602 lines
16 KiB
C
602 lines
16 KiB
C
/* Functions for manipulating expressions designed to be executed on the agent
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Copyright (C) 1998-2018 Free Software Foundation, Inc.
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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 3 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, see <http://www.gnu.org/licenses/>. */
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/* Despite what the above comment says about this file being part of
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GDB, we would like to keep these functions free of GDB
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dependencies, since we want to be able to use them in contexts
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outside of GDB (test suites, the stub, etc.) */
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#include "defs.h"
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#include "ax.h"
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#include "value.h"
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#include "user-regs.h"
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static void grow_expr (struct agent_expr *x, int n);
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static void append_const (struct agent_expr *x, LONGEST val, int n);
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static LONGEST read_const (struct agent_expr *x, int o, int n);
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static void generic_ext (struct agent_expr *x, enum agent_op op, int n);
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/* Functions for building expressions. */
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agent_expr::agent_expr (struct gdbarch *gdbarch, CORE_ADDR scope)
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{
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this->len = 0;
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this->size = 1; /* Change this to a larger value once
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reallocation code is tested. */
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this->buf = (unsigned char *) xmalloc (this->size);
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this->gdbarch = gdbarch;
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this->scope = scope;
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/* Bit vector for registers used. */
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this->reg_mask_len = 1;
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this->reg_mask = XCNEWVEC (unsigned char, this->reg_mask_len);
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this->tracing = 0;
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this->trace_string = 0;
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}
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agent_expr::~agent_expr ()
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{
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xfree (this->buf);
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xfree (this->reg_mask);
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}
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/* Make sure that X has room for at least N more bytes. This doesn't
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affect the length, just the allocated size. */
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static void
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grow_expr (struct agent_expr *x, int n)
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{
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if (x->len + n > x->size)
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{
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x->size *= 2;
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if (x->size < x->len + n)
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x->size = x->len + n + 10;
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x->buf = (unsigned char *) xrealloc (x->buf, x->size);
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}
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}
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/* Append the low N bytes of VAL as an N-byte integer to the
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expression X, in big-endian order. */
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static void
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append_const (struct agent_expr *x, LONGEST val, int n)
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{
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int i;
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grow_expr (x, n);
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for (i = n - 1; i >= 0; i--)
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{
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x->buf[x->len + i] = val & 0xff;
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val >>= 8;
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}
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x->len += n;
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}
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/* Extract an N-byte big-endian unsigned integer from expression X at
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offset O. */
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static LONGEST
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read_const (struct agent_expr *x, int o, int n)
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{
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int i;
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LONGEST accum = 0;
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/* Make sure we're not reading off the end of the expression. */
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if (o + n > x->len)
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error (_("GDB bug: ax-general.c (read_const): incomplete constant"));
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for (i = 0; i < n; i++)
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accum = (accum << 8) | x->buf[o + i];
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return accum;
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}
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/* See ax.h. */
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void
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ax_raw_byte (struct agent_expr *x, gdb_byte byte)
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{
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grow_expr (x, 1);
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x->buf[x->len++] = byte;
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}
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/* Append a simple operator OP to EXPR. */
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void
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ax_simple (struct agent_expr *x, enum agent_op op)
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{
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ax_raw_byte (x, op);
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}
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/* Append a pick operator to EXPR. DEPTH is the stack item to pick,
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with 0 being top of stack. */
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void
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ax_pick (struct agent_expr *x, int depth)
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{
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if (depth < 0 || depth > 255)
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error (_("GDB bug: ax-general.c (ax_pick): stack depth out of range"));
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ax_simple (x, aop_pick);
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append_const (x, 1, depth);
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}
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/* Append a sign-extension or zero-extension instruction to EXPR, to
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extend an N-bit value. */
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static void
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generic_ext (struct agent_expr *x, enum agent_op op, int n)
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{
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/* N must fit in a byte. */
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if (n < 0 || n > 255)
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error (_("GDB bug: ax-general.c (generic_ext): bit count out of range"));
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/* That had better be enough range. */
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if (sizeof (LONGEST) * 8 > 255)
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error (_("GDB bug: ax-general.c (generic_ext): "
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"opcode has inadequate range"));
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grow_expr (x, 2);
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x->buf[x->len++] = op;
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x->buf[x->len++] = n;
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}
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/* Append a sign-extension instruction to EXPR, to extend an N-bit value. */
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void
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ax_ext (struct agent_expr *x, int n)
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{
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generic_ext (x, aop_ext, n);
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}
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/* Append a zero-extension instruction to EXPR, to extend an N-bit value. */
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void
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ax_zero_ext (struct agent_expr *x, int n)
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{
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generic_ext (x, aop_zero_ext, n);
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}
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/* Append a trace_quick instruction to EXPR, to record N bytes. */
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void
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ax_trace_quick (struct agent_expr *x, int n)
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{
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/* N must fit in a byte. */
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if (n < 0 || n > 255)
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error (_("GDB bug: ax-general.c (ax_trace_quick): "
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"size out of range for trace_quick"));
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grow_expr (x, 2);
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x->buf[x->len++] = aop_trace_quick;
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x->buf[x->len++] = n;
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}
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/* Append a goto op to EXPR. OP is the actual op (must be aop_goto or
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aop_if_goto). We assume we don't know the target offset yet,
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because it's probably a forward branch, so we leave space in EXPR
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for the target, and return the offset in EXPR of that space, so we
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can backpatch it once we do know the target offset. Use ax_label
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to do the backpatching. */
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int
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ax_goto (struct agent_expr *x, enum agent_op op)
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{
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grow_expr (x, 3);
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x->buf[x->len + 0] = op;
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x->buf[x->len + 1] = 0xff;
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x->buf[x->len + 2] = 0xff;
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x->len += 3;
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return x->len - 2;
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}
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/* Suppose a given call to ax_goto returns some value PATCH. When you
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know the offset TARGET that goto should jump to, call
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ax_label (EXPR, PATCH, TARGET)
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to patch TARGET into the ax_goto instruction. */
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void
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ax_label (struct agent_expr *x, int patch, int target)
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{
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/* Make sure the value is in range. Don't accept 0xffff as an
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offset; that's our magic sentinel value for unpatched branches. */
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if (target < 0 || target >= 0xffff)
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error (_("GDB bug: ax-general.c (ax_label): label target out of range"));
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x->buf[patch] = (target >> 8) & 0xff;
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x->buf[patch + 1] = target & 0xff;
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}
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/* Assemble code to push a constant on the stack. */
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void
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ax_const_l (struct agent_expr *x, LONGEST l)
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{
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static enum agent_op ops[]
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=
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{aop_const8, aop_const16, aop_const32, aop_const64};
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int size;
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int op;
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/* How big is the number? 'op' keeps track of which opcode to use.
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Notice that we don't really care whether the original number was
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signed or unsigned; we always reproduce the value exactly, and
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use the shortest representation. */
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for (op = 0, size = 8; size < 64; size *= 2, op++)
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{
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LONGEST lim = ((LONGEST) 1) << (size - 1);
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if (-lim <= l && l <= lim - 1)
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break;
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}
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/* Emit the right opcode... */
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ax_simple (x, ops[op]);
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/* Emit the low SIZE bytes as an unsigned number. We know that
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sign-extending this will yield l. */
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append_const (x, l, size / 8);
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/* Now, if it was negative, and not full-sized, sign-extend it. */
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if (l < 0 && size < 64)
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ax_ext (x, size);
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}
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void
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ax_const_d (struct agent_expr *x, LONGEST d)
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{
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/* FIXME: floating-point support not present yet. */
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error (_("GDB bug: ax-general.c (ax_const_d): "
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"floating point not supported yet"));
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}
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/* Assemble code to push the value of register number REG on the
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stack. */
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void
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ax_reg (struct agent_expr *x, int reg)
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{
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if (reg >= gdbarch_num_regs (x->gdbarch))
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{
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/* This is a pseudo-register. */
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if (!gdbarch_ax_pseudo_register_push_stack_p (x->gdbarch))
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error (_("'%s' is a pseudo-register; "
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"GDB cannot yet trace its contents."),
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user_reg_map_regnum_to_name (x->gdbarch, reg));
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if (gdbarch_ax_pseudo_register_push_stack (x->gdbarch, x, reg))
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error (_("Trace '%s' failed."),
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user_reg_map_regnum_to_name (x->gdbarch, reg));
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}
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else
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{
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/* Get the remote register number. */
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reg = gdbarch_remote_register_number (x->gdbarch, reg);
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/* Make sure the register number is in range. */
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if (reg < 0 || reg > 0xffff)
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error (_("GDB bug: ax-general.c (ax_reg): "
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"register number out of range"));
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grow_expr (x, 3);
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x->buf[x->len] = aop_reg;
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x->buf[x->len + 1] = (reg >> 8) & 0xff;
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x->buf[x->len + 2] = (reg) & 0xff;
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x->len += 3;
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}
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}
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/* Assemble code to operate on a trace state variable. */
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void
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ax_tsv (struct agent_expr *x, enum agent_op op, int num)
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{
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/* Make sure the tsv number is in range. */
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if (num < 0 || num > 0xffff)
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internal_error (__FILE__, __LINE__,
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_("ax-general.c (ax_tsv): variable "
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"number is %d, out of range"), num);
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grow_expr (x, 3);
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x->buf[x->len] = op;
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x->buf[x->len + 1] = (num >> 8) & 0xff;
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x->buf[x->len + 2] = (num) & 0xff;
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x->len += 3;
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}
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/* Append a string to the expression. Note that the string is going
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into the bytecodes directly, not on the stack. As a precaution,
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include both length as prefix, and terminate with a NUL. (The NUL
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is counted in the length.) */
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void
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ax_string (struct agent_expr *x, const char *str, int slen)
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{
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int i;
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/* Make sure the string length is reasonable. */
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if (slen < 0 || slen > 0xffff)
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internal_error (__FILE__, __LINE__,
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_("ax-general.c (ax_string): string "
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"length is %d, out of allowed range"), slen);
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grow_expr (x, 2 + slen + 1);
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x->buf[x->len++] = ((slen + 1) >> 8) & 0xff;
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x->buf[x->len++] = (slen + 1) & 0xff;
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for (i = 0; i < slen; ++i)
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x->buf[x->len++] = str[i];
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x->buf[x->len++] = '\0';
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}
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/* Functions for disassembling agent expressions, and otherwise
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debugging the expression compiler. */
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struct aop_map aop_map[] =
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{
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{0, 0, 0, 0, 0}
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#define DEFOP(NAME, SIZE, DATA_SIZE, CONSUMED, PRODUCED, VALUE) \
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, { # NAME, SIZE, DATA_SIZE, CONSUMED, PRODUCED }
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#include "ax.def"
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#undef DEFOP
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};
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/* Disassemble the expression EXPR, writing to F. */
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void
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ax_print (struct ui_file *f, struct agent_expr *x)
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{
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int i;
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fprintf_filtered (f, _("Scope: %s\n"), paddress (x->gdbarch, x->scope));
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fprintf_filtered (f, _("Reg mask:"));
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for (i = 0; i < x->reg_mask_len; ++i)
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fprintf_filtered (f, _(" %02x"), x->reg_mask[i]);
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fprintf_filtered (f, _("\n"));
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/* Check the size of the name array against the number of entries in
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the enum, to catch additions that people didn't sync. */
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if ((sizeof (aop_map) / sizeof (aop_map[0]))
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!= aop_last)
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error (_("GDB bug: ax-general.c (ax_print): opcode map out of sync"));
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for (i = 0; i < x->len;)
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{
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enum agent_op op = (enum agent_op) x->buf[i];
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if (op >= (sizeof (aop_map) / sizeof (aop_map[0]))
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|| !aop_map[op].name)
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{
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fprintf_filtered (f, _("%3d <bad opcode %02x>\n"), i, op);
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i++;
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continue;
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}
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if (i + 1 + aop_map[op].op_size > x->len)
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{
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fprintf_filtered (f, _("%3d <incomplete opcode %s>\n"),
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i, aop_map[op].name);
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break;
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}
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fprintf_filtered (f, "%3d %s", i, aop_map[op].name);
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if (aop_map[op].op_size > 0)
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{
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fputs_filtered (" ", f);
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print_longest (f, 'd', 0,
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read_const (x, i + 1, aop_map[op].op_size));
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}
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/* Handle the complicated printf arguments specially. */
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else if (op == aop_printf)
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{
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int slen, nargs;
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i++;
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nargs = x->buf[i++];
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slen = x->buf[i++];
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slen = slen * 256 + x->buf[i++];
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fprintf_filtered (f, _(" \"%s\", %d args"),
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&(x->buf[i]), nargs);
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i += slen - 1;
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}
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fprintf_filtered (f, "\n");
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i += 1 + aop_map[op].op_size;
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}
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}
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/* Add register REG to the register mask for expression AX. */
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void
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ax_reg_mask (struct agent_expr *ax, int reg)
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{
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if (reg >= gdbarch_num_regs (ax->gdbarch))
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{
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/* This is a pseudo-register. */
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if (!gdbarch_ax_pseudo_register_collect_p (ax->gdbarch))
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error (_("'%s' is a pseudo-register; "
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"GDB cannot yet trace its contents."),
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user_reg_map_regnum_to_name (ax->gdbarch, reg));
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if (gdbarch_ax_pseudo_register_collect (ax->gdbarch, ax, reg))
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error (_("Trace '%s' failed."),
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user_reg_map_regnum_to_name (ax->gdbarch, reg));
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}
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else
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{
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int byte;
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/* Get the remote register number. */
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reg = gdbarch_remote_register_number (ax->gdbarch, reg);
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byte = reg / 8;
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/* Grow the bit mask if necessary. */
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if (byte >= ax->reg_mask_len)
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{
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/* It's not appropriate to double here. This isn't a
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string buffer. */
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int new_len = byte + 1;
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unsigned char *new_reg_mask
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= XRESIZEVEC (unsigned char, ax->reg_mask, new_len);
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memset (new_reg_mask + ax->reg_mask_len, 0,
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(new_len - ax->reg_mask_len) * sizeof (ax->reg_mask[0]));
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ax->reg_mask_len = new_len;
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ax->reg_mask = new_reg_mask;
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}
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ax->reg_mask[byte] |= 1 << (reg % 8);
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}
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}
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/* Given an agent expression AX, fill in requirements and other descriptive
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bits. */
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void
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ax_reqs (struct agent_expr *ax)
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{
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int i;
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int height;
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/* Jump target table. targets[i] is non-zero iff we have found a
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jump to offset i. */
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char *targets = (char *) alloca (ax->len * sizeof (targets[0]));
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/* Instruction boundary table. boundary[i] is non-zero iff our scan
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has reached an instruction starting at offset i. */
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char *boundary = (char *) alloca (ax->len * sizeof (boundary[0]));
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/* Stack height record. If either targets[i] or boundary[i] is
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non-zero, heights[i] is the height the stack should have before
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executing the bytecode at that point. */
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int *heights = (int *) alloca (ax->len * sizeof (heights[0]));
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/* Pointer to a description of the present op. */
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struct aop_map *op;
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memset (targets, 0, ax->len * sizeof (targets[0]));
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memset (boundary, 0, ax->len * sizeof (boundary[0]));
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ax->max_height = ax->min_height = height = 0;
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ax->flaw = agent_flaw_none;
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ax->max_data_size = 0;
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for (i = 0; i < ax->len; i += 1 + op->op_size)
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{
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if (ax->buf[i] > (sizeof (aop_map) / sizeof (aop_map[0])))
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{
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ax->flaw = agent_flaw_bad_instruction;
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return;
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}
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op = &aop_map[ax->buf[i]];
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if (!op->name)
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{
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ax->flaw = agent_flaw_bad_instruction;
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return;
|
||
}
|
||
|
||
if (i + 1 + op->op_size > ax->len)
|
||
{
|
||
ax->flaw = agent_flaw_incomplete_instruction;
|
||
return;
|
||
}
|
||
|
||
/* If this instruction is a forward jump target, does the
|
||
current stack height match the stack height at the jump
|
||
source? */
|
||
if (targets[i] && (heights[i] != height))
|
||
{
|
||
ax->flaw = agent_flaw_height_mismatch;
|
||
return;
|
||
}
|
||
|
||
boundary[i] = 1;
|
||
heights[i] = height;
|
||
|
||
height -= op->consumed;
|
||
if (height < ax->min_height)
|
||
ax->min_height = height;
|
||
height += op->produced;
|
||
if (height > ax->max_height)
|
||
ax->max_height = height;
|
||
|
||
if (op->data_size > ax->max_data_size)
|
||
ax->max_data_size = op->data_size;
|
||
|
||
/* For jump instructions, check that the target is a valid
|
||
offset. If it is, record the fact that that location is a
|
||
jump target, and record the height we expect there. */
|
||
if (aop_goto == op - aop_map
|
||
|| aop_if_goto == op - aop_map)
|
||
{
|
||
int target = read_const (ax, i + 1, 2);
|
||
if (target < 0 || target >= ax->len)
|
||
{
|
||
ax->flaw = agent_flaw_bad_jump;
|
||
return;
|
||
}
|
||
|
||
/* Do we have any information about what the stack height
|
||
should be at the target? */
|
||
if (targets[target] || boundary[target])
|
||
{
|
||
if (heights[target] != height)
|
||
{
|
||
ax->flaw = agent_flaw_height_mismatch;
|
||
return;
|
||
}
|
||
}
|
||
|
||
/* Record the target, along with the stack height we expect. */
|
||
targets[target] = 1;
|
||
heights[target] = height;
|
||
}
|
||
|
||
/* For unconditional jumps with a successor, check that the
|
||
successor is a target, and pick up its stack height. */
|
||
if (aop_goto == op - aop_map
|
||
&& i + 3 < ax->len)
|
||
{
|
||
if (!targets[i + 3])
|
||
{
|
||
ax->flaw = agent_flaw_hole;
|
||
return;
|
||
}
|
||
|
||
height = heights[i + 3];
|
||
}
|
||
|
||
/* For reg instructions, record the register in the bit mask. */
|
||
if (aop_reg == op - aop_map)
|
||
{
|
||
int reg = read_const (ax, i + 1, 2);
|
||
|
||
ax_reg_mask (ax, reg);
|
||
}
|
||
}
|
||
|
||
/* Check that all the targets are on boundaries. */
|
||
for (i = 0; i < ax->len; i++)
|
||
if (targets[i] && !boundary[i])
|
||
{
|
||
ax->flaw = agent_flaw_bad_jump;
|
||
return;
|
||
}
|
||
|
||
ax->final_height = height;
|
||
}
|