| /* Functions for manipulating expressions designed to be executed on the agent |
| Copyright (C) 1998-2021 Free Software Foundation, Inc. |
| |
| 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 3 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, see <http://www.gnu.org/licenses/>. */ |
| |
| /* Despite what the above comment says about this file being part of |
| GDB, we would like to keep these functions free of GDB |
| dependencies, since we want to be able to use them in contexts |
| outside of GDB (test suites, the stub, etc.) */ |
| |
| #include "defs.h" |
| #include "ax.h" |
| #include "gdbarch.h" |
| |
| #include "value.h" |
| #include "user-regs.h" |
| |
| static void grow_expr (struct agent_expr *x, int n); |
| |
| static void append_const (struct agent_expr *x, LONGEST val, int n); |
| |
| static LONGEST read_const (struct agent_expr *x, int o, int n); |
| |
| static void generic_ext (struct agent_expr *x, enum agent_op op, int n); |
| |
| /* Functions for building expressions. */ |
| |
| agent_expr::agent_expr (struct gdbarch *gdbarch, CORE_ADDR scope) |
| { |
| this->len = 0; |
| this->size = 1; /* Change this to a larger value once |
| reallocation code is tested. */ |
| this->buf = (unsigned char *) xmalloc (this->size); |
| |
| this->gdbarch = gdbarch; |
| this->scope = scope; |
| |
| /* Bit vector for registers used. */ |
| this->reg_mask_len = 1; |
| this->reg_mask = XCNEWVEC (unsigned char, this->reg_mask_len); |
| |
| this->tracing = 0; |
| this->trace_string = 0; |
| } |
| |
| agent_expr::~agent_expr () |
| { |
| xfree (this->buf); |
| xfree (this->reg_mask); |
| } |
| |
| /* Make sure that X has room for at least N more bytes. This doesn't |
| affect the length, just the allocated size. */ |
| static void |
| grow_expr (struct agent_expr *x, int n) |
| { |
| if (x->len + n > x->size) |
| { |
| x->size *= 2; |
| if (x->size < x->len + n) |
| x->size = x->len + n + 10; |
| x->buf = (unsigned char *) xrealloc (x->buf, x->size); |
| } |
| } |
| |
| |
| /* Append the low N bytes of VAL as an N-byte integer to the |
| expression X, in big-endian order. */ |
| static void |
| append_const (struct agent_expr *x, LONGEST val, int n) |
| { |
| int i; |
| |
| grow_expr (x, n); |
| for (i = n - 1; i >= 0; i--) |
| { |
| x->buf[x->len + i] = val & 0xff; |
| val >>= 8; |
| } |
| x->len += n; |
| } |
| |
| |
| /* Extract an N-byte big-endian unsigned integer from expression X at |
| offset O. */ |
| static LONGEST |
| read_const (struct agent_expr *x, int o, int n) |
| { |
| int i; |
| LONGEST accum = 0; |
| |
| /* Make sure we're not reading off the end of the expression. */ |
| if (o + n > x->len) |
| error (_("GDB bug: ax-general.c (read_const): incomplete constant")); |
| |
| for (i = 0; i < n; i++) |
| accum = (accum << 8) | x->buf[o + i]; |
| |
| return accum; |
| } |
| |
| /* See ax.h. */ |
| |
| void |
| ax_raw_byte (struct agent_expr *x, gdb_byte byte) |
| { |
| grow_expr (x, 1); |
| x->buf[x->len++] = byte; |
| } |
| |
| /* Append a simple operator OP to EXPR. */ |
| void |
| ax_simple (struct agent_expr *x, enum agent_op op) |
| { |
| ax_raw_byte (x, op); |
| } |
| |
| /* Append a pick operator to EXPR. DEPTH is the stack item to pick, |
| with 0 being top of stack. */ |
| |
| void |
| ax_pick (struct agent_expr *x, int depth) |
| { |
| if (depth < 0 || depth > 255) |
| error (_("GDB bug: ax-general.c (ax_pick): stack depth out of range")); |
| ax_simple (x, aop_pick); |
| append_const (x, 1, depth); |
| } |
| |
| |
| /* Append a sign-extension or zero-extension instruction to EXPR, to |
| extend an N-bit value. */ |
| static void |
| generic_ext (struct agent_expr *x, enum agent_op op, int n) |
| { |
| /* N must fit in a byte. */ |
| if (n < 0 || n > 255) |
| error (_("GDB bug: ax-general.c (generic_ext): bit count out of range")); |
| /* That had better be enough range. */ |
| if (sizeof (LONGEST) * 8 > 255) |
| error (_("GDB bug: ax-general.c (generic_ext): " |
| "opcode has inadequate range")); |
| |
| grow_expr (x, 2); |
| x->buf[x->len++] = op; |
| x->buf[x->len++] = n; |
| } |
| |
| |
| /* Append a sign-extension instruction to EXPR, to extend an N-bit value. */ |
| void |
| ax_ext (struct agent_expr *x, int n) |
| { |
| generic_ext (x, aop_ext, n); |
| } |
| |
| |
| /* Append a zero-extension instruction to EXPR, to extend an N-bit value. */ |
| void |
| ax_zero_ext (struct agent_expr *x, int n) |
| { |
| generic_ext (x, aop_zero_ext, n); |
| } |
| |
| |
| /* Append a trace_quick instruction to EXPR, to record N bytes. */ |
| void |
| ax_trace_quick (struct agent_expr *x, int n) |
| { |
| /* N must fit in a byte. */ |
| if (n < 0 || n > 255) |
| error (_("GDB bug: ax-general.c (ax_trace_quick): " |
| "size out of range for trace_quick")); |
| |
| grow_expr (x, 2); |
| x->buf[x->len++] = aop_trace_quick; |
| x->buf[x->len++] = n; |
| } |
| |
| |
| /* Append a goto op to EXPR. OP is the actual op (must be aop_goto or |
| aop_if_goto). We assume we don't know the target offset yet, |
| because it's probably a forward branch, so we leave space in EXPR |
| for the target, and return the offset in EXPR of that space, so we |
| can backpatch it once we do know the target offset. Use ax_label |
| to do the backpatching. */ |
| int |
| ax_goto (struct agent_expr *x, enum agent_op op) |
| { |
| grow_expr (x, 3); |
| x->buf[x->len + 0] = op; |
| x->buf[x->len + 1] = 0xff; |
| x->buf[x->len + 2] = 0xff; |
| x->len += 3; |
| return x->len - 2; |
| } |
| |
| /* Suppose a given call to ax_goto returns some value PATCH. When you |
| know the offset TARGET that goto should jump to, call |
| ax_label (EXPR, PATCH, TARGET) |
| to patch TARGET into the ax_goto instruction. */ |
| void |
| ax_label (struct agent_expr *x, int patch, int target) |
| { |
| /* Make sure the value is in range. Don't accept 0xffff as an |
| offset; that's our magic sentinel value for unpatched branches. */ |
| if (target < 0 || target >= 0xffff) |
| error (_("GDB bug: ax-general.c (ax_label): label target out of range")); |
| |
| x->buf[patch] = (target >> 8) & 0xff; |
| x->buf[patch + 1] = target & 0xff; |
| } |
| |
| |
| /* Assemble code to push a constant on the stack. */ |
| void |
| ax_const_l (struct agent_expr *x, LONGEST l) |
| { |
| static enum agent_op ops[] |
| = |
| {aop_const8, aop_const16, aop_const32, aop_const64}; |
| int size; |
| int op; |
| |
| /* How big is the number? 'op' keeps track of which opcode to use. |
| Notice that we don't really care whether the original number was |
| signed or unsigned; we always reproduce the value exactly, and |
| use the shortest representation. */ |
| for (op = 0, size = 8; size < 64; size *= 2, op++) |
| { |
| LONGEST lim = ((LONGEST) 1) << (size - 1); |
| |
| if (-lim <= l && l <= lim - 1) |
| break; |
| } |
| |
| /* Emit the right opcode... */ |
| ax_simple (x, ops[op]); |
| |
| /* Emit the low SIZE bytes as an unsigned number. We know that |
| sign-extending this will yield l. */ |
| append_const (x, l, size / 8); |
| |
| /* Now, if it was negative, and not full-sized, sign-extend it. */ |
| if (l < 0 && size < 64) |
| ax_ext (x, size); |
| } |
| |
| |
| void |
| ax_const_d (struct agent_expr *x, LONGEST d) |
| { |
| /* FIXME: floating-point support not present yet. */ |
| error (_("GDB bug: ax-general.c (ax_const_d): " |
| "floating point not supported yet")); |
| } |
| |
| |
| /* Assemble code to push the value of register number REG on the |
| stack. */ |
| void |
| ax_reg (struct agent_expr *x, int reg) |
| { |
| if (reg >= gdbarch_num_regs (x->gdbarch)) |
| { |
| /* This is a pseudo-register. */ |
| if (!gdbarch_ax_pseudo_register_push_stack_p (x->gdbarch)) |
| error (_("'%s' is a pseudo-register; " |
| "GDB cannot yet trace its contents."), |
| user_reg_map_regnum_to_name (x->gdbarch, reg)); |
| if (gdbarch_ax_pseudo_register_push_stack (x->gdbarch, x, reg)) |
| error (_("Trace '%s' failed."), |
| user_reg_map_regnum_to_name (x->gdbarch, reg)); |
| } |
| else |
| { |
| /* Get the remote register number. */ |
| reg = gdbarch_remote_register_number (x->gdbarch, reg); |
| |
| /* Make sure the register number is in range. */ |
| if (reg < 0 || reg > 0xffff) |
| error (_("GDB bug: ax-general.c (ax_reg): " |
| "register number out of range")); |
| grow_expr (x, 3); |
| x->buf[x->len] = aop_reg; |
| x->buf[x->len + 1] = (reg >> 8) & 0xff; |
| x->buf[x->len + 2] = (reg) & 0xff; |
| x->len += 3; |
| } |
| } |
| |
| /* Assemble code to operate on a trace state variable. */ |
| |
| void |
| ax_tsv (struct agent_expr *x, enum agent_op op, int num) |
| { |
| /* Make sure the tsv number is in range. */ |
| if (num < 0 || num > 0xffff) |
| internal_error (__FILE__, __LINE__, |
| _("ax-general.c (ax_tsv): variable " |
| "number is %d, out of range"), num); |
| |
| grow_expr (x, 3); |
| x->buf[x->len] = op; |
| x->buf[x->len + 1] = (num >> 8) & 0xff; |
| x->buf[x->len + 2] = (num) & 0xff; |
| x->len += 3; |
| } |
| |
| /* Append a string to the expression. Note that the string is going |
| into the bytecodes directly, not on the stack. As a precaution, |
| include both length as prefix, and terminate with a NUL. (The NUL |
| is counted in the length.) */ |
| |
| void |
| ax_string (struct agent_expr *x, const char *str, int slen) |
| { |
| int i; |
| |
| /* Make sure the string length is reasonable. */ |
| if (slen < 0 || slen > 0xffff) |
| internal_error (__FILE__, __LINE__, |
| _("ax-general.c (ax_string): string " |
| "length is %d, out of allowed range"), slen); |
| |
| grow_expr (x, 2 + slen + 1); |
| x->buf[x->len++] = ((slen + 1) >> 8) & 0xff; |
| x->buf[x->len++] = (slen + 1) & 0xff; |
| for (i = 0; i < slen; ++i) |
| x->buf[x->len++] = str[i]; |
| x->buf[x->len++] = '\0'; |
| } |
| |
| |
| |
| /* Functions for disassembling agent expressions, and otherwise |
| debugging the expression compiler. */ |
| |
| struct aop_map aop_map[] = |
| { |
| {0, 0, 0, 0, 0} |
| #define DEFOP(NAME, SIZE, DATA_SIZE, CONSUMED, PRODUCED, VALUE) \ |
| , { # NAME, SIZE, DATA_SIZE, CONSUMED, PRODUCED } |
| #include "gdbsupport/ax.def" |
| #undef DEFOP |
| }; |
| |
| |
| /* Disassemble the expression EXPR, writing to F. */ |
| void |
| ax_print (struct ui_file *f, struct agent_expr *x) |
| { |
| int i; |
| |
| fprintf_filtered (f, _("Scope: %s\n"), paddress (x->gdbarch, x->scope)); |
| fprintf_filtered (f, _("Reg mask:")); |
| for (i = 0; i < x->reg_mask_len; ++i) |
| fprintf_filtered (f, _(" %02x"), x->reg_mask[i]); |
| fprintf_filtered (f, _("\n")); |
| |
| /* Check the size of the name array against the number of entries in |
| the enum, to catch additions that people didn't sync. */ |
| if ((sizeof (aop_map) / sizeof (aop_map[0])) |
| != aop_last) |
| error (_("GDB bug: ax-general.c (ax_print): opcode map out of sync")); |
| |
| for (i = 0; i < x->len;) |
| { |
| enum agent_op op = (enum agent_op) x->buf[i]; |
| |
| if (op >= (sizeof (aop_map) / sizeof (aop_map[0])) |
| || !aop_map[op].name) |
| { |
| fprintf_filtered (f, _("%3d <bad opcode %02x>\n"), i, op); |
| i++; |
| continue; |
| } |
| if (i + 1 + aop_map[op].op_size > x->len) |
| { |
| fprintf_filtered (f, _("%3d <incomplete opcode %s>\n"), |
| i, aop_map[op].name); |
| break; |
| } |
| |
| fprintf_filtered (f, "%3d %s", i, aop_map[op].name); |
| if (aop_map[op].op_size > 0) |
| { |
| fputs_filtered (" ", f); |
| |
| print_longest (f, 'd', 0, |
| read_const (x, i + 1, aop_map[op].op_size)); |
| } |
| /* Handle the complicated printf arguments specially. */ |
| else if (op == aop_printf) |
| { |
| int slen, nargs; |
| |
| i++; |
| nargs = x->buf[i++]; |
| slen = x->buf[i++]; |
| slen = slen * 256 + x->buf[i++]; |
| fprintf_filtered (f, _(" \"%s\", %d args"), |
| &(x->buf[i]), nargs); |
| i += slen - 1; |
| } |
| fprintf_filtered (f, "\n"); |
| i += 1 + aop_map[op].op_size; |
| } |
| } |
| |
| /* Add register REG to the register mask for expression AX. */ |
| void |
| ax_reg_mask (struct agent_expr *ax, int reg) |
| { |
| if (reg >= gdbarch_num_regs (ax->gdbarch)) |
| { |
| /* This is a pseudo-register. */ |
| if (!gdbarch_ax_pseudo_register_collect_p (ax->gdbarch)) |
| error (_("'%s' is a pseudo-register; " |
| "GDB cannot yet trace its contents."), |
| user_reg_map_regnum_to_name (ax->gdbarch, reg)); |
| if (gdbarch_ax_pseudo_register_collect (ax->gdbarch, ax, reg)) |
| error (_("Trace '%s' failed."), |
| user_reg_map_regnum_to_name (ax->gdbarch, reg)); |
| } |
| else |
| { |
| int byte; |
| |
| /* Get the remote register number. */ |
| reg = gdbarch_remote_register_number (ax->gdbarch, reg); |
| byte = reg / 8; |
| |
| /* Grow the bit mask if necessary. */ |
| if (byte >= ax->reg_mask_len) |
| { |
| /* It's not appropriate to double here. This isn't a |
| string buffer. */ |
| int new_len = byte + 1; |
| unsigned char *new_reg_mask |
| = XRESIZEVEC (unsigned char, ax->reg_mask, new_len); |
| |
| memset (new_reg_mask + ax->reg_mask_len, 0, |
| (new_len - ax->reg_mask_len) * sizeof (ax->reg_mask[0])); |
| ax->reg_mask_len = new_len; |
| ax->reg_mask = new_reg_mask; |
| } |
| |
| ax->reg_mask[byte] |= 1 << (reg % 8); |
| } |
| } |
| |
| /* Given an agent expression AX, fill in requirements and other descriptive |
| bits. */ |
| void |
| ax_reqs (struct agent_expr *ax) |
| { |
| int i; |
| int height; |
| |
| /* Jump target table. targets[i] is non-zero iff we have found a |
| jump to offset i. */ |
| char *targets = (char *) alloca (ax->len * sizeof (targets[0])); |
| |
| /* Instruction boundary table. boundary[i] is non-zero iff our scan |
| has reached an instruction starting at offset i. */ |
| char *boundary = (char *) alloca (ax->len * sizeof (boundary[0])); |
| |
| /* Stack height record. If either targets[i] or boundary[i] is |
| non-zero, heights[i] is the height the stack should have before |
| executing the bytecode at that point. */ |
| int *heights = (int *) alloca (ax->len * sizeof (heights[0])); |
| |
| /* Pointer to a description of the present op. */ |
| struct aop_map *op; |
| |
| memset (targets, 0, ax->len * sizeof (targets[0])); |
| memset (boundary, 0, ax->len * sizeof (boundary[0])); |
| |
| ax->max_height = ax->min_height = height = 0; |
| ax->flaw = agent_flaw_none; |
| ax->max_data_size = 0; |
| |
| for (i = 0; i < ax->len; i += 1 + op->op_size) |
| { |
| if (ax->buf[i] > (sizeof (aop_map) / sizeof (aop_map[0]))) |
| { |
| ax->flaw = agent_flaw_bad_instruction; |
| return; |
| } |
| |
| op = &aop_map[ax->buf[i]]; |
| |
| if (!op->name) |
| { |
| ax->flaw = agent_flaw_bad_instruction; |
| 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; |
| } |