| /* Frame unwinder for frames with DWARF Call Frame Information. |
| |
| Copyright 2003 Free Software Foundation, Inc. |
| |
| Contributed by Mark Kettenis. |
| |
| This file is part of GDB. |
| |
| This program is free software; you can redistribute it and/or modify |
| it under the terms of the GNU General Public License as published by |
| the Free Software Foundation; either version 2 of the License, or |
| (at your option) any later version. |
| |
| This program is distributed in the hope that it will be useful, |
| but WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| GNU General Public License for more details. |
| |
| You should have received a copy of the GNU General Public License |
| along with this program; if not, write to the Free Software |
| Foundation, Inc., 59 Temple Place - Suite 330, |
| Boston, MA 02111-1307, USA. */ |
| |
| #include "defs.h" |
| #include "dwarf2expr.h" |
| #include "elf/dwarf2.h" |
| #include "frame.h" |
| #include "frame-base.h" |
| #include "frame-unwind.h" |
| #include "gdbcore.h" |
| #include "gdbtypes.h" |
| #include "symtab.h" |
| #include "objfiles.h" |
| #include "regcache.h" |
| |
| #include "gdb_assert.h" |
| #include "gdb_string.h" |
| |
| #include "dwarf2-frame.h" |
| |
| /* Call Frame Information (CFI). */ |
| |
| /* Common Information Entry (CIE). */ |
| |
| struct dwarf2_cie |
| { |
| /* Offset into the .debug_frame section where this CIE was found. |
| Used to identify this CIE. */ |
| ULONGEST cie_pointer; |
| |
| /* Constant that is factored out of all advance location |
| instructions. */ |
| ULONGEST code_alignment_factor; |
| |
| /* Constants that is factored out of all offset instructions. */ |
| LONGEST data_alignment_factor; |
| |
| /* Return address column. */ |
| ULONGEST return_address_register; |
| |
| /* Instruction sequence to initialize a register set. */ |
| unsigned char *initial_instructions; |
| unsigned char *end; |
| |
| /* Encoding of addresses. */ |
| unsigned char encoding; |
| |
| /* True if a 'z' augmentation existed. */ |
| unsigned char saw_z_augmentation; |
| |
| struct dwarf2_cie *next; |
| }; |
| |
| /* Frame Description Entry (FDE). */ |
| |
| struct dwarf2_fde |
| { |
| /* CIE for this FDE. */ |
| struct dwarf2_cie *cie; |
| |
| /* First location associated with this FDE. */ |
| CORE_ADDR initial_location; |
| |
| /* Number of bytes of program instructions described by this FDE. */ |
| CORE_ADDR address_range; |
| |
| /* Instruction sequence. */ |
| unsigned char *instructions; |
| unsigned char *end; |
| |
| struct dwarf2_fde *next; |
| }; |
| |
| static struct dwarf2_fde *dwarf2_frame_find_fde (CORE_ADDR *pc); |
| |
| |
| /* Structure describing a frame state. */ |
| |
| struct dwarf2_frame_state |
| { |
| /* Each register save state can be described in terms of a CFA slot, |
| another register, or a location expression. */ |
| struct dwarf2_frame_state_reg_info |
| { |
| struct dwarf2_frame_state_reg |
| { |
| union { |
| LONGEST offset; |
| ULONGEST reg; |
| unsigned char *exp; |
| } loc; |
| ULONGEST exp_len; |
| enum { |
| REG_UNSAVED, |
| REG_SAVED_OFFSET, |
| REG_SAVED_REG, |
| REG_SAVED_EXP, |
| REG_UNMODIFIED |
| } how; |
| } *reg; |
| int num_regs; |
| |
| /* Used to implement DW_CFA_remember_state. */ |
| struct dwarf2_frame_state_reg_info *prev; |
| } regs; |
| |
| LONGEST cfa_offset; |
| ULONGEST cfa_reg; |
| unsigned char *cfa_exp; |
| enum { |
| CFA_UNSET, |
| CFA_REG_OFFSET, |
| CFA_EXP |
| } cfa_how; |
| |
| /* The PC described by the current frame state. */ |
| CORE_ADDR pc; |
| |
| /* Initial register set from the CIE. |
| Used to implement DW_CFA_restore. */ |
| struct dwarf2_frame_state_reg_info initial; |
| |
| /* The information we care about from the CIE. */ |
| LONGEST data_align; |
| ULONGEST code_align; |
| ULONGEST retaddr_column; |
| }; |
| |
| /* Store the length the expression for the CFA in the `cfa_reg' field, |
| which is unused in that case. */ |
| #define cfa_exp_len cfa_reg |
| |
| /* Assert that the register set RS is large enough to store NUM_REGS |
| columns. If necessary, enlarge the register set. */ |
| |
| static void |
| dwarf2_frame_state_alloc_regs (struct dwarf2_frame_state_reg_info *rs, |
| int num_regs) |
| { |
| size_t size = sizeof (struct dwarf2_frame_state_reg); |
| |
| if (num_regs <= rs->num_regs) |
| return; |
| |
| rs->reg = (struct dwarf2_frame_state_reg *) |
| xrealloc (rs->reg, num_regs * size); |
| |
| /* Initialize newly allocated registers. */ |
| memset (rs->reg + rs->num_regs, 0, (num_regs - rs->num_regs) * size); |
| rs->num_regs = num_regs; |
| } |
| |
| /* Copy the register columns in register set RS into newly allocated |
| memory and return a pointer to this newly created copy. */ |
| |
| static struct dwarf2_frame_state_reg * |
| dwarf2_frame_state_copy_regs (struct dwarf2_frame_state_reg_info *rs) |
| { |
| size_t size = rs->num_regs * sizeof (struct dwarf2_frame_state_reg_info); |
| struct dwarf2_frame_state_reg *reg; |
| |
| reg = (struct dwarf2_frame_state_reg *) xmalloc (size); |
| memcpy (reg, rs->reg, size); |
| |
| return reg; |
| } |
| |
| /* Release the memory allocated to register set RS. */ |
| |
| static void |
| dwarf2_frame_state_free_regs (struct dwarf2_frame_state_reg_info *rs) |
| { |
| if (rs) |
| { |
| dwarf2_frame_state_free_regs (rs->prev); |
| |
| xfree (rs->reg); |
| xfree (rs); |
| } |
| } |
| |
| /* Release the memory allocated to the frame state FS. */ |
| |
| static void |
| dwarf2_frame_state_free (void *p) |
| { |
| struct dwarf2_frame_state *fs = p; |
| |
| dwarf2_frame_state_free_regs (fs->initial.prev); |
| dwarf2_frame_state_free_regs (fs->regs.prev); |
| xfree (fs->initial.reg); |
| xfree (fs->regs.reg); |
| xfree (fs); |
| } |
| |
| |
| /* Helper functions for execute_stack_op. */ |
| |
| static CORE_ADDR |
| read_reg (void *baton, int reg) |
| { |
| struct frame_info *next_frame = (struct frame_info *) baton; |
| int regnum; |
| char *buf; |
| |
| regnum = DWARF2_REG_TO_REGNUM (reg); |
| |
| buf = (char *) alloca (register_size (current_gdbarch, regnum)); |
| frame_unwind_register (next_frame, regnum, buf); |
| return extract_typed_address (buf, builtin_type_void_data_ptr); |
| } |
| |
| static void |
| read_mem (void *baton, char *buf, CORE_ADDR addr, size_t len) |
| { |
| read_memory (addr, buf, len); |
| } |
| |
| static void |
| no_get_frame_base (void *baton, unsigned char **start, size_t *length) |
| { |
| internal_error (__FILE__, __LINE__, |
| "Support for DW_OP_fbreg is unimplemented"); |
| } |
| |
| static CORE_ADDR |
| no_get_tls_address (void *baton, CORE_ADDR offset) |
| { |
| internal_error (__FILE__, __LINE__, |
| "Support for DW_OP_GNU_push_tls_address is unimplemented"); |
| } |
| |
| static CORE_ADDR |
| execute_stack_op (unsigned char *exp, ULONGEST len, |
| struct frame_info *next_frame, CORE_ADDR initial) |
| { |
| struct dwarf_expr_context *ctx; |
| CORE_ADDR result; |
| |
| ctx = new_dwarf_expr_context (); |
| ctx->baton = next_frame; |
| ctx->read_reg = read_reg; |
| ctx->read_mem = read_mem; |
| ctx->get_frame_base = no_get_frame_base; |
| ctx->get_tls_address = no_get_tls_address; |
| |
| dwarf_expr_push (ctx, initial); |
| dwarf_expr_eval (ctx, exp, len); |
| result = dwarf_expr_fetch (ctx, 0); |
| |
| if (ctx->in_reg) |
| result = read_reg (next_frame, result); |
| |
| free_dwarf_expr_context (ctx); |
| |
| return result; |
| } |
| |
| |
| static void |
| execute_cfa_program (unsigned char *insn_ptr, unsigned char *insn_end, |
| struct frame_info *next_frame, |
| struct dwarf2_frame_state *fs) |
| { |
| CORE_ADDR pc = frame_pc_unwind (next_frame); |
| int bytes_read; |
| |
| while (insn_ptr < insn_end && fs->pc <= pc) |
| { |
| unsigned char insn = *insn_ptr++; |
| ULONGEST utmp, reg; |
| LONGEST offset; |
| |
| if ((insn & 0xc0) == DW_CFA_advance_loc) |
| fs->pc += (insn & 0x3f) * fs->code_align; |
| else if ((insn & 0xc0) == DW_CFA_offset) |
| { |
| reg = insn & 0x3f; |
| insn_ptr = read_uleb128 (insn_ptr, insn_end, &utmp); |
| offset = utmp * fs->data_align; |
| dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1); |
| fs->regs.reg[reg].how = REG_SAVED_OFFSET; |
| fs->regs.reg[reg].loc.offset = offset; |
| } |
| else if ((insn & 0xc0) == DW_CFA_restore) |
| { |
| gdb_assert (fs->initial.reg); |
| reg = insn & 0x3f; |
| dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1); |
| fs->regs.reg[reg] = fs->initial.reg[reg]; |
| } |
| else |
| { |
| switch (insn) |
| { |
| case DW_CFA_set_loc: |
| fs->pc = dwarf2_read_address (insn_ptr, insn_end, &bytes_read); |
| insn_ptr += bytes_read; |
| break; |
| |
| case DW_CFA_advance_loc1: |
| utmp = extract_unsigned_integer (insn_ptr, 1); |
| fs->pc += utmp * fs->code_align; |
| insn_ptr++; |
| break; |
| case DW_CFA_advance_loc2: |
| utmp = extract_unsigned_integer (insn_ptr, 2); |
| fs->pc += utmp * fs->code_align; |
| insn_ptr += 2; |
| break; |
| case DW_CFA_advance_loc4: |
| utmp = extract_unsigned_integer (insn_ptr, 4); |
| fs->pc += utmp * fs->code_align; |
| insn_ptr += 4; |
| break; |
| |
| case DW_CFA_offset_extended: |
| insn_ptr = read_uleb128 (insn_ptr, insn_end, ®); |
| insn_ptr = read_uleb128 (insn_ptr, insn_end, &utmp); |
| offset = utmp * fs->data_align; |
| dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1); |
| fs->regs.reg[reg].how = REG_SAVED_OFFSET; |
| fs->regs.reg[reg].loc.offset = offset; |
| break; |
| |
| case DW_CFA_restore_extended: |
| gdb_assert (fs->initial.reg); |
| insn_ptr = read_uleb128 (insn_ptr, insn_end, ®); |
| dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1); |
| fs->regs.reg[reg] = fs->initial.reg[reg]; |
| break; |
| |
| case DW_CFA_undefined: |
| insn_ptr = read_uleb128 (insn_ptr, insn_end, ®); |
| dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1); |
| fs->regs.reg[reg].how = REG_UNSAVED; |
| break; |
| |
| case DW_CFA_same_value: |
| insn_ptr = read_uleb128 (insn_ptr, insn_end, ®); |
| dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1); |
| fs->regs.reg[reg].how = REG_UNMODIFIED; |
| break; |
| |
| case DW_CFA_register: |
| insn_ptr = read_uleb128 (insn_ptr, insn_end, ®); |
| insn_ptr = read_uleb128 (insn_ptr, insn_end, &utmp); |
| dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1); |
| fs->regs.reg[reg].loc.reg = utmp; |
| break; |
| |
| case DW_CFA_remember_state: |
| { |
| struct dwarf2_frame_state_reg_info *new_rs; |
| |
| new_rs = XMALLOC (struct dwarf2_frame_state_reg_info); |
| *new_rs = fs->regs; |
| fs->regs.reg = dwarf2_frame_state_copy_regs (&fs->regs); |
| fs->regs.prev = new_rs; |
| } |
| break; |
| |
| case DW_CFA_restore_state: |
| { |
| struct dwarf2_frame_state_reg_info *old_rs = fs->regs.prev; |
| |
| gdb_assert (old_rs); |
| |
| xfree (fs->regs.reg); |
| fs->regs = *old_rs; |
| xfree (old_rs); |
| } |
| break; |
| |
| case DW_CFA_def_cfa: |
| insn_ptr = read_uleb128 (insn_ptr, insn_end, &fs->cfa_reg); |
| insn_ptr = read_uleb128 (insn_ptr, insn_end, &utmp); |
| fs->cfa_offset = utmp; |
| fs->cfa_how = CFA_REG_OFFSET; |
| break; |
| |
| case DW_CFA_def_cfa_register: |
| insn_ptr = read_uleb128 (insn_ptr, insn_end, &fs->cfa_reg); |
| fs->cfa_how = CFA_REG_OFFSET; |
| break; |
| |
| case DW_CFA_def_cfa_offset: |
| insn_ptr = read_uleb128 (insn_ptr, insn_end, &fs->cfa_offset); |
| /* cfa_how deliberately not set. */ |
| break; |
| |
| case DW_CFA_def_cfa_expression: |
| insn_ptr = read_uleb128 (insn_ptr, insn_end, &fs->cfa_exp_len); |
| fs->cfa_exp = insn_ptr; |
| fs->cfa_how = CFA_EXP; |
| insn_ptr += fs->cfa_exp_len; |
| break; |
| |
| case DW_CFA_expression: |
| insn_ptr = read_uleb128 (insn_ptr, insn_end, ®); |
| dwarf2_frame_state_alloc_regs (&fs->regs, reg + 1); |
| insn_ptr = read_uleb128 (insn_ptr, insn_end, &utmp); |
| fs->regs.reg[reg].loc.exp = insn_ptr; |
| fs->regs.reg[reg].exp_len = utmp; |
| fs->regs.reg[reg].how = REG_SAVED_EXP; |
| insn_ptr += utmp; |
| break; |
| |
| case DW_CFA_nop: |
| break; |
| |
| case DW_CFA_GNU_args_size: |
| /* Ignored. */ |
| insn_ptr = read_uleb128 (insn_ptr, insn_end, &utmp); |
| break; |
| |
| default: |
| internal_error (__FILE__, __LINE__, "Unknown CFI encountered."); |
| } |
| } |
| } |
| |
| /* Don't allow remember/restore between CIE and FDE programs. */ |
| dwarf2_frame_state_free_regs (fs->regs.prev); |
| fs->regs.prev = NULL; |
| } |
| |
| struct dwarf2_frame_cache |
| { |
| /* DWARF Call Frame Address. */ |
| CORE_ADDR cfa; |
| |
| /* Saved registers, indexed by GDB register number, not by DWARF |
| register number. */ |
| struct dwarf2_frame_state_reg *reg; |
| }; |
| |
| static struct dwarf2_frame_cache * |
| dwarf2_frame_cache (struct frame_info *next_frame, void **this_cache) |
| { |
| struct cleanup *old_chain; |
| int num_regs = NUM_REGS + NUM_PSEUDO_REGS; |
| struct dwarf2_frame_cache *cache; |
| struct dwarf2_frame_state *fs; |
| struct dwarf2_fde *fde; |
| int reg; |
| |
| if (*this_cache) |
| return *this_cache; |
| |
| /* Allocate a new cache. */ |
| cache = FRAME_OBSTACK_ZALLOC (struct dwarf2_frame_cache); |
| cache->reg = FRAME_OBSTACK_CALLOC (num_regs, struct dwarf2_frame_state_reg); |
| |
| /* Allocate and initialize the frame state. */ |
| fs = XMALLOC (struct dwarf2_frame_state); |
| memset (fs, 0, sizeof (struct dwarf2_frame_state)); |
| old_chain = make_cleanup (dwarf2_frame_state_free, fs); |
| |
| /* Unwind the PC. |
| |
| Note that if NEXT_FRAME is never supposed to return (i.e. a call |
| to abort), the compiler might optimize away the instruction at |
| NEXT_FRAME's return address. As a result the return address will |
| point at some random instruction, and the CFI for that |
| instruction is probably wortless to us. GCC's unwinder solves |
| this problem by substracting 1 from the return address to get an |
| address in the middle of a presumed call instruction (or the |
| instruction in the associated delay slot). This should only be |
| done for "normal" frames and not for resume-type frames (signal |
| handlers, sentinel frames, dummy frames). |
| |
| We don't do what GCC's does here (yet). It's not clear how |
| reliable the method is. There's also a problem with finding the |
| right FDE; see the comment in dwarf_frame_p. If dwarf_frame_p |
| selected this frame unwinder because it found the FDE for the |
| next function, using the adjusted return address might not yield |
| a FDE at all. The problem isn't specific to DWARF CFI; other |
| unwinders loose in similar ways. Therefore it's probably |
| acceptable to leave things slightly broken for now. */ |
| fs->pc = frame_pc_unwind (next_frame); |
| |
| /* Find the correct FDE. */ |
| fde = dwarf2_frame_find_fde (&fs->pc); |
| gdb_assert (fde != NULL); |
| |
| /* Extract any interesting information from the CIE. */ |
| fs->data_align = fde->cie->data_alignment_factor; |
| fs->code_align = fde->cie->code_alignment_factor; |
| fs->retaddr_column = fde->cie->return_address_register; |
| |
| /* First decode all the insns in the CIE. */ |
| execute_cfa_program (fde->cie->initial_instructions, |
| fde->cie->end, next_frame, fs); |
| |
| /* Save the initialized register set. */ |
| fs->initial = fs->regs; |
| fs->initial.reg = dwarf2_frame_state_copy_regs (&fs->regs); |
| |
| /* Then decode the insns in the FDE up to our target PC. */ |
| execute_cfa_program (fde->instructions, fde->end, next_frame, fs); |
| |
| /* Caclulate the CFA. */ |
| switch (fs->cfa_how) |
| { |
| case CFA_REG_OFFSET: |
| cache->cfa = read_reg (next_frame, fs->cfa_reg); |
| cache->cfa += fs->cfa_offset; |
| break; |
| |
| case CFA_EXP: |
| cache->cfa = |
| execute_stack_op (fs->cfa_exp, fs->cfa_exp_len, next_frame, 0); |
| break; |
| |
| default: |
| internal_error (__FILE__, __LINE__, "Unknown CFA rule."); |
| } |
| |
| /* Save the register info in the cache. */ |
| for (reg = 0; reg < fs->regs.num_regs; reg++) |
| { |
| int regnum; |
| |
| /* Skip the return address column. */ |
| if (reg == fs->retaddr_column) |
| /* NOTE: cagney/2003-06-07: Is this right? What if the |
| RETADDR_COLUM corresponds to a real register (and, worse, |
| that isn't the PC_REGNUM)? I'm guessing that the PC_REGNUM |
| further down is trying to handle this. That can't be right |
| though - PC_REGNUM may not be valid (it can be -ve). I |
| think, instead when RETADDR_COLUM isn't a real register, it |
| should map itself onto frame_pc_unwind. */ |
| continue; |
| |
| /* Use the GDB register number as index. */ |
| regnum = DWARF2_REG_TO_REGNUM (reg); |
| |
| if (regnum >= 0 && regnum < num_regs) |
| cache->reg[regnum] = fs->regs.reg[reg]; |
| } |
| |
| /* Store the location of the return addess. If the return address |
| column (adjusted) is not the same as gdb's PC_REGNUM, then this |
| implies a copy from the ra column register. */ |
| if (fs->retaddr_column < fs->regs.num_regs |
| && fs->regs.reg[fs->retaddr_column].how != REG_UNSAVED) |
| { |
| /* See comment above about a possibly -ve PC_REGNUM. If this |
| assertion fails, it's a problem with this code and not the |
| architecture. */ |
| gdb_assert (PC_REGNUM >= 0); |
| cache->reg[PC_REGNUM] = fs->regs.reg[fs->retaddr_column]; |
| } |
| else |
| { |
| reg = DWARF2_REG_TO_REGNUM (fs->retaddr_column); |
| if (reg != PC_REGNUM) |
| { |
| /* See comment above about PC_REGNUM being -ve. If this |
| assertion fails, it's a problem with this code and not |
| the architecture. */ |
| gdb_assert (PC_REGNUM >= 0); |
| cache->reg[PC_REGNUM].loc.reg = reg; |
| cache->reg[PC_REGNUM].how = REG_SAVED_REG; |
| } |
| } |
| |
| do_cleanups (old_chain); |
| |
| *this_cache = cache; |
| return cache; |
| } |
| |
| static void |
| dwarf2_frame_this_id (struct frame_info *next_frame, void **this_cache, |
| struct frame_id *this_id) |
| { |
| struct dwarf2_frame_cache *cache = |
| dwarf2_frame_cache (next_frame, this_cache); |
| |
| (*this_id) = frame_id_build (cache->cfa, frame_func_unwind (next_frame)); |
| } |
| |
| static void |
| dwarf2_frame_prev_register (struct frame_info *next_frame, void **this_cache, |
| int regnum, int *optimizedp, |
| enum lval_type *lvalp, CORE_ADDR *addrp, |
| int *realnump, void *valuep) |
| { |
| struct dwarf2_frame_cache *cache = |
| dwarf2_frame_cache (next_frame, this_cache); |
| |
| switch (cache->reg[regnum].how) |
| { |
| case REG_UNSAVED: |
| *optimizedp = 1; |
| *lvalp = not_lval; |
| *addrp = 0; |
| *realnump = -1; |
| if (regnum == SP_REGNUM) |
| { |
| /* GCC defines the CFA as the value of the stack pointer |
| just before the call instruction is executed. Do other |
| compilers use the same definition? */ |
| /* DWARF V3 Draft 7 p102: Typically, the CFA is defined to |
| be the value of the stack pointer at the call site in the |
| previous frame (which may be different from its value on |
| entry to the current frame). */ |
| /* DWARF V3 Draft 7 p103: The first column of the rules |
| defines the rule which computes the CFA value; it may be |
| either a register and a signed offset that are added |
| together or a DWARF expression that is evaluated. */ |
| /* FIXME: cagney/2003-07-07: I don't understand this. The |
| CFI info should have provided unwind information for the |
| SP register and then pointed ->cfa_reg at it, not the |
| reverse. Assuming that SP_REGNUM is !-ve, there is a |
| very real posibility that CFA is an offset from some |
| other register, having nothing to do with the unwound SP |
| value. */ |
| *optimizedp = 0; |
| if (valuep) |
| { |
| /* Store the value. */ |
| store_typed_address (valuep, builtin_type_void_data_ptr, |
| cache->cfa); |
| } |
| } |
| else if (valuep) |
| { |
| /* In some cases, for example %eflags on the i386, we have |
| to provide a sane value, even though this register wasn't |
| saved. Assume we can get it from NEXT_FRAME. */ |
| frame_unwind_register (next_frame, regnum, valuep); |
| } |
| break; |
| |
| case REG_SAVED_OFFSET: |
| *optimizedp = 0; |
| *lvalp = lval_memory; |
| *addrp = cache->cfa + cache->reg[regnum].loc.offset; |
| *realnump = -1; |
| if (valuep) |
| { |
| /* Read the value in from memory. */ |
| read_memory (*addrp, valuep, |
| register_size (current_gdbarch, regnum)); |
| } |
| break; |
| |
| case REG_SAVED_REG: |
| regnum = DWARF2_REG_TO_REGNUM (cache->reg[regnum].loc.reg); |
| frame_register_unwind (next_frame, regnum, |
| optimizedp, lvalp, addrp, realnump, valuep); |
| break; |
| |
| case REG_SAVED_EXP: |
| *optimizedp = 0; |
| *lvalp = lval_memory; |
| *addrp = execute_stack_op (cache->reg[regnum].loc.exp, |
| cache->reg[regnum].exp_len, |
| next_frame, cache->cfa); |
| *realnump = -1; |
| if (valuep) |
| { |
| /* Read the value in from memory. */ |
| read_memory (*addrp, valuep, |
| register_size (current_gdbarch, regnum)); |
| } |
| break; |
| |
| case REG_UNMODIFIED: |
| frame_register_unwind (next_frame, regnum, |
| optimizedp, lvalp, addrp, realnump, valuep); |
| break; |
| |
| default: |
| internal_error (__FILE__, __LINE__, "Unknown register rule."); |
| } |
| } |
| |
| static const struct frame_unwind dwarf2_frame_unwind = |
| { |
| NORMAL_FRAME, |
| dwarf2_frame_this_id, |
| dwarf2_frame_prev_register |
| }; |
| |
| const struct frame_unwind * |
| dwarf2_frame_p (CORE_ADDR pc) |
| { |
| /* The way GDB works, this function can be called with PC just after |
| the last instruction of the function we're supposed to return the |
| unwind methods for. In that case we won't find the correct FDE; |
| instead we find the FDE for the next function, or we won't find |
| an FDE at all. There is a possible solution (see the comment in |
| dwarf2_frame_cache), GDB doesn't pass us enough information to |
| implement it. */ |
| if (dwarf2_frame_find_fde (&pc)) |
| return &dwarf2_frame_unwind; |
| |
| return NULL; |
| } |
| |
| |
| /* There is no explicitly defined relationship between the CFA and the |
| location of frame's local variables and arguments/parameters. |
| Therefore, frame base methods on this page should probably only be |
| used as a last resort, just to avoid printing total garbage as a |
| response to the "info frame" command. */ |
| |
| static CORE_ADDR |
| dwarf2_frame_base_address (struct frame_info *next_frame, void **this_cache) |
| { |
| struct dwarf2_frame_cache *cache = |
| dwarf2_frame_cache (next_frame, this_cache); |
| |
| return cache->cfa; |
| } |
| |
| static const struct frame_base dwarf2_frame_base = |
| { |
| &dwarf2_frame_unwind, |
| dwarf2_frame_base_address, |
| dwarf2_frame_base_address, |
| dwarf2_frame_base_address |
| }; |
| |
| const struct frame_base * |
| dwarf2_frame_base_p (CORE_ADDR pc) |
| { |
| if (dwarf2_frame_find_fde (&pc)) |
| return &dwarf2_frame_base; |
| |
| return NULL; |
| } |
| |
| /* A minimal decoding of DWARF2 compilation units. We only decode |
| what's needed to get to the call frame information. */ |
| |
| struct comp_unit |
| { |
| /* Keep the bfd convenient. */ |
| bfd *abfd; |
| |
| struct objfile *objfile; |
| |
| /* Linked list of CIEs for this object. */ |
| struct dwarf2_cie *cie; |
| |
| /* Address size for this unit - from unit header. */ |
| unsigned char addr_size; |
| |
| /* Pointer to the .debug_frame section loaded into memory. */ |
| char *dwarf_frame_buffer; |
| |
| /* Length of the loaded .debug_frame section. */ |
| unsigned long dwarf_frame_size; |
| |
| /* Pointer to the .debug_frame section. */ |
| asection *dwarf_frame_section; |
| |
| /* Base for DW_EH_PE_datarel encodings. */ |
| bfd_vma dbase; |
| }; |
| |
| static unsigned int |
| read_1_byte (bfd *bfd, char *buf) |
| { |
| return bfd_get_8 (abfd, (bfd_byte *) buf); |
| } |
| |
| static unsigned int |
| read_4_bytes (bfd *abfd, char *buf) |
| { |
| return bfd_get_32 (abfd, (bfd_byte *) buf); |
| } |
| |
| static ULONGEST |
| read_8_bytes (bfd *abfd, char *buf) |
| { |
| return bfd_get_64 (abfd, (bfd_byte *) buf); |
| } |
| |
| static ULONGEST |
| read_unsigned_leb128 (bfd *abfd, char *buf, unsigned int *bytes_read_ptr) |
| { |
| ULONGEST result; |
| unsigned int num_read; |
| int shift; |
| unsigned char byte; |
| |
| result = 0; |
| shift = 0; |
| num_read = 0; |
| |
| do |
| { |
| byte = bfd_get_8 (abfd, (bfd_byte *) buf); |
| buf++; |
| num_read++; |
| result |= ((byte & 0x7f) << shift); |
| shift += 7; |
| } |
| while (byte & 0x80); |
| |
| *bytes_read_ptr = num_read; |
| |
| return result; |
| } |
| |
| static LONGEST |
| read_signed_leb128 (bfd *abfd, char *buf, unsigned int *bytes_read_ptr) |
| { |
| LONGEST result; |
| int shift; |
| unsigned int num_read; |
| unsigned char byte; |
| |
| result = 0; |
| shift = 0; |
| num_read = 0; |
| |
| do |
| { |
| byte = bfd_get_8 (abfd, (bfd_byte *) buf); |
| buf++; |
| num_read++; |
| result |= ((byte & 0x7f) << shift); |
| shift += 7; |
| } |
| while (byte & 0x80); |
| |
| if ((shift < 32) && (byte & 0x40)) |
| result |= -(1 << shift); |
| |
| *bytes_read_ptr = num_read; |
| |
| return result; |
| } |
| |
| static ULONGEST |
| read_initial_length (bfd *abfd, char *buf, unsigned int *bytes_read_ptr) |
| { |
| LONGEST result; |
| |
| result = bfd_get_32 (abfd, (bfd_byte *) buf); |
| if (result == 0xffffffff) |
| { |
| result = bfd_get_64 (abfd, (bfd_byte *) buf + 4); |
| *bytes_read_ptr = 12; |
| } |
| else |
| *bytes_read_ptr = 4; |
| |
| return result; |
| } |
| |
| |
| /* Pointer encoding helper functions. */ |
| |
| /* GCC supports exception handling based on DWARF2 CFI. However, for |
| technical reasons, it encodes addresses in its FDE's in a different |
| way. Several "pointer encodings" are supported. The encoding |
| that's used for a particular FDE is determined by the 'R' |
| augmentation in the associated CIE. The argument of this |
| augmentation is a single byte. |
| |
| The address can be encoded as 2 bytes, 4 bytes, 8 bytes, or as a |
| LEB128. This is encoded in bits 0, 1 and 2. Bit 3 encodes whether |
| the address is signed or unsigned. Bits 4, 5 and 6 encode how the |
| address should be interpreted (absolute, relative to the current |
| position in the FDE, ...). Bit 7, indicates that the address |
| should be dereferenced. */ |
| |
| static unsigned char |
| encoding_for_size (unsigned int size) |
| { |
| switch (size) |
| { |
| case 2: |
| return DW_EH_PE_udata2; |
| case 4: |
| return DW_EH_PE_udata4; |
| case 8: |
| return DW_EH_PE_udata8; |
| default: |
| internal_error (__FILE__, __LINE__, "Unsupported address size"); |
| } |
| } |
| |
| static unsigned int |
| size_of_encoded_value (unsigned char encoding) |
| { |
| if (encoding == DW_EH_PE_omit) |
| return 0; |
| |
| switch (encoding & 0x07) |
| { |
| case DW_EH_PE_absptr: |
| return TYPE_LENGTH (builtin_type_void_data_ptr); |
| case DW_EH_PE_udata2: |
| return 2; |
| case DW_EH_PE_udata4: |
| return 4; |
| case DW_EH_PE_udata8: |
| return 8; |
| default: |
| internal_error (__FILE__, __LINE__, "Invalid or unsupported encoding"); |
| } |
| } |
| |
| static CORE_ADDR |
| read_encoded_value (struct comp_unit *unit, unsigned char encoding, |
| char *buf, unsigned int *bytes_read_ptr) |
| { |
| CORE_ADDR base; |
| |
| /* GCC currently doesn't generate DW_EH_PE_indirect encodings for |
| FDE's. */ |
| if (encoding & DW_EH_PE_indirect) |
| internal_error (__FILE__, __LINE__, |
| "Unsupported encoding: DW_EH_PE_indirect"); |
| |
| switch (encoding & 0x70) |
| { |
| case DW_EH_PE_absptr: |
| base = 0; |
| break; |
| case DW_EH_PE_pcrel: |
| base = bfd_get_section_vma (unit->bfd, unit->dwarf_frame_section); |
| base += (buf - unit->dwarf_frame_buffer); |
| break; |
| case DW_EH_PE_datarel: |
| base = unit->dbase; |
| break; |
| default: |
| internal_error (__FILE__, __LINE__, "Invalid or unsupported encoding"); |
| } |
| |
| if ((encoding & 0x0f) == 0x00) |
| encoding |= encoding_for_size (TYPE_LENGTH(builtin_type_void_data_ptr)); |
| |
| switch (encoding & 0x0f) |
| { |
| case DW_EH_PE_udata2: |
| *bytes_read_ptr = 2; |
| return (base + bfd_get_16 (unit->abfd, (bfd_byte *) buf)); |
| case DW_EH_PE_udata4: |
| *bytes_read_ptr = 4; |
| return (base + bfd_get_32 (unit->abfd, (bfd_byte *) buf)); |
| case DW_EH_PE_udata8: |
| *bytes_read_ptr = 8; |
| return (base + bfd_get_64 (unit->abfd, (bfd_byte *) buf)); |
| case DW_EH_PE_sdata2: |
| *bytes_read_ptr = 2; |
| return (base + bfd_get_signed_16 (unit->abfd, (bfd_byte *) buf)); |
| case DW_EH_PE_sdata4: |
| *bytes_read_ptr = 4; |
| return (base + bfd_get_signed_32 (unit->abfd, (bfd_byte *) buf)); |
| case DW_EH_PE_sdata8: |
| *bytes_read_ptr = 8; |
| return (base + bfd_get_signed_64 (unit->abfd, (bfd_byte *) buf)); |
| default: |
| internal_error (__FILE__, __LINE__, "Invalid or unsupported encoding"); |
| } |
| } |
| |
| |
| /* GCC uses a single CIE for all FDEs in a .debug_frame section. |
| That's why we use a simple linked list here. */ |
| |
| static struct dwarf2_cie * |
| find_cie (struct comp_unit *unit, ULONGEST cie_pointer) |
| { |
| struct dwarf2_cie *cie = unit->cie; |
| |
| while (cie) |
| { |
| if (cie->cie_pointer == cie_pointer) |
| return cie; |
| |
| cie = cie->next; |
| } |
| |
| return NULL; |
| } |
| |
| static void |
| add_cie (struct comp_unit *unit, struct dwarf2_cie *cie) |
| { |
| cie->next = unit->cie; |
| unit->cie = cie; |
| } |
| |
| /* Find the FDE for *PC. Return a pointer to the FDE, and store the |
| inital location associated with it into *PC. */ |
| |
| static struct dwarf2_fde * |
| dwarf2_frame_find_fde (CORE_ADDR *pc) |
| { |
| struct objfile *objfile; |
| |
| ALL_OBJFILES (objfile) |
| { |
| struct dwarf2_fde *fde; |
| CORE_ADDR offset; |
| |
| offset = ANOFFSET (objfile->section_offsets, SECT_OFF_TEXT (objfile)); |
| |
| fde = objfile->sym_private; |
| while (fde) |
| { |
| if (*pc >= fde->initial_location + offset |
| && *pc < fde->initial_location + offset + fde->address_range) |
| { |
| *pc = fde->initial_location + offset; |
| return fde; |
| } |
| |
| fde = fde->next; |
| } |
| } |
| |
| return NULL; |
| } |
| |
| static void |
| add_fde (struct comp_unit *unit, struct dwarf2_fde *fde) |
| { |
| fde->next = unit->objfile->sym_private; |
| unit->objfile->sym_private = fde; |
| } |
| |
| #ifdef CC_HAS_LONG_LONG |
| #define DW64_CIE_ID 0xffffffffffffffffULL |
| #else |
| #define DW64_CIE_ID ~0 |
| #endif |
| |
| /* Read a CIE or FDE in BUF and decode it. */ |
| |
| static char * |
| decode_frame_entry (struct comp_unit *unit, char *buf, int eh_frame_p) |
| { |
| LONGEST length; |
| unsigned int bytes_read; |
| int dwarf64_p = 0; |
| ULONGEST cie_id = DW_CIE_ID; |
| ULONGEST cie_pointer; |
| char *start = buf; |
| char *end; |
| |
| length = read_initial_length (unit->abfd, buf, &bytes_read); |
| buf += bytes_read; |
| end = buf + length; |
| |
| if (length == 0) |
| return end; |
| |
| if (bytes_read == 12) |
| dwarf64_p = 1; |
| |
| /* In a .eh_frame section, zero is used to distinguish CIEs from |
| FDEs. */ |
| if (eh_frame_p) |
| cie_id = 0; |
| else if (dwarf64_p) |
| cie_id = DW64_CIE_ID; |
| |
| if (dwarf64_p) |
| { |
| cie_pointer = read_8_bytes (unit->abfd, buf); |
| buf += 8; |
| } |
| else |
| { |
| cie_pointer = read_4_bytes (unit->abfd, buf); |
| buf += 4; |
| } |
| |
| if (cie_pointer == cie_id) |
| { |
| /* This is a CIE. */ |
| struct dwarf2_cie *cie; |
| char *augmentation; |
| |
| /* Record the offset into the .debug_frame section of this CIE. */ |
| cie_pointer = start - unit->dwarf_frame_buffer; |
| |
| /* Check whether we've already read it. */ |
| if (find_cie (unit, cie_pointer)) |
| return end; |
| |
| cie = (struct dwarf2_cie *) |
| obstack_alloc (&unit->objfile->psymbol_obstack, |
| sizeof (struct dwarf2_cie)); |
| cie->initial_instructions = NULL; |
| cie->cie_pointer = cie_pointer; |
| |
| /* The encoding for FDE's in a normal .debug_frame section |
| depends on the target address size as specified in the |
| Compilation Unit Header. */ |
| cie->encoding = encoding_for_size (unit->addr_size); |
| |
| /* Check version number. */ |
| gdb_assert (read_1_byte (unit->abfd, buf) == DW_CIE_VERSION); |
| buf += 1; |
| |
| /* Interpret the interesting bits of the augmentation. */ |
| augmentation = buf; |
| buf = augmentation + strlen (augmentation) + 1; |
| |
| /* The GCC 2.x "eh" augmentation has a pointer immediately |
| following the augmentation string, so it must be handled |
| first. */ |
| if (augmentation[0] == 'e' && augmentation[1] == 'h') |
| { |
| /* Skip. */ |
| buf += TYPE_LENGTH (builtin_type_void_data_ptr); |
| augmentation += 2; |
| } |
| |
| cie->code_alignment_factor = |
| read_unsigned_leb128 (unit->abfd, buf, &bytes_read); |
| buf += bytes_read; |
| |
| cie->data_alignment_factor = |
| read_signed_leb128 (unit->abfd, buf, &bytes_read); |
| buf += bytes_read; |
| |
| cie->return_address_register = read_1_byte (unit->abfd, buf); |
| buf += 1; |
| |
| cie->saw_z_augmentation = (*augmentation == 'z'); |
| if (cie->saw_z_augmentation) |
| { |
| ULONGEST length; |
| |
| length = read_unsigned_leb128 (unit->abfd, buf, &bytes_read); |
| buf += bytes_read; |
| cie->initial_instructions = buf + length; |
| augmentation++; |
| } |
| |
| while (*augmentation) |
| { |
| /* "L" indicates a byte showing how the LSDA pointer is encoded. */ |
| if (*augmentation == 'L') |
| { |
| /* Skip. */ |
| buf++; |
| augmentation++; |
| } |
| |
| /* "R" indicates a byte indicating how FDE addresses are encoded. */ |
| else if (*augmentation == 'R') |
| { |
| cie->encoding = *buf++; |
| augmentation++; |
| } |
| |
| /* "P" indicates a personality routine in the CIE augmentation. */ |
| else if (*augmentation == 'P') |
| { |
| /* Skip. */ |
| buf += size_of_encoded_value (*buf++); |
| augmentation++; |
| } |
| |
| /* Otherwise we have an unknown augmentation. |
| Bail out unless we saw a 'z' prefix. */ |
| else |
| { |
| if (cie->initial_instructions == NULL) |
| return end; |
| |
| /* Skip unknown augmentations. */ |
| buf = cie->initial_instructions; |
| break; |
| } |
| } |
| |
| cie->initial_instructions = buf; |
| cie->end = end; |
| |
| add_cie (unit, cie); |
| } |
| else |
| { |
| /* This is a FDE. */ |
| struct dwarf2_fde *fde; |
| |
| if (eh_frame_p) |
| { |
| /* In an .eh_frame section, the CIE pointer is the delta |
| between the address within the FDE where the CIE pointer |
| is stored and the address of the CIE. Convert it to an |
| offset into the .eh_frame section. */ |
| cie_pointer = buf - unit->dwarf_frame_buffer - cie_pointer; |
| cie_pointer -= (dwarf64_p ? 8 : 4); |
| } |
| |
| fde = (struct dwarf2_fde *) |
| obstack_alloc (&unit->objfile->psymbol_obstack, |
| sizeof (struct dwarf2_fde)); |
| fde->cie = find_cie (unit, cie_pointer); |
| if (fde->cie == NULL) |
| { |
| decode_frame_entry (unit, unit->dwarf_frame_buffer + cie_pointer, |
| eh_frame_p); |
| fde->cie = find_cie (unit, cie_pointer); |
| } |
| |
| gdb_assert (fde->cie != NULL); |
| |
| fde->initial_location = |
| read_encoded_value (unit, fde->cie->encoding, buf, &bytes_read); |
| buf += bytes_read; |
| |
| fde->address_range = |
| read_encoded_value (unit, fde->cie->encoding & 0x0f, buf, &bytes_read); |
| buf += bytes_read; |
| |
| /* A 'z' augmentation in the CIE implies the presence of an |
| augmentation field in the FDE as well. The only thing known |
| to be in here at present is the LSDA entry for EH. So we |
| can skip the whole thing. */ |
| if (fde->cie->saw_z_augmentation) |
| { |
| ULONGEST length; |
| |
| length = read_unsigned_leb128 (unit->abfd, buf, &bytes_read); |
| buf += bytes_read + length; |
| } |
| |
| fde->instructions = buf; |
| fde->end = end; |
| |
| add_fde (unit, fde); |
| } |
| |
| return end; |
| } |
| |
| |
| /* FIXME: kettenis/20030504: This still needs to be integrated with |
| dwarf2read.c in a better way. */ |
| |
| /* Imported from dwarf2read.c. */ |
| extern file_ptr dwarf_frame_offset; |
| extern unsigned int dwarf_frame_size; |
| extern asection *dwarf_frame_section; |
| extern file_ptr dwarf_eh_frame_offset; |
| extern unsigned int dwarf_eh_frame_size; |
| extern asection *dwarf_eh_frame_section; |
| |
| /* Imported from dwarf2read.c. */ |
| extern char *dwarf2_read_section (struct objfile *objfile, file_ptr offset, |
| unsigned int size, asection *sectp); |
| |
| void |
| dwarf2_build_frame_info (struct objfile *objfile) |
| { |
| struct comp_unit unit; |
| char *frame_ptr; |
| |
| /* Build a minimal decoding of the DWARF2 compilation unit. */ |
| unit.abfd = objfile->obfd; |
| unit.objfile = objfile; |
| unit.addr_size = objfile->obfd->arch_info->bits_per_address / 8; |
| unit.dbase = 0; |
| |
| /* First add the information from the .eh_frame section. That way, |
| the FDEs from that section are searched last. */ |
| if (dwarf_eh_frame_offset) |
| { |
| asection *got; |
| |
| unit.cie = NULL; |
| unit.dwarf_frame_buffer = dwarf2_read_section (objfile, |
| dwarf_eh_frame_offset, |
| dwarf_eh_frame_size, |
| dwarf_eh_frame_section); |
| |
| unit.dwarf_frame_size = dwarf_eh_frame_size; |
| unit.dwarf_frame_section = dwarf_eh_frame_section; |
| |
| /* FIXME: kettenis/20030602: This is the DW_EH_PE_datarel base |
| that for the i386/amd64 target, which currently is the only |
| target in GCC that supports/uses the DW_EH_PE_datarel |
| encoding. */ |
| got = bfd_get_section_by_name (unit.abfd, ".got"); |
| if (got) |
| unit.dbase = got->vma; |
| |
| frame_ptr = unit.dwarf_frame_buffer; |
| while (frame_ptr < unit.dwarf_frame_buffer + unit.dwarf_frame_size) |
| frame_ptr = decode_frame_entry (&unit, frame_ptr, 1); |
| } |
| |
| if (dwarf_frame_offset) |
| { |
| unit.cie = NULL; |
| unit.dwarf_frame_buffer = dwarf2_read_section (objfile, |
| dwarf_frame_offset, |
| dwarf_frame_size, |
| dwarf_frame_section); |
| unit.dwarf_frame_size = dwarf_frame_size; |
| unit.dwarf_frame_section = dwarf_frame_section; |
| |
| frame_ptr = unit.dwarf_frame_buffer; |
| while (frame_ptr < unit.dwarf_frame_buffer + unit.dwarf_frame_size) |
| frame_ptr = decode_frame_entry (&unit, frame_ptr, 0); |
| } |
| } |