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Diffstat (limited to 'gdb/dwarf2/expr.h')
| -rw-r--r-- | gdb/dwarf2/expr.h | 325 |
1 files changed, 325 insertions, 0 deletions
diff --git a/gdb/dwarf2/expr.h b/gdb/dwarf2/expr.h new file mode 100644 index 0000000..2f3d2ce --- /dev/null +++ b/gdb/dwarf2/expr.h @@ -0,0 +1,325 @@ +/* DWARF 2 Expression Evaluator. + + Copyright (C) 2001-2020 Free Software Foundation, Inc. + + Contributed by Daniel Berlin <dan@dberlin.org>. + + 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/>. */ + +#if !defined (DWARF2EXPR_H) +#define DWARF2EXPR_H + +#include "leb128.h" +#include "gdbtypes.h" + +/* The location of a value. */ +enum dwarf_value_location +{ + /* The piece is in memory. + The value on the dwarf stack is its address. */ + DWARF_VALUE_MEMORY, + + /* The piece is in a register. + The value on the dwarf stack is the register number. */ + DWARF_VALUE_REGISTER, + + /* The piece is on the dwarf stack. */ + DWARF_VALUE_STACK, + + /* The piece is a literal. */ + DWARF_VALUE_LITERAL, + + /* The piece was optimized out. */ + DWARF_VALUE_OPTIMIZED_OUT, + + /* The piece is an implicit pointer. */ + DWARF_VALUE_IMPLICIT_POINTER +}; + +/* A piece of an object, as recorded by DW_OP_piece or DW_OP_bit_piece. */ +struct dwarf_expr_piece +{ + enum dwarf_value_location location; + + union + { + struct + { + /* This piece's address, for DWARF_VALUE_MEMORY pieces. */ + CORE_ADDR addr; + /* Non-zero if the piece is known to be in memory and on + the program's stack. */ + bool in_stack_memory; + } mem; + + /* The piece's register number, for DWARF_VALUE_REGISTER pieces. */ + int regno; + + /* The piece's literal value, for DWARF_VALUE_STACK pieces. */ + struct value *value; + + struct + { + /* A pointer to the data making up this piece, + for DWARF_VALUE_LITERAL pieces. */ + const gdb_byte *data; + /* The length of the available data. */ + ULONGEST length; + } literal; + + /* Used for DWARF_VALUE_IMPLICIT_POINTER. */ + struct + { + /* The referent DIE from DW_OP_implicit_pointer. */ + sect_offset die_sect_off; + /* The byte offset into the resulting data. */ + LONGEST offset; + } ptr; + } v; + + /* The length of the piece, in bits. */ + ULONGEST size; + /* The piece offset, in bits. */ + ULONGEST offset; +}; + +/* The dwarf expression stack. */ + +struct dwarf_stack_value +{ + dwarf_stack_value (struct value *value_, int in_stack_memory_) + : value (value_), in_stack_memory (in_stack_memory_) + {} + + struct value *value; + + /* True if the piece is in memory and is known to be on the program's stack. + It is always ok to set this to zero. This is used, for example, to + optimize memory access from the target. It can vastly speed up backtraces + on long latency connections when "set stack-cache on". */ + bool in_stack_memory; +}; + +/* The expression evaluator works with a dwarf_expr_context, describing + its current state and its callbacks. */ +struct dwarf_expr_context +{ + dwarf_expr_context (); + virtual ~dwarf_expr_context () = default; + + void push_address (CORE_ADDR value, bool in_stack_memory); + void eval (const gdb_byte *addr, size_t len); + struct value *fetch (int n); + CORE_ADDR fetch_address (int n); + bool fetch_in_stack_memory (int n); + + /* The stack of values. */ + std::vector<dwarf_stack_value> stack; + + /* Target architecture to use for address operations. */ + struct gdbarch *gdbarch; + + /* Target address size in bytes. */ + int addr_size; + + /* DW_FORM_ref_addr size in bytes. If -1 DWARF is executed from a frame + context and operations depending on DW_FORM_ref_addr are not allowed. */ + int ref_addr_size; + + /* Offset used to relocate DW_OP_addr, DW_OP_addrx, and + DW_OP_GNU_addr_index arguments. */ + CORE_ADDR offset; + + /* The current depth of dwarf expression recursion, via DW_OP_call*, + DW_OP_fbreg, DW_OP_push_object_address, etc., and the maximum + depth we'll tolerate before raising an error. */ + int recursion_depth, max_recursion_depth; + + /* Location of the value. */ + enum dwarf_value_location location; + + /* For DWARF_VALUE_LITERAL, the current literal value's length and + data. For DWARF_VALUE_IMPLICIT_POINTER, LEN is the offset of the + target DIE of sect_offset kind. */ + ULONGEST len; + const gdb_byte *data; + + /* Initialization status of variable: Non-zero if variable has been + initialized; zero otherwise. */ + int initialized; + + /* A vector of pieces. + + Each time DW_OP_piece is executed, we add a new element to the + end of this array, recording the current top of the stack, the + current location, and the size given as the operand to + DW_OP_piece. We then pop the top value from the stack, reset the + location, and resume evaluation. + + The Dwarf spec doesn't say whether DW_OP_piece pops the top value + from the stack. We do, ensuring that clients of this interface + expecting to see a value left on the top of the stack (say, code + evaluating frame base expressions or CFA's specified with + DW_CFA_def_cfa_expression) will get an error if the expression + actually marks all the values it computes as pieces. + + If an expression never uses DW_OP_piece, num_pieces will be zero. + (It would be nice to present these cases as expressions yielding + a single piece, so that callers need not distinguish between the + no-DW_OP_piece and one-DW_OP_piece cases. But expressions with + no DW_OP_piece operations have no value to place in a piece's + 'size' field; the size comes from the surrounding data. So the + two cases need to be handled separately.) */ + std::vector<dwarf_expr_piece> pieces; + + /* Return the value of register number REGNUM (a DWARF register number), + read as an address. */ + virtual CORE_ADDR read_addr_from_reg (int regnum) = 0; + + /* Return a value of type TYPE, stored in register number REGNUM + of the frame associated to the given BATON. + + REGNUM is a DWARF register number. */ + virtual struct value *get_reg_value (struct type *type, int regnum) = 0; + + /* Read LENGTH bytes at ADDR into BUF. */ + virtual void read_mem (gdb_byte *buf, CORE_ADDR addr, size_t length) = 0; + + /* Return the location expression for the frame base attribute, in + START and LENGTH. The result must be live until the current + expression evaluation is complete. */ + virtual void get_frame_base (const gdb_byte **start, size_t *length) = 0; + + /* Return the CFA for the frame. */ + virtual CORE_ADDR get_frame_cfa () = 0; + + /* Return the PC for the frame. */ + virtual CORE_ADDR get_frame_pc () + { + error (_("%s is invalid in this context"), "DW_OP_implicit_pointer"); + } + + /* Return the thread-local storage address for + DW_OP_GNU_push_tls_address or DW_OP_form_tls_address. */ + virtual CORE_ADDR get_tls_address (CORE_ADDR offset) = 0; + + /* Execute DW_AT_location expression for the DWARF expression + subroutine in the DIE at DIE_CU_OFF in the CU. Do not touch + STACK while it being passed to and returned from the called DWARF + subroutine. */ + virtual void dwarf_call (cu_offset die_cu_off) = 0; + + /* Execute "variable value" operation on the DIE at SECT_OFF. */ + virtual struct value *dwarf_variable_value (sect_offset sect_off) = 0; + + /* Return the base type given by the indicated DIE at DIE_CU_OFF. + This can throw an exception if the DIE is invalid or does not + represent a base type. SIZE is non-zero if this function should + verify that the resulting type has the correct size. */ + virtual struct type *get_base_type (cu_offset die_cu_off, int size) + { + /* Anything will do. */ + return builtin_type (this->gdbarch)->builtin_int; + } + + /* Push on DWARF stack an entry evaluated for DW_TAG_call_site's + parameter matching KIND and KIND_U at the caller of specified BATON. + If DEREF_SIZE is not -1 then use DW_AT_call_data_value instead of + DW_AT_call_value. */ + virtual void push_dwarf_reg_entry_value (enum call_site_parameter_kind kind, + union call_site_parameter_u kind_u, + int deref_size) = 0; + + /* Return the address indexed by DW_OP_addrx or DW_OP_GNU_addr_index. + This can throw an exception if the index is out of range. */ + virtual CORE_ADDR get_addr_index (unsigned int index) = 0; + + /* Return the `object address' for DW_OP_push_object_address. */ + virtual CORE_ADDR get_object_address () = 0; + +private: + + struct type *address_type () const; + void push (struct value *value, bool in_stack_memory); + bool stack_empty_p () const; + void add_piece (ULONGEST size, ULONGEST offset); + void execute_stack_op (const gdb_byte *op_ptr, const gdb_byte *op_end); + void pop (); +}; + +void dwarf_expr_require_composition (const gdb_byte *, const gdb_byte *, + const char *); + +int dwarf_block_to_dwarf_reg (const gdb_byte *buf, const gdb_byte *buf_end); + +int dwarf_block_to_dwarf_reg_deref (const gdb_byte *buf, + const gdb_byte *buf_end, + CORE_ADDR *deref_size_return); + +int dwarf_block_to_fb_offset (const gdb_byte *buf, const gdb_byte *buf_end, + CORE_ADDR *fb_offset_return); + +int dwarf_block_to_sp_offset (struct gdbarch *gdbarch, const gdb_byte *buf, + const gdb_byte *buf_end, + CORE_ADDR *sp_offset_return); + +/* Wrappers around the leb128 reader routines to simplify them for our + purposes. */ + +static inline const gdb_byte * +gdb_read_uleb128 (const gdb_byte *buf, const gdb_byte *buf_end, + uint64_t *r) +{ + size_t bytes_read = read_uleb128_to_uint64 (buf, buf_end, r); + + if (bytes_read == 0) + return NULL; + return buf + bytes_read; +} + +static inline const gdb_byte * +gdb_read_sleb128 (const gdb_byte *buf, const gdb_byte *buf_end, + int64_t *r) +{ + size_t bytes_read = read_sleb128_to_int64 (buf, buf_end, r); + + if (bytes_read == 0) + return NULL; + return buf + bytes_read; +} + +static inline const gdb_byte * +gdb_skip_leb128 (const gdb_byte *buf, const gdb_byte *buf_end) +{ + size_t bytes_read = skip_leb128 (buf, buf_end); + + if (bytes_read == 0) + return NULL; + return buf + bytes_read; +} + +extern const gdb_byte *safe_read_uleb128 (const gdb_byte *buf, + const gdb_byte *buf_end, + uint64_t *r); + +extern const gdb_byte *safe_read_sleb128 (const gdb_byte *buf, + const gdb_byte *buf_end, + int64_t *r); + +extern const gdb_byte *safe_skip_leb128 (const gdb_byte *buf, + const gdb_byte *buf_end); + +#endif /* dwarf2expr.h */ |