716 lines
17 KiB
C
716 lines
17 KiB
C
/* DWARF 2 Expression Evaluator.
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Copyright 2001, 2002, 2003, 2005 Free Software Foundation, Inc.
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Contributed by Daniel Berlin (dan@dberlin.org)
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This file is part of GDB.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place - Suite 330,
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Boston, MA 02111-1307, USA. */
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#include "defs.h"
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#include "symtab.h"
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#include "gdbtypes.h"
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#include "value.h"
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#include "gdbcore.h"
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#include "elf/dwarf2.h"
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#include "dwarf2expr.h"
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/* Local prototypes. */
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static void execute_stack_op (struct dwarf_expr_context *,
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gdb_byte *, gdb_byte *);
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/* Create a new context for the expression evaluator. */
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struct dwarf_expr_context *
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new_dwarf_expr_context (void)
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{
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struct dwarf_expr_context *retval;
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retval = xcalloc (1, sizeof (struct dwarf_expr_context));
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retval->stack_len = 0;
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retval->stack_allocated = 10;
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retval->stack = xmalloc (retval->stack_allocated * sizeof (CORE_ADDR));
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retval->num_pieces = 0;
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retval->pieces = 0;
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return retval;
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}
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/* Release the memory allocated to CTX. */
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void
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free_dwarf_expr_context (struct dwarf_expr_context *ctx)
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{
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xfree (ctx->stack);
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xfree (ctx->pieces);
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xfree (ctx);
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}
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/* Expand the memory allocated to CTX's stack to contain at least
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NEED more elements than are currently used. */
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static void
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dwarf_expr_grow_stack (struct dwarf_expr_context *ctx, size_t need)
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{
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if (ctx->stack_len + need > ctx->stack_allocated)
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{
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size_t newlen = ctx->stack_len + need + 10;
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ctx->stack = xrealloc (ctx->stack,
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newlen * sizeof (CORE_ADDR));
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ctx->stack_allocated = newlen;
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}
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}
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/* Push VALUE onto CTX's stack. */
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void
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dwarf_expr_push (struct dwarf_expr_context *ctx, CORE_ADDR value)
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{
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dwarf_expr_grow_stack (ctx, 1);
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ctx->stack[ctx->stack_len++] = value;
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}
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/* Pop the top item off of CTX's stack. */
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void
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dwarf_expr_pop (struct dwarf_expr_context *ctx)
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{
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if (ctx->stack_len <= 0)
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error (_("dwarf expression stack underflow"));
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ctx->stack_len--;
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}
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/* Retrieve the N'th item on CTX's stack. */
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CORE_ADDR
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dwarf_expr_fetch (struct dwarf_expr_context *ctx, int n)
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{
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if (ctx->stack_len <= n)
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error (_("Asked for position %d of stack, stack only has %d elements on it."),
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n, ctx->stack_len);
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return ctx->stack[ctx->stack_len - (1 + n)];
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}
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/* Add a new piece to CTX's piece list. */
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static void
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add_piece (struct dwarf_expr_context *ctx,
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int in_reg, CORE_ADDR value, ULONGEST size)
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{
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struct dwarf_expr_piece *p;
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ctx->num_pieces++;
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if (ctx->pieces)
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ctx->pieces = xrealloc (ctx->pieces,
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(ctx->num_pieces
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* sizeof (struct dwarf_expr_piece)));
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else
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ctx->pieces = xmalloc (ctx->num_pieces
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* sizeof (struct dwarf_expr_piece));
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p = &ctx->pieces[ctx->num_pieces - 1];
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p->in_reg = in_reg;
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p->value = value;
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p->size = size;
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}
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/* Evaluate the expression at ADDR (LEN bytes long) using the context
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CTX. */
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void
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dwarf_expr_eval (struct dwarf_expr_context *ctx, gdb_byte *addr, size_t len)
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{
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execute_stack_op (ctx, addr, addr + len);
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}
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/* Decode the unsigned LEB128 constant at BUF into the variable pointed to
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by R, and return the new value of BUF. Verify that it doesn't extend
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past BUF_END. */
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gdb_byte *
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read_uleb128 (gdb_byte *buf, gdb_byte *buf_end, ULONGEST * r)
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{
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unsigned shift = 0;
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ULONGEST result = 0;
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gdb_byte byte;
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while (1)
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{
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if (buf >= buf_end)
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error (_("read_uleb128: Corrupted DWARF expression."));
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byte = *buf++;
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result |= (byte & 0x7f) << shift;
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if ((byte & 0x80) == 0)
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break;
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shift += 7;
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}
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*r = result;
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return buf;
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}
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/* Decode the signed LEB128 constant at BUF into the variable pointed to
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by R, and return the new value of BUF. Verify that it doesn't extend
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past BUF_END. */
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gdb_byte *
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read_sleb128 (gdb_byte *buf, gdb_byte *buf_end, LONGEST * r)
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{
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unsigned shift = 0;
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LONGEST result = 0;
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gdb_byte byte;
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while (1)
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{
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if (buf >= buf_end)
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error (_("read_sleb128: Corrupted DWARF expression."));
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byte = *buf++;
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result |= (byte & 0x7f) << shift;
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shift += 7;
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if ((byte & 0x80) == 0)
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break;
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}
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if (shift < (sizeof (*r) * 8) && (byte & 0x40) != 0)
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result |= -(1 << shift);
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*r = result;
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return buf;
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}
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/* Read an address from BUF, and verify that it doesn't extend past
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BUF_END. The address is returned, and *BYTES_READ is set to the
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number of bytes read from BUF. */
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CORE_ADDR
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dwarf2_read_address (gdb_byte *buf, gdb_byte *buf_end, int *bytes_read)
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{
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CORE_ADDR result;
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if (buf_end - buf < TARGET_ADDR_BIT / TARGET_CHAR_BIT)
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error (_("dwarf2_read_address: Corrupted DWARF expression."));
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*bytes_read = TARGET_ADDR_BIT / TARGET_CHAR_BIT;
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/* NOTE: cagney/2003-05-22: This extract is assuming that a DWARF 2
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address is always unsigned. That may or may not be true. */
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result = extract_unsigned_integer (buf, TARGET_ADDR_BIT / TARGET_CHAR_BIT);
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return result;
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}
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/* Return the type of an address, for unsigned arithmetic. */
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static struct type *
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unsigned_address_type (void)
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{
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switch (TARGET_ADDR_BIT / TARGET_CHAR_BIT)
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{
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case 2:
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return builtin_type_uint16;
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case 4:
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return builtin_type_uint32;
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case 8:
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return builtin_type_uint64;
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default:
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internal_error (__FILE__, __LINE__,
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_("Unsupported address size.\n"));
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}
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}
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/* Return the type of an address, for signed arithmetic. */
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static struct type *
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signed_address_type (void)
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{
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switch (TARGET_ADDR_BIT / TARGET_CHAR_BIT)
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{
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case 2:
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return builtin_type_int16;
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case 4:
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return builtin_type_int32;
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case 8:
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return builtin_type_int64;
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default:
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internal_error (__FILE__, __LINE__,
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_("Unsupported address size.\n"));
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}
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}
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/* The engine for the expression evaluator. Using the context in CTX,
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evaluate the expression between OP_PTR and OP_END. */
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static void
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execute_stack_op (struct dwarf_expr_context *ctx,
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gdb_byte *op_ptr, gdb_byte *op_end)
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{
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ctx->in_reg = 0;
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while (op_ptr < op_end)
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{
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enum dwarf_location_atom op = *op_ptr++;
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CORE_ADDR result;
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ULONGEST uoffset, reg;
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LONGEST offset;
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int bytes_read;
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switch (op)
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{
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case DW_OP_lit0:
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case DW_OP_lit1:
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case DW_OP_lit2:
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case DW_OP_lit3:
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case DW_OP_lit4:
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case DW_OP_lit5:
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case DW_OP_lit6:
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case DW_OP_lit7:
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case DW_OP_lit8:
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case DW_OP_lit9:
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case DW_OP_lit10:
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case DW_OP_lit11:
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case DW_OP_lit12:
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case DW_OP_lit13:
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case DW_OP_lit14:
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case DW_OP_lit15:
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case DW_OP_lit16:
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case DW_OP_lit17:
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case DW_OP_lit18:
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case DW_OP_lit19:
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case DW_OP_lit20:
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case DW_OP_lit21:
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case DW_OP_lit22:
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case DW_OP_lit23:
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case DW_OP_lit24:
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case DW_OP_lit25:
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case DW_OP_lit26:
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case DW_OP_lit27:
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case DW_OP_lit28:
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case DW_OP_lit29:
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case DW_OP_lit30:
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case DW_OP_lit31:
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result = op - DW_OP_lit0;
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break;
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case DW_OP_addr:
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result = dwarf2_read_address (op_ptr, op_end, &bytes_read);
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op_ptr += bytes_read;
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break;
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case DW_OP_const1u:
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result = extract_unsigned_integer (op_ptr, 1);
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op_ptr += 1;
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break;
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case DW_OP_const1s:
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result = extract_signed_integer (op_ptr, 1);
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op_ptr += 1;
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break;
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case DW_OP_const2u:
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result = extract_unsigned_integer (op_ptr, 2);
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op_ptr += 2;
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break;
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case DW_OP_const2s:
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result = extract_signed_integer (op_ptr, 2);
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op_ptr += 2;
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break;
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case DW_OP_const4u:
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result = extract_unsigned_integer (op_ptr, 4);
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op_ptr += 4;
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break;
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case DW_OP_const4s:
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result = extract_signed_integer (op_ptr, 4);
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op_ptr += 4;
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break;
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case DW_OP_const8u:
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result = extract_unsigned_integer (op_ptr, 8);
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op_ptr += 8;
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break;
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case DW_OP_const8s:
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result = extract_signed_integer (op_ptr, 8);
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op_ptr += 8;
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break;
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case DW_OP_constu:
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op_ptr = read_uleb128 (op_ptr, op_end, &uoffset);
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result = uoffset;
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break;
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case DW_OP_consts:
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op_ptr = read_sleb128 (op_ptr, op_end, &offset);
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result = offset;
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break;
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/* The DW_OP_reg operations are required to occur alone in
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location expressions. */
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case DW_OP_reg0:
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case DW_OP_reg1:
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case DW_OP_reg2:
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case DW_OP_reg3:
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case DW_OP_reg4:
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case DW_OP_reg5:
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case DW_OP_reg6:
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case DW_OP_reg7:
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case DW_OP_reg8:
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case DW_OP_reg9:
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case DW_OP_reg10:
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case DW_OP_reg11:
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case DW_OP_reg12:
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case DW_OP_reg13:
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case DW_OP_reg14:
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case DW_OP_reg15:
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case DW_OP_reg16:
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case DW_OP_reg17:
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case DW_OP_reg18:
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case DW_OP_reg19:
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case DW_OP_reg20:
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case DW_OP_reg21:
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case DW_OP_reg22:
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case DW_OP_reg23:
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case DW_OP_reg24:
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case DW_OP_reg25:
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case DW_OP_reg26:
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case DW_OP_reg27:
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case DW_OP_reg28:
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case DW_OP_reg29:
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case DW_OP_reg30:
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case DW_OP_reg31:
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if (op_ptr != op_end && *op_ptr != DW_OP_piece)
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error (_("DWARF-2 expression error: DW_OP_reg operations must be "
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"used either alone or in conjuction with DW_OP_piece."));
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result = op - DW_OP_reg0;
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ctx->in_reg = 1;
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break;
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case DW_OP_regx:
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op_ptr = read_uleb128 (op_ptr, op_end, ®);
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if (op_ptr != op_end && *op_ptr != DW_OP_piece)
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error (_("DWARF-2 expression error: DW_OP_reg operations must be "
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"used either alone or in conjuction with DW_OP_piece."));
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result = reg;
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ctx->in_reg = 1;
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break;
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case DW_OP_breg0:
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case DW_OP_breg1:
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case DW_OP_breg2:
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case DW_OP_breg3:
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case DW_OP_breg4:
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case DW_OP_breg5:
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case DW_OP_breg6:
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case DW_OP_breg7:
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case DW_OP_breg8:
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case DW_OP_breg9:
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case DW_OP_breg10:
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case DW_OP_breg11:
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case DW_OP_breg12:
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case DW_OP_breg13:
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case DW_OP_breg14:
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case DW_OP_breg15:
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case DW_OP_breg16:
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case DW_OP_breg17:
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case DW_OP_breg18:
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case DW_OP_breg19:
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case DW_OP_breg20:
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case DW_OP_breg21:
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case DW_OP_breg22:
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case DW_OP_breg23:
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case DW_OP_breg24:
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case DW_OP_breg25:
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case DW_OP_breg26:
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case DW_OP_breg27:
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case DW_OP_breg28:
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case DW_OP_breg29:
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case DW_OP_breg30:
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case DW_OP_breg31:
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{
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op_ptr = read_sleb128 (op_ptr, op_end, &offset);
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result = (ctx->read_reg) (ctx->baton, op - DW_OP_breg0);
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result += offset;
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}
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break;
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case DW_OP_bregx:
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{
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op_ptr = read_uleb128 (op_ptr, op_end, ®);
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op_ptr = read_sleb128 (op_ptr, op_end, &offset);
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result = (ctx->read_reg) (ctx->baton, reg);
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result += offset;
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}
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break;
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case DW_OP_fbreg:
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{
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gdb_byte *datastart;
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size_t datalen;
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unsigned int before_stack_len;
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op_ptr = read_sleb128 (op_ptr, op_end, &offset);
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/* Rather than create a whole new context, we simply
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record the stack length before execution, then reset it
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afterwards, effectively erasing whatever the recursive
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call put there. */
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before_stack_len = ctx->stack_len;
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/* FIXME: cagney/2003-03-26: This code should be using
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get_frame_base_address(), and then implement a dwarf2
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specific this_base method. */
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(ctx->get_frame_base) (ctx->baton, &datastart, &datalen);
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dwarf_expr_eval (ctx, datastart, datalen);
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result = dwarf_expr_fetch (ctx, 0);
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if (ctx->in_reg)
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result = (ctx->read_reg) (ctx->baton, result);
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result = result + offset;
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ctx->stack_len = before_stack_len;
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ctx->in_reg = 0;
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}
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break;
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case DW_OP_dup:
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result = dwarf_expr_fetch (ctx, 0);
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break;
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case DW_OP_drop:
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dwarf_expr_pop (ctx);
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goto no_push;
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case DW_OP_pick:
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offset = *op_ptr++;
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result = dwarf_expr_fetch (ctx, offset);
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break;
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case DW_OP_over:
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result = dwarf_expr_fetch (ctx, 1);
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break;
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case DW_OP_rot:
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{
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CORE_ADDR t1, t2, t3;
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if (ctx->stack_len < 3)
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error (_("Not enough elements for DW_OP_rot. Need 3, have %d."),
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ctx->stack_len);
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t1 = ctx->stack[ctx->stack_len - 1];
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t2 = ctx->stack[ctx->stack_len - 2];
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t3 = ctx->stack[ctx->stack_len - 3];
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ctx->stack[ctx->stack_len - 1] = t2;
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ctx->stack[ctx->stack_len - 2] = t3;
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ctx->stack[ctx->stack_len - 3] = t1;
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goto no_push;
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}
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case DW_OP_deref:
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case DW_OP_deref_size:
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case DW_OP_abs:
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case DW_OP_neg:
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case DW_OP_not:
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case DW_OP_plus_uconst:
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/* Unary operations. */
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result = dwarf_expr_fetch (ctx, 0);
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dwarf_expr_pop (ctx);
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switch (op)
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{
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case DW_OP_deref:
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{
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gdb_byte *buf = alloca (TARGET_ADDR_BIT / TARGET_CHAR_BIT);
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int bytes_read;
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(ctx->read_mem) (ctx->baton, buf, result,
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TARGET_ADDR_BIT / TARGET_CHAR_BIT);
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result = dwarf2_read_address (buf,
|
||
buf + (TARGET_ADDR_BIT
|
||
/ TARGET_CHAR_BIT),
|
||
&bytes_read);
|
||
}
|
||
break;
|
||
|
||
case DW_OP_deref_size:
|
||
{
|
||
gdb_byte *buf = alloca (TARGET_ADDR_BIT / TARGET_CHAR_BIT);
|
||
int bytes_read;
|
||
|
||
(ctx->read_mem) (ctx->baton, buf, result, *op_ptr++);
|
||
result = dwarf2_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, 0);
|
||
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;
|
||
break;
|
||
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;
|
||
break;
|
||
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:
|
||
/* Variable is at a constant offset in the thread-local
|
||
storage block into the objfile for the current thread and
|
||
the dynamic linker module containing this expression. Here
|
||
we return returns the offset from that base. The top of the
|
||
stack has the offset from the beginning of the thread
|
||
control block at which the variable is located. Nothing
|
||
should follow this operator, so the top of stack would be
|
||
returned. */
|
||
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;
|
||
|
||
case DW_OP_piece:
|
||
{
|
||
ULONGEST size;
|
||
CORE_ADDR addr_or_regnum;
|
||
|
||
/* Record the piece. */
|
||
op_ptr = read_uleb128 (op_ptr, op_end, &size);
|
||
addr_or_regnum = dwarf_expr_fetch (ctx, 0);
|
||
add_piece (ctx, ctx->in_reg, addr_or_regnum, size);
|
||
|
||
/* Pop off the address/regnum, and clear the in_reg flag. */
|
||
dwarf_expr_pop (ctx);
|
||
ctx->in_reg = 0;
|
||
}
|
||
goto no_push;
|
||
|
||
default:
|
||
error (_("Unhandled dwarf expression opcode 0x%x"), op);
|
||
}
|
||
|
||
/* Most things push a result value. */
|
||
dwarf_expr_push (ctx, result);
|
||
no_push:;
|
||
}
|
||
}
|