, because they can be arbitrarily
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+ * aligned. Return 'n' - the number of bytes read.
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+ */
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+static inline int dwarf_read_addr(unsigned long *src, unsigned long *dst)
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+{
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+ u32 val = get_unaligned(src);
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+ put_unaligned(val, dst);
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+ return sizeof(unsigned long *);
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+}
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+
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+/**
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+ * dwarf_read_uleb128 - read unsigned LEB128 data
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+ * @addr: the address where the ULEB128 data is stored
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+ * @ret: address to store the result
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+ *
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+ * Decode an unsigned LEB128 encoded datum. The algorithm is taken
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+ * from Appendix C of the DWARF 3 spec. For information on the
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+ * encodings refer to section "7.6 - Variable Length Data". Return
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+ * the number of bytes read.
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+ */
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+static inline unsigned long dwarf_read_uleb128(char *addr, unsigned int *ret)
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+{
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+ unsigned int result;
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+ unsigned char byte;
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+ int shift, count;
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+
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+ result = 0;
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+ shift = 0;
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+ count = 0;
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+
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+ while (1) {
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+ byte = __raw_readb(addr);
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+ addr++;
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+ count++;
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+
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+ result |= (byte & 0x7f) << shift;
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+ shift += 7;
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+
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+ if (!(byte & 0x80))
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+ break;
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+ }
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+
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+ *ret = result;
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+
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+ return count;
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+}
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+
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+/**
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+ * dwarf_read_leb128 - read signed LEB128 data
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+ * @addr: the address of the LEB128 encoded data
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+ * @ret: address to store the result
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+ *
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+ * Decode signed LEB128 data. The algorithm is taken from Appendix
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+ * C of the DWARF 3 spec. Return the number of bytes read.
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+ */
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+static inline unsigned long dwarf_read_leb128(char *addr, int *ret)
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+{
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+ unsigned char byte;
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+ int result, shift;
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+ int num_bits;
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+ int count;
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+
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+ result = 0;
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+ shift = 0;
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+ count = 0;
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+
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+ while (1) {
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+ byte = __raw_readb(addr);
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+ addr++;
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+ result |= (byte & 0x7f) << shift;
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+ shift += 7;
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+ count++;
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+
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+ if (!(byte & 0x80))
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+ break;
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+ }
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+
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+ /* The number of bits in a signed integer. */
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+ num_bits = 8 * sizeof(result);
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+
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+ if ((shift < num_bits) && (byte & 0x40))
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+ result |= (-1 << shift);
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+
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+ *ret = result;
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+
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+ return count;
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+}
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+
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+/**
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+ * dwarf_read_encoded_value - return the decoded value at @addr
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+ * @addr: the address of the encoded value
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+ * @val: where to write the decoded value
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+ * @encoding: the encoding with which we can decode @addr
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+ *
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+ * GCC emits encoded address in the .eh_frame FDE entries. Decode
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+ * the value at @addr using @encoding. The decoded value is written
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+ * to @val and the number of bytes read is returned.
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+ */
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+static int dwarf_read_encoded_value(char *addr, unsigned long *val,
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+ char encoding)
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+{
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+ unsigned long decoded_addr = 0;
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+ int count = 0;
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+
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+ switch (encoding & 0x70) {
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+ case DW_EH_PE_absptr:
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+ break;
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+ case DW_EH_PE_pcrel:
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+ decoded_addr = (unsigned long)addr;
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+ break;
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+ default:
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+ pr_debug("encoding=0x%x\n", (encoding & 0x70));
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+ BUG();
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+ }
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+
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+ if ((encoding & 0x07) == 0x00)
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+ encoding |= DW_EH_PE_udata4;
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+
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+ switch (encoding & 0x0f) {
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+ case DW_EH_PE_sdata4:
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+ case DW_EH_PE_udata4:
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+ count += 4;
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+ decoded_addr += get_unaligned((u32 *)addr);
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+ __raw_writel(decoded_addr, val);
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+ break;
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+ default:
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+ pr_debug("encoding=0x%x\n", encoding);
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+ BUG();
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+ }
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+
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+ return count;
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+}
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+
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+/**
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+ * dwarf_entry_len - return the length of an FDE or CIE
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+ * @addr: the address of the entry
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+ * @len: the length of the entry
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+ *
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+ * Read the initial_length field of the entry and store the size of
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+ * the entry in @len. We return the number of bytes read. Return a
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+ * count of 0 on error.
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+ */
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+static inline int dwarf_entry_len(char *addr, unsigned long *len)
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+{
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+ u32 initial_len;
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+ int count;
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+
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+ initial_len = get_unaligned((u32 *)addr);
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+ count = 4;
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+
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+ /*
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+ * An initial length field value in the range DW_LEN_EXT_LO -
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+ * DW_LEN_EXT_HI indicates an extension, and should not be
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+ * interpreted as a length. The only extension that we currently
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+ * understand is the use of DWARF64 addresses.
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+ */
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+ if (initial_len >= DW_EXT_LO && initial_len <= DW_EXT_HI) {
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+ /*
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+ * The 64-bit length field immediately follows the
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+ * compulsory 32-bit length field.
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+ */
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+ if (initial_len == DW_EXT_DWARF64) {
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+ *len = get_unaligned((u64 *)addr + 4);
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+ count = 12;
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+ } else {
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+ printk(KERN_WARNING "Unknown DWARF extension\n");
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+ count = 0;
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+ }
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+ } else
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+ *len = initial_len;
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+
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+ return count;
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+}
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+
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+/**
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+ * dwarf_lookup_cie - locate the cie
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+ * @cie_ptr: pointer to help with lookup
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+ */
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+static struct dwarf_cie *dwarf_lookup_cie(unsigned long cie_ptr)
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+{
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+ struct dwarf_cie *cie, *n;
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+ unsigned long flags;
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+
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+ spin_lock_irqsave(&dwarf_cie_lock, flags);
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+
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+ /*
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+ * We've cached the last CIE we looked up because chances are
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+ * that the FDE wants this CIE.
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+ */
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+ if (cached_cie && cached_cie->cie_pointer == cie_ptr) {
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+ cie = cached_cie;
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+ goto out;
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+ }
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+
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+ list_for_each_entry_safe(cie, n, &dwarf_cie_list, link) {
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+ if (cie->cie_pointer == cie_ptr) {
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+ cached_cie = cie;
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+ break;
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+ }
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+ }
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+
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+ /* Couldn't find the entry in the list. */
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+ if (&cie->link == &dwarf_cie_list)
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+ cie = NULL;
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+out:
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+ spin_unlock_irqrestore(&dwarf_cie_lock, flags);
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+ return cie;
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+}
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+
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+/**
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+ * dwarf_lookup_fde - locate the FDE that covers pc
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+ * @pc: the program counter
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+ */
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+struct dwarf_fde *dwarf_lookup_fde(unsigned long pc)
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+{
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+ unsigned long flags;
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+ struct dwarf_fde *fde, *n;
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+
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+ spin_lock_irqsave(&dwarf_fde_lock, flags);
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+ list_for_each_entry_safe(fde, n, &dwarf_fde_list, link) {
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+ unsigned long start, end;
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+
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+ start = fde->initial_location;
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+ end = fde->initial_location + fde->address_range;
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+
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+ if (pc >= start && pc < end)
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+ break;
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+ }
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+
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+ /* Couldn't find the entry in the list. */
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+ if (&fde->link == &dwarf_fde_list)
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+ fde = NULL;
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+
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+ spin_unlock_irqrestore(&dwarf_fde_lock, flags);
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+
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+ return fde;
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+}
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+
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+/**
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+ * dwarf_cfa_execute_insns - execute instructions to calculate a CFA
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+ * @insn_start: address of the first instruction
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+ * @insn_end: address of the last instruction
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+ * @cie: the CIE for this function
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+ * @fde: the FDE for this function
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+ * @frame: the instructions calculate the CFA for this frame
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+ * @pc: the program counter of the address we're interested in
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+ * @define_ra: keep executing insns until the return addr reg is defined?
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+ *
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+ * Execute the Call Frame instruction sequence starting at
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+ * @insn_start and ending at @insn_end. The instructions describe
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+ * how to calculate the Canonical Frame Address of a stackframe.
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+ * Store the results in @frame.
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+ */
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+static int dwarf_cfa_execute_insns(unsigned char *insn_start,
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+ unsigned char *insn_end,
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+ struct dwarf_cie *cie,
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+ struct dwarf_fde *fde,
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+ struct dwarf_frame *frame,
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+ unsigned long pc,
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+ bool define_ra)
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+{
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+ unsigned char insn;
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+ unsigned char *current_insn;
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+ unsigned int count, delta, reg, expr_len, offset;
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+ bool seen_ra_reg;
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+
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+ current_insn = insn_start;
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+
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+ /*
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+ * If we're executing instructions for the dwarf_unwind_stack()
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+ * FDE we need to keep executing instructions until the value of
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+ * DWARF_ARCH_RA_REG is defined. See the comment in
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+ * dwarf_unwind_stack() for more details.
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+ */
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+ if (define_ra)
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+ seen_ra_reg = false;
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+ else
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+ seen_ra_reg = true;
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+
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+ while (current_insn < insn_end && (frame->pc <= pc || !seen_ra_reg) ) {
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+ insn = __raw_readb(current_insn++);
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+
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+ if (!seen_ra_reg) {
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+ if (frame->num_regs >= DWARF_ARCH_RA_REG &&
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+ frame->regs[DWARF_ARCH_RA_REG].flags)
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+ seen_ra_reg = true;
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+ }
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+
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+ /*
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+ * Firstly, handle the opcodes that embed their operands
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+ * in the instructions.
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+ */
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+ switch (DW_CFA_opcode(insn)) {
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+ case DW_CFA_advance_loc:
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+ delta = DW_CFA_operand(insn);
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+ delta *= cie->code_alignment_factor;
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+ frame->pc += delta;
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+ continue;
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+ /* NOTREACHED */
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+ case DW_CFA_offset:
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+ reg = DW_CFA_operand(insn);
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+ count = dwarf_read_uleb128(current_insn, &offset);
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+ current_insn += count;
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+ offset *= cie->data_alignment_factor;
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+ dwarf_frame_alloc_regs(frame, reg);
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+ frame->regs[reg].addr = offset;
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+ frame->regs[reg].flags |= DWARF_REG_OFFSET;
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+ continue;
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+ /* NOTREACHED */
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+ case DW_CFA_restore:
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+ reg = DW_CFA_operand(insn);
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+ continue;
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+ /* NOTREACHED */
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+ }
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+
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+ /*
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+ * Secondly, handle the opcodes that don't embed their
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+ * operands in the instruction.
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+ */
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+ switch (insn) {
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+ case DW_CFA_nop:
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+ continue;
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+ case DW_CFA_advance_loc1:
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+ delta = *current_insn++;
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+ frame->pc += delta * cie->code_alignment_factor;
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+ break;
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+ case DW_CFA_advance_loc2:
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+ delta = get_unaligned((u16 *)current_insn);
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+ current_insn += 2;
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+ frame->pc += delta * cie->code_alignment_factor;
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+ break;
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+ case DW_CFA_advance_loc4:
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+ delta = get_unaligned((u32 *)current_insn);
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+ current_insn += 4;
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+ frame->pc += delta * cie->code_alignment_factor;
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+ break;
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+ case DW_CFA_offset_extended:
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+ count = dwarf_read_uleb128(current_insn, ®);
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|
+ 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;
|
|
|
+ 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;
|
|
|
+ dwarf_frame_alloc_regs(frame, reg);
|
|
|
+ frame->regs[reg].flags |= DWARF_REG_OFFSET;
|
|
|
+ frame->regs[reg].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;
|
|
|
+ frame->regs[reg].flags |= DWARF_REG_OFFSET;
|
|
|
+ frame->regs[reg].addr = offset;
|
|
|
+ break;
|
|
|
+ default:
|
|
|
+ pr_debug("unhandled DWARF instruction 0x%x\n", insn);
|
|
|
+ break;
|
|
|
+ }
|
|
|
+ }
|
|
|
+
|
|
|
+ return 0;
|
|
|
+}
|
|
|
+
|
|
|
+/**
|
|
|
+ * dwarf_unwind_stack - recursively 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;
|
|
|
+ unsigned long addr;
|
|
|
+ int i, offset;
|
|
|
+ bool define_ra = false;
|
|
|
+
|
|
|
+ /*
|
|
|
+ * If this is the first invocation of this recursive function we
|
|
|
+ * need get the contents of a physical register to get the CFA
|
|
|
+ * in order to begin the virtual unwinding of the stack.
|
|
|
+ *
|
|
|
+ * Setting "define_ra" to true indictates that we want
|
|
|
+ * dwarf_cfa_execute_insns() to continue executing instructions
|
|
|
+ * until we know how to calculate the value of DWARF_ARCH_RA_REG
|
|
|
+ * (which we need in order to kick off the whole unwinding
|
|
|
+ * process).
|
|
|
+ *
|
|
|
+ * 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)&dwarf_unwind_stack;
|
|
|
+ define_ra = true;
|
|
|
+ }
|
|
|
+
|
|
|
+ frame = kzalloc(sizeof(*frame), GFP_KERNEL);
|
|
|
+ if (!frame)
|
|
|
+ return NULL;
|
|
|
+
|
|
|
+ frame->prev = prev;
|
|
|
+
|
|
|
+ fde = dwarf_lookup_fde(pc);
|
|
|
+ if (!fde) {
|
|
|
+ /*
|
|
|
+ * This is our normal exit path - the one that stops the
|
|
|
+ * recursion. There's 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.
|
|
|
+ */
|
|
|
+ return NULL;
|
|
|
+ }
|
|
|
+
|
|
|
+ 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, false);
|
|
|
+
|
|
|
+ /* FDE instructions */
|
|
|
+ dwarf_cfa_execute_insns(fde->instructions, fde->end, cie,
|
|
|
+ fde, frame, pc, define_ra);
|
|
|
+
|
|
|
+ /* Calculate the CFA */
|
|
|
+ switch (frame->flags) {
|
|
|
+ case DWARF_FRAME_CFA_REG_OFFSET:
|
|
|
+ if (prev) {
|
|
|
+ BUG_ON(!prev->regs[frame->cfa_register].flags);
|
|
|
+
|
|
|
+ addr = prev->cfa;
|
|
|
+ addr += prev->regs[frame->cfa_register].addr;
|
|
|
+ frame->cfa = __raw_readl(addr);
|
|
|
+
|
|
|
+ } else {
|
|
|
+ /*
|
|
|
+ * Again, this is the first invocation of this
|
|
|
+ * recurisve function. 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:
|
|
|
+ BUG();
|
|
|
+ }
|
|
|
+
|
|
|
+ /* If we haven't seen the return address reg, we're screwed. */
|
|
|
+ BUG_ON(!frame->regs[DWARF_ARCH_RA_REG].flags);
|
|
|
+
|
|
|
+ for (i = 0; i <= frame->num_regs; i++) {
|
|
|
+ struct dwarf_reg *reg = &frame->regs[i];
|
|
|
+
|
|
|
+ if (!reg->flags)
|
|
|
+ continue;
|
|
|
+
|
|
|
+ offset = reg->addr;
|
|
|
+ offset += frame->cfa;
|
|
|
+ }
|
|
|
+
|
|
|
+ addr = frame->cfa + frame->regs[DWARF_ARCH_RA_REG].addr;
|
|
|
+ frame->return_addr = __raw_readl(addr);
|
|
|
+
|
|
|
+ frame->next = dwarf_unwind_stack(frame->return_addr, frame);
|
|
|
+ return frame;
|
|
|
+}
|
|
|
+
|
|
|
+static int dwarf_parse_cie(void *entry, void *p, unsigned long len,
|
|
|
+ unsigned char *end)
|
|
|
+{
|
|
|
+ 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++;
|
|
|
+ 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;
|
|
|
+
|
|
|
+ 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.
|
|
|
+ */
|
|
|
+ BUG();
|
|
|
+ } else if (*cie->augmentation == 'S') {
|
|
|
+ BUG();
|
|
|
+ } else {
|
|
|
+ /*
|
|
|
+ * Unknown augmentation. Assume
|
|
|
+ * 'z' augmentation.
|
|
|
+ */
|
|
|
+ p = cie->initial_instructions;
|
|
|
+ BUG_ON(!p);
|
|
|
+ break;
|
|
|
+ }
|
|
|
+ }
|
|
|
+
|
|
|
+ cie->initial_instructions = p;
|
|
|
+ cie->instructions_end = end;
|
|
|
+
|
|
|
+ /* Add to list */
|
|
|
+ spin_lock_irqsave(&dwarf_cie_lock, flags);
|
|
|
+ list_add_tail(&cie->link, &dwarf_cie_list);
|
|
|
+ spin_unlock_irqrestore(&dwarf_cie_lock, flags);
|
|
|
+
|
|
|
+ return 0;
|
|
|
+}
|
|
|
+
|
|
|
+static int dwarf_parse_fde(void *entry, u32 entry_type,
|
|
|
+ void *start, unsigned long len)
|
|
|
+{
|
|
|
+ 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 = start + len;
|
|
|
+
|
|
|
+ /* Add to list. */
|
|
|
+ spin_lock_irqsave(&dwarf_fde_lock, flags);
|
|
|
+ list_add_tail(&fde->link, &dwarf_fde_list);
|
|
|
+ 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 = dwarf_unwind_stack(0, NULL);
|
|
|
+
|
|
|
+ while (frame && frame->return_addr) {
|
|
|
+ ops->address(data, frame->return_addr, 1);
|
|
|
+ frame = frame->next;
|
|
|
+ }
|
|
|
+}
|
|
|
+
|
|
|
+static struct unwinder dwarf_unwinder = {
|
|
|
+ .name = "dwarf-unwinder",
|
|
|
+ .dump = dwarf_unwinder_dump,
|
|
|
+ .rating = 150,
|
|
|
+};
|
|
|
+
|
|
|
+static void dwarf_unwinder_cleanup(void)
|
|
|
+{
|
|
|
+ struct dwarf_cie *cie, *m;
|
|
|
+ struct dwarf_fde *fde, *n;
|
|
|
+ unsigned long flags;
|
|
|
+
|
|
|
+ /*
|
|
|
+ * 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.
|
|
|
+ */
|
|
|
+ spin_lock_irqsave(&dwarf_cie_lock, flags);
|
|
|
+ list_for_each_entry_safe(cie, m, &dwarf_cie_list, link)
|
|
|
+ kfree(cie);
|
|
|
+ spin_unlock_irqrestore(&dwarf_cie_lock, flags);
|
|
|
+
|
|
|
+ spin_lock_irqsave(&dwarf_fde_lock, flags);
|
|
|
+ list_for_each_entry_safe(fde, n, &dwarf_fde_list, link)
|
|
|
+ kfree(fde);
|
|
|
+ spin_unlock_irqrestore(&dwarf_fde_lock, flags);
|
|
|
+}
|
|
|
+
|
|
|
+/**
|
|
|
+ * 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.
|
|
|
+ */
|
|
|
+void dwarf_unwinder_init(void)
|
|
|
+{
|
|
|
+ u32 entry_type;
|
|
|
+ void *p, *entry;
|
|
|
+ int count, err;
|
|
|
+ unsigned long len;
|
|
|
+ unsigned int c_entries, f_entries;
|
|
|
+ unsigned char *end;
|
|
|
+ INIT_LIST_HEAD(&dwarf_cie_list);
|
|
|
+ INIT_LIST_HEAD(&dwarf_fde_list);
|
|
|
+
|
|
|
+ c_entries = 0;
|
|
|
+ f_entries = 0;
|
|
|
+ entry = &__start_eh_frame;
|
|
|
+
|
|
|
+ while ((char *)entry < __stop_eh_frame) {
|
|
|
+ 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.
|
|
|
+ */
|
|
|
+ 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);
|
|
|
+ if (err < 0)
|
|
|
+ goto out;
|
|
|
+ else
|
|
|
+ c_entries++;
|
|
|
+ } else {
|
|
|
+ err = dwarf_parse_fde(entry, entry_type, p, len);
|
|
|
+ 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);
|
|
|
+
|
|
|
+ err = unwinder_register(&dwarf_unwinder);
|
|
|
+ if (err)
|
|
|
+ goto out;
|
|
|
+
|
|
|
+ return;
|
|
|
+
|
|
|
+out:
|
|
|
+ printk(KERN_ERR "Failed to initialise DWARF unwinder: %d\n", err);
|
|
|
+ dwarf_unwinder_cleanup();
|
|
|
+}
|
Paul Mundt