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Diffstat (limited to 'gdb/stap-probe.c')
| -rw-r--r-- | gdb/stap-probe.c | 1558 |
1 files changed, 1558 insertions, 0 deletions
diff --git a/gdb/stap-probe.c b/gdb/stap-probe.c new file mode 100644 index 0000000..13ba281 --- /dev/null +++ b/gdb/stap-probe.c @@ -0,0 +1,1558 @@ +/* SystemTap probe support for GDB. + + Copyright (C) 2012 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/>. */ + +#include "defs.h" +#include "stap-probe.h" +#include "probe.h" +#include "vec.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 "exceptions.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 <ctype.h> + +/* The name of the SystemTap section where we will find information about + the probes. */ + +#define STAP_BASE_SECTION_NAME ".stapsdt.base" + +/* Forward declaration. */ + +static const struct probe_ops stap_probe_ops; + +/* Should we display debug information for the probe's argument expression + parsing? */ + +static 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_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_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 +{ + /* 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. */ + struct expression *aexpr; +}; + +typedef struct stap_probe_arg stap_probe_arg_s; +DEF_VEC_O (stap_probe_arg_s); + +struct stap_probe +{ + /* Generic information about the probe. This shall be the first element + of this struct, in order to maintain binary compatibility with the + `struct probe' and be able to fully abstract it. */ + struct probe p; + + /* If the probe has a semaphore associated, then this is the value of + it. */ + CORE_ADDR sem_addr; + + unsigned int args_parsed : 1; + union + { + const char *text; + + /* Information about each argument. This is an array of `stap_probe_arg', + with each entry representing one argument. */ + VEC (stap_probe_arg_s) *vec; + } + args_u; +}; + +/* 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 + <http://sourceware.org/binutils/docs/as/Infix-Ops.html#Infix-Ops>, 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 void stap_parse_argument_1 (struct stap_parse_info *p, int has_lhs, + enum stap_operand_prec prec); + +static void stap_parse_argument_conditionally (struct stap_parse_info *p); + +/* Returns 1 if *S is an operator, zero otherwise. */ + +static int stap_is_operator (char op); + +static void +show_stapexpressiondebug (struct ui_file *file, int from_tty, + struct cmd_list_element *c, const char *value) +{ + fprintf_filtered (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 and fills the OP pointer with its code. + Return 1 on success, zero if the operator was not recognized. */ + +static int +stap_get_opcode (const char **s, enum exp_opcode *op) +{ + const char c = **s; + int ret = 1; + + *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 '=': + if (**s != '=') + { + ret = 0; + break; + } + *op = BINOP_EQUAL; + break; + + default: + /* We didn't find any operator. */ + *s -= 1; + return 0; + } + + return ret; +} + +/* Given the bitness of the argument, represented by B, return the + corresponding `struct type *'. */ + +static struct type * +stap_get_expected_argument_type (struct gdbarch *gdbarch, + enum stap_arg_bitness b) +{ + 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_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: + internal_error (__FILE__, __LINE__, + _("Undefined bitness for probe.")); + break; + } +} + +/* 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 void +stap_parse_register_operand (struct stap_parse_info *p) +{ + /* Simple flag to indicate whether we have seen a minus signal before + certain number. */ + int got_minus = 0; + + /* Flags to indicate whether this register access is being displaced and/or + indirected. */ + int disp_p = 0, indirect_p = 0; + struct gdbarch *gdbarch = p->gdbarch; + + /* Needed to generate the register name as a part of an expression. */ + struct stoken str; + + /* Variables used to extract the register name from the probe's + argument. */ + const char *start; + char *regname; + int len; + + /* Prefixes for the parser. */ + const char *reg_prefix = gdbarch_stap_register_prefix (gdbarch); + const char *reg_ind_prefix + = gdbarch_stap_register_indirection_prefix (gdbarch); + const char *gdb_reg_prefix = gdbarch_stap_gdb_register_prefix (gdbarch); + int reg_prefix_len = reg_prefix ? strlen (reg_prefix) : 0; + int reg_ind_prefix_len = reg_ind_prefix ? strlen (reg_ind_prefix) : 0; + int gdb_reg_prefix_len = gdb_reg_prefix ? strlen (gdb_reg_prefix) : 0; + + /* Suffixes for the parser. */ + const char *reg_suffix = gdbarch_stap_register_suffix (gdbarch); + const char *reg_ind_suffix + = gdbarch_stap_register_indirection_suffix (gdbarch); + const char *gdb_reg_suffix = gdbarch_stap_gdb_register_suffix (gdbarch); + int reg_suffix_len = reg_suffix ? strlen (reg_suffix) : 0; + int reg_ind_suffix_len = reg_ind_suffix ? strlen (reg_ind_suffix) : 0; + int gdb_reg_suffix_len = gdb_reg_suffix ? strlen (gdb_reg_suffix) : 0; + + /* 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; + } + + if (*p->arg == '-') + { + got_minus = 1; + ++p->arg; + } + + if (isdigit (*p->arg)) + { + /* The value of the displacement. */ + long displacement; + + disp_p = 1; + displacement = strtol (p->arg, (char **) &p->arg, 10); + + /* Generating the expression for the displacement. */ + write_exp_elt_opcode (OP_LONG); + write_exp_elt_type (builtin_type (gdbarch)->builtin_long); + write_exp_elt_longcst (displacement); + write_exp_elt_opcode (OP_LONG); + if (got_minus) + write_exp_elt_opcode (UNOP_NEG); + } + + /* Getting rid of register indirection prefix. */ + if (reg_ind_prefix + && strncmp (p->arg, reg_ind_prefix, reg_ind_prefix_len) == 0) + { + indirect_p = 1; + p->arg += reg_ind_prefix_len; + } + + if (disp_p && !indirect_p) + error (_("Invalid register displacement syntax on expression `%s'."), + p->saved_arg); + + /* Getting rid of register prefix. */ + if (reg_prefix && strncmp (p->arg, reg_prefix, reg_prefix_len) == 0) + p->arg += reg_prefix_len; + + /* 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; + + len = p->arg - start; + + regname = alloca (len + gdb_reg_prefix_len + gdb_reg_suffix_len + 1); + regname[0] = '\0'; + + /* We only add the GDB's register prefix/suffix if we are dealing with + a numeric register. */ + if (gdb_reg_prefix && isdigit (*start)) + { + strncpy (regname, gdb_reg_prefix, gdb_reg_prefix_len); + strncpy (regname + gdb_reg_prefix_len, start, len); + + if (gdb_reg_suffix) + strncpy (regname + gdb_reg_prefix_len + len, + gdb_reg_suffix, gdb_reg_suffix_len); + + len += gdb_reg_prefix_len + gdb_reg_suffix_len; + } + else + strncpy (regname, start, len); + + regname[len] = '\0'; + + /* Is this a valid register name? */ + if (user_reg_map_name_to_regnum (gdbarch, regname, len) == -1) + error (_("Invalid register name `%s' on expression `%s'."), + regname, p->saved_arg); + + write_exp_elt_opcode (OP_REGISTER); + str.ptr = regname; + str.length = len; + write_exp_string (str); + write_exp_elt_opcode (OP_REGISTER); + + if (indirect_p) + { + if (disp_p) + write_exp_elt_opcode (BINOP_ADD); + + /* Casting to the expected type. */ + write_exp_elt_opcode (UNOP_CAST); + write_exp_elt_type (lookup_pointer_type (p->arg_type)); + write_exp_elt_opcode (UNOP_CAST); + + write_exp_elt_opcode (UNOP_IND); + } + + /* Getting rid of the register name suffix. */ + if (reg_suffix) + { + if (strncmp (p->arg, reg_suffix, reg_suffix_len) != 0) + error (_("Missing register name suffix `%s' on expression `%s'."), + reg_suffix, p->saved_arg); + + p->arg += reg_suffix_len; + } + + /* Getting rid of the register indirection suffix. */ + if (indirect_p && reg_ind_suffix) + { + if (strncmp (p->arg, reg_ind_suffix, reg_ind_suffix_len) != 0) + error (_("Missing indirection suffix `%s' on expression `%s'."), + reg_ind_suffix, p->saved_arg); + + p->arg += reg_ind_suffix_len; + } +} + +/* 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 void +stap_parse_single_operand (struct stap_parse_info *p) +{ + struct gdbarch *gdbarch = p->gdbarch; + + /* Prefixes for the parser. */ + const char *const_prefix = gdbarch_stap_integer_prefix (gdbarch); + const char *reg_prefix = gdbarch_stap_register_prefix (gdbarch); + const char *reg_ind_prefix + = gdbarch_stap_register_indirection_prefix (gdbarch); + int const_prefix_len = const_prefix ? strlen (const_prefix) : 0; + int reg_prefix_len = reg_prefix ? strlen (reg_prefix) : 0; + int reg_ind_prefix_len = reg_ind_prefix ? strlen (reg_ind_prefix) : 0; + + /* Suffixes for the parser. */ + const char *const_suffix = gdbarch_stap_integer_suffix (gdbarch); + const char *reg_suffix = gdbarch_stap_register_suffix (gdbarch); + const char *reg_ind_suffix + = gdbarch_stap_register_indirection_suffix (gdbarch); + int const_suffix_len = const_suffix ? strlen (const_suffix) : 0; + int reg_suffix_len = reg_suffix ? strlen (reg_suffix) : 0; + int reg_ind_suffix_len = reg_ind_suffix ? strlen (reg_ind_suffix) : 0; + + /* We first try to parse this token as a "special token". */ + if (gdbarch_stap_parse_special_token_p (gdbarch)) + { + int ret = gdbarch_stap_parse_special_token (gdbarch, p); + + if (ret) + { + /* If the return value of the above function is not zero, + it means it successfully parsed the special token. + + If it is NULL, we try to parse it using our method. */ + return; + } + } + + if (*p->arg == '-' || *p->arg == '~' || *p->arg == '+') + { + char c = *p->arg; + int number; + + /* We use this variable to do a lookahead. */ + const char *tmp = p->arg; + + ++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_const (tmp); + + if (isdigit (*tmp)) + number = strtol (tmp, (char **) &tmp, 10); + + if (!reg_ind_prefix + || strncmp (tmp, reg_ind_prefix, reg_ind_prefix_len) != 0) + { + /* This is not a displacement. We skip the operator, and deal + with it later. */ + ++p->arg; + stap_parse_argument_conditionally (p); + if (c == '-') + write_exp_elt_opcode (UNOP_NEG); + else if (c == '~') + write_exp_elt_opcode (UNOP_COMPLEMENT); + } + else + { + /* If we are here, it means it is a displacement. The only + operations allowed here are `-' and `+'. */ + if (c == '~') + error (_("Invalid operator `%c' for register displacement " + "on expression `%s'."), c, p->saved_arg); + + stap_parse_register_operand (p); + } + } + else if (isdigit (*p->arg)) + { + /* A temporary variable, needed for lookahead. */ + const char *tmp = p->arg; + long number; + + /* We can be dealing with a numeric constant (if `const_prefix' is + NULL), or with a register displacement. */ + number = strtol (tmp, (char **) &tmp, 10); + + if (p->inside_paren_p) + tmp = skip_spaces_const (tmp); + if (!const_prefix && reg_ind_prefix + && strncmp (tmp, reg_ind_prefix, reg_ind_prefix_len) != 0) + { + /* We are dealing with a numeric constant. */ + write_exp_elt_opcode (OP_LONG); + write_exp_elt_type (builtin_type (gdbarch)->builtin_long); + write_exp_elt_longcst (number); + write_exp_elt_opcode (OP_LONG); + + p->arg = tmp; + + if (const_suffix) + { + if (strncmp (p->arg, const_suffix, const_suffix_len) == 0) + p->arg += const_suffix_len; + else + error (_("Invalid constant suffix on expression `%s'."), + p->saved_arg); + } + } + else if (reg_ind_prefix + && strncmp (tmp, reg_ind_prefix, reg_ind_prefix_len) == 0) + stap_parse_register_operand (p); + else + error (_("Unknown numeric token on expression `%s'."), + p->saved_arg); + } + else if (const_prefix + && strncmp (p->arg, const_prefix, const_prefix_len) == 0) + { + /* We are dealing with a numeric constant. */ + long number; + + p->arg += const_prefix_len; + number = strtol (p->arg, (char **) &p->arg, 10); + + write_exp_elt_opcode (OP_LONG); + write_exp_elt_type (builtin_type (gdbarch)->builtin_long); + write_exp_elt_longcst (number); + write_exp_elt_opcode (OP_LONG); + + if (const_suffix) + { + if (strncmp (p->arg, const_suffix, const_suffix_len) == 0) + p->arg += const_suffix_len; + else + error (_("Invalid constant suffix on expression `%s'."), + p->saved_arg); + } + } + else if ((reg_prefix + && strncmp (p->arg, reg_prefix, reg_prefix_len) == 0) + || (reg_ind_prefix + && strncmp (p->arg, reg_ind_prefix, reg_ind_prefix_len) == 0)) + stap_parse_register_operand (p); + else + error (_("Operator `%c' not recognized on expression `%s'."), + *p->arg, p->saved_arg); +} + +/* 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 void +stap_parse_argument_conditionally (struct stap_parse_info *p) +{ + if (*p->arg == '-' || *p->arg == '~' || *p->arg == '+' /* Unary. */ + || isdigit (*p->arg) + || gdbarch_stap_is_single_operand (p->gdbarch, p->arg)) + 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_const (p->arg); + ++p->inside_paren_p; + + stap_parse_argument_1 (p, 0, STAP_OPERAND_PREC_NONE); + + --p->inside_paren_p; + if (*p->arg != ')') + error (_("Missign close-paren on expression `%s'."), + p->saved_arg); + + ++p->arg; + if (p->inside_paren_p) + p->arg = skip_spaces_const (p->arg); + } + else + error (_("Cannot parse expression `%s'."), p->saved_arg); +} + +/* Helper function for `stap_parse_argument'. Please, see its comments to + better understand what this function does. */ + +static void +stap_parse_argument_1 (struct stap_parse_info *p, int has_lhs, + 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. */ + + if (p->inside_paren_p) + p->arg = skip_spaces_const (p->arg); + + if (!has_lhs) + { + /* 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. */ + stap_parse_argument_conditionally (p); + } + + /* 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 && *p->arg && *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; + stap_get_opcode (&tmp_exp_buf, &opcode); + + 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_const (p->arg); + + /* Parse the right-side of the expression. */ + stap_parse_argument_conditionally (p); + + /* While we still have operators, try to parse another + right-side, but using the current right-side as a left-side. */ + while (*p->arg && 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; + stap_get_opcode (&tmp_exp_buf, &lookahead_opcode); + 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, but since we already + have a left-side at this point, set `has_lhs' to 1. */ + stap_parse_argument_1 (p, 1, lookahead_prec); + } + + write_exp_elt_opcode (opcode); + } +} + +/* 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 1 if the argument has been parsed + successfully, or zero otherwise. */ + +static struct expression * +stap_parse_argument (const char **arg, struct type *atype, + struct gdbarch *gdbarch) +{ + struct stap_parse_info p; + volatile struct gdb_exception e; + struct cleanup *back_to; + + /* We need to initialize the expression buffer, in order to begin + our parsing efforts. The language here does not matter, since we + are using our own parser. */ + initialize_expout (10, current_language, gdbarch); + back_to = make_cleanup (free_current_contents, &expout); + + p.saved_arg = *arg; + p.arg = *arg; + p.arg_type = atype; + p.gdbarch = gdbarch; + p.inside_paren_p = 0; + + stap_parse_argument_1 (&p, 0, STAP_OPERAND_PREC_NONE); + + discard_cleanups (back_to); + + gdb_assert (p.inside_paren_p == 0); + + /* Casting the final expression to the appropriate type. */ + write_exp_elt_opcode (UNOP_CAST); + write_exp_elt_type (atype); + write_exp_elt_opcode (UNOP_CAST); + + reallocate_expout (); + + p.arg = skip_spaces_const (p.arg); + *arg = p.arg; + + return expout; +} + +/* Function which parses an argument string from 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. */ + +static void +stap_parse_probe_arguments (struct stap_probe *probe, struct objfile *objfile) +{ + const char *cur; + struct gdbarch *gdbarch = get_objfile_arch (objfile); + + gdb_assert (!probe->args_parsed); + cur = probe->args_u.text; + probe->args_parsed = 1; + probe->args_u.vec = NULL; + + if (!cur || !*cur || *cur == ':') + return; + + while (*cur) + { + struct stap_probe_arg arg; + enum stap_arg_bitness b; + int got_minus = 0; + struct expression *expr; + + memset (&arg, 0, sizeof (arg)); + + /* We expect to find something like: + + N@OP + + Where `N' can be [+,-][4,8]. This is not mandatory, so + we check it here. If we don't find it, go to the next + state. */ + if ((*cur == '-' && cur[1] && cur[2] != '@') + && cur[1] != '@') + arg.bitness = STAP_ARG_BITNESS_UNDEFINED; + else + { + if (*cur == '-') + { + /* Discard the `-'. */ + ++cur; + got_minus = 1; + } + + if (*cur == '4') + b = (got_minus ? STAP_ARG_BITNESS_32BIT_SIGNED + : STAP_ARG_BITNESS_32BIT_UNSIGNED); + else if (*cur == '8') + b = (got_minus ? STAP_ARG_BITNESS_64BIT_SIGNED + : STAP_ARG_BITNESS_64BIT_UNSIGNED); + else + { + /* We have an error, because we don't expect anything + except 4 and 8. */ + complaint (&symfile_complaints, + _("unrecognized bitness `%c' for probe `%s'"), + *cur, probe->p.name); + return; + } + + arg.bitness = b; + arg.atype = stap_get_expected_argument_type (gdbarch, b); + + /* Discard the number and the `@' sign. */ + cur += 2; + } + + expr = stap_parse_argument (&cur, arg.atype, gdbarch); + + if (stap_expression_debug) + dump_raw_expression (expr, gdb_stdlog, + "before conversion to prefix form"); + + prefixify_expression (expr); + + if (stap_expression_debug) + dump_prefix_expression (expr, gdb_stdlog); + + arg.aexpr = expr; + + /* Start it over again. */ + cur = skip_spaces_const (cur); + + VEC_safe_push (stap_probe_arg_s, probe->args_u.vec, &arg); + } +} + +/* Given PROBE, returns the number of arguments present in that probe's + argument string. */ + +static unsigned +stap_get_probe_argument_count (struct probe *probe_generic, + struct objfile *objfile) +{ + struct stap_probe *probe = (struct stap_probe *) probe_generic; + + gdb_assert (probe_generic->pops == &stap_probe_ops); + + if (!probe->args_parsed) + stap_parse_probe_arguments (probe, objfile); + + gdb_assert (probe->args_parsed); + return VEC_length (stap_probe_arg_s, probe->args_u.vec); +} + +/* Return 1 if OP is a valid operator inside a probe argument, or zero + otherwise. */ + +static int +stap_is_operator (char op) +{ + return (op == '+' || op == '-' || op == '*' || op == '/' + || op == '>' || op == '<' || op == '!' || op == '^' + || op == '|' || op == '&' || op == '%' || op == '='); +} + +static struct stap_probe_arg * +stap_get_arg (struct stap_probe *probe, struct objfile *objfile, unsigned n) +{ + if (!probe->args_parsed) + stap_parse_probe_arguments (probe, objfile); + + return VEC_index (stap_probe_arg_s, probe->args_u.vec, n); +} + +/* Evaluate the probe's argument N (indexed from 0), returning a value + corresponding to it. Assertion is thrown if N does not exist. */ + +static struct value * +stap_evaluate_probe_argument (struct probe *probe_generic, + struct objfile *objfile, unsigned n) +{ + struct stap_probe *stap_probe = (struct stap_probe *) probe_generic; + struct stap_probe_arg *arg; + int pos = 0; + + gdb_assert (probe_generic->pops == &stap_probe_ops); + + arg = stap_get_arg (stap_probe, objfile, n); + return evaluate_subexp_standard (arg->atype, arg->aexpr, &pos, EVAL_NORMAL); +} + +/* Compile the probe's argument N (indexed from 0) to agent expression. + Assertion is thrown if N does not exist. */ + +static void +stap_compile_to_ax (struct probe *probe_generic, struct objfile *objfile, + struct agent_expr *expr, struct axs_value *value, + unsigned n) +{ + struct stap_probe *stap_probe = (struct stap_probe *) probe_generic; + struct stap_probe_arg *arg; + union exp_element *pc; + + gdb_assert (probe_generic->pops == &stap_probe_ops); + + arg = stap_get_arg (stap_probe, objfile, n); + + pc = arg->aexpr->elts; + gen_expr (arg->aexpr, &pc, expr, value); + + require_rvalue (expr, value); + value->type = arg->atype; +} + +/* Destroy (free) the data related to PROBE. PROBE memory itself is not feed + as it is allocated from OBJFILE_OBSTACK. */ + +static void +stap_probe_destroy (struct probe *probe_generic) +{ + struct stap_probe *probe = (struct stap_probe *) probe_generic; + + gdb_assert (probe_generic->pops == &stap_probe_ops); + + if (probe->args_parsed) + { + struct stap_probe_arg *arg; + int ix; + + for (ix = 0; VEC_iterate (stap_probe_arg_s, probe->args_u.vec, ix, arg); + ++ix) + xfree (arg->aexpr); + VEC_free (stap_probe_arg_s, probe->args_u.vec); + } +} + + + +/* This is called to compute the value of one of the $_probe_arg* + convenience variables. */ + +static struct value * +compute_probe_arg (struct gdbarch *arch, struct internalvar *ivar, + void *data) +{ + struct frame_info *frame = get_selected_frame (_("No frame selected")); + CORE_ADDR pc = get_frame_pc (frame); + int sel = (int) (uintptr_t) data; + struct objfile *objfile; + struct probe *pc_probe; + unsigned n_args; + + /* SEL == -1 means "_probe_argc". */ + gdb_assert (sel >= -1); + + pc_probe = find_probe_by_pc (pc, &objfile); + if (pc_probe == NULL) + error (_("No SystemTap probe at PC %s"), core_addr_to_string (pc)); + + n_args + = objfile->sf->sym_probe_fns->sym_get_probe_argument_count (objfile, + pc_probe); + if (sel == -1) + return value_from_longest (builtin_type (arch)->builtin_int, n_args); + + if (sel >= n_args) + error (_("Invalid probe argument %d -- probe has %u arguments available"), + sel, n_args); + + return objfile->sf->sym_probe_fns->sym_evaluate_probe_argument (objfile, + pc_probe, + sel); +} + +/* This is called to compile one of the $_probe_arg* convenience + variables into an agent expression. */ + +static void +compile_probe_arg (struct internalvar *ivar, struct agent_expr *expr, + struct axs_value *value, void *data) +{ + CORE_ADDR pc = expr->scope; + int sel = (int) (uintptr_t) data; + struct objfile *objfile; + struct probe *pc_probe; + int n_probes; + + /* SEL == -1 means "_probe_argc". */ + gdb_assert (sel >= -1); + + pc_probe = find_probe_by_pc (pc, &objfile); + if (pc_probe == NULL) + error (_("No SystemTap probe at PC %s"), core_addr_to_string (pc)); + + n_probes + = objfile->sf->sym_probe_fns->sym_get_probe_argument_count (objfile, + pc_probe); + if (sel == -1) + { + value->kind = axs_rvalue; + value->type = builtin_type (expr->gdbarch)->builtin_int; + ax_const_l (expr, n_probes); + return; + } + + gdb_assert (sel >= 0); + if (sel >= n_probes) + error (_("Invalid probe argument %d -- probe has %d arguments available"), + sel, n_probes); + + objfile->sf->sym_probe_fns->sym_compile_to_ax (objfile, pc_probe, + expr, value, sel); +} + + + +/* 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_semaphore_down' + and `stap_semaphore_up'. */ + +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; + + if (address == 0) + return; + + /* Swallow errors. */ + if (target_read_memory (address, bytes, TYPE_LENGTH (type)) != 0) + { + warning (_("Could not read the value of a SystemTap semaphore.")); + return; + } + + value = extract_unsigned_integer (bytes, TYPE_LENGTH (type), + gdbarch_byte_order (gdbarch)); + /* Note that we explicitly don't worry about overflow or + underflow. */ + if (set) + ++value; + else + --value; + + store_unsigned_integer (bytes, TYPE_LENGTH (type), + gdbarch_byte_order (gdbarch), value); + + if (target_write_memory (address, bytes, TYPE_LENGTH (type)) != 0) + warning (_("Could not write the value of a SystemTap semaphore.")); +} + +/* Set a SystemTap semaphore. SEM is the semaphore's address. Semaphores + act as reference counters, so calls to this function must be paired with + calls to `stap_semaphore_down'. + + This function and `stap_semaphore_down' race with another tool changing + the probes, but that is too rare to care. */ + +static void +stap_set_semaphore (struct probe *probe_generic, struct gdbarch *gdbarch) +{ + struct stap_probe *probe = (struct stap_probe *) probe_generic; + + gdb_assert (probe_generic->pops == &stap_probe_ops); + + stap_modify_semaphore (probe->sem_addr, 1, gdbarch); +} + +/* Clear a SystemTap semaphore. SEM is the semaphore's address. */ + +static void +stap_clear_semaphore (struct probe *probe_generic, struct gdbarch *gdbarch) +{ + struct stap_probe *probe = (struct stap_probe *) probe_generic; + + gdb_assert (probe_generic->pops == &stap_probe_ops); + + stap_modify_semaphore (probe->sem_addr, 0, gdbarch); +} + +/* Implementation of `$_probe_arg*' set of variables. */ + +static const struct internalvar_funcs probe_funcs = +{ + compute_probe_arg, + compile_probe_arg, + NULL +}; + +/* 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 + + This function returns 1 if the handling was successful, and zero + otherwise. */ + +static void +handle_stap_probe (struct objfile *objfile, struct sdt_note *el, + VEC (probe_p) **probesp, CORE_ADDR base) +{ + bfd *abfd = objfile->obfd; + int size = bfd_get_arch_size (abfd) / 8; + struct gdbarch *gdbarch = get_objfile_arch (objfile); + enum bfd_endian byte_order = gdbarch_byte_order (gdbarch); + struct type *ptr_type = builtin_type (gdbarch)->builtin_data_ptr; + CORE_ADDR base_ref; + const char *probe_args = NULL; + struct stap_probe *ret; + + ret = obstack_alloc (&objfile->objfile_obstack, sizeof (*ret)); + ret->p.pops = &stap_probe_ops; + + /* Provider and the name of the probe. */ + ret->p.provider = &el->data[3 * size]; + ret->p.name = memchr (ret->p.provider, '\0', + (char *) el->data + el->size - ret->p.provider); + /* Making sure there is a name. */ + if (!ret->p.name) + { + complaint (&symfile_complaints, _("corrupt probe name when " + "reading `%s'"), objfile->name); + + /* There is no way to use a probe without a name or a provider, so + returning zero here makes sense. */ + return; + } + else + ++ret->p.name; + + /* Retrieving the probe's address. */ + ret->p.address = extract_typed_address (&el->data[0], ptr_type); + + /* Link-time sh_addr of `.stapsdt.base' section. */ + base_ref = extract_typed_address (&el->data[size], ptr_type); + + /* Semaphore address. */ + ret->sem_addr = extract_typed_address (&el->data[2 * size], ptr_type); + + ret->p.address += (ANOFFSET (objfile->section_offsets, + SECT_OFF_TEXT (objfile)) + + base - base_ref); + if (ret->sem_addr) + ret->sem_addr += (ANOFFSET (objfile->section_offsets, + SECT_OFF_DATA (objfile)) + + base - base_ref); + + /* Arguments. We can only extract the argument format if there is a valid + name for this probe. */ + probe_args = memchr (ret->p.name, '\0', + (char *) el->data + el->size - ret->p.name); + + if (probe_args != NULL) + ++probe_args; + + if (probe_args == NULL || (memchr (probe_args, '\0', + (char *) el->data + el->size - ret->p.name) + != el->data + el->size - 1)) + { + complaint (&symfile_complaints, _("corrupt probe argument when " + "reading `%s'"), objfile->name); + /* If the argument string is NULL, it means some problem happened with + it. So we return 0. */ + return; + } + + ret->args_parsed = 0; + ret->args_u.text = (void *) probe_args; + + /* Successfully created probe. */ + VEC_safe_push (probe_p, *probesp, (struct probe *) ret); +} + +/* Helper function which tries to find the base address of the SystemTap + base section named STAP_BASE_SECTION_NAME. */ + +static void +get_stap_base_address_1 (bfd *abfd, asection *sect, void *obj) +{ + asection **ret = obj; + + if ((sect->flags & (SEC_DATA | SEC_ALLOC | SEC_HAS_CONTENTS)) + && sect->name && !strcmp (sect->name, STAP_BASE_SECTION_NAME)) + *ret = sect; +} + +/* 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; + + bfd_map_over_sections (obfd, get_stap_base_address_1, (void *) &ret); + + if (!ret) + { + complaint (&symfile_complaints, _("could not obtain base address for " + "SystemTap section on objfile `%s'."), + obfd->filename); + return 0; + } + + if (base) + *base = ret->vma; + + return 1; +} + +/* Helper function for `elf_get_probes', which gathers information about all + SystemTap probes from OBJFILE. */ + +static void +stap_get_probes (VEC (probe_p) **probesp, struct objfile *objfile) +{ + /* 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; + bfd_vma base; + struct sdt_note *iter; + unsigned save_probesp_len = VEC_length (probe_p, *probesp); + + if (!elf_tdata (obfd)->sdt_note_head) + { + /* 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; 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 == VEC_length (probe_p, *probesp)) + { + /* If we are here, it means we have failed to parse every known + probe. */ + complaint (&symfile_complaints, _("could not parse SystemTap probe(s) " + "from inferior")); + return; + } +} + +static void +stap_relocate (struct probe *probe_generic, CORE_ADDR delta) +{ + struct stap_probe *probe = (struct stap_probe *) probe_generic; + + gdb_assert (probe_generic->pops == &stap_probe_ops); + + probe->p.address += delta; + if (probe->sem_addr) + probe->sem_addr += delta; +} + +static int +stap_probe_is_linespec (const char **linespecp) +{ + static const char *const keywords[] = { "-pstap", "-probe-stap", NULL }; + + return probe_is_linespec_by_keyword (linespecp, keywords); +} + +static void +stap_gen_info_probes_table_header (VEC (info_probe_column_s) **heads) +{ + info_probe_column_s stap_probe_column; + + stap_probe_column.field_name = "semaphore"; + stap_probe_column.print_name = _("Semaphore"); + + VEC_safe_push (info_probe_column_s, *heads, &stap_probe_column); +} + +static void +stap_gen_info_probes_table_values (struct probe *probe_generic, + struct objfile *objfile, + VEC (const_char_ptr) **ret) +{ + struct stap_probe *probe = (struct stap_probe *) probe_generic; + struct gdbarch *gdbarch = get_objfile_arch (objfile); + const char *val = NULL; + + gdb_assert (probe_generic->pops == &stap_probe_ops); + + if (probe->sem_addr) + val = print_core_address (gdbarch, probe->sem_addr); + + VEC_safe_push (const_char_ptr, *ret, val); +} + +/* SystemTap probe_ops. */ + +static const struct probe_ops stap_probe_ops = +{ + stap_probe_is_linespec, + stap_get_probes, + stap_relocate, + stap_get_probe_argument_count, + stap_evaluate_probe_argument, + stap_compile_to_ax, + stap_set_semaphore, + stap_clear_semaphore, + stap_probe_destroy, + stap_gen_info_probes_table_header, + stap_gen_info_probes_table_values, +}; + +/* Implementation of the `info probes stap' command. */ + +static void +info_probes_stap_command (char *arg, int from_tty) +{ + info_probes_for_ops (arg, from_tty, &stap_probe_ops); +} + +void _initialize_stap_probe (void); + +void +_initialize_stap_probe (void) +{ + VEC_safe_push (probe_ops_cp, all_probe_ops, &stap_probe_ops); + + add_setshow_zinteger_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); + + create_internalvar_type_lazy ("_probe_argc", &probe_funcs, + (void *) (uintptr_t) -1); + create_internalvar_type_lazy ("_probe_arg0", &probe_funcs, + (void *) (uintptr_t) 0); + create_internalvar_type_lazy ("_probe_arg1", &probe_funcs, + (void *) (uintptr_t) 1); + create_internalvar_type_lazy ("_probe_arg2", &probe_funcs, + (void *) (uintptr_t) 2); + create_internalvar_type_lazy ("_probe_arg3", &probe_funcs, + (void *) (uintptr_t) 3); + create_internalvar_type_lazy ("_probe_arg4", &probe_funcs, + (void *) (uintptr_t) 4); + create_internalvar_type_lazy ("_probe_arg5", &probe_funcs, + (void *) (uintptr_t) 5); + create_internalvar_type_lazy ("_probe_arg6", &probe_funcs, + (void *) (uintptr_t) 6); + create_internalvar_type_lazy ("_probe_arg7", &probe_funcs, + (void *) (uintptr_t) 7); + create_internalvar_type_lazy ("_probe_arg8", &probe_funcs, + (void *) (uintptr_t) 8); + create_internalvar_type_lazy ("_probe_arg9", &probe_funcs, + (void *) (uintptr_t) 9); + create_internalvar_type_lazy ("_probe_arg10", &probe_funcs, + (void *) (uintptr_t) 10); + create_internalvar_type_lazy ("_probe_arg11", &probe_funcs, + (void *) (uintptr_t) 11); + + 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 ()); + +} |