Merge branch 'sh/dwarf-unwinder'

13 files changed, 1363 insertions, 1 deletions

diff --git a/arch/sh/Kconfig.debug b/arch/sh/Kconfig.debug
index 763b792b1611..741d20fab2e1 100644
--- a/arch/sh/Kconfig.debug
+++ b/arch/sh/Kconfig.debug
@@ -110,6 +110,14 @@ config DUMP_CODE
 
           Those looking for more verbose debugging output should say Y.
 
+config DWARF_UNWINDER
+        bool "Enable the DWARF unwinder for stacktraces"
+        select FRAME_POINTER
+        default n
+        help
+          Enabling this option will make stacktraces more accurate, at
+          the cost of an increase in overall kernel size.
+
 config SH_NO_BSS_INIT
         bool "Avoid zeroing BSS (to speed-up startup on suitable platforms)"
         depends on DEBUG_KERNEL
diff --git a/arch/sh/Makefile b/arch/sh/Makefile
index b6ff337fd856..e26421bf9976 100644
--- a/arch/sh/Makefile
+++ b/arch/sh/Makefile
@@ -191,6 +191,10 @@ ifeq ($(CONFIG_MCOUNT),y)
   KBUILD_CFLAGS += -pg
 endif
 
+ifeq ($(CONFIG_DWARF_UNWINDER),y)
+  KBUILD_CFLAGS += -fasynchronous-unwind-tables
+endif
+
 libs-$(CONFIG_SUPERH32)         := arch/sh/lib/ $(libs-y)
 libs-$(CONFIG_SUPERH64)         := arch/sh/lib64/ $(libs-y)
 
diff --git a/arch/sh/include/asm/dwarf.h b/arch/sh/include/asm/dwarf.h
new file mode 100644
index 000000000000..60b180728d8d
--- /dev/null
+++ b/arch/sh/include/asm/dwarf.h
@@ -0,0 +1,402 @@
+/*
+ * 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.
+ *
+ */
+#ifndef __ASM_SH_DWARF_H
+#define __ASM_SH_DWARF_H
+
+#ifdef CONFIG_DWARF_UNWINDER
+
+/*
+ * DWARF expression operations
+ */
+#define DW_OP_addr      0x03
+#define DW_OP_deref     0x06
+#define DW_OP_const1u   0x08
+#define DW_OP_const1s   0x09
+#define DW_OP_const2u   0x0a
+#define DW_OP_const2s   0x0b
+#define DW_OP_const4u   0x0c
+#define DW_OP_const4s   0x0d
+#define DW_OP_const8u   0x0e
+#define DW_OP_const8s   0x0f
+#define DW_OP_constu    0x10
+#define DW_OP_consts    0x11
+#define DW_OP_dup       0x12
+#define DW_OP_drop      0x13
+#define DW_OP_over      0x14
+#define DW_OP_pick      0x15
+#define DW_OP_swap      0x16
+#define DW_OP_rot       0x17
+#define DW_OP_xderef    0x18
+#define DW_OP_abs       0x19
+#define DW_OP_and       0x1a
+#define DW_OP_div       0x1b
+#define DW_OP_minus     0x1c
+#define DW_OP_mod       0x1d
+#define DW_OP_mul       0x1e
+#define DW_OP_neg       0x1f
+#define DW_OP_not       0x20
+#define DW_OP_or        0x21
+#define DW_OP_plus      0x22
+#define DW_OP_plus_uconst       0x23
+#define DW_OP_shl       0x24
+#define DW_OP_shr       0x25
+#define DW_OP_shra      0x26
+#define DW_OP_xor       0x27
+#define DW_OP_skip      0x2f
+#define DW_OP_bra       0x28
+#define DW_OP_eq        0x29
+#define DW_OP_ge        0x2a
+#define DW_OP_gt        0x2b
+#define DW_OP_le        0x2c
+#define DW_OP_lt        0x2d
+#define DW_OP_ne        0x2e
+#define DW_OP_lit0      0x30
+#define DW_OP_lit1      0x31
+#define DW_OP_lit2      0x32
+#define DW_OP_lit3      0x33
+#define DW_OP_lit4      0x34
+#define DW_OP_lit5      0x35
+#define DW_OP_lit6      0x36
+#define DW_OP_lit7      0x37
+#define DW_OP_lit8      0x38
+#define DW_OP_lit9      0x39
+#define DW_OP_lit10     0x3a
+#define DW_OP_lit11     0x3b
+#define DW_OP_lit12     0x3c
+#define DW_OP_lit13     0x3d
+#define DW_OP_lit14     0x3e
+#define DW_OP_lit15     0x3f
+#define DW_OP_lit16     0x40
+#define DW_OP_lit17     0x41
+#define DW_OP_lit18     0x42
+#define DW_OP_lit19     0x43
+#define DW_OP_lit20     0x44
+#define DW_OP_lit21     0x45
+#define DW_OP_lit22     0x46
+#define DW_OP_lit23     0x47
+#define DW_OP_lit24     0x48
+#define DW_OP_lit25     0x49
+#define DW_OP_lit26     0x4a
+#define DW_OP_lit27     0x4b
+#define DW_OP_lit28     0x4c
+#define DW_OP_lit29     0x4d
+#define DW_OP_lit30     0x4e
+#define DW_OP_lit31     0x4f
+#define DW_OP_reg0      0x50
+#define DW_OP_reg1      0x51
+#define DW_OP_reg2      0x52
+#define DW_OP_reg3      0x53
+#define DW_OP_reg4      0x54
+#define DW_OP_reg5      0x55
+#define DW_OP_reg6      0x56
+#define DW_OP_reg7      0x57
+#define DW_OP_reg8      0x58
+#define DW_OP_reg9      0x59
+#define DW_OP_reg10     0x5a
+#define DW_OP_reg11     0x5b
+#define DW_OP_reg12     0x5c
+#define DW_OP_reg13     0x5d
+#define DW_OP_reg14     0x5e
+#define DW_OP_reg15     0x5f
+#define DW_OP_reg16     0x60
+#define DW_OP_reg17     0x61
+#define DW_OP_reg18     0x62
+#define DW_OP_reg19     0x63
+#define DW_OP_reg20     0x64
+#define DW_OP_reg21     0x65
+#define DW_OP_reg22     0x66
+#define DW_OP_reg23     0x67
+#define DW_OP_reg24     0x68
+#define DW_OP_reg25     0x69
+#define DW_OP_reg26     0x6a
+#define DW_OP_reg27     0x6b
+#define DW_OP_reg28     0x6c
+#define DW_OP_reg29     0x6d
+#define DW_OP_reg30     0x6e
+#define DW_OP_reg31     0x6f
+#define DW_OP_breg0     0x70
+#define DW_OP_breg1     0x71
+#define DW_OP_breg2     0x72
+#define DW_OP_breg3     0x73
+#define DW_OP_breg4     0x74
+#define DW_OP_breg5     0x75
+#define DW_OP_breg6     0x76
+#define DW_OP_breg7     0x77
+#define DW_OP_breg8     0x78
+#define DW_OP_breg9     0x79
+#define DW_OP_breg10    0x7a
+#define DW_OP_breg11    0x7b
+#define DW_OP_breg12    0x7c
+#define DW_OP_breg13    0x7d
+#define DW_OP_breg14    0x7e
+#define DW_OP_breg15    0x7f
+#define DW_OP_breg16    0x80
+#define DW_OP_breg17    0x81
+#define DW_OP_breg18    0x82
+#define DW_OP_breg19    0x83
+#define DW_OP_breg20    0x84
+#define DW_OP_breg21    0x85
+#define DW_OP_breg22    0x86
+#define DW_OP_breg23    0x87
+#define DW_OP_breg24    0x88
+#define DW_OP_breg25    0x89
+#define DW_OP_breg26    0x8a
+#define DW_OP_breg27    0x8b
+#define DW_OP_breg28    0x8c
+#define DW_OP_breg29    0x8d
+#define DW_OP_breg30    0x8e
+#define DW_OP_breg31    0x8f
+#define DW_OP_regx      0x90
+#define DW_OP_fbreg     0x91
+#define DW_OP_bregx     0x92
+#define DW_OP_piece     0x93
+#define DW_OP_deref_size        0x94
+#define DW_OP_xderef_size       0x95
+#define DW_OP_nop       0x96
+#define DW_OP_push_object_address       0x97
+#define DW_OP_call2     0x98
+#define DW_OP_call4     0x99
+#define DW_OP_call_ref  0x9a
+#define DW_OP_form_tls_address  0x9b
+#define DW_OP_call_frame_cfa    0x9c
+#define DW_OP_bit_piece 0x9d
+#define DW_OP_lo_user   0xe0
+#define DW_OP_hi_user   0xff
+
+/*
+ * Addresses used in FDE entries in the .eh_frame section may be encoded
+ * using one of the following encodings.
+ */
+#define DW_EH_PE_absptr 0x00
+#define DW_EH_PE_omit   0xff
+#define DW_EH_PE_uleb128        0x01
+#define DW_EH_PE_udata2 0x02
+#define DW_EH_PE_udata4 0x03
+#define DW_EH_PE_udata8 0x04
+#define DW_EH_PE_sleb128        0x09
+#define DW_EH_PE_sdata2 0x0a
+#define DW_EH_PE_sdata4 0x0b
+#define DW_EH_PE_sdata8 0x0c
+#define DW_EH_PE_signed 0x09
+
+#define DW_EH_PE_pcrel  0x10
+
+/*
+ * The architecture-specific register number that contains the return
+ * address in the .debug_frame table.
+ */
+#define DWARF_ARCH_RA_REG       17
+
+#ifndef __ASSEMBLY__
+/*
+ * Read either the frame pointer (r14) or the stack pointer (r15).
+ * NOTE: this MUST be inlined.
+ */
+static __always_inline unsigned long dwarf_read_arch_reg(unsigned int reg)
+{
+        unsigned long value;
+
+        switch (reg) {
+        case 14:
+                __asm__ __volatile__("mov r14, %0\n" : "=r" (value));
+                break;
+        case 15:
+                __asm__ __volatile__("mov r15, %0\n" : "=r" (value));
+                break;
+        default:
+                BUG();
+        }
+
+        return value;
+}
+
+/**
+ *      dwarf_cie - Common Information Entry
+ */
+struct dwarf_cie {
+        unsigned long length;
+        unsigned long cie_id;
+        unsigned char version;
+        const char *augmentation;
+        unsigned int code_alignment_factor;
+        int data_alignment_factor;
+
+        /* Which column in the rule table represents return addr of func. */
+        unsigned int return_address_reg;
+
+        unsigned char *initial_instructions;
+        unsigned char *instructions_end;
+
+        unsigned char encoding;
+
+        unsigned long cie_pointer;
+
+        struct list_head link;
+
+        unsigned long flags;
+#define DWARF_CIE_Z_AUGMENTATION        (1 << 0)
+};
+
+/**
+ *      dwarf_fde - Frame Description Entry
+ */
+struct dwarf_fde {
+        unsigned long length;
+        unsigned long cie_pointer;
+        struct dwarf_cie *cie;
+        unsigned long initial_location;
+        unsigned long address_range;
+        unsigned char *instructions;
+        unsigned char *end;
+        struct list_head link;
+};
+
+/**
+ *      dwarf_frame - DWARF information for a frame in the call stack
+ */
+struct dwarf_frame {
+        struct dwarf_frame *prev, *next;
+
+        unsigned long pc;
+
+        struct dwarf_reg *regs;
+        unsigned int num_regs;  /* how many regs are allocated? */
+
+        unsigned int depth;     /* what level are we in the callstack? */
+
+        unsigned long cfa;
+
+        /* Valid when DW_FRAME_CFA_REG_OFFSET is set in flags */
+        unsigned int cfa_register;
+        unsigned int cfa_offset;
+
+        /* Valid when DW_FRAME_CFA_REG_EXP is set in flags */
+        unsigned char *cfa_expr;
+        unsigned int cfa_expr_len;
+
+        unsigned long flags;
+#define DWARF_FRAME_CFA_REG_OFFSET      (1 << 0)
+#define DWARF_FRAME_CFA_REG_EXP         (1 << 1)
+
+        unsigned long return_addr;
+};
+
+/**
+ *      dwarf_reg - DWARF register
+ *      @flags: Describes how to calculate the value of this register
+ */
+struct dwarf_reg {
+        unsigned long addr;
+        unsigned long flags;
+#define DWARF_REG_OFFSET        (1 << 0)
+};
+
+/**
+ *      dwarf_stack - a DWARF stack contains a collection of DWARF frames
+ *      @depth: the number of frames in the stack
+ *      @level: an array of DWARF frames, indexed by stack level
+ *
+ */
+struct dwarf_stack {
+        unsigned int depth;
+        struct dwarf_frame **level;
+};
+
+/*
+ * Call Frame instruction opcodes.
+ */
+#define DW_CFA_advance_loc      0x40
+#define DW_CFA_offset           0x80
+#define DW_CFA_restore          0xc0
+#define DW_CFA_nop              0x00
+#define DW_CFA_set_loc          0x01
+#define DW_CFA_advance_loc1     0x02
+#define DW_CFA_advance_loc2     0x03
+#define DW_CFA_advance_loc4     0x04
+#define DW_CFA_offset_extended  0x05
+#define DW_CFA_restore_extended 0x06
+#define DW_CFA_undefined        0x07
+#define DW_CFA_same_value       0x08
+#define DW_CFA_register         0x09
+#define DW_CFA_remember_state   0x0a
+#define DW_CFA_restore_state    0x0b
+#define DW_CFA_def_cfa          0x0c
+#define DW_CFA_def_cfa_register 0x0d
+#define DW_CFA_def_cfa_offset   0x0e
+#define DW_CFA_def_cfa_expression       0x0f
+#define DW_CFA_expression       0x10
+#define DW_CFA_offset_extended_sf       0x11
+#define DW_CFA_def_cfa_sf       0x12
+#define DW_CFA_def_cfa_offset_sf        0x13
+#define DW_CFA_val_offset       0x14
+#define DW_CFA_val_offset_sf    0x15
+#define DW_CFA_val_expression   0x16
+#define DW_CFA_lo_user          0x1c
+#define DW_CFA_hi_user          0x3f
+
+/*
+ * Some call frame instructions encode their operands in the opcode. We
+ * need some helper functions to extract both the opcode and operands
+ * from an instruction.
+ */
+static inline unsigned int DW_CFA_opcode(unsigned long insn)
+{
+        return (insn & 0xc0);
+}
+
+static inline unsigned int DW_CFA_operand(unsigned long insn)
+{
+        return (insn & 0x3f);
+}
+
+#define DW_EH_FRAME_CIE 0               /* .eh_frame CIE IDs are 0 */
+#define DW_CIE_ID       0xffffffff
+#define DW64_CIE_ID     0xffffffffffffffffULL
+
+/*
+ * DWARF FDE/CIE length field values.
+ */
+#define DW_EXT_LO       0xfffffff0
+#define DW_EXT_HI       0xffffffff
+#define DW_EXT_DWARF64  DW_EXT_HI
+
+extern void dwarf_unwinder_init(void);
+
+extern struct dwarf_frame *dwarf_unwind_stack(unsigned long,
+                                              struct dwarf_frame *);
+#endif /* __ASSEMBLY__ */
+
+#define CFI_STARTPROC   .cfi_startproc
+#define CFI_ENDPROC     .cfi_endproc
+#define CFI_DEF_CFA     .cfi_def_cfa
+#define CFI_REGISTER    .cfi_register
+#define CFI_REL_OFFSET  .cfi_rel_offset
+
+#else
+
+/*
+ * Use the asm comment character to ignore the rest of the line.
+ */
+#define CFI_IGNORE      !
+
+#define CFI_STARTPROC   CFI_IGNORE
+#define CFI_ENDPROC     CFI_IGNORE
+#define CFI_DEF_CFA     CFI_IGNORE
+#define CFI_REGISTER    CFI_IGNORE
+#define CFI_REL_OFFSET  CFI_IGNORE
+
+#ifndef __ASSEMBLY__
+static inline void dwarf_unwinder_init(void)
+{
+}
+#endif
+
+#endif /* CONFIG_DWARF_UNWINDER */
+
+#endif /* __ASM_SH_DWARF_H */
diff --git a/arch/sh/include/asm/entry-macros.S b/arch/sh/include/asm/entry-macros.S
index 1bdd93891cd7..64fd0de24daf 100644
--- a/arch/sh/include/asm/entry-macros.S
+++ b/arch/sh/include/asm/entry-macros.S
@@ -108,3 +108,15 @@
 #else
 # define PREF(x)        nop
 #endif
+
+        /*
+         * Macro for use within assembly. Because the DWARF unwinder
+         * needs to use the frame register to unwind the stack, we
+         * need to setup r14 with the value of the stack pointer as
+         * the return address is usually on the stack somewhere.
+         */
+        .macro  setup_frame_reg
+#ifdef CONFIG_DWARF_UNWINDER
+        mov     r15, r14
+#endif
+        .endm
diff --git a/arch/sh/include/asm/sections.h b/arch/sh/include/asm/sections.h
index 01a4076a3719..a78701da775b 100644
--- a/arch/sh/include/asm/sections.h
+++ b/arch/sh/include/asm/sections.h
@@ -7,6 +7,7 @@ extern void __nosave_begin, __nosave_end;
 extern long __machvec_start, __machvec_end;
 extern char __uncached_start, __uncached_end;
 extern char _ebss[];
+extern char __start_eh_frame[], __stop_eh_frame[];
 
 #endif /* __ASM_SH_SECTIONS_H */
 
diff --git a/arch/sh/include/asm/vmlinux.lds.h b/arch/sh/include/asm/vmlinux.lds.h
new file mode 100644
index 000000000000..244ec4ad9a79
--- /dev/null
+++ b/arch/sh/include/asm/vmlinux.lds.h
@@ -0,0 +1,17 @@
+#ifndef __ASM_SH_VMLINUX_LDS_H
+#define __ASM_SH_VMLINUX_LDS_H
+
+#include <asm-generic/vmlinux.lds.h>
+
+#ifdef CONFIG_DWARF_UNWINDER
+#define DWARF_EH_FRAME                                                  \
+        .eh_frame : AT(ADDR(.eh_frame) - LOAD_OFFSET) {                 \
+                  VMLINUX_SYMBOL(__start_eh_frame) = .;                 \
+                  *(.eh_frame)                                          \
+                  VMLINUX_SYMBOL(__stop_eh_frame) = .;                  \
+        }
+#else
+#define DWARF_EH_FRAME
+#endif
+
+#endif /* __ASM_SH_VMLINUX_LDS_H */
diff --git a/arch/sh/kernel/Makefile_32 b/arch/sh/kernel/Makefile_32
index 37a3b7704fc6..f2245ebf0b31 100644
--- a/arch/sh/kernel/Makefile_32
+++ b/arch/sh/kernel/Makefile_32
@@ -33,6 +33,7 @@ obj-$(CONFIG_FTRACE_SYSCALLS)	+= ftrace.o
 obj-$(CONFIG_FUNCTION_GRAPH_TRACER) += ftrace.o
 obj-$(CONFIG_DUMP_CODE)         += disassemble.o
 obj-$(CONFIG_HIBERNATION)       += swsusp.o
+obj-$(CONFIG_DWARF_UNWINDER)    += dwarf.o
 
 obj-$(CONFIG_GENERIC_CLOCKEVENTS_BROADCAST)     += localtimer.o
 
diff --git a/arch/sh/kernel/Makefile_64 b/arch/sh/kernel/Makefile_64
index 00b73e7598cb..639ee514266c 100644
--- a/arch/sh/kernel/Makefile_64
+++ b/arch/sh/kernel/Makefile_64
@@ -13,6 +13,7 @@ obj-$(CONFIG_CRASH_DUMP)	+= crash_dump.o
 obj-$(CONFIG_STACKTRACE)        += stacktrace.o
 obj-$(CONFIG_IO_TRAPPED)        += io_trapped.o
 obj-$(CONFIG_GENERIC_GPIO)      += gpio.o
+obj-$(CONFIG_DWARF_UNWINDER)    += dwarf.o
 
 obj-$(CONFIG_GENERIC_CLOCKEVENTS_BROADCAST)     += localtimer.o
 
diff --git a/arch/sh/kernel/cpu/sh3/entry.S b/arch/sh/kernel/cpu/sh3/entry.S
index 3cb531f233f2..67ad6467c694 100644
--- a/arch/sh/kernel/cpu/sh3/entry.S
+++ b/arch/sh/kernel/cpu/sh3/entry.S
@@ -137,6 +137,7 @@ ENTRY(tlb_protection_violation_store)
          mov    #1, r5
 
 call_dpf:
+        setup_frame_reg
         mov.l   1f, r0
         mov     r5, r8
         mov.l   @r0, r6
diff --git a/arch/sh/kernel/dwarf.c b/arch/sh/kernel/dwarf.c
new file mode 100644
index 000000000000..83f3cc92549f
--- /dev/null
+++ b/arch/sh/kernel/dwarf.c
@@ -0,0 +1,901 @@
+/*
+ * 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.
+ */
+
+/* #define DEBUG */
+#include <linux/kernel.h>
+#include <linux/io.h>
+#include <linux/list.h>
+#include <linux/mm.h>
+#include <asm/dwarf.h>
+#include <asm/unwinder.h>
+#include <asm/sections.h>
+#include <asm/unaligned.h>
+#include <asm/dwarf.h>
+#include <asm/stacktrace.h>
+
+static LIST_HEAD(dwarf_cie_list);
+DEFINE_SPINLOCK(dwarf_cie_lock);
+
+static LIST_HEAD(dwarf_fde_list);
+DEFINE_SPINLOCK(dwarf_fde_lock);
+
+static struct dwarf_cie *cached_cie;
+
+/*
+ * Figure out whether we need to allocate some dwarf registers. If dwarf
+ * registers have already been allocated then we may need to realloc
+ * them. "reg" is a register number that we need to be able to access
+ * after this call.
+ *
+ * Register numbers start at zero, therefore we need to allocate space
+ * for "reg" + 1 registers.
+ */
+static void dwarf_frame_alloc_regs(struct dwarf_frame *frame,
+                                   unsigned int reg)
+{
+        struct dwarf_reg *regs;
+        unsigned int num_regs = reg + 1;
+        size_t new_size;
+        size_t old_size;
+
+        new_size = num_regs * sizeof(*regs);
+        old_size = frame->num_regs * sizeof(*regs);
+
+        /* Fast path: don't allocate any regs if we've already got enough. */
+        if (frame->num_regs >= num_regs)
+                return;
+
+        regs = kzalloc(new_size, GFP_KERNEL);
+        if (!regs) {
+                printk(KERN_WARNING "Unable to allocate DWARF registers\n");
+                /*
+                 * Let's just bomb hard here, we have no way to
+                 * gracefully recover.
+                 */
+                BUG();
+        }
+
+        if (frame->regs) {
+                memcpy(regs, frame->regs, old_size);
+                kfree(frame->regs);
+        }
+
+        frame->regs = regs;
+        frame->num_regs = num_regs;
+}
+
+/**
+ *      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));
+                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);
+                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 dwarf_cie *cie, *n;
+        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;
+        }
+
+        list_for_each_entry_safe(cie, n, &dwarf_cie_list, link) {
+                if (cie->cie_pointer == cie_ptr) {
+                        cached_cie = cie;
+                        break;
+                }
+        }
+
+        /* Couldn't find the entry in the list. */
+        if (&cie->link == &dwarf_cie_list)
+                cie = NULL;
+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)
+{
+        unsigned long flags;
+        struct dwarf_fde *fde, *n;
+
+        spin_lock_irqsave(&dwarf_fde_lock, flags);
+        list_for_each_entry_safe(fde, n, &dwarf_fde_list, link) {
+                unsigned long start, end;
+
+                start = fde->initial_location;
+                end = fde->initial_location + fde->address_range;
+
+                if (pc >= start && pc < end)
+                        break;
+        }
+
+        /* Couldn't find the entry in the list. */
+        if (&fde->link == &dwarf_fde_list)
+                fde = NULL;
+
+        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
+ *      @define_ra: keep executing insns until the return addr reg is defined?
+ *
+ *      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,
+                                   bool define_ra)
+{
+        unsigned char insn;
+        unsigned char *current_insn;
+        unsigned int count, delta, reg, expr_len, offset;
+        bool seen_ra_reg;
+
+        current_insn = insn_start;
+
+        /*
+         * If we're executing instructions for the dwarf_unwind_stack()
+         * FDE we need to keep executing instructions until the value of
+         * DWARF_ARCH_RA_REG is defined. See the comment in
+         * dwarf_unwind_stack() for more details.
+         */
+        if (define_ra)
+                seen_ra_reg = false;
+        else
+                seen_ra_reg = true;
+
+        while (current_insn < insn_end && (frame->pc <= pc || !seen_ra_reg) ) {
+                insn = __raw_readb(current_insn++);
+
+                if (!seen_ra_reg) {
+                        if (frame->num_regs >= DWARF_ARCH_RA_REG &&
+                            frame->regs[DWARF_ARCH_RA_REG].flags)
+                                seen_ra_reg = true;
+                }
+
+                /*
+                 * 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;
+                        dwarf_frame_alloc_regs(frame, reg);
+                        frame->regs[reg].addr = offset;
+                        frame->regs[reg].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;
+                        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;
+                        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, &reg);
+                        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();
+}
diff --git a/arch/sh/kernel/entry-common.S b/arch/sh/kernel/entry-common.S
index fc26ccd82789..e63178fefb9b 100644
--- a/arch/sh/kernel/entry-common.S
+++ b/arch/sh/kernel/entry-common.S
@@ -43,6 +43,7 @@
  *      syscall #
  *
  */
+#include <asm/dwarf.h>
 
 #if defined(CONFIG_PREEMPT)
 #  define preempt_stop()        cli ; TRACE_IRQS_OFF
@@ -66,6 +67,11 @@ ENTRY(exception_error)
 
         .align  2
 ret_from_exception:
+        CFI_STARTPROC simple
+        CFI_DEF_CFA r14, 0
+        CFI_REL_OFFSET 17, 64
+        CFI_REL_OFFSET 15, 0
+        CFI_REL_OFFSET 14, 56
         preempt_stop()
 ENTRY(ret_from_irq)
         !
@@ -240,6 +246,7 @@ debug_trap:
          nop
         bra     __restore_all
          nop
+        CFI_ENDPROC
 
         .align  2
 1:      .long   debug_trap_table
@@ -285,6 +292,7 @@ ret_from_fork:
  * system calls and debug traps through their respective jump tables.
  */
 ENTRY(system_call)
+        setup_frame_reg
 #if !defined(CONFIG_CPU_SH2)
         mov.l   1f, r9
         mov.l   @r9, r8         ! Read from TRA (Trap Address) Register
diff --git a/arch/sh/kernel/irq.c b/arch/sh/kernel/irq.c
index 278c68c60488..2bb43dc74f22 100644
--- a/arch/sh/kernel/irq.c
+++ b/arch/sh/kernel/irq.c
@@ -14,6 +14,7 @@
 #include <asm/processor.h>
 #include <asm/machvec.h>
 #include <asm/uaccess.h>
+#include <asm/dwarf.h>
 #include <asm/thread_info.h>
 #include <cpu/mmu_context.h>
 
@@ -261,6 +262,9 @@ void __init init_IRQ(void)
                 sh_mv.mv_init_irq();
 
         irq_ctx_init(smp_processor_id());
+
+        /* This needs to be early, but not too early.. */
+        dwarf_unwinder_init();
 }
 
 #ifdef CONFIG_SPARSE_IRQ
diff --git a/arch/sh/kernel/vmlinux.lds.S b/arch/sh/kernel/vmlinux.lds.S
index 80dc9f8d9412..1b7d9d541e01 100644
--- a/arch/sh/kernel/vmlinux.lds.S
+++ b/arch/sh/kernel/vmlinux.lds.S
@@ -12,7 +12,7 @@ OUTPUT_ARCH(sh)
 
 #include <asm/thread_info.h>
 #include <asm/cache.h>
-#include <asm-generic/vmlinux.lds.h>
+#include <asm/vmlinux.lds.h>
 
 ENTRY(_start)
 SECTIONS
@@ -70,6 +70,8 @@ SECTIONS
 
         _edata = .;                     /* End of data section */
 
+        DWARF_EH_FRAME
+
         . = ALIGN(PAGE_SIZE);           /* Init code and data */
         __init_begin = .;
         INIT_TEXT_SECTION(PAGE_SIZE)