On ia64-linux, GDB sometimes prints the following error when trying
to switch to a different task:
(gdb) task 3
Register 0 is not available
This is a random failure that sometimes happens, sometimes does not.
The error comes from the fact that the libunwind library is requesting
the value of register 0 (zero): This eventually leads us to
ia64-linux-nat.c:ia64_linux_fetch_register.
This function relies on ia64_cannot_fetch_register to determine
whether or not we have access to the register's value. The ptrace
interface does not provide the r0 value, and so we end up telling
the regcache that this register's value is not available. And yet,
for r0, we do not need to ask ptrace for its value, since it is
always zero.
So, the fix was to add a special rule for supplying a nul value
when regnum == IA64_GR0_REGNUM.
gdb/ChangeLog:
* ia64-linux-nat.c (ia64_linux_fetch_register): Add special
handling for r0.
set_gdbarch_process_record.
Initialize `arm_swi_record' field.
* arm-tdep.c (arm_process_record): New function.
(deallocate_reg_mem): New function.
(decode_insn): New function.
(thumb_record_branch): New function.
(thumb_record_ldm_stm_swi(): New function.
(thumb_record_misc): New function.
(thumb_record_ld_st_stack): New function.
(thumb_record_ld_st_imm_offset): New function.
(thumb_record_ld_st_reg_offset(): New function.
(thumb_record_add_sub_cmp_mov): New function.
(thumb_record_shift_add_sub): New function.
(arm_record_coproc_data_proc): New function.
(arm_record_coproc): New function.
(arm_record_b_bl): New function.
(arm_record_ld_st_multiple): New function.
(arm_record_ld_st_reg_offset): New function.
(arm_record_ld_st_imm_offset): New function.
(arm_record_data_proc_imm): New function.
(arm_record_data_proc_misc_ld_str): New function.
(arm_record_extension_space): New function.
(arm_record_strx): New function.
(sbo_sbz): New function.
(struct insn_decode_record): New structure for arm insn record.
(REG_ALLOC): New macro for reg allocations.
(MEM_ALLOC): New macro for memory allocations.
* arm-tdep.h (struct gdbarch_tdep): New field 'arm_swi_record'
Python scripting: Add new method Value.referenced_value to
gdb.Value which can dereference pointer as well as reference
values.
* NEWS: Add entry under 'Python scripting' about the new method
Value.referenced_value on gdb.Value objects.
* python/py-value.c (valpy_referenced_value): New function
defining a new method on gdb.Value objects which can dereference
pointer and reference values.
* testsuite/gdb.python/py-value.cc: Add test case for
testing the methodology exposing C++ values to Python.
* testsuite/gdb.python/py-value-cc.exp: Add tests testing the
methodology exposing C++ values to Python.
* testsuite/gdb.python/Makefile.in: Add py-value-cc to
EXECUTABLES.
* docs/gdb.texinfo (Python API/Values From Inferior): Add
description about the new method Value.referenced_value. Add
description on how Value.dereference is different (and similar)
to Value.referenced_value.
To reproduce the problem, simply try the following with any program:
(gdb) maintenance agent-eval 1.0
Critical error handler: process [...] terminated due to access violation
(this is on Windows; on GNU/Linux, the libc copes better)
The problem is quite simple: gen_expr is given an expression that
contains an unrecognized operator (OP_DOUBLE in this case). When that
happens, it tries to report an error with a string image of the operator
in the error message. Conversion of the opcode into a string is done
using op_string which, despite its name, probably is not what the author
was looking for. This function returns NULL for a lot of the opcodes,
thus triggering the crash.
There is a function that corresponds to what we are looking for:
expprint.c:op_name. It was static, though, so I made it non-static,
and used it from ax-gdb.c:gen_expr.
gdb/ChangeLog:
* expression.h (op_name): Add declaration.
* expprint.c (op_name): Remove declaration. Make non-static.
* ax-gdb.c (gen_expr): Use op_name instead of op_string.
* gdb.base/auxv.c (func2): setrlimit to infinity to enable core dumps.
* gdb.base/auxv.exp: Try to compile it with -DUSE_RLIMIT first.
(generate native core dump): Make the test unsupported if core cannot
be generated.
Code cleanup.
* python/py-auto-load.c (source_section_scripts): New variable back_to.
Turn fclose and xfree calls into make_cleanup_fclose and make_cleanup
with xfree.
(auto_load_objfile_script): Turn fclose into make_cleanup_fclose.
* NEWS: Describe new options --init-command=FILE, -ix and
--init-eval-command=COMMAND, -iex.
* main.c (struct cmdarg): New enum items CMDARG_INIT_FILE and
CMDARG_INIT_COMMAND.
(captured_main): New enum items OPT_IX and OPT_IEX. Add
"init-command", "init-eval-command", "ix" and "iex" to the variable
long_options. Handle OPT_IX and OPT_IEX. Process them from CMDARG_VEC.
New comment for CMDARG_FILE and CMDARG_COMMAND processing.
(print_gdb_help): Describe --init-command=FILE, -ix and
--init-eval-command=COMMAND, -iex.
gdb/doc/
* gdb.texinfo (File Options): Describe --init-command=FILE, -ix and
--init-eval-command=COMMAND, -iex.
(Startup): Describe -iex and -ix. Simplify the example
for "set auto-load-scripts off".
gdb/testsuite/
* gdb.gdb/selftest.exp (do_steps_and_nexts): New entry
for cmdarg_vec = NULL. Remove entries for cmdsize = 1, cmdarg = and
ncmd = 0. New entry for VEC_cleanup cmdarg_s.
Code cleanup.
* main.c (struct cmdarg): Move it here from main. Add more comments.
(cmdarg_s, VEC (cmdarg_s)): New.
(main): Move struct cmdarg from here. New variables cmdarg_vec and
cmdarg_p. Remove variables cmdsize and ncmd and their initialization.
Install cleanup for cmdarg_vec. Update filling for options 'x' and
'X'. Replace cmdarg processing by cmdarg_vec processing. Remove xfree
of CMDARG.
Jan Kratochvil <jan.kratochvil@redhat.com>
* server.c (cont_thread, general_thread): Add describing comments.
(start_inferior): Clear `cont_thread'.
(handle_v_cont): Don't set `cont_thread' if resuming all threads
of a process.
