We noticed the following hang trying to run a program where one
of the subroutines we built without debugging info (opaque_routine):
$ gdb my_program
(gdb) break opaque_routine
(gdb) run
[...hangs...]
The problem comes from the fact that, at the breakpoint's address,
we have the following code:
=> 0x0000000000401994 <+4>: pop %rbp
At some point after hitting the breakpoint and stopping, GDB calls
amd64_windows_frame_decode_epilogue, which then gets stuck in the
following infinite loop:
| /* We don't care about the instruction deallocating the frame:
| if it hasn't been executed, the pc is still in the body,
| if it has been executed, the following epilog decoding will work. */
|
| /* First decode:
| - pop reg [41 58-5f] or [58-5f]. */
|
| while (1)
| {
| /* Read opcode. */
| if (target_read_memory (pc, &op, 1) != 0)
| return -1;
|
| if (op >= 0x40 && op <= 0x4f)
| {
| /* REX prefix. */
| rex = op;
|
| /* Read opcode. */
| if (target_read_memory (pc + 1, &op, 1) != 0)
| return -1;
| }
| else
| rex = 0;
|
| if (op >= 0x58 && op <= 0x5f)
| {
| /* pop reg */
| gdb_byte reg = (op & 0x0f) | ((rex & 1) << 3);
|
| cache->prev_reg_addr[amd64_windows_w2gdb_regnum[reg]] = cur_sp;
| cur_sp += 8;
| }
| else
| break;
|
| /* Allow the user to break this loop. This shouldn't happen as the
| number of consecutive pop should be small. */
| QUIT;
| }
Nothing in that loop updates PC, and therefore, because the instruction
we stopped at is a "pop", we keep looping forever doing the same thing
over and over!
This patch fixes the issue by advancing PC to the beginning of
the next instruction if the current one is a "pop reg" instruction.
gdb/ChangeLog:
* amd64-windows-tdep.c (amd64_windows_frame_decode_epilogue):
Increment PC in while loop skipping "pop reg" instructions.
Unwind info in system dlls uses almost all possible codes, contrary to unwind
info generated by gcc. A few issues have been discovered: incorrect handling
of SAVE_NONVOL opcodes and incorrect in prologue range checks. Furthermore I
added comments not to forget what has been investigated.
gdb/ChangeLog:
* amd64-windows-tdep.c (amd64_windows_find_unwind_info): Move
redirection code to ...
(amd64_windows_frame_decode_insns): ... Here. Fix in prologue
checks. Fix SAVE_NONVOL operations. Add debug code and comments.
This commit introduces a new inline common function "startswith"
which takes two string arguments and returns nonzero if the first
string starts with the second. It also updates the 295 places
where this logic was written out longhand to use the new function.
gdb/ChangeLog:
* common/common-utils.h (startswith): New inline function.
All places where this logic was used updated to use the above.
This is a trace which would have been useful when trying to understand
why the debugger was not decoding the stream of unwind codes I was
expecting. This patch adds a trace first informing us that we are
following the unwind info to the next unwind record in that chain.
gdb/ChangeLog:
* amd64-windows-tdep.c (amd64_windows_frame_decode_insns):
Add debug trace.
On x86_64-windows, GDB is unable to unwind past some code in
mswsock.dll. For instance:
(gdb) bt
#0 0x00000000778712fa in ntdll!ZwWaitForSingleObject ()
from C:\Windows\SYSTEM32\ntdll.dll
#1 0x000007fefcfb0f75 in WSPStartup ()
from C:\Windows\system32\mswsock.dll
Backtrace stopped: previous frame inner to this frame (corrupt stack?)
The UNWIND_INFO record for frame #1's PC has a UNW_FLAG_CHAININFO
flag, and so after having decoded this unwind record, GDB's decoder
next tries to locate the next unwind record on the chain. Unfortunately,
the location of that unwind info appears to be miscomputed. This is
the expression used:
chain_vma = cache->image_base + unwind_info
+ sizeof (ex_ui) + ((codes_count + 1) & ~1) * 2 + 8;
The chain-info is expected to be right after the "Unwind codes
array" which is itself after all the fields of ex_ui's struct.
So the "+ 8" offset at the end should not be there.
Because of that extra offset, we were reading no longer processing
correct unwind info, leading the unwinder computing the wrong frame
size, computing the wrong return address, etc.
gdb/ChangeLog:
* amd64-windows-tdep.c (amd64_windows_frame_decode_insns):
Remove "+ 8" offset in computation of CHAIN_VMA.
We've observed in Windows 2012 that ntdll.dll contains some unwind
records with the version field set to 2. This patch adjusts the
decoder to accept records flagged with this version as well.
Version 2 appears to still be largely undocumented at this stage.
However, apart from a mysterious opcode 6, everything else still
seems to remain the same. So this patch also changes the decoder
to ignore those opcodes; before this change, the debugger would
silently stop the decoding, and let the frame unwinder make do
with what it the decoder managed to decode up to that point.
It's unclear at this point what we're losing by not being able to
decode that opcode. But the information does not appear to be critical,
at least as far as call unwinding is concerned.
gdb/ChangeLog:
(from Tristan Gingold <gingold@adacore.com>)
(from Joel Brobecker <brobecker@adacore.com>)
* amd64-windows-tdep.c (amd64_windows_frame_decode_insns):
Accept version 2. Ignore operations using opcode 6.
* amd64-windows-tdep.c: Remove inclusion of "solib.h" and
"solib-target.h".
(amd64_windows_init_abi): Don't call set_solib_ops and
set_gdbarch_iterate_over_objfiles_in_search_order. Call
windows_init_abi instead.
* i386-cygwin-tdep.c: Remove inclusion of "solib.h" and
"solib-target.h".
(i386_cygwin_init_abi): Don't call set_solib_ops,
set_gdbarch_has_dos_based_file_system and
set_gdbarch_iterate_over_objfiles_in_search_order. Call
windows_init_abi instead.
* windows-tdep.c: Include "solib.h" and "solib-target.h".
(windows_init_abi): New function.
(windows_iterate_over_objfiles_in_search_order): Make it
static.
* windows-tdep.h (windows_init_abi): Declare.
(windows_iterate_over_objfiles_in_search_order): Remove
declaration.
AMD64_R15_REGNUM when a register index is expected.
* amd64-windows-tdep.c (amd64_windows_dummy_call_integer_regs):
Substitute in array.
* amd64-tdep.c (amd64_dwarf_regmap): Ditto.
(amd64_push_arguments): Substitute in integer_regnum array.
This patch provides a standalone implementation of function calls
on amd64-windows, instead of providing some bits and pieces hooking
into the function call implementation meant for sysV (in amd64-tdep).
It makes better sense to do it this way, because the two ABIs are
actually very different; for instance, the concept of argument
classification, which is so central in the sysV ABI and drove the
the implementation in amd64-tdep, makes no sense for Windows. It
is therefore better for the Windows implementation to be completely
separate, rather than rely on adaptations of the sysV implementation.
gdb/ChangeLog:
* amd64-tdep.c: #include "value.h"
(amd64_windows_classify): Delete.
(amd64_windows_passed_by_integer_register)
(amd64_windows_passed_by_xmm_register)
(amd64_windows_passed_by_pointer)
(amd64_windows_adjust_args_passed_by_pointer)
(amd64_windows_store_arg_in_reg, amd64_windows_push_arguments)
(amd64_windows_push_dummy_call): New functions.
(amd64_windows_init_abi): Remove setting of
tdep->call_dummy_num_integer_regs, tdep->call_dummy_integer_regs,
tdep->classify, tdep->memory_args_by_pointer and
tdep->integer_param_regs_saved_in_caller_frame.
Add call to set_gdbarch_push_dummy_call.
* NEWS: Add entry mentioning support for native Windows x64
SEH data.
* amd64-windows-tdep.c: #include "objfiles.h", "frame-unwind.h",
"coff/internal.h", "coff/i386.h", "coff/pe.h" and "libcoff.h".
(struct amd64_windows_frame_cache): New struct.
(amd64_windows_w2gdb_regnum): New global.
(pc_in_range, amd64_windows_frame_decode_epilogue)
(amd64_windows_frame_decode_insns, amd64_windows_find_unwind_info)
(amd64_windows_frame_cache, amd64_windows_frame_prev_register)
(amd64_windows_frame_this_id): New functions.
(amd64_windows_frame_unwind): New static global.
(amd64_windows_skip_prologue): New function.
(amd64_windows_init_abi): Call frame_unwind_prepend_unwinder
with amd64_windows_frame_unwind. Call set_gdbarch_skip_prologue
with amd64_windows_skip_prologue.
Two modifications:
1. The addition of 2013 to the copyright year range for every file;
2. The use of a single year range, instead of potentially multiple
year ranges, as approved by the FSF.
Type wchar_t is only 2 bytes long on x86_64-windows.
gdb/ChangeLog:
* amd64-windows-tdep.c (amd64_windows_auto_wide_charset): New
function.
(amd64_windows_init_abi): Set auto_wide_charset gdbarch method
to amd64_windows_auto_wide_charset.
This patch sets the windows target to use their own version of
the iterate_over_objfiles_in_search_order gdbarch method, in
order to make global symbol searches sensitive to the current
objfile.
gdb/ChangeLog:
* windows-tdep.h (windows_iterate_over_objfiles_in_search_order):
Add declaration.
* windows-tdep.c: #include "objfiles.h".
(windows_iterate_over_objfiles_in_search_order): New function.
* amd64-windows-tdep.c (amd64_windows_init_abi): Set
iterate_over_objfiles_in_search_order gdbarch method to
windows_iterate_over_objfiles_in_search_order.
* i386-cygwin-tdep.c (i386_cygwin_init_abi): Likewise.
* breakpoint.h (bp_location): Add related_address member.
* inferior.h (get_return_value): Take a pointer to struct value
instead of struct type for the function requested.
* value.h (using_struct_return): Likewise.
* gdbarch.sh (return_value): Take a pointer to struct value
instead of struct type for the function requested.
* breakpoint.c (set_breakpoint_location_function): Initialize
related_address for bp_gnu_ifunc_resolver breakpoints.
* elfread.c (elf_gnu_ifunc_resolver_return_stop): Pass the
requested function's address to gdbarch_return_value.
* eval.c (evaluate_subexp_standard): Pass the requested
function's address to using_struct_return.
* infcall.c (call_function_by_hand): Pass the requested
function's address to using_struct_return and
gdbarch_return_value.
* infcmd.c (get_return_value): Take a pointer to struct value
instead of struct type for the function requested.
(print_return_value): Update accordingly.
(finish_command_continuation): Likewise.
* stack.c (return_command): Pass the requested function's
address to using_struct_return and gdbarch_return_value.
* value.c (using_struct_return): Take a pointer to struct value
instead of struct type for the function requested. Pass the
requested function's address to gdbarch_return_value.
* python/py-finishbreakpoint.c (finish_breakpoint_object):
New function_value member, replacing function_type.
(bpfinishpy_dealloc): Update accordingly.
(bpfinishpy_pre_stop_hook): Likewise.
(bpfinishpy_init): Likewise. Record the requested function's
address.
* mips-tdep.c (mips_fval_reg): New enum.
(mips_o32_push_dummy_call): For MIPS16 FP doubles do not swap
words put in GP registers.
(mips_o64_push_dummy_call): Update a comment.
(mips_o32_return_value): Take a pointer to struct value instead
of struct type for the function requested and use it to check if
using the MIPS16 calling convention. Return the designated
general purpose registers for floating-point values returned in
MIPS16 mode.
(mips_o64_return_value): Likewise.
* ppc-tdep.h (ppc_sysv_abi_return_value): Update prototype.
(ppc_sysv_abi_broken_return_value): Likewise.
(ppc64_sysv_abi_return_value): Likewise.
* alpha-tdep.c (alpha_return_value): Take a pointer to struct
value instead of struct type for the function requested.
* amd64-tdep.c (amd64_return_value): Likewise.
* amd64-windows-tdep.c (amd64_windows_return_value): Likewise.
* arm-tdep.c (arm_return_value): Likewise.
* avr-tdep.c (avr_return_value): Likewise.
* bfin-tdep.c (bfin_return_value): Likewise.
* cris-tdep.c (cris_return_value): Likewise.
* frv-tdep.c (frv_return_value): Likewise.
* h8300-tdep.c (h8300_return_value): Likewise.
(h8300h_return_value): Likewise.
* hppa-tdep.c (hppa32_return_value): Likewise.
(hppa64_return_value): Likewise.
* i386-tdep.c (i386_return_value): Likewise.
* ia64-tdep.c (ia64_return_value): Likewise.
* iq2000-tdep.c (iq2000_return_value): Likewise.
* lm32-tdep.c (lm32_return_value): Likewise.
* m32c-tdep.c (m32c_return_value): Likewise.
* m32r-tdep.c (m32r_return_value): Likewise.
* m68hc11-tdep.c (m68hc11_return_value): Likewise.
* m68k-tdep.c (m68k_return_value): Likewise.
(m68k_svr4_return_value): Likewise.
* m88k-tdep.c (m88k_return_value): Likewise.
* mep-tdep.c (mep_return_value): Likewise.
* microblaze-tdep.c (microblaze_return_value): Likewise.
* mn10300-tdep.c (mn10300_return_value): Likewise.
* moxie-tdep.c (moxie_return_value): Likewise.
* mt-tdep.c (mt_return_value): Likewise.
* ppc-linux-tdep.c (ppc_linux_return_value): Likewise.
* ppc-sysv-tdep.c (ppc_sysv_abi_return_value): Likewise.
(ppc_sysv_abi_broken_return_value): Likewise.
(ppc64_sysv_abi_return_value): Likewise.
* ppcnbsd-tdep.c (ppcnbsd_return_value): Likewise.
* rl78-tdep.c (rl78_return_value): Likewise.
* rs6000-aix-tdep.c (rs6000_return_value): Likewise.
* rx-tdep.c (rx_return_value): Likewise.
* s390-tdep.c (s390_return_value): Likewise.
* score-tdep.c (score_return_value): Likewise.
* sh-tdep.c (sh_return_value_nofpu): Likewise.
(sh_return_value_fpu): Likewise.
* sh64-tdep.c (sh64_return_value): Likewise.
* sparc-tdep.c (sparc32_return_value): Likewise.
* sparc64-tdep.c (sparc64_return_value): Likewise.
* spu-tdep.c (spu_return_value): Likewise.
* tic6x-tdep.c (tic6x_return_value): Likewise.
* v850-tdep.c (v850_return_value): Likewise.
* vax-tdep.c (vax_return_value): Likewise.
* xstormy16-tdep.c (xstormy16_return_value): Likewise.
* xtensa-tdep.c (xtensa_return_value): Likewise.
* gdbarch.c: Regenerate.
* gdbarch.h: Regenerate.
gdb/testsuite/
* gdb.base/return-nodebug.exp: Also test float and double types.
Fix -Wmissing-prototypes build.
* alpha-tdep.c (alpha_deal_with_atomic_sequence): Make it static.
* amd64-darwin-tdep.c (_initialize_amd64_darwin_tdep): New prototype.
* amd64-windows-tdep.c (_initialize_amd64_windows_tdep): Likewise.
* arm-symbian-tdep.c (arm_symbian_skip_trampoline_code): Make it static.
(_initialize_arm_symbian_tdep): New prototype.
* arm-wince-tdep.c (arm_wince_skip_main_prologue): Make it static.
* i386-darwin-tdep.c (_initialize_i386_darwin_tdep): New prototype.
* i386-linux-tdep.c (i386_linux_displaced_step_copy_insn): Make it
static.
* lm32-tdep.c (_initialize_lm32_tdep): New prototype.
* microblaze-linux-tdep.c (_initialize_microblaze_linux_tdep): New
prototype.
* microblaze-tdep.c (microblaze_debug, microblaze_fetch_instruction)
(microblaze_skip_prologue, microblaze_frame_cache): Make them static.
* mips-linux-tdep.c (mips_linux_regset_from_core_section): Make it
static.
* moxie-tdep.c (moxie_process_record): Likewise.
* remote-mips.c (mips_can_use_watchpoint, mips_insert_watchpoint)
(mips_remove_watchpoint, mips_stopped_by_watchpoint): Make them static.
* rl78-tdep.c (rl78_breakpoint_from_pc): Make it static.
(_initialize_rl78_tdep): New prototype.
* rx-tdep.c (rx_breakpoint_from_pc): Make it static.
(_initialize_rx_tdep): New prototype.
* solib-darwin.c (darwin_in_dynsym_resolve_code): Make it static.
(_initialize_darwin_solib): New prototype.
* solib-spu.c: Include solib-spu.h.
(_initialize_spu_solib): New prototype.
* spu-multiarch.c (_initialize_spu_multiarch): New prototype.
* tic6x-tdep.c (tic6x_analyze_prologue, tic6x_skip_prologue)
(tic6x_breakpoint_from_pc, tic6x_frame_unwind_cache)
(tic6x_software_single_step): Make it static.
(_initialize_tic6x_tdep): New prototype.
* amd64-windows-tdep.c: #include gdbcore.h and regcache.h.
(amd64_windows_return_value): New function.
(amd64_windows_init_abi): Call set_gdbarch_return_value with
amd64_windows_return_value.
* i386-tdep.h (struct gdbarch_tdep): Add new field
integer_param_regs_saved_in_caller_frame.
* amd64-windows-tdep.c (amd64_windows_init_abi): Set
tdep->integer_param_regs_saved_in_caller_frame to 1.
* amd64-tdep.c (amd64_push_dummy_call): Allocate some memory on
stack if tdep->integer_param_regs_saved_in_caller_frame is set.
* i386-tdep.h (gdbarch_tdep): Add field memory_args_by_pointer.
* amd64-tdep.c (amd64_push_arguments): Add handling of architectures
where tdep->memory_args_by_pointer is non-zero.
* amd64-windows-tdep.c (amd64_windows_init_abi): Set
tdep->memory_args_by_pointer to 1.
gdb/ChangeLog:
* i386-tdep.h (enum amd64_reg_class): New, moved here from
amd64-tdep.c.
(struct gdbarch_tdep): Add fields call_dummy_num_integer_regs,
call_dummy_integer_regs, and classify.
* amd64-tdep.h (amd64_classify): Add declaration.
* amd64-tdep.c (amd64_dummy_call_integer_regs): New static constant.
(amd64_reg_class): Delete, moved to i386-tdep.h.
(amd64_classify): Make non-static. Move declaration to amd64-tdep.h.
Replace call to amd64_classify by call to tdep->classify.
(amd64_push_arguments): Get the list of registers to use for
passing integer parameters from the gdbarch tdep structure,
rather than using a hardcoded one. Replace calls to amd64_classify
by calls to tdep->classify.
(amd64_push_dummy_call): Get the register number used for
the "hidden" argument from tdep->call_dummy_integer_regs.
(amd64_init_abi): Initialize tdep->call_dummy_num_integer_regs
and tdep->call_dummy_integer_regs. Set tdep->classify.
* amd64-windows-tdep.c: Add include of gdbtypes.h.
(amd64_windows_dummy_call_integer_regs): New static global.
(amd64_windows_classify): New function.
(amd64_windows_init_abi): Initialize tdep->call_dummy_num_integer_regs
tdep->call_dummy_integer_regs and tdep->classify.
gdb/testsuite/ChangeLog:
* gdb.ada/call_pn: New testcase.
* config/i386/mingw64.mh, config/i386/nm-cygwin64.h: New files.
* configure.host, configure.tgt: Add handling for x86_64/windows.
* config/djgpp/fnchange.lst: Add entries for amd64-windows-nat.c
and amd64-windows-tdep.c.
Joel Brobecker
Simon Marchi
Tristan Gingold
Gary Benson
Tom Tromey
Yao Qi
Pierre Muller
Joel Brobecker
Pedro Alves
Maciej W. Rozycki
Jan Kratochvil