binutils-gdb/gdb/disasm.h
Yao Qi d8b49cf0c8 Don't throw exception in dis_asm_memory_error
Hi,
GDB calls some APIs from opcodes to do disassembly and provide some
call backs.  This model makes troubles on C++ exception unwinding,
because GDB is a C++ program, and opcodes is still compiled as C.
As we can see, frame #10 and #12 are C++, while #frame 11 is C,

 #10 0x0000000000544228 in memory_error (err=TARGET_XFER_E_IO, memaddr=<optimized out>) at ../../binutils-gdb/gdb/corefile.c:237
 #11 0x00000000006b0a54 in print_insn_aarch64 (pc=0, info=0xffffffffeeb0) at ../../binutils-gdb/opcodes/aarch64-dis.c:3185
 #12 0x0000000000553590 in gdb_pretty_print_insn (gdbarch=gdbarch@entry=0xbbceb0, uiout=uiout@entry=0xbc73d0, di=di@entry=0xffffffffeeb0,
    insn=0xffffffffed40, insn@entry=0xffffffffed90, flags=flags@entry=0,

C++ exception unwinder can't go across frame #11 unless it has
unwind table.  However, C program on many architectures doesn't
have it in default.  As a result, GDB aborts, which is described
in PR 20939.

This is not the first time we see this kind of problem.  We've
had a commit 89525768cd
"Propagate GDB/C++ exceptions across readline using sj/lj-based TRY/CATCH".
We can fix the disassembly bug in a similar way, this is the option one.

Since opcodes is built with gdb, we fix this problem in a different
way as we did for the same issue with readline.  Instead of throwing
exception in dis_asm_memory_error, we record the failed memory
address, and throw exception when GDB returns from opcodes disassemblers.

gdb:

2017-01-26  Yao Qi  <yao.qi@linaro.org>
	    Pedro Alves  <palves@redhat.com>

	PR gdb/20939
	* disasm.c (gdb_disassembler::dis_asm_memory_error): Don't
	call memory_error, save memaddr instead.
	(gdb_disassembler::print_insn): If gdbarch_print_insn returns
	negative, cal memory_error.
	* disasm.h (gdb_disassembler) <m_err_memaddr>: New field.

gdb/testsuite:

2017-01-26  Yao Qi  <yao.qi@linaro.org>

	* gdb.base/all-architectures.exp.in (do_arch_tests): Test
	disassemble on address 0.
2017-01-26 14:29:20 +00:00

118 lines
3.7 KiB
C++

/* Disassemble support for GDB.
Copyright (C) 2002-2017 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/>. */
#ifndef DISASM_H
#define DISASM_H
#include "dis-asm.h"
#define DISASSEMBLY_SOURCE_DEPRECATED (0x1 << 0)
#define DISASSEMBLY_RAW_INSN (0x1 << 1)
#define DISASSEMBLY_OMIT_FNAME (0x1 << 2)
#define DISASSEMBLY_FILENAME (0x1 << 3)
#define DISASSEMBLY_OMIT_PC (0x1 << 4)
#define DISASSEMBLY_SOURCE (0x1 << 5)
#define DISASSEMBLY_SPECULATIVE (0x1 << 6)
struct gdbarch;
struct ui_out;
struct ui_file;
class gdb_disassembler
{
using di_read_memory_ftype = decltype (disassemble_info::read_memory_func);
public:
gdb_disassembler (struct gdbarch *gdbarch, struct ui_file *file)
: gdb_disassembler (gdbarch, file, dis_asm_read_memory)
{}
int print_insn (CORE_ADDR memaddr, int *branch_delay_insns = NULL);
/* Prints the instruction INSN into UIOUT and returns the length of
the printed instruction in bytes. */
int pretty_print_insn (struct ui_out *uiout,
const struct disasm_insn *insn, int flags);
/* Return the gdbarch of gdb_disassembler. */
struct gdbarch *arch ()
{ return m_gdbarch; }
protected:
gdb_disassembler (struct gdbarch *gdbarch, struct ui_file *file,
di_read_memory_ftype func);
struct ui_file *stream ()
{ return (struct ui_file *) m_di.stream; }
private:
struct gdbarch *m_gdbarch;
/* Stores data required for disassembling instructions in
opcodes. */
struct disassemble_info m_di;
CORE_ADDR m_err_memaddr;
static int dis_asm_read_memory (bfd_vma memaddr, gdb_byte *myaddr,
unsigned int len,
struct disassemble_info *info);
static void dis_asm_memory_error (int err, bfd_vma memaddr,
struct disassemble_info *info);
static void dis_asm_print_address (bfd_vma addr,
struct disassemble_info *info);
};
/* An instruction to be disassembled. */
struct disasm_insn
{
/* The address of the memory containing the instruction. */
CORE_ADDR addr;
/* An optional instruction number. If non-zero, it is printed first. */
unsigned int number;
/* True if the instruction was executed speculatively. */
unsigned int is_speculative:1;
};
extern void gdb_disassembly (struct gdbarch *gdbarch, struct ui_out *uiout,
char *file_string, int flags, int how_many,
CORE_ADDR low, CORE_ADDR high);
/* Print the instruction at address MEMADDR in debugged memory,
on STREAM. Returns the length of the instruction, in bytes,
and, if requested, the number of branch delay slot instructions. */
extern int gdb_print_insn (struct gdbarch *gdbarch, CORE_ADDR memaddr,
struct ui_file *stream, int *branch_delay_insns);
/* Return the length in bytes of the instruction at address MEMADDR in
debugged memory. */
extern int gdb_insn_length (struct gdbarch *gdbarch, CORE_ADDR memaddr);
/* Return the length in bytes of INSN, originally at MEMADDR. MAX_LEN
is the size of the buffer containing INSN. */
extern int gdb_buffered_insn_length (struct gdbarch *gdbarch,
const gdb_byte *insn, int max_len,
CORE_ADDR memaddr);
#endif