sh: dwarf unwinder support.

This is a first cut at a generic DWARF unwinder for the kernel. It's
still lacking DWARF64 support and the DWARF expression support hasn't
been tested very well but it is generating proper stacktraces on SH for
WARN_ON() and NULL dereferences.

Signed-off-by: Matt Fleming <matt@console-pimps.org>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>

3 files changed, 425 insertions, 0 deletions

diff --git a/arch/sh/include/asm/dwarf.h b/arch/sh/include/asm/dwarf.h
new file mode 100644
index 00000000000..23eba12880b
--- /dev/null
+++ b/arch/sh/include/asm/dwarf.h
@@ -0,0 +1,407 @@
+/*
+ * 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
+
+/*
+ * At what offset into dwarf_unwind_stack() is DWARF_ARCH_RA_REG setup?
+ */
+#define DWARF_ARCH_UNWIND_OFFSET        0x20
+
+#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/sections.h b/arch/sh/include/asm/sections.h
index 01a4076a371..a78701da775 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 00000000000..244ec4ad9a7
--- /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 */