| /* Dwarf2 Expression Evaluator |
| Copyright 2001, 2002, 2003 Free Software Foundation, Inc. |
| Contributed by Daniel Berlin (dan@dberlin.org) |
| |
| 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 "symtab.h" |
| #include "gdbtypes.h" |
| #include "value.h" |
| #include "gdbcore.h" |
| #include "elf/dwarf2.h" |
| #include "dwarf2expr.h" |
| |
| /* Local prototypes. */ |
| |
| static void execute_stack_op (struct dwarf_expr_context *, |
| unsigned char *, unsigned char *); |
| |
| /* Create a new context for the expression evaluator. */ |
| |
| struct dwarf_expr_context * |
| new_dwarf_expr_context (void) |
| { |
| struct dwarf_expr_context *retval; |
| retval = xcalloc (1, sizeof (struct dwarf_expr_context)); |
| retval->stack_len = 10; |
| retval->stack = xmalloc (10 * sizeof (CORE_ADDR)); |
| return retval; |
| } |
| |
| /* Release the memory allocated to CTX. */ |
| |
| void |
| free_dwarf_expr_context (struct dwarf_expr_context *ctx) |
| { |
| xfree (ctx->stack); |
| xfree (ctx); |
| } |
| |
| /* Expand the memory allocated to CTX's stack to contain at least |
| NEED more elements than are currently used. */ |
| |
| static void |
| dwarf_expr_grow_stack (struct dwarf_expr_context *ctx, size_t need) |
| { |
| if (ctx->stack_len + need > ctx->stack_allocated) |
| { |
| size_t templen = ctx->stack_len * 2; |
| while (templen < (ctx->stack_len + need)) |
| templen *= 2; |
| ctx->stack = xrealloc (ctx->stack, |
| templen * sizeof (CORE_ADDR)); |
| ctx->stack_allocated = templen; |
| } |
| } |
| |
| /* Push VALUE onto CTX's stack. */ |
| |
| void |
| dwarf_expr_push (struct dwarf_expr_context *ctx, CORE_ADDR value) |
| { |
| dwarf_expr_grow_stack (ctx, 1); |
| ctx->stack[ctx->stack_len++] = value; |
| } |
| |
| /* Pop the top item off of CTX's stack. */ |
| |
| void |
| dwarf_expr_pop (struct dwarf_expr_context *ctx) |
| { |
| if (ctx->stack_len <= 0) |
| error ("dwarf expression stack underflow"); |
| ctx->stack_len--; |
| } |
| |
| /* Retrieve the N'th item on CTX's stack. */ |
| |
| CORE_ADDR |
| dwarf_expr_fetch (struct dwarf_expr_context *ctx, int n) |
| { |
| if (ctx->stack_len < n) |
| error ("Asked for position %d of stack, stack only has %d elements on it\n", |
| n, ctx->stack_len); |
| return ctx->stack[ctx->stack_len - (1 + n)]; |
| |
| } |
| |
| /* Evaluate the expression at ADDR (LEN bytes long) using the context |
| CTX. */ |
| |
| void |
| dwarf_expr_eval (struct dwarf_expr_context *ctx, unsigned char *addr, |
| size_t len) |
| { |
| execute_stack_op (ctx, addr, addr + len); |
| } |
| |
| /* Decode the unsigned LEB128 constant at BUF into the variable pointed to |
| by R, and return the new value of BUF. Verify that it doesn't extend |
| past BUF_END. */ |
| |
| unsigned char * |
| read_uleb128 (unsigned char *buf, unsigned char *buf_end, ULONGEST * r) |
| { |
| unsigned shift = 0; |
| ULONGEST result = 0; |
| unsigned char byte; |
| |
| while (1) |
| { |
| if (buf >= buf_end) |
| error ("read_uleb128: Corrupted DWARF expression."); |
| |
| byte = *buf++; |
| result |= (byte & 0x7f) << shift; |
| if ((byte & 0x80) == 0) |
| break; |
| shift += 7; |
| } |
| *r = result; |
| return buf; |
| } |
| |
| /* Decode the signed LEB128 constant at BUF into the variable pointed to |
| by R, and return the new value of BUF. Verify that it doesn't extend |
| past BUF_END. */ |
| |
| unsigned char * |
| read_sleb128 (unsigned char *buf, unsigned char *buf_end, LONGEST * r) |
| { |
| unsigned shift = 0; |
| LONGEST result = 0; |
| unsigned char byte; |
| |
| while (1) |
| { |
| if (buf >= buf_end) |
| error ("read_sleb128: Corrupted DWARF expression."); |
| |
| byte = *buf++; |
| result |= (byte & 0x7f) << shift; |
| shift += 7; |
| if ((byte & 0x80) == 0) |
| break; |
| } |
| if (shift < (sizeof (*r) * 8) && (byte & 0x40) != 0) |
| result |= -(1 << shift); |
| |
| *r = result; |
| return buf; |
| } |
| |
| /* Read an address from BUF, and verify that it doesn't extend past |
| BUF_END. The address is returned, and *BYTES_READ is set to the |
| number of bytes read from BUF. */ |
| |
| static CORE_ADDR |
| read_address (unsigned char *buf, unsigned char *buf_end, int *bytes_read) |
| { |
| CORE_ADDR result; |
| |
| if (buf_end - buf < TARGET_ADDR_BIT / TARGET_CHAR_BIT) |
| error ("read_address: Corrupted DWARF expression."); |
| |
| *bytes_read = TARGET_ADDR_BIT / TARGET_CHAR_BIT; |
| result = extract_address (buf, TARGET_ADDR_BIT / TARGET_CHAR_BIT); |
| return result; |
| } |
| |
| /* Return the type of an address, for unsigned arithmetic. */ |
| |
| static struct type * |
| unsigned_address_type (void) |
| { |
| switch (TARGET_ADDR_BIT / TARGET_CHAR_BIT) |
| { |
| case 2: |
| return builtin_type_uint16; |
| case 4: |
| return builtin_type_uint32; |
| case 8: |
| return builtin_type_uint64; |
| default: |
| internal_error (__FILE__, __LINE__, |
| "Unsupported address size.\n"); |
| } |
| } |
| |
| /* Return the type of an address, for signed arithmetic. */ |
| |
| static struct type * |
| signed_address_type (void) |
| { |
| switch (TARGET_ADDR_BIT / TARGET_CHAR_BIT) |
| { |
| case 2: |
| return builtin_type_int16; |
| case 4: |
| return builtin_type_int32; |
| case 8: |
| return builtin_type_int64; |
| default: |
| internal_error (__FILE__, __LINE__, |
| "Unsupported address size.\n"); |
| } |
| } |
| |
| /* The engine for the expression evaluator. Using the context in CTX, |
| evaluate the expression between OP_PTR and OP_END. */ |
| |
| static void |
| execute_stack_op (struct dwarf_expr_context *ctx, unsigned char *op_ptr, |
| unsigned char *op_end) |
| { |
| while (op_ptr < op_end) |
| { |
| enum dwarf_location_atom op = *op_ptr++; |
| CORE_ADDR result, memaddr; |
| ULONGEST uoffset, reg; |
| LONGEST offset; |
| int bytes_read; |
| enum lval_type expr_lval; |
| |
| ctx->in_reg = 0; |
| |
| switch (op) |
| { |
| case DW_OP_lit0: |
| case DW_OP_lit1: |
| case DW_OP_lit2: |
| case DW_OP_lit3: |
| case DW_OP_lit4: |
| case DW_OP_lit5: |
| case DW_OP_lit6: |
| case DW_OP_lit7: |
| case DW_OP_lit8: |
| case DW_OP_lit9: |
| case DW_OP_lit10: |
| case DW_OP_lit11: |
| case DW_OP_lit12: |
| case DW_OP_lit13: |
| case DW_OP_lit14: |
| case DW_OP_lit15: |
| case DW_OP_lit16: |
| case DW_OP_lit17: |
| case DW_OP_lit18: |
| case DW_OP_lit19: |
| case DW_OP_lit20: |
| case DW_OP_lit21: |
| case DW_OP_lit22: |
| case DW_OP_lit23: |
| case DW_OP_lit24: |
| case DW_OP_lit25: |
| case DW_OP_lit26: |
| case DW_OP_lit27: |
| case DW_OP_lit28: |
| case DW_OP_lit29: |
| case DW_OP_lit30: |
| case DW_OP_lit31: |
| result = op - DW_OP_lit0; |
| break; |
| |
| case DW_OP_addr: |
| result = read_address (op_ptr, op_end, &bytes_read); |
| op_ptr += bytes_read; |
| break; |
| |
| case DW_OP_const1u: |
| result = extract_unsigned_integer (op_ptr, 1); |
| op_ptr += 1; |
| break; |
| case DW_OP_const1s: |
| result = extract_signed_integer (op_ptr, 1); |
| op_ptr += 1; |
| break; |
| case DW_OP_const2u: |
| result = extract_unsigned_integer (op_ptr, 2); |
| op_ptr += 2; |
| break; |
| case DW_OP_const2s: |
| result = extract_signed_integer (op_ptr, 2); |
| op_ptr += 2; |
| break; |
| case DW_OP_const4u: |
| result = extract_unsigned_integer (op_ptr, 4); |
| op_ptr += 4; |
| break; |
| case DW_OP_const4s: |
| result = extract_signed_integer (op_ptr, 4); |
| op_ptr += 4; |
| break; |
| case DW_OP_const8u: |
| result = extract_unsigned_integer (op_ptr, 8); |
| op_ptr += 8; |
| break; |
| case DW_OP_const8s: |
| result = extract_signed_integer (op_ptr, 8); |
| op_ptr += 8; |
| break; |
| case DW_OP_constu: |
| op_ptr = read_uleb128 (op_ptr, op_end, &uoffset); |
| result = uoffset; |
| break; |
| case DW_OP_consts: |
| op_ptr = read_sleb128 (op_ptr, op_end, &offset); |
| result = offset; |
| break; |
| |
| /* The DW_OP_reg operations are required to occur alone in |
| location expressions. */ |
| case DW_OP_reg0: |
| case DW_OP_reg1: |
| case DW_OP_reg2: |
| case DW_OP_reg3: |
| case DW_OP_reg4: |
| case DW_OP_reg5: |
| case DW_OP_reg6: |
| case DW_OP_reg7: |
| case DW_OP_reg8: |
| case DW_OP_reg9: |
| case DW_OP_reg10: |
| case DW_OP_reg11: |
| case DW_OP_reg12: |
| case DW_OP_reg13: |
| case DW_OP_reg14: |
| case DW_OP_reg15: |
| case DW_OP_reg16: |
| case DW_OP_reg17: |
| case DW_OP_reg18: |
| case DW_OP_reg19: |
| case DW_OP_reg20: |
| case DW_OP_reg21: |
| case DW_OP_reg22: |
| case DW_OP_reg23: |
| case DW_OP_reg24: |
| case DW_OP_reg25: |
| case DW_OP_reg26: |
| case DW_OP_reg27: |
| case DW_OP_reg28: |
| case DW_OP_reg29: |
| case DW_OP_reg30: |
| case DW_OP_reg31: |
| /* NOTE: in the presence of DW_OP_piece this check is incorrect. */ |
| if (op_ptr != op_end) |
| error ("DWARF-2 expression error: DW_OP_reg operations must be " |
| "used alone."); |
| |
| /* FIXME drow/2003-02-21: This call to read_reg could be pushed |
| into the evaluator's caller by changing the semantics for in_reg. |
| Then we wouldn't need to return an lval_type and a memaddr. */ |
| result = (ctx->read_reg) (ctx->baton, op - DW_OP_reg0, &expr_lval, |
| &memaddr); |
| |
| if (expr_lval == lval_register) |
| { |
| ctx->regnum = op - DW_OP_reg0; |
| ctx->in_reg = 1; |
| } |
| else |
| result = memaddr; |
| |
| break; |
| |
| case DW_OP_regx: |
| op_ptr = read_uleb128 (op_ptr, op_end, ®); |
| if (op_ptr != op_end) |
| error ("DWARF-2 expression error: DW_OP_reg operations must be " |
| "used alone."); |
| |
| result = (ctx->read_reg) (ctx->baton, reg, &expr_lval, &memaddr); |
| |
| if (expr_lval == lval_register) |
| { |
| ctx->regnum = reg; |
| ctx->in_reg = 1; |
| } |
| else |
| result = memaddr; |
| |
| break; |
| |
| case DW_OP_breg0: |
| case DW_OP_breg1: |
| case DW_OP_breg2: |
| case DW_OP_breg3: |
| case DW_OP_breg4: |
| case DW_OP_breg5: |
| case DW_OP_breg6: |
| case DW_OP_breg7: |
| case DW_OP_breg8: |
| case DW_OP_breg9: |
| case DW_OP_breg10: |
| case DW_OP_breg11: |
| case DW_OP_breg12: |
| case DW_OP_breg13: |
| case DW_OP_breg14: |
| case DW_OP_breg15: |
| case DW_OP_breg16: |
| case DW_OP_breg17: |
| case DW_OP_breg18: |
| case DW_OP_breg19: |
| case DW_OP_breg20: |
| case DW_OP_breg21: |
| case DW_OP_breg22: |
| case DW_OP_breg23: |
| case DW_OP_breg24: |
| case DW_OP_breg25: |
| case DW_OP_breg26: |
| case DW_OP_breg27: |
| case DW_OP_breg28: |
| case DW_OP_breg29: |
| case DW_OP_breg30: |
| case DW_OP_breg31: |
| { |
| op_ptr = read_sleb128 (op_ptr, op_end, &offset); |
| result = (ctx->read_reg) (ctx->baton, op - DW_OP_breg0, |
| &expr_lval, &memaddr); |
| result += offset; |
| } |
| break; |
| case DW_OP_bregx: |
| { |
| op_ptr = read_uleb128 (op_ptr, op_end, ®); |
| op_ptr = read_sleb128 (op_ptr, op_end, &offset); |
| result = (ctx->read_reg) (ctx->baton, reg, &expr_lval, &memaddr); |
| result += offset; |
| } |
| break; |
| case DW_OP_fbreg: |
| { |
| unsigned char *datastart; |
| size_t datalen; |
| unsigned int before_stack_len; |
| |
| op_ptr = read_sleb128 (op_ptr, op_end, &offset); |
| /* Rather than create a whole new context, we simply |
| record the stack length before execution, then reset it |
| afterwards, effectively erasing whatever the recursive |
| call put there. */ |
| before_stack_len = ctx->stack_len; |
| (ctx->get_frame_base) (ctx->baton, &datastart, &datalen); |
| dwarf_expr_eval (ctx, datastart, datalen); |
| result = dwarf_expr_fetch (ctx, 0); |
| if (! ctx->in_reg) |
| { |
| char *buf = alloca (TARGET_ADDR_BIT / TARGET_CHAR_BIT); |
| int bytes_read; |
| |
| (ctx->read_mem) (ctx->baton, buf, result, |
| TARGET_ADDR_BIT / TARGET_CHAR_BIT); |
| result = read_address (buf, |
| buf + TARGET_ADDR_BIT / TARGET_CHAR_BIT, |
| &bytes_read); |
| } |
| result = result + offset; |
| ctx->stack_len = before_stack_len; |
| ctx->in_reg = 0; |
| } |
| break; |
| case DW_OP_dup: |
| result = dwarf_expr_fetch (ctx, 0); |
| break; |
| |
| case DW_OP_drop: |
| dwarf_expr_pop (ctx); |
| goto no_push; |
| |
| case DW_OP_pick: |
| offset = *op_ptr++; |
| result = dwarf_expr_fetch (ctx, offset); |
| break; |
| |
| case DW_OP_over: |
| result = dwarf_expr_fetch (ctx, 1); |
| break; |
| |
| case DW_OP_rot: |
| { |
| CORE_ADDR t1, t2, t3; |
| |
| if (ctx->stack_len < 3) |
| error ("Not enough elements for DW_OP_rot. Need 3, have %d\n", |
| ctx->stack_len); |
| t1 = ctx->stack[ctx->stack_len - 1]; |
| t2 = ctx->stack[ctx->stack_len - 2]; |
| t3 = ctx->stack[ctx->stack_len - 3]; |
| ctx->stack[ctx->stack_len - 1] = t2; |
| ctx->stack[ctx->stack_len - 2] = t3; |
| ctx->stack[ctx->stack_len - 3] = t1; |
| goto no_push; |
| } |
| |
| case DW_OP_deref: |
| case DW_OP_deref_size: |
| case DW_OP_abs: |
| case DW_OP_neg: |
| case DW_OP_not: |
| case DW_OP_plus_uconst: |
| /* Unary operations. */ |
| result = dwarf_expr_fetch (ctx, 0); |
| dwarf_expr_pop (ctx); |
| |
| switch (op) |
| { |
| case DW_OP_deref: |
| { |
| char *buf = alloca (TARGET_ADDR_BIT / TARGET_CHAR_BIT); |
| int bytes_read; |
| |
| (ctx->read_mem) (ctx->baton, buf, result, |
| TARGET_ADDR_BIT / TARGET_CHAR_BIT); |
| result = read_address (buf, |
| buf + TARGET_ADDR_BIT / TARGET_CHAR_BIT, |
| &bytes_read); |
| } |
| break; |
| |
| case DW_OP_deref_size: |
| { |
| char *buf = alloca (TARGET_ADDR_BIT / TARGET_CHAR_BIT); |
| int bytes_read; |
| |
| (ctx->read_mem) (ctx->baton, buf, result, *op_ptr++); |
| result = read_address (buf, |
| buf + TARGET_ADDR_BIT / TARGET_CHAR_BIT, |
| &bytes_read); |
| } |
| break; |
| |
| case DW_OP_abs: |
| if ((signed int) result < 0) |
| result = -result; |
| break; |
| case DW_OP_neg: |
| result = -result; |
| break; |
| case DW_OP_not: |
| result = ~result; |
| break; |
| case DW_OP_plus_uconst: |
| op_ptr = read_uleb128 (op_ptr, op_end, ®); |
| result += reg; |
| break; |
| } |
| break; |
| |
| case DW_OP_and: |
| case DW_OP_div: |
| case DW_OP_minus: |
| case DW_OP_mod: |
| case DW_OP_mul: |
| case DW_OP_or: |
| case DW_OP_plus: |
| case DW_OP_shl: |
| case DW_OP_shr: |
| case DW_OP_shra: |
| case DW_OP_xor: |
| case DW_OP_le: |
| case DW_OP_ge: |
| case DW_OP_eq: |
| case DW_OP_lt: |
| case DW_OP_gt: |
| case DW_OP_ne: |
| { |
| /* Binary operations. Use the value engine to do computations in |
| the right width. */ |
| CORE_ADDR first, second; |
| enum exp_opcode binop; |
| struct value *val1, *val2; |
| |
| second = dwarf_expr_fetch (ctx, 0); |
| dwarf_expr_pop (ctx); |
| |
| first = dwarf_expr_fetch (ctx, 1); |
| dwarf_expr_pop (ctx); |
| |
| val1 = value_from_longest (unsigned_address_type (), first); |
| val2 = value_from_longest (unsigned_address_type (), second); |
| |
| switch (op) |
| { |
| case DW_OP_and: |
| binop = BINOP_BITWISE_AND; |
| break; |
| case DW_OP_div: |
| binop = BINOP_DIV; |
| case DW_OP_minus: |
| binop = BINOP_SUB; |
| break; |
| case DW_OP_mod: |
| binop = BINOP_MOD; |
| break; |
| case DW_OP_mul: |
| binop = BINOP_MUL; |
| break; |
| case DW_OP_or: |
| binop = BINOP_BITWISE_IOR; |
| break; |
| case DW_OP_plus: |
| binop = BINOP_ADD; |
| break; |
| case DW_OP_shl: |
| binop = BINOP_LSH; |
| break; |
| case DW_OP_shr: |
| binop = BINOP_RSH; |
| case DW_OP_shra: |
| binop = BINOP_RSH; |
| val1 = value_from_longest (signed_address_type (), first); |
| break; |
| case DW_OP_xor: |
| binop = BINOP_BITWISE_XOR; |
| break; |
| case DW_OP_le: |
| binop = BINOP_LEQ; |
| break; |
| case DW_OP_ge: |
| binop = BINOP_GEQ; |
| break; |
| case DW_OP_eq: |
| binop = BINOP_EQUAL; |
| break; |
| case DW_OP_lt: |
| binop = BINOP_LESS; |
| break; |
| case DW_OP_gt: |
| binop = BINOP_GTR; |
| break; |
| case DW_OP_ne: |
| binop = BINOP_NOTEQUAL; |
| break; |
| default: |
| internal_error (__FILE__, __LINE__, |
| "Can't be reached."); |
| } |
| result = value_as_long (value_binop (val1, val2, binop)); |
| } |
| break; |
| |
| case DW_OP_GNU_push_tls_address: |
| result = dwarf_expr_fetch (ctx, 0); |
| dwarf_expr_pop (ctx); |
| result = (ctx->get_tls_address) (ctx->baton, result); |
| break; |
| |
| case DW_OP_skip: |
| offset = extract_signed_integer (op_ptr, 2); |
| op_ptr += 2; |
| op_ptr += offset; |
| goto no_push; |
| |
| case DW_OP_bra: |
| offset = extract_signed_integer (op_ptr, 2); |
| op_ptr += 2; |
| if (dwarf_expr_fetch (ctx, 0) != 0) |
| op_ptr += offset; |
| dwarf_expr_pop (ctx); |
| goto no_push; |
| |
| case DW_OP_nop: |
| goto no_push; |
| |
| default: |
| error ("Unhandled dwarf expression opcode"); |
| } |
| |
| /* Most things push a result value. */ |
| dwarf_expr_push (ctx, result); |
| no_push:; |
| } |
| } |