/* SystemTap probe support for GDB. Copyright (C) 2012-2023 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 . */ #include "defs.h" #include "stap-probe.h" #include "probe.h" #include "ui-out.h" #include "objfiles.h" #include "arch-utils.h" #include "command.h" #include "gdbcmd.h" #include "filenames.h" #include "value.h" #include "ax.h" #include "ax-gdb.h" #include "complaints.h" #include "cli/cli-utils.h" #include "linespec.h" #include "user-regs.h" #include "parser-defs.h" #include "language.h" #include "elf-bfd.h" #include "expop.h" #include #include "gdbsupport/hash_enum.h" #include /* The name of the SystemTap section where we will find information about the probes. */ #define STAP_BASE_SECTION_NAME ".stapsdt.base" /* Should we display debug information for the probe's argument expression parsing? */ static unsigned int stap_expression_debug = 0; /* The various possibilities of bitness defined for a probe's argument. The relationship is: - STAP_ARG_BITNESS_UNDEFINED: The user hasn't specified the bitness. - STAP_ARG_BITNESS_8BIT_UNSIGNED: argument string starts with `1@'. - STAP_ARG_BITNESS_8BIT_SIGNED: argument string starts with `-1@'. - STAP_ARG_BITNESS_16BIT_UNSIGNED: argument string starts with `2@'. - STAP_ARG_BITNESS_16BIT_SIGNED: argument string starts with `-2@'. - STAP_ARG_BITNESS_32BIT_UNSIGNED: argument string starts with `4@'. - STAP_ARG_BITNESS_32BIT_SIGNED: argument string starts with `-4@'. - STAP_ARG_BITNESS_64BIT_UNSIGNED: argument string starts with `8@'. - STAP_ARG_BITNESS_64BIT_SIGNED: argument string starts with `-8@'. */ enum stap_arg_bitness { STAP_ARG_BITNESS_UNDEFINED, STAP_ARG_BITNESS_8BIT_UNSIGNED, STAP_ARG_BITNESS_8BIT_SIGNED, STAP_ARG_BITNESS_16BIT_UNSIGNED, STAP_ARG_BITNESS_16BIT_SIGNED, STAP_ARG_BITNESS_32BIT_UNSIGNED, STAP_ARG_BITNESS_32BIT_SIGNED, STAP_ARG_BITNESS_64BIT_UNSIGNED, STAP_ARG_BITNESS_64BIT_SIGNED, }; /* The following structure represents a single argument for the probe. */ struct stap_probe_arg { /* Constructor for stap_probe_arg. */ stap_probe_arg (enum stap_arg_bitness bitness_, struct type *atype_, expression_up &&aexpr_) : bitness (bitness_), atype (atype_), aexpr (std::move (aexpr_)) {} /* The bitness of this argument. */ enum stap_arg_bitness bitness; /* The corresponding `struct type *' to the bitness. */ struct type *atype; /* The argument converted to an internal GDB expression. */ expression_up aexpr; }; /* Class that implements the static probe methods for "stap" probes. */ class stap_static_probe_ops : public static_probe_ops { public: /* We need a user-provided constructor to placate some compilers. See PR build/24937. */ stap_static_probe_ops () { } /* See probe.h. */ bool is_linespec (const char **linespecp) const override; /* See probe.h. */ void get_probes (std::vector> *probesp, struct objfile *objfile) const override; /* See probe.h. */ const char *type_name () const override; /* See probe.h. */ std::vector gen_info_probes_table_header () const override; }; /* SystemTap static_probe_ops. */ const stap_static_probe_ops stap_static_probe_ops {}; class stap_probe : public probe { public: /* Constructor for stap_probe. */ stap_probe (std::string &&name_, std::string &&provider_, CORE_ADDR address_, struct gdbarch *arch_, CORE_ADDR sem_addr, const char *args_text) : probe (std::move (name_), std::move (provider_), address_, arch_), m_sem_addr (sem_addr), m_have_parsed_args (false), m_unparsed_args_text (args_text) {} /* See probe.h. */ CORE_ADDR get_relocated_address (struct objfile *objfile) override; /* See probe.h. */ unsigned get_argument_count (struct gdbarch *gdbarch) override; /* See probe.h. */ bool can_evaluate_arguments () const override; /* See probe.h. */ struct value *evaluate_argument (unsigned n, frame_info_ptr frame) override; /* See probe.h. */ void compile_to_ax (struct agent_expr *aexpr, struct axs_value *axs_value, unsigned n) override; /* See probe.h. */ void set_semaphore (struct objfile *objfile, struct gdbarch *gdbarch) override; /* See probe.h. */ void clear_semaphore (struct objfile *objfile, struct gdbarch *gdbarch) override; /* See probe.h. */ const static_probe_ops *get_static_ops () const override; /* See probe.h. */ std::vector gen_info_probes_table_values () const override; /* Return argument N of probe. If the probe's arguments have not been parsed yet, parse them. If there are no arguments, throw an exception (error). Otherwise, return the requested argument. */ struct stap_probe_arg *get_arg_by_number (unsigned n, struct gdbarch *gdbarch) { if (!m_have_parsed_args) this->parse_arguments (gdbarch); gdb_assert (m_have_parsed_args); if (m_parsed_args.empty ()) internal_error (_("Probe '%s' apparently does not have arguments, but \n" "GDB is requesting its argument number %u anyway. " "This should not happen. Please report this bug."), this->get_name ().c_str (), n); if (n > m_parsed_args.size ()) internal_error (_("Probe '%s' has %d arguments, but GDB is requesting\n" "argument %u. This should not happen. Please\n" "report this bug."), this->get_name ().c_str (), (int) m_parsed_args.size (), n); return &m_parsed_args[n]; } /* Function which parses an argument string from the probe, correctly splitting the arguments and storing their information in properly ways. Consider the following argument string (x86 syntax): `4@%eax 4@$10' We have two arguments, `%eax' and `$10', both with 32-bit unsigned bitness. This function basically handles them, properly filling some structures with this information. */ void parse_arguments (struct gdbarch *gdbarch); private: /* If the probe has a semaphore associated, then this is the value of it, relative to SECT_OFF_DATA. */ CORE_ADDR m_sem_addr; /* True if the arguments have been parsed. */ bool m_have_parsed_args; /* The text version of the probe's arguments, unparsed. */ const char *m_unparsed_args_text; /* Information about each argument. This is an array of `stap_probe_arg', with each entry representing one argument. This is only valid if M_ARGS_PARSED is true. */ std::vector m_parsed_args; }; /* When parsing the arguments, we have to establish different precedences for the various kinds of asm operators. This enumeration represents those precedences. This logic behind this is available at , or using the command "info '(as)Infix Ops'". */ enum stap_operand_prec { /* Lowest precedence, used for non-recognized operands or for the beginning of the parsing process. */ STAP_OPERAND_PREC_NONE = 0, /* Precedence of logical OR. */ STAP_OPERAND_PREC_LOGICAL_OR, /* Precedence of logical AND. */ STAP_OPERAND_PREC_LOGICAL_AND, /* Precedence of additive (plus, minus) and comparative (equal, less, greater-than, etc) operands. */ STAP_OPERAND_PREC_ADD_CMP, /* Precedence of bitwise operands (bitwise OR, XOR, bitwise AND, logical NOT). */ STAP_OPERAND_PREC_BITWISE, /* Precedence of multiplicative operands (multiplication, division, remainder, left shift and right shift). */ STAP_OPERAND_PREC_MUL }; static expr::operation_up stap_parse_argument_1 (struct stap_parse_info *p, expr::operation_up &&lhs, enum stap_operand_prec prec) ATTRIBUTE_UNUSED_RESULT; static expr::operation_up stap_parse_argument_conditionally (struct stap_parse_info *p) ATTRIBUTE_UNUSED_RESULT; /* Returns true if *S is an operator, false otherwise. */ static bool stap_is_operator (const char *op); static void show_stapexpressiondebug (struct ui_file *file, int from_tty, struct cmd_list_element *c, const char *value) { gdb_printf (file, _("SystemTap Probe expression debugging is %s.\n"), value); } /* Returns the operator precedence level of OP, or STAP_OPERAND_PREC_NONE if the operator code was not recognized. */ static enum stap_operand_prec stap_get_operator_prec (enum exp_opcode op) { switch (op) { case BINOP_LOGICAL_OR: return STAP_OPERAND_PREC_LOGICAL_OR; case BINOP_LOGICAL_AND: return STAP_OPERAND_PREC_LOGICAL_AND; case BINOP_ADD: case BINOP_SUB: case BINOP_EQUAL: case BINOP_NOTEQUAL: case BINOP_LESS: case BINOP_LEQ: case BINOP_GTR: case BINOP_GEQ: return STAP_OPERAND_PREC_ADD_CMP; case BINOP_BITWISE_IOR: case BINOP_BITWISE_AND: case BINOP_BITWISE_XOR: case UNOP_LOGICAL_NOT: return STAP_OPERAND_PREC_BITWISE; case BINOP_MUL: case BINOP_DIV: case BINOP_REM: case BINOP_LSH: case BINOP_RSH: return STAP_OPERAND_PREC_MUL; default: return STAP_OPERAND_PREC_NONE; } } /* Given S, read the operator in it. Return the EXP_OPCODE which represents the operator detected, or throw an error if no operator was found. */ static enum exp_opcode stap_get_opcode (const char **s) { const char c = **s; enum exp_opcode op; *s += 1; switch (c) { case '*': op = BINOP_MUL; break; case '/': op = BINOP_DIV; break; case '%': op = BINOP_REM; break; case '<': op = BINOP_LESS; if (**s == '<') { *s += 1; op = BINOP_LSH; } else if (**s == '=') { *s += 1; op = BINOP_LEQ; } else if (**s == '>') { *s += 1; op = BINOP_NOTEQUAL; } break; case '>': op = BINOP_GTR; if (**s == '>') { *s += 1; op = BINOP_RSH; } else if (**s == '=') { *s += 1; op = BINOP_GEQ; } break; case '|': op = BINOP_BITWISE_IOR; if (**s == '|') { *s += 1; op = BINOP_LOGICAL_OR; } break; case '&': op = BINOP_BITWISE_AND; if (**s == '&') { *s += 1; op = BINOP_LOGICAL_AND; } break; case '^': op = BINOP_BITWISE_XOR; break; case '!': op = UNOP_LOGICAL_NOT; break; case '+': op = BINOP_ADD; break; case '-': op = BINOP_SUB; break; case '=': gdb_assert (**s == '='); op = BINOP_EQUAL; break; default: error (_("Invalid opcode in expression `%s' for SystemTap" "probe"), *s); } return op; } typedef expr::operation_up binop_maker_ftype (expr::operation_up &&, expr::operation_up &&); /* Map from an expression opcode to a function that can create a binary operation of that type. */ static std::unordered_map> stap_maker_map; /* Helper function to create a binary operation. */ static expr::operation_up stap_make_binop (enum exp_opcode opcode, expr::operation_up &&lhs, expr::operation_up &&rhs) { auto iter = stap_maker_map.find (opcode); gdb_assert (iter != stap_maker_map.end ()); return iter->second (std::move (lhs), std::move (rhs)); } /* Given the bitness of the argument, represented by B, return the corresponding `struct type *', or throw an error if B is unknown. */ static struct type * stap_get_expected_argument_type (struct gdbarch *gdbarch, enum stap_arg_bitness b, const char *probe_name) { switch (b) { case STAP_ARG_BITNESS_UNDEFINED: if (gdbarch_addr_bit (gdbarch) == 32) return builtin_type (gdbarch)->builtin_uint32; else return builtin_type (gdbarch)->builtin_uint64; case STAP_ARG_BITNESS_8BIT_UNSIGNED: return builtin_type (gdbarch)->builtin_uint8; case STAP_ARG_BITNESS_8BIT_SIGNED: return builtin_type (gdbarch)->builtin_int8; case STAP_ARG_BITNESS_16BIT_UNSIGNED: return builtin_type (gdbarch)->builtin_uint16; case STAP_ARG_BITNESS_16BIT_SIGNED: return builtin_type (gdbarch)->builtin_int16; case STAP_ARG_BITNESS_32BIT_SIGNED: return builtin_type (gdbarch)->builtin_int32; case STAP_ARG_BITNESS_32BIT_UNSIGNED: return builtin_type (gdbarch)->builtin_uint32; case STAP_ARG_BITNESS_64BIT_SIGNED: return builtin_type (gdbarch)->builtin_int64; case STAP_ARG_BITNESS_64BIT_UNSIGNED: return builtin_type (gdbarch)->builtin_uint64; default: error (_("Undefined bitness for probe '%s'."), probe_name); break; } } /* Helper function to check for a generic list of prefixes. GDBARCH is the current gdbarch being used. S is the expression being analyzed. If R is not NULL, it will be used to return the found prefix. PREFIXES is the list of expected prefixes. This function does a case-insensitive match. Return true if any prefix has been found, false otherwise. */ static bool stap_is_generic_prefix (struct gdbarch *gdbarch, const char *s, const char **r, const char *const *prefixes) { const char *const *p; if (prefixes == NULL) { if (r != NULL) *r = ""; return true; } for (p = prefixes; *p != NULL; ++p) if (strncasecmp (s, *p, strlen (*p)) == 0) { if (r != NULL) *r = *p; return true; } return false; } /* Return true if S points to a register prefix, false otherwise. For a description of the arguments, look at stap_is_generic_prefix. */ static bool stap_is_register_prefix (struct gdbarch *gdbarch, const char *s, const char **r) { const char *const *t = gdbarch_stap_register_prefixes (gdbarch); return stap_is_generic_prefix (gdbarch, s, r, t); } /* Return true if S points to a register indirection prefix, false otherwise. For a description of the arguments, look at stap_is_generic_prefix. */ static bool stap_is_register_indirection_prefix (struct gdbarch *gdbarch, const char *s, const char **r) { const char *const *t = gdbarch_stap_register_indirection_prefixes (gdbarch); return stap_is_generic_prefix (gdbarch, s, r, t); } /* Return true if S points to an integer prefix, false otherwise. For a description of the arguments, look at stap_is_generic_prefix. This function takes care of analyzing whether we are dealing with an expected integer prefix, or, if there is no integer prefix to be expected, whether we are dealing with a digit. It does a case-insensitive match. */ static bool stap_is_integer_prefix (struct gdbarch *gdbarch, const char *s, const char **r) { const char *const *t = gdbarch_stap_integer_prefixes (gdbarch); const char *const *p; if (t == NULL) { /* A NULL value here means that integers do not have a prefix. We just check for a digit then. */ if (r != NULL) *r = ""; return isdigit (*s) > 0; } for (p = t; *p != NULL; ++p) { size_t len = strlen (*p); if ((len == 0 && isdigit (*s)) || (len > 0 && strncasecmp (s, *p, len) == 0)) { /* Integers may or may not have a prefix. The "len == 0" check covers the case when integers do not have a prefix (therefore, we just check if we have a digit). The call to "strncasecmp" covers the case when they have a prefix. */ if (r != NULL) *r = *p; return true; } } return false; } /* Helper function to check for a generic list of suffixes. If we are not expecting any suffixes, then it just returns 1. If we are expecting at least one suffix, then it returns true if a suffix has been found, false otherwise. GDBARCH is the current gdbarch being used. S is the expression being analyzed. If R is not NULL, it will be used to return the found suffix. SUFFIXES is the list of expected suffixes. This function does a case-insensitive match. */ static bool stap_generic_check_suffix (struct gdbarch *gdbarch, const char *s, const char **r, const char *const *suffixes) { const char *const *p; bool found = false; if (suffixes == NULL) { if (r != NULL) *r = ""; return true; } for (p = suffixes; *p != NULL; ++p) if (strncasecmp (s, *p, strlen (*p)) == 0) { if (r != NULL) *r = *p; found = true; break; } return found; } /* Return true if S points to an integer suffix, false otherwise. For a description of the arguments, look at stap_generic_check_suffix. */ static bool stap_check_integer_suffix (struct gdbarch *gdbarch, const char *s, const char **r) { const char *const *p = gdbarch_stap_integer_suffixes (gdbarch); return stap_generic_check_suffix (gdbarch, s, r, p); } /* Return true if S points to a register suffix, false otherwise. For a description of the arguments, look at stap_generic_check_suffix. */ static bool stap_check_register_suffix (struct gdbarch *gdbarch, const char *s, const char **r) { const char *const *p = gdbarch_stap_register_suffixes (gdbarch); return stap_generic_check_suffix (gdbarch, s, r, p); } /* Return true if S points to a register indirection suffix, false otherwise. For a description of the arguments, look at stap_generic_check_suffix. */ static bool stap_check_register_indirection_suffix (struct gdbarch *gdbarch, const char *s, const char **r) { const char *const *p = gdbarch_stap_register_indirection_suffixes (gdbarch); return stap_generic_check_suffix (gdbarch, s, r, p); } /* Function responsible for parsing a register operand according to SystemTap parlance. Assuming: RP = register prefix RS = register suffix RIP = register indirection prefix RIS = register indirection suffix Then a register operand can be: [RIP] [RP] REGISTER [RS] [RIS] This function takes care of a register's indirection, displacement and direct access. It also takes into consideration the fact that some registers are named differently inside and outside GDB, e.g., PPC's general-purpose registers are represented by integers in the assembly language (e.g., `15' is the 15th general-purpose register), but inside GDB they have a prefix (the letter `r') appended. */ static expr::operation_up stap_parse_register_operand (struct stap_parse_info *p) { /* Simple flag to indicate whether we have seen a minus signal before certain number. */ bool got_minus = false; /* Flag to indicate whether this register access is being indirected. */ bool indirect_p = false; struct gdbarch *gdbarch = p->gdbarch; /* Variables used to extract the register name from the probe's argument. */ const char *start; const char *gdb_reg_prefix = gdbarch_stap_gdb_register_prefix (gdbarch); const char *gdb_reg_suffix = gdbarch_stap_gdb_register_suffix (gdbarch); const char *reg_prefix; const char *reg_ind_prefix; const char *reg_suffix; const char *reg_ind_suffix; using namespace expr; /* Checking for a displacement argument. */ if (*p->arg == '+') { /* If it's a plus sign, we don't need to do anything, just advance the pointer. */ ++p->arg; } else if (*p->arg == '-') { got_minus = true; ++p->arg; } struct type *long_type = builtin_type (gdbarch)->builtin_long; operation_up disp_op; if (isdigit (*p->arg)) { /* The value of the displacement. */ long displacement; char *endp; displacement = strtol (p->arg, &endp, 10); p->arg = endp; /* Generating the expression for the displacement. */ if (got_minus) displacement = -displacement; disp_op = make_operation (long_type, displacement); } /* Getting rid of register indirection prefix. */ if (stap_is_register_indirection_prefix (gdbarch, p->arg, ®_ind_prefix)) { indirect_p = true; p->arg += strlen (reg_ind_prefix); } if (disp_op != nullptr && !indirect_p) error (_("Invalid register displacement syntax on expression `%s'."), p->saved_arg); /* Getting rid of register prefix. */ if (stap_is_register_prefix (gdbarch, p->arg, ®_prefix)) p->arg += strlen (reg_prefix); /* Now we should have only the register name. Let's extract it and get the associated number. */ start = p->arg; /* We assume the register name is composed by letters and numbers. */ while (isalnum (*p->arg)) ++p->arg; std::string regname (start, p->arg - start); /* We only add the GDB's register prefix/suffix if we are dealing with a numeric register. */ if (isdigit (*start)) { if (gdb_reg_prefix != NULL) regname = gdb_reg_prefix + regname; if (gdb_reg_suffix != NULL) regname += gdb_reg_suffix; } int regnum = user_reg_map_name_to_regnum (gdbarch, regname.c_str (), regname.size ()); /* Is this a valid register name? */ if (regnum == -1) error (_("Invalid register name `%s' on expression `%s'."), regname.c_str (), p->saved_arg); /* Check if there's any special treatment that the arch-specific code would like to perform on the register name. */ if (gdbarch_stap_adjust_register_p (gdbarch)) { std::string newregname = gdbarch_stap_adjust_register (gdbarch, p, regname, regnum); if (regname != newregname) { /* This is just a check we perform to make sure that the arch-dependent code has provided us with a valid register name. */ regnum = user_reg_map_name_to_regnum (gdbarch, newregname.c_str (), newregname.size ()); if (regnum == -1) internal_error (_("Invalid register name '%s' after replacing it" " (previous name was '%s')"), newregname.c_str (), regname.c_str ()); regname = std::move (newregname); } } operation_up reg = make_operation (std::move (regname)); /* If the argument has been placed into a vector register then (for most architectures), the type of this register will be a union of arrays. As a result, attempting to cast from the register type to the scalar argument type will not be possible (GDB will throw an error during expression evaluation). The solution is to extract the scalar type from the value contents of the entire register value. */ if (!is_scalar_type (gdbarch_register_type (gdbarch, regnum))) { gdb_assert (is_scalar_type (p->arg_type)); reg = make_operation (std::move (reg), p->arg_type); } if (indirect_p) { if (disp_op != nullptr) reg = make_operation (std::move (disp_op), std::move (reg)); /* Casting to the expected type. */ struct type *arg_ptr_type = lookup_pointer_type (p->arg_type); reg = make_operation (std::move (reg), arg_ptr_type); reg = make_operation (std::move (reg)); } /* Getting rid of the register name suffix. */ if (stap_check_register_suffix (gdbarch, p->arg, ®_suffix)) p->arg += strlen (reg_suffix); else error (_("Missing register name suffix on expression `%s'."), p->saved_arg); /* Getting rid of the register indirection suffix. */ if (indirect_p) { if (stap_check_register_indirection_suffix (gdbarch, p->arg, ®_ind_suffix)) p->arg += strlen (reg_ind_suffix); else error (_("Missing indirection suffix on expression `%s'."), p->saved_arg); } return reg; } /* This function is responsible for parsing a single operand. A single operand can be: - an unary operation (e.g., `-5', `~2', or even with subexpressions like `-(2 + 1)') - a register displacement, which will be treated as a register operand (e.g., `-4(%eax)' on x86) - a numeric constant, or - a register operand (see function `stap_parse_register_operand') The function also calls special-handling functions to deal with unrecognized operands, allowing arch-specific parsers to be created. */ static expr::operation_up stap_parse_single_operand (struct stap_parse_info *p) { struct gdbarch *gdbarch = p->gdbarch; const char *int_prefix = NULL; using namespace expr; /* We first try to parse this token as a "special token". */ if (gdbarch_stap_parse_special_token_p (gdbarch)) { operation_up token = gdbarch_stap_parse_special_token (gdbarch, p); if (token != nullptr) return token; } struct type *long_type = builtin_type (gdbarch)->builtin_long; operation_up result; if (*p->arg == '-' || *p->arg == '~' || *p->arg == '+' || *p->arg == '!') { char c = *p->arg; /* We use this variable to do a lookahead. */ const char *tmp = p->arg; bool has_digit = false; /* Skipping signal. */ ++tmp; /* This is an unary operation. Here is a list of allowed tokens here: - numeric literal; - number (from register displacement) - subexpression (beginning with `(') We handle the register displacement here, and the other cases recursively. */ if (p->inside_paren_p) tmp = skip_spaces (tmp); while (isdigit (*tmp)) { /* We skip the digit here because we are only interested in knowing what kind of unary operation this is. The digit will be handled by one of the functions that will be called below ('stap_parse_argument_conditionally' or 'stap_parse_register_operand'). */ ++tmp; has_digit = true; } if (has_digit && stap_is_register_indirection_prefix (gdbarch, tmp, NULL)) { /* If we are here, it means it is a displacement. The only operations allowed here are `-' and `+'. */ if (c != '-' && c != '+') error (_("Invalid operator `%c' for register displacement " "on expression `%s'."), c, p->saved_arg); result = stap_parse_register_operand (p); } else { /* This is not a displacement. We skip the operator, and deal with it when the recursion returns. */ ++p->arg; result = stap_parse_argument_conditionally (p); if (c == '-') result = make_operation (std::move (result)); else if (c == '~') result = (make_operation (std::move (result))); else if (c == '!') result = (make_operation (std::move (result))); } } else if (isdigit (*p->arg)) { /* A temporary variable, needed for lookahead. */ const char *tmp = p->arg; char *endp; long number; /* We can be dealing with a numeric constant, or with a register displacement. */ number = strtol (tmp, &endp, 10); tmp = endp; if (p->inside_paren_p) tmp = skip_spaces (tmp); /* If "stap_is_integer_prefix" returns true, it means we can accept integers without a prefix here. But we also need to check whether the next token (i.e., "tmp") is not a register indirection prefix. */ if (stap_is_integer_prefix (gdbarch, p->arg, NULL) && !stap_is_register_indirection_prefix (gdbarch, tmp, NULL)) { const char *int_suffix; /* We are dealing with a numeric constant. */ result = make_operation (long_type, number); p->arg = tmp; if (stap_check_integer_suffix (gdbarch, p->arg, &int_suffix)) p->arg += strlen (int_suffix); else error (_("Invalid constant suffix on expression `%s'."), p->saved_arg); } else if (stap_is_register_indirection_prefix (gdbarch, tmp, NULL)) result = stap_parse_register_operand (p); else error (_("Unknown numeric token on expression `%s'."), p->saved_arg); } else if (stap_is_integer_prefix (gdbarch, p->arg, &int_prefix)) { /* We are dealing with a numeric constant. */ long number; char *endp; const char *int_suffix; p->arg += strlen (int_prefix); number = strtol (p->arg, &endp, 10); p->arg = endp; result = make_operation (long_type, number); if (stap_check_integer_suffix (gdbarch, p->arg, &int_suffix)) p->arg += strlen (int_suffix); else error (_("Invalid constant suffix on expression `%s'."), p->saved_arg); } else if (stap_is_register_prefix (gdbarch, p->arg, NULL) || stap_is_register_indirection_prefix (gdbarch, p->arg, NULL)) result = stap_parse_register_operand (p); else error (_("Operator `%c' not recognized on expression `%s'."), *p->arg, p->saved_arg); return result; } /* This function parses an argument conditionally, based on single or non-single operands. A non-single operand would be a parenthesized expression (e.g., `(2 + 1)'), and a single operand is anything that starts with `-', `~', `+' (i.e., unary operators), a digit, or something recognized by `gdbarch_stap_is_single_operand'. */ static expr::operation_up stap_parse_argument_conditionally (struct stap_parse_info *p) { gdb_assert (gdbarch_stap_is_single_operand_p (p->gdbarch)); expr::operation_up result; if (*p->arg == '-' || *p->arg == '~' || *p->arg == '+' || *p->arg == '!' || isdigit (*p->arg) || gdbarch_stap_is_single_operand (p->gdbarch, p->arg)) result = stap_parse_single_operand (p); else if (*p->arg == '(') { /* We are dealing with a parenthesized operand. It means we have to parse it as it was a separate expression, without left-side or precedence. */ ++p->arg; p->arg = skip_spaces (p->arg); ++p->inside_paren_p; result = stap_parse_argument_1 (p, {}, STAP_OPERAND_PREC_NONE); p->arg = skip_spaces (p->arg); if (*p->arg != ')') error (_("Missing close-parenthesis on expression `%s'."), p->saved_arg); --p->inside_paren_p; ++p->arg; if (p->inside_paren_p) p->arg = skip_spaces (p->arg); } else error (_("Cannot parse expression `%s'."), p->saved_arg); return result; } /* Helper function for `stap_parse_argument'. Please, see its comments to better understand what this function does. */ static expr::operation_up ATTRIBUTE_UNUSED_RESULT stap_parse_argument_1 (struct stap_parse_info *p, expr::operation_up &&lhs_in, enum stap_operand_prec prec) { /* This is an operator-precedence parser. We work with left- and right-sides of expressions, and parse them depending on the precedence of the operators we find. */ gdb_assert (p->arg != NULL); if (p->inside_paren_p) p->arg = skip_spaces (p->arg); using namespace expr; operation_up lhs = std::move (lhs_in); if (lhs == nullptr) { /* We were called without a left-side, either because this is the first call, or because we were called to parse a parenthesized expression. It doesn't really matter; we have to parse the left-side in order to continue the process. */ lhs = stap_parse_argument_conditionally (p); } if (p->inside_paren_p) p->arg = skip_spaces (p->arg); /* Start to parse the right-side, and to "join" left and right sides depending on the operation specified. This loop shall continue until we run out of characters in the input, or until we find a close-parenthesis, which means that we've reached the end of a sub-expression. */ while (*p->arg != '\0' && *p->arg != ')' && !isspace (*p->arg)) { const char *tmp_exp_buf; enum exp_opcode opcode; enum stap_operand_prec cur_prec; if (!stap_is_operator (p->arg)) error (_("Invalid operator `%c' on expression `%s'."), *p->arg, p->saved_arg); /* We have to save the current value of the expression buffer because the `stap_get_opcode' modifies it in order to get the current operator. If this operator's precedence is lower than PREC, we should return and not advance the expression buffer pointer. */ tmp_exp_buf = p->arg; opcode = stap_get_opcode (&tmp_exp_buf); cur_prec = stap_get_operator_prec (opcode); if (cur_prec < prec) { /* If the precedence of the operator that we are seeing now is lower than the precedence of the first operator seen before this parsing process began, it means we should stop parsing and return. */ break; } p->arg = tmp_exp_buf; if (p->inside_paren_p) p->arg = skip_spaces (p->arg); /* Parse the right-side of the expression. We save whether the right-side is a parenthesized subexpression because, if it is, we will have to finish processing this part of the expression before continuing. */ bool paren_subexp = *p->arg == '('; operation_up rhs = stap_parse_argument_conditionally (p); if (p->inside_paren_p) p->arg = skip_spaces (p->arg); if (paren_subexp) { lhs = stap_make_binop (opcode, std::move (lhs), std::move (rhs)); continue; } /* While we still have operators, try to parse another right-side, but using the current right-side as a left-side. */ while (*p->arg != '\0' && stap_is_operator (p->arg)) { enum exp_opcode lookahead_opcode; enum stap_operand_prec lookahead_prec; /* Saving the current expression buffer position. The explanation is the same as above. */ tmp_exp_buf = p->arg; lookahead_opcode = stap_get_opcode (&tmp_exp_buf); lookahead_prec = stap_get_operator_prec (lookahead_opcode); if (lookahead_prec <= prec) { /* If we are dealing with an operator whose precedence is lower than the first one, just abandon the attempt. */ break; } /* Parse the right-side of the expression, using the current right-hand-side as the left-hand-side of the new subexpression. */ rhs = stap_parse_argument_1 (p, std::move (rhs), lookahead_prec); if (p->inside_paren_p) p->arg = skip_spaces (p->arg); } lhs = stap_make_binop (opcode, std::move (lhs), std::move (rhs)); } return lhs; } /* Parse a probe's argument. Assuming that: LP = literal integer prefix LS = literal integer suffix RP = register prefix RS = register suffix RIP = register indirection prefix RIS = register indirection suffix This routine assumes that arguments' tokens are of the form: - [LP] NUMBER [LS] - [RP] REGISTER [RS] - [RIP] [RP] REGISTER [RS] [RIS] - If we find a number without LP, we try to parse it as a literal integer constant (if LP == NULL), or as a register displacement. - We count parenthesis, and only skip whitespaces if we are inside them. - If we find an operator, we skip it. This function can also call a special function that will try to match unknown tokens. It will return the expression_up generated from parsing the argument. */ static expression_up stap_parse_argument (const char **arg, struct type *atype, struct gdbarch *gdbarch) { /* We need to initialize the expression buffer, in order to begin our parsing efforts. We use language_c here because we may need to do pointer arithmetics. */ struct stap_parse_info p (*arg, atype, language_def (language_c), gdbarch); using namespace expr; operation_up result = stap_parse_argument_1 (&p, {}, STAP_OPERAND_PREC_NONE); gdb_assert (p.inside_paren_p == 0); /* Casting the final expression to the appropriate type. */ result = make_operation (std::move (result), atype); p.pstate.set_operation (std::move (result)); p.arg = skip_spaces (p.arg); *arg = p.arg; return p.pstate.release (); } /* Implementation of 'parse_arguments' method. */ void stap_probe::parse_arguments (struct gdbarch *gdbarch) { const char *cur; gdb_assert (!m_have_parsed_args); cur = m_unparsed_args_text; m_have_parsed_args = true; if (cur == NULL || *cur == '\0' || *cur == ':') return; while (*cur != '\0') { enum stap_arg_bitness bitness; bool got_minus = false; /* We expect to find something like: N@OP Where `N' can be [+,-][1,2,4,8]. This is not mandatory, so we check it here. If we don't find it, go to the next state. */ if ((cur[0] == '-' && isdigit (cur[1]) && cur[2] == '@') || (isdigit (cur[0]) && cur[1] == '@')) { if (*cur == '-') { /* Discard the `-'. */ ++cur; got_minus = true; } /* Defining the bitness. */ switch (*cur) { case '1': bitness = (got_minus ? STAP_ARG_BITNESS_8BIT_SIGNED : STAP_ARG_BITNESS_8BIT_UNSIGNED); break; case '2': bitness = (got_minus ? STAP_ARG_BITNESS_16BIT_SIGNED : STAP_ARG_BITNESS_16BIT_UNSIGNED); break; case '4': bitness = (got_minus ? STAP_ARG_BITNESS_32BIT_SIGNED : STAP_ARG_BITNESS_32BIT_UNSIGNED); break; case '8': bitness = (got_minus ? STAP_ARG_BITNESS_64BIT_SIGNED : STAP_ARG_BITNESS_64BIT_UNSIGNED); break; default: { /* We have an error, because we don't expect anything except 1, 2, 4 and 8. */ warning (_("unrecognized bitness %s%c' for probe `%s'"), got_minus ? "`-" : "`", *cur, this->get_name ().c_str ()); return; } } /* Discard the number and the `@' sign. */ cur += 2; } else bitness = STAP_ARG_BITNESS_UNDEFINED; struct type *atype = stap_get_expected_argument_type (gdbarch, bitness, this->get_name ().c_str ()); expression_up expr = stap_parse_argument (&cur, atype, gdbarch); if (stap_expression_debug) expr->dump (gdb_stdlog); m_parsed_args.emplace_back (bitness, atype, std::move (expr)); /* Start it over again. */ cur = skip_spaces (cur); } } /* Helper function to relocate an address. */ static CORE_ADDR relocate_address (CORE_ADDR address, struct objfile *objfile) { return address + objfile->text_section_offset (); } /* Implementation of the get_relocated_address method. */ CORE_ADDR stap_probe::get_relocated_address (struct objfile *objfile) { return relocate_address (this->get_address (), objfile); } /* Given PROBE, returns the number of arguments present in that probe's argument string. */ unsigned stap_probe::get_argument_count (struct gdbarch *gdbarch) { if (!m_have_parsed_args) { if (this->can_evaluate_arguments ()) this->parse_arguments (gdbarch); else { static bool have_warned_stap_incomplete = false; if (!have_warned_stap_incomplete) { warning (_( "The SystemTap SDT probe support is not fully implemented on this target;\n" "you will not be able to inspect the arguments of the probes.\n" "Please report a bug against GDB requesting a port to this target.")); have_warned_stap_incomplete = true; } /* Marking the arguments as "already parsed". */ m_have_parsed_args = true; } } gdb_assert (m_have_parsed_args); return m_parsed_args.size (); } /* Return true if OP is a valid operator inside a probe argument, or false otherwise. */ static bool stap_is_operator (const char *op) { bool ret = true; switch (*op) { case '*': case '/': case '%': case '^': case '!': case '+': case '-': case '<': case '>': case '|': case '&': break; case '=': if (op[1] != '=') ret = false; break; default: /* We didn't find any operator. */ ret = false; } return ret; } /* Implement the `can_evaluate_arguments' method. */ bool stap_probe::can_evaluate_arguments () const { struct gdbarch *gdbarch = this->get_gdbarch (); /* For SystemTap probes, we have to guarantee that the method stap_is_single_operand is defined on gdbarch. If it is not, then it means that argument evaluation is not implemented on this target. */ return gdbarch_stap_is_single_operand_p (gdbarch); } /* Evaluate the probe's argument N (indexed from 0), returning a value corresponding to it. Assertion is thrown if N does not exist. */ struct value * stap_probe::evaluate_argument (unsigned n, frame_info_ptr frame) { struct stap_probe_arg *arg; struct gdbarch *gdbarch = get_frame_arch (frame); arg = this->get_arg_by_number (n, gdbarch); return evaluate_expression (arg->aexpr.get (), arg->atype); } /* Compile the probe's argument N (indexed from 0) to agent expression. Assertion is thrown if N does not exist. */ void stap_probe::compile_to_ax (struct agent_expr *expr, struct axs_value *value, unsigned n) { struct stap_probe_arg *arg; arg = this->get_arg_by_number (n, expr->gdbarch); arg->aexpr->op->generate_ax (arg->aexpr.get (), expr, value); require_rvalue (expr, value); value->type = arg->atype; } /* Set or clear a SystemTap semaphore. ADDRESS is the semaphore's address. SET is zero if the semaphore should be cleared, or one if it should be set. This is a helper function for 'stap_probe::set_semaphore' and 'stap_probe::clear_semaphore'. */ static void stap_modify_semaphore (CORE_ADDR address, int set, struct gdbarch *gdbarch) { gdb_byte bytes[sizeof (LONGEST)]; /* The ABI specifies "unsigned short". */ struct type *type = builtin_type (gdbarch)->builtin_unsigned_short; ULONGEST value; /* Swallow errors. */ if (target_read_memory (address, bytes, type->length ()) != 0) { warning (_("Could not read the value of a SystemTap semaphore.")); return; } enum bfd_endian byte_order = type_byte_order (type); value = extract_unsigned_integer (bytes, type->length (), byte_order); /* Note that we explicitly don't worry about overflow or underflow. */ if (set) ++value; else --value; store_unsigned_integer (bytes, type->length (), byte_order, value); if (target_write_memory (address, bytes, type->length ()) != 0) warning (_("Could not write the value of a SystemTap semaphore.")); } /* Implementation of the 'set_semaphore' method. SystemTap semaphores act as reference counters, so calls to this function must be paired with calls to 'clear_semaphore'. This function and 'clear_semaphore' race with another tool changing the probes, but that is too rare to care. */ void stap_probe::set_semaphore (struct objfile *objfile, struct gdbarch *gdbarch) { if (m_sem_addr == 0) return; stap_modify_semaphore (relocate_address (m_sem_addr, objfile), 1, gdbarch); } /* Implementation of the 'clear_semaphore' method. */ void stap_probe::clear_semaphore (struct objfile *objfile, struct gdbarch *gdbarch) { if (m_sem_addr == 0) return; stap_modify_semaphore (relocate_address (m_sem_addr, objfile), 0, gdbarch); } /* Implementation of the 'get_static_ops' method. */ const static_probe_ops * stap_probe::get_static_ops () const { return &stap_static_probe_ops; } /* Implementation of the 'gen_info_probes_table_values' method. */ std::vector stap_probe::gen_info_probes_table_values () const { const char *val = NULL; if (m_sem_addr != 0) val = print_core_address (this->get_gdbarch (), m_sem_addr); return std::vector { val }; } /* Helper function that parses the information contained in a SystemTap's probe. Basically, the information consists in: - Probe's PC address; - Link-time section address of `.stapsdt.base' section; - Link-time address of the semaphore variable, or ZERO if the probe doesn't have an associated semaphore; - Probe's provider name; - Probe's name; - Probe's argument format. */ static void handle_stap_probe (struct objfile *objfile, struct sdt_note *el, std::vector> *probesp, CORE_ADDR base) { bfd *abfd = objfile->obfd.get (); int size = bfd_get_arch_size (abfd) / 8; struct gdbarch *gdbarch = objfile->arch (); struct type *ptr_type = builtin_type (gdbarch)->builtin_data_ptr; /* Provider and the name of the probe. */ const char *provider = (const char *) &el->data[3 * size]; const char *name = ((const char *) memchr (provider, '\0', (char *) el->data + el->size - provider)); /* Making sure there is a name. */ if (name == NULL) { complaint (_("corrupt probe name when reading `%s'"), objfile_name (objfile)); /* There is no way to use a probe without a name or a provider, so returning here makes sense. */ return; } else ++name; /* Retrieving the probe's address. */ CORE_ADDR address = extract_typed_address (&el->data[0], ptr_type); /* Link-time sh_addr of `.stapsdt.base' section. */ CORE_ADDR base_ref = extract_typed_address (&el->data[size], ptr_type); /* Semaphore address. */ CORE_ADDR sem_addr = extract_typed_address (&el->data[2 * size], ptr_type); address += base - base_ref; if (sem_addr != 0) sem_addr += base - base_ref; /* Arguments. We can only extract the argument format if there is a valid name for this probe. */ const char *probe_args = ((const char*) memchr (name, '\0', (char *) el->data + el->size - name)); if (probe_args != NULL) ++probe_args; if (probe_args == NULL || (memchr (probe_args, '\0', (char *) el->data + el->size - name) != el->data + el->size - 1)) { complaint (_("corrupt probe argument when reading `%s'"), objfile_name (objfile)); /* If the argument string is NULL, it means some problem happened with it. So we return. */ return; } stap_probe *ret = new stap_probe (std::string (name), std::string (provider), address, gdbarch, sem_addr, probe_args); /* Successfully created probe. */ probesp->emplace_back (ret); } /* Helper function which iterates over every section in the BFD file, trying to find the base address of the SystemTap base section. Returns 1 if found (setting BASE to the proper value), zero otherwise. */ static int get_stap_base_address (bfd *obfd, bfd_vma *base) { asection *ret = NULL; for (asection *sect : gdb_bfd_sections (obfd)) if ((sect->flags & (SEC_DATA | SEC_ALLOC | SEC_HAS_CONTENTS)) && sect->name && !strcmp (sect->name, STAP_BASE_SECTION_NAME)) ret = sect; if (ret == NULL) { complaint (_("could not obtain base address for " "SystemTap section on objfile `%s'."), bfd_get_filename (obfd)); return 0; } if (base != NULL) *base = ret->vma; return 1; } /* Implementation of the 'is_linespec' method. */ bool stap_static_probe_ops::is_linespec (const char **linespecp) const { static const char *const keywords[] = { "-pstap", "-probe-stap", NULL }; return probe_is_linespec_by_keyword (linespecp, keywords); } /* Implementation of the 'get_probes' method. */ void stap_static_probe_ops::get_probes (std::vector> *probesp, struct objfile *objfile) const { /* If we are here, then this is the first time we are parsing the SystemTap probe's information. We basically have to count how many probes the objfile has, and then fill in the necessary information for each one. */ bfd *obfd = objfile->obfd.get (); bfd_vma base; struct sdt_note *iter; unsigned save_probesp_len = probesp->size (); if (objfile->separate_debug_objfile_backlink != NULL) { /* This is a .debug file, not the objfile itself. */ return; } if (elf_tdata (obfd)->sdt_note_head == NULL) { /* There isn't any probe here. */ return; } if (!get_stap_base_address (obfd, &base)) { /* There was an error finding the base address for the section. Just return NULL. */ return; } /* Parsing each probe's information. */ for (iter = elf_tdata (obfd)->sdt_note_head; iter != NULL; iter = iter->next) { /* We first have to handle all the information about the probe which is present in the section. */ handle_stap_probe (objfile, iter, probesp, base); } if (save_probesp_len == probesp->size ()) { /* If we are here, it means we have failed to parse every known probe. */ complaint (_("could not parse SystemTap probe(s) from inferior")); return; } } /* Implementation of the type_name method. */ const char * stap_static_probe_ops::type_name () const { return "stap"; } /* Implementation of the 'gen_info_probes_table_header' method. */ std::vector stap_static_probe_ops::gen_info_probes_table_header () const { struct info_probe_column stap_probe_column; stap_probe_column.field_name = "semaphore"; stap_probe_column.print_name = _("Semaphore"); return std::vector { stap_probe_column }; } /* Implementation of the `info probes stap' command. */ static void info_probes_stap_command (const char *arg, int from_tty) { info_probes_for_spops (arg, from_tty, &stap_static_probe_ops); } void _initialize_stap_probe (); void _initialize_stap_probe () { all_static_probe_ops.push_back (&stap_static_probe_ops); add_setshow_zuinteger_cmd ("stap-expression", class_maintenance, &stap_expression_debug, _("Set SystemTap expression debugging."), _("Show SystemTap expression debugging."), _("When non-zero, the internal representation " "of SystemTap expressions will be printed."), NULL, show_stapexpressiondebug, &setdebuglist, &showdebuglist); add_cmd ("stap", class_info, info_probes_stap_command, _("\ Show information about SystemTap static probes.\n\ Usage: info probes stap [PROVIDER [NAME [OBJECT]]]\n\ Each argument is a regular expression, used to select probes.\n\ PROVIDER matches probe provider names.\n\ NAME matches the probe names.\n\ OBJECT matches the executable or shared library name."), info_probes_cmdlist_get ()); using namespace expr; stap_maker_map[BINOP_ADD] = make_operation; stap_maker_map[BINOP_BITWISE_AND] = make_operation; stap_maker_map[BINOP_BITWISE_IOR] = make_operation; stap_maker_map[BINOP_BITWISE_XOR] = make_operation; stap_maker_map[BINOP_DIV] = make_operation; stap_maker_map[BINOP_EQUAL] = make_operation; stap_maker_map[BINOP_GEQ] = make_operation; stap_maker_map[BINOP_GTR] = make_operation; stap_maker_map[BINOP_LEQ] = make_operation; stap_maker_map[BINOP_LESS] = make_operation; stap_maker_map[BINOP_LOGICAL_AND] = make_operation; stap_maker_map[BINOP_LOGICAL_OR] = make_operation; stap_maker_map[BINOP_LSH] = make_operation; stap_maker_map[BINOP_MUL] = make_operation; stap_maker_map[BINOP_NOTEQUAL] = make_operation; stap_maker_map[BINOP_REM] = make_operation; stap_maker_map[BINOP_RSH] = make_operation; stap_maker_map[BINOP_SUB] = make_operation; }