The ch_type field in Elf64_External_Chdr is 4 bytes. We should use
bfd_get_32 and bfd_put_32 to access it.
* bfd.c (bfd_update_compression_header): Use bfd_put_32 on
ch_type.
(bfd_check_compression_header): Use bfd_get_32 on ch_type.
(bfd_convert_section_contents): Use bfd_get_32 and bfd_put_32
on ch_type.
Two missing consts, found while doing cxx-conversion work. We end up
with a char*, even though we pass a const char* to strstr. I am pushing
this as obvious.
gdb/ChangeLog:
* cli/cli-setshow.c (cmd_show_list): Constify a variable.
* linespec.c (linespec_lexer_lex_string): Same.
The ch_type field in Elf64_External_Chdr is 4 bytes, followed by a
4-byte padding. This change doesn't introduce any functional change
since only the lower 32 bits of the ch_type field are used.
* external.h (Elf64_External_Chdr): Change ch_type to 4 bytes
and add ch_reserved.
When installing a fast tracepoint, we create a jump pad with a
spin-lock. This way, only one thread can collect a given tracepoint at
any time. This test case checks that this lock actually works as
expected.
This test works by creating a function which overrides the in-process
agent library's gdb_collect function. On start up, GDBserver will ask
GDB with the 'qSymbol' packet about symbols present in the inferior.
GDB will reply with the gdb_agent_gdb_collect function from the test
case instead of the one from the agent.
gdb/testsuite/ChangeLog:
* gdb.trace/ftrace-lock.c: New file.
* gdb.trace/ftrace-lock.exp: New file.
This test case makes sure that relocating PC relative instructions does
not change their behaviors. All PC relative AArch64 instructions are
covered. While call and jump (32 bit relative) instructions are covered
on x86.
The test case creates a static array of function pointers for each
supported architecture. Each function in this array tests a specific
instruction using inline assembly. They all need to contain a symbol in
the form of 'set_point\[0-9\]+' and finish by either calling pass or
fail. The number of 'set_pointN' needs to go from 0 to
(ARRAY_SIZE - 1).
The test will:
- look up the number of function pointers in the static array.
- set fast tracepoints on each 'set_point\[0-9\]+' symbol, one in each
functions from 0 to (ARRAY_SIZE - 1).
- run the trace experiment and make sure the pass function is called for
every function.
gdb/testsuite/ChangeLog:
* gdb.arch/insn-reloc.c: New file.
* gdb.arch/ftrace-insn-reloc.exp: New file.
This patch implements compiling agent expressions to native code for
AArch64. This allows us to compile conditions set on fast tracepoints.
The compiled function has the following prologue:
High *------------------------------------------------------*
| LR |
| FP | <- FP
| x1 (ULONGEST *value) |
| x0 (unsigned char *regs) |
Low *------------------------------------------------------*
We save the function's argument on the stack as well as the return
address and the frame pointer. We then set the current frame pointer to
point to the previous one.
The generated code for the expression will freely update the stack
pointer so we use the frame pointer to refer to `*value' and `*regs'.
`*value' needs to be accessed in the epilogue of the function, in order
to set it to whatever is on top of the stack. `*regs' needs to be passed
down to the `gdb_agent_get_raw_reg' function with the `reg' operation.
gdb/gdbserver/ChangeLog:
* linux-aarch64-low-.c: Include ax.h and tracepoint.h.
(enum aarch64_opcodes) <RET>, <SUBS>, <AND>, <ORR>, <ORN>,
<EOR>, <LSLV>, <LSRV>, <ASRV>, <SBFM>, <UBFM>, <CSINC>, <MUL>,
<NOP>: New.
(enum aarch64_condition_codes): New enum.
(w0): New static global.
(fp): Likewise.
(lr): Likewise.
(struct aarch64_memory_operand) <type>: New
MEMORY_OPERAND_POSTINDEX type.
(postindex_memory_operand): New helper function.
(emit_ret): New function.
(emit_load_store_pair): New function, factored out of emit_stp
with support for MEMORY_OPERAND_POSTINDEX.
(emit_stp): Rewrite using emit_load_store_pair.
(emit_ldp): New function.
(emit_load_store): Likewise.
(emit_ldr): Mention post-index instruction in comment.
(emit_ldrh): New function.
(emit_ldrb): New function.
(emit_ldrsw): Mention post-index instruction in comment.
(emit_str): Likewise.
(emit_subs): New function.
(emit_cmp): Likewise.
(emit_and): Likewise.
(emit_orr): Likewise.
(emit_orn): Likewise.
(emit_eor): Likewise.
(emit_mvn): Likewise.
(emit_lslv): Likewise.
(emit_lsrv): Likewise.
(emit_asrv): Likewise.
(emit_mul): Likewise.
(emit_sbfm): Likewise.
(emit_sbfx): Likewise.
(emit_ubfm): Likewise.
(emit_ubfx): Likewise.
(emit_csinc): Likewise.
(emit_cset): Likewise.
(emit_nop): Likewise.
(emit_ops_insns): New helper function.
(emit_pop): Likewise.
(emit_push): Likewise.
(aarch64_emit_prologue): New function.
(aarch64_emit_epilogue): Likewise.
(aarch64_emit_add): Likewise.
(aarch64_emit_sub): Likewise.
(aarch64_emit_mul): Likewise.
(aarch64_emit_lsh): Likewise.
(aarch64_emit_rsh_signed): Likewise.
(aarch64_emit_rsh_unsigned): Likewise.
(aarch64_emit_ext): Likewise.
(aarch64_emit_log_not): Likewise.
(aarch64_emit_bit_and): Likewise.
(aarch64_emit_bit_or): Likewise.
(aarch64_emit_bit_xor): Likewise.
(aarch64_emit_bit_not): Likewise.
(aarch64_emit_equal): Likewise.
(aarch64_emit_less_signed): Likewise.
(aarch64_emit_less_unsigned): Likewise.
(aarch64_emit_ref): Likewise.
(aarch64_emit_if_goto): Likewise.
(aarch64_emit_goto): Likewise.
(aarch64_write_goto_address): Likewise.
(aarch64_emit_const): Likewise.
(aarch64_emit_call): Likewise.
(aarch64_emit_reg): Likewise.
(aarch64_emit_pop): Likewise.
(aarch64_emit_stack_flush): Likewise.
(aarch64_emit_zero_ext): Likewise.
(aarch64_emit_swap): Likewise.
(aarch64_emit_stack_adjust): Likewise.
(aarch64_emit_int_call_1): Likewise.
(aarch64_emit_void_call_2): Likewise.
(aarch64_emit_eq_goto): Likewise.
(aarch64_emit_ne_goto): Likewise.
(aarch64_emit_lt_goto): Likewise.
(aarch64_emit_le_goto): Likewise.
(aarch64_emit_gt_goto): Likewise.
(aarch64_emit_ge_got): Likewise.
(aarch64_emit_ops_impl): New static global variable.
(aarch64_emit_ops): New target function, return
&aarch64_emit_ops_impl.
(struct linux_target_ops): Install it.
This patch adds support for fast tracepoints for aarch64-linux. With this
implementation, a tracepoint can only be placed in a +/- 128MB range of
the jump pad. This is due to the unconditional branch instruction
being limited to a (26 bit << 2) offset from the current PC.
Three target operations are implemented:
- target_install_fast_tracepoint_jump_pad
Building the jump pad the biggest change of this patch. We need to add
functions to emit all instructions needed to save and restore the
current state when the tracepoint is hit. As well as implementing a
lock and creating a collecting_t object identifying the current thread.
Steps performed by the jump pad:
* Save the current state on the stack.
* Push a collecting_t object on the stack. We read the special
tpidr_el0 system register to get the thread ID.
* Spin-lock on the shared memory location of all tracing threads. We
write the address of our collecting_t object there once we have the
lock.
* Call gdb_collect.
* Release the lock.
* Restore the state.
* Execute the replaced instruction which will have been relocated.
* Jump back to the program.
- target_get_thread_area
As implemented in ps_get_thread_area, target_get_thread_area uses ptrace
to fetch the NT_ARM_TLS register. At the architecture level, NT_ARM_TLS
represents the tpidr_el0 system register.
So this ptrace call (if lwpid is the current thread):
~~~
ptrace (PTRACE_GETREGSET, lwpid, NT_ARM_TLS, &iovec);
~~~
Is equivalent to the following instruction:
~~~
msr x0, tpidr_el0
~~~
This instruction is used when creating the collecting_t object that
GDBserver can read to know if a given thread is currently tracing.
So target_get_thread_area must get the same thread IDs as what the jump
pad writes into its collecting_t object.
- target_get_min_fast_tracepoint_insn_len
This just returns 4.
gdb/gdbserver/ChangeLog:
* Makefile.in (linux-aarch64-ipa.o, aarch64-ipa.o): New rules.
* configure.srv (aarch64*-*-linux*): Add linux-aarch64-ipa.o and
aarch64-ipa.o.
* linux-aarch64-ipa.c: New file.
* linux-aarch64-low.c: Include arch/aarch64-insn.h, inttypes.h
and endian.h.
(aarch64_get_thread_area): New target method.
(extract_signed_bitfield): New helper function.
(aarch64_decode_ldr_literal): New function.
(enum aarch64_opcodes): New enum.
(struct aarch64_register): New struct.
(struct aarch64_operand): New struct.
(x0): New static global.
(x1): Likewise.
(x2): Likewise.
(x3): Likewise.
(x4): Likewise.
(w2): Likewise.
(ip0): Likewise.
(sp): Likewise.
(xzr): Likewise.
(aarch64_register): New helper function.
(register_operand): Likewise.
(immediate_operand): Likewise.
(struct aarch64_memory_operand): New struct.
(offset_memory_operand): New helper function.
(preindex_memory_operand): Likewise.
(enum aarch64_system_control_registers): New enum.
(ENCODE): New macro.
(emit_insn): New helper function.
(emit_b): New function.
(emit_bcond): Likewise.
(emit_cb): Likewise.
(emit_tb): Likewise.
(emit_blr): Likewise.
(emit_stp): Likewise.
(emit_ldp_q_offset): Likewise.
(emit_stp_q_offset): Likewise.
(emit_load_store): Likewise.
(emit_ldr): Likewise.
(emit_ldrsw): Likewise.
(emit_str): Likewise.
(emit_ldaxr): Likewise.
(emit_stxr): Likewise.
(emit_stlr): Likewise.
(emit_data_processing_reg): Likewise.
(emit_data_processing): Likewise.
(emit_add): Likewise.
(emit_sub): Likewise.
(emit_mov): Likewise.
(emit_movk): Likewise.
(emit_mov_addr): Likewise.
(emit_mrs): Likewise.
(emit_msr): Likewise.
(emit_sevl): Likewise.
(emit_wfe): Likewise.
(append_insns): Likewise.
(can_encode_int32_in): New helper function.
(aarch64_relocate_instruction): New function.
(aarch64_install_fast_tracepoint_jump_pad): Likewise.
(aarch64_get_min_fast_tracepoint_insn_len): Likewise.
(struct linux_target_ops): Install aarch64_get_thread_area,
aarch64_install_fast_tracepoint_jump_pad and
aarch64_get_min_fast_tracepoint_insn_len.
We will need to decode both ADR and ADRP instructions in GDBserver.
This patch makes common code handle both cases, even if GDB only needs
to decode the ADRP instruction.
gdb/ChangeLog:
* aarch64-tdep.c (aarch64_analyze_prologue): New is_adrp
variable. Call aarch64_decode_adr instead of
aarch64_decode_adrp.
* arch/aarch64-insn.h (aarch64_decode_adrp): Delete.
(aarch64_decode_adr): New function declaration.
* arch/aarch64-insn.c (aarch64_decode_adrp): Delete.
(aarch64_decode_adr): New function, factored out from
aarch64_decode_adrp to decode both adr and adrp instructions.
This patch moves the following functions into the arch/ common
directory, in new files arch/aarch64-insn.{h,c}. They are prefixed with
'aarch64_':
- aarch64_decode_adrp
- aarch64_decode_b
- aarch64_decode_cb
- aarch64_decode_tb
We will need them to implement fast tracepoints in GDBserver.
For consistency, this patch also adds the 'aarch64_' prefix to static
decoding functions that do not need to be shared right now.
V2:
make sure the formatting issues propagated
fix `gdbserver/configure.srv'.
gdb/ChangeLog:
* Makefile.in (ALL_64_TARGET_OBS): Add aarch64-insn.o.
(HFILES_NO_SRCDIR): Add arch/aarch64-insn.h.
(aarch64-insn.o): New rule.
* configure.tgt (aarch64*-*-elf): Add aarch64-insn.o.
(aarch64*-*-linux*): Likewise.
* arch/aarch64-insn.c: New file.
* arch/aarch64-insn.h: New file.
* aarch64-tdep.c: Include arch/aarch64-insn.h.
(aarch64_debug): Move to arch/aarch64-insn.c. Declare in
arch/aarch64-insn.h.
(decode_add_sub_imm): Rename to ...
(aarch64_decode_add_sub_imm): ... this.
(decode_adrp): Rename to ...
(aarch64_decode_adrp): ... this. Move to arch/aarch64-insn.c.
Declare in arch/aarch64-insn.h.
(decode_b): Rename to ...
(aarch64_decode_b): ... this. Move to arch/aarch64-insn.c.
Declare in arch/aarch64-insn.h.
(decode_bcond): Rename to ...
(aarch64_decode_bcond): ... this. Move to arch/aarch64-insn.c.
Declare in arch/aarch64-insn.h.
(decode_br): Rename to ...
(aarch64_decode_br): ... this.
(decode_cb): Rename to ...
(aarch64_decode_cb): ... this. Move to arch/aarch64-insn.c.
Declare in arch/aarch64-insn.h.
(decode_eret): Rename to ...
(aarch64_decode_eret): ... this.
(decode_movz): Rename to ...
(aarch64_decode_movz): ... this.
(decode_orr_shifted_register_x): Rename to ...
(aarch64_decode_orr_shifted_register_x): ... this.
(decode_ret): Rename to ...
(aarch64_decode_ret): ... this.
(decode_stp_offset): Rename to ...
(aarch64_decode_stp_offset): ... this.
(decode_stp_offset_wb): Rename to ...
(aarch64_decode_stp_offset_wb): ... this.
(decode_stur): Rename to ...
(aarch64_decode_stur): ... this.
(decode_tb): Rename to ...
(aarch64_decode_tb): ... this. Move to arch/aarch64-insn.c.
Declare in arch/aarch64-insn.h.
(aarch64_analyze_prologue): Adjust calls to renamed functions.
gdb/gdbserver/ChangeLog:
* Makefile.in (aarch64-insn.o): New rule.
* configure.srv (aarch64*-*-linux*): Add aarch64-insn.o.
Hi,
I see the following build warning with recent GCC built from mainline,
aarch64-none-linux-gnu-gcc -g -O2 -I. -I/home/yao/SourceCode/gnu/gdb/git/gdb/gdbserver -I/home/yao/SourceCode/gnu/gdb/git/gdb/gdbserver/../common -I/home/yao/SourceCode/gnu/gdb/git/gdb/gdbserver/../regformats -I/home/yao/SourceCode/gnu/gdb/git/gdb/gdbserver/.. -I/home/yao/SourceCode/gnu/gdb/git/gdb/gdbserver/../../include -I/home/yao/SourceCode/gnu/gdb/git/gdb/gdbserver/../gnulib/import -Ibuild-gnulib-gdbserver/import -Wall -Wpointer-arith -Wformat-nonliteral -Wno-char-subscripts -Wempty-body -Wdeclaration-after-statement -Werror -DGDBSERVER -DCONFIG_UST_GDB_INTEGRATION -fPIC -DIN_PROCESS_AGENT -fvisibility=hidden -c -o ax-ipa.o -MT ax-ipa.o -MMD -MP -MF .deps/ax-ipa.Tpo `echo " -Wall -Wpointer-arith -Wformat-nonliteral -Wno-char-subscripts -Wempty-body -Wdeclaration-after-statement " | sed "s/ -Wformat-nonliteral / -Wno-format-nonliteral /g"` /home/yao/SourceCode/gnu/gdb/git/gdb/gdbserver/ax.c
/home/yao/SourceCode/gnu/gdb/git/gdb/gdbserver/ax.c:73:28: error: 'gdb_agent_op_sizes' defined but not used [-Werror=unused-const-variable]
static const unsigned char gdb_agent_op_sizes [gdb_agent_op_last] =
^
cc1: all warnings being treated as errors
gdb_agent_op_sizes is only used in function is_goto_target, which is
defined inside #ifndef IN_PROCESS_AGENT. This warning is not arch
specific, so GCC mainline for other targets should produce this warning
too, although this warning is triggered by enabling aarch64 fast
tracepoint. The fix is to move gdb_agent_op_sizes to
gdb/gdbserver:
2015-09-21 Yao Qi <yao.qi@linaro.org>
* ax.c [!IN_PROCESS_AGENT] (gdb_agent_op_sizes): Define it.
This patch is to remove max_jump_pad_size which isn't used else where,
and it causes a recent gcc warning like this,
gdb/gdbserver/tracepoint.c:2920:18: error: 'max_jump_pad_size' defined but not used [-Werror=unused-const-variable]
static const int max_jump_pad_size = 0x100;
^
cc1: all warnings being treated as errors
This variable max_jump_pad_size wasn't used since it was added in 2010
by https://sourceware.org/ml/gdb-patches/2010-06/msg00002.html
gdb/gdbserver:
2015-09-21 Yao Qi <yao.qi@linaro.org>
* tracepoint.c (max_jump_pad_size): Remove.
We have noticed that GDB would sometimes crash trying to print
from a nested function the value of a variable declared in an
enclosing scope. This appears to be target dependent, although
that correlation might only be fortuitious. We noticed the issue
on x86_64-darwin, x86-vxworks6 and x86-solaris. The investigation
was done on Darwin.
This is a new feature that was introduced by:
commit 63e43d3aed
Date: Thu Feb 5 17:00:06 2015 +0100
DWARF: handle non-local references in nested functions
We can reproduce the problem with one of the testcases that was
added with the patch (gdb.base/nested-subp1.exp), where we have...
18 int
19 foo (int i1)
20 {
21 int
22 nested (int i2)
23 {
[...]
27 return i1 * i2; /* STOP */
28 }
... After building the example program, and running until line 27,
try printing the value of "i1":
% gdb gdb.base/nested-subp1
(gdb) break foo.c:27
(gdb) run
Breakpoint 1, nested (i2=2) at /[...]/nested-subp1.c:27
27 return i1 * i2; /* STOP */
(gdb) p i1
[1] 73090 segmentation fault ../gdb -q gdb.base/nested-subp1
Ooops!
What happens is that, because the reference is non-local, we are trying
to follow the function's static link, which does...
/* If we don't know how to compute FRAME's base address, don't give up:
maybe the frame we are looking for is upper in the stace frame. */
if (framefunc != NULL
&& SYMBOL_BLOCK_OPS (framefunc)->get_frame_base != NULL
&& (SYMBOL_BLOCK_OPS (framefunc)->get_frame_base (framefunc, frame)
== upper_frame_base))
... or, in other words, calls the get_frame_base "method" of
framefunc's struct symbol_block_ops data. This resolves to
the block_op_get_frame_base function.
Looking at the function's implementation, we see:
struct dwarf2_locexpr_baton *dlbaton;
[...]
dlbaton = SYMBOL_LOCATION_BATON (framefunc);
[...]
result = dwarf2_evaluate_loc_desc (type, frame, start, length,
dlbaton->per_cu);
^^^^^^^^^^^^^^^
Printing dlbaton->per_cu gives a value that seems fairly bogus for
a memory address (0x60). Because of it, dwarf2_evaluate_loc_desc
then crashes trying to dereference it.
What's different on Darwin compared to Linux is that the function's
frame base is encoded using the following form:
.byte 0x40 # uleb128 0x40; (DW_AT_frame_base)
.byte 0x6 # uleb128 0x6; (DW_FORM_data4)
... and so dwarf2_symbol_mark_computed ends up creating
a SYMBOL_LOCATION_BATON as a struct dwarf2_loclist_baton:
if (attr_form_is_section_offset (attr)
/* .debug_loc{,.dwo} may not exist at all, or the offset may be outside
the section. If so, fall through to the complaint in the
other branch. */
&& DW_UNSND (attr) < dwarf2_section_size (objfile, section))
{
struct dwarf2_loclist_baton *baton;
[...]
SYMBOL_LOCATION_BATON (sym) = baton;
However, if you look more closely at block_op_get_frame_base's
implementation, you'll notice that the function extracts the
symbol's SYMBOL_LOCATION_BATON as a dwarf2_locexpr_baton
(a DWARF _expression_ rather than a _location list_).
That's why we end up decoding the DLBATON improperly, and thus
pass a random dlbaton->per_cu when calling dwarf2_evaluate_loc_desc.
This works on x86_64-linux, because we indeed have the frame base
described using a different form:
.uleb128 0x40 # (DW_AT_frame_base)
.uleb128 0x18 # (DW_FORM_exprloc)
This patch fixes the issue by doing what we do for most (if not all)
other such methods: providing one implementation each for loc-list,
and loc-expr. Both implementations are nearly identical, so perhaps
we might later want to improve this. But this patch first tries to
fix the crash first, leaving the design issue for later.
gdb/ChangeLog:
* dwarf2loc.c (locexpr_get_frame_base): Renames
block_op_get_frame_base.
(dwarf2_block_frame_base_locexpr_funcs): Replace reference to
block_op_get_frame_base by reference to locexpr_get_frame_base.
(loclist_get_frame_base): New function, near identical copy of
locexpr_get_frame_base.
(dwarf2_block_frame_base_loclist_funcs): Replace reference to
block_op_get_frame_base by reference to loclist_get_frame_base.
Tested on x86_64-darwin (AdaCore testsuite), and x86_64-linux
(official testsuite).
bfd/ChangeLog:
* targets.c (enum bfd_flavour): Add comment.
(bfd_flavour_name): New function.
* bfd-in2.h: Regenerate.
gdb/ChangeLog:
* findvar.c (default_read_var_value) <LOC_UNRESOLVED>: Include the
kind of minimal symbol in the error message.
* objfiles.c (objfile_flavour_name): New function.
* objfiles.h (objfile_flavour_name): Declare.
gdb/testsuite/ChangeLog:
* gdb.dwarf2/dw2-bad-unresolved.c: New file.
* gdb.dwarf2/dw2-bad-unresolved.exp: New file.
2015-09-18 Sandra Loosemore <sandra@codesourcery.com>
gdb/testsuite/
* gdb.mi/mi-pending.exp: Don't use directory prefix when setting
the pending breakpoint. Remove timeout override for "Run till
MI pending breakpoint on pendfunc3 on thread 2" test.
With the kernle fix <http://lists.infradead.org/pipermail/linux-arm-kernel/2015-July/356511.html>,
aarch64 GDB is able to read the base of thread area of 32-bit arm
program through NT_ARM_TLS.
This patch is to teach both GDB and GDBserver to read the base of
thread area correctly in the multi-arch case. A new function
aarch64_ps_get_thread_area is added, and is shared between GDB and
GDBserver.
With this patch applied, the following fails in multi-arch testing
(GDB is aarch64 but the test cases are arm) are fixed,
-FAIL: gdb.threads/tls-nodebug.exp: thread local storage
-FAIL: gdb.threads/tls-shared.exp: print thread local storage variable
-FAIL: gdb.threads/tls-so_extern.exp: print thread local storage variable
-FAIL: gdb.threads/tls-var.exp: print tls_var
-FAIL: gdb.threads/tls.exp: first thread local storage
-FAIL: gdb.threads/tls.exp: first another thread local storage
-FAIL: gdb.threads/tls.exp: p a_thread_local
-FAIL: gdb.threads/tls.exp: p file2_thread_local
-FAIL: gdb.threads/tls.exp: p a_thread_local second time
gdb:
2015-09-18 Yao Qi <yao.qi@linaro.org>
* nat/aarch64-linux.c: Include elf/common.h,
nat/gdb_ptrace.h, asm/ptrace.h and sys/uio.h.
(aarch64_ps_get_thread_area): New function.
* nat/aarch64-linux.h: Include gdb_proc_service.h.
(aarch64_ps_get_thread_area): Declare.
* aarch64-linux-nat.c (ps_get_thread_area): Call
aarch64_ps_get_thread_area.
gdb/gdbserver:
2015-09-18 Yao Qi <yao.qi@linaro.org>
* linux-aarch64-low.c: Don't include sys/uio.h.
(ps_get_thread_area): Call aarch64_ps_get_thread_area.
In all-stop mode, record btrace maintains the old behaviour of an implicit
scheduler-locking on.
Now that we added a scheduler-locking mode to model this old behaviour, we
don't need the respective code in record btrace anymore. Remove it.
For all-stop targets, step inferior_ptid and continue other threads matching
the argument ptid. Assert that inferior_ptid matches the argument ptid.
This should make record btrace honour scheduler-locking.
gdb/
* record-btrace.c (record_btrace_resume): Honour scheduler-locking.
testsuite/
* gdb.btrace/multi-thread-step.exp: Test scheduler-locking on, step,
and replay.
Record targets behave as if scheduler-locking were on in replay mode. Add a
new scheduler-locking option "replay" to make this implicit behaviour explicit.
It behaves like "on" in replay mode and like "off" in record mode.
By making the current behaviour a scheduler-locking option, we allow the user
to change it. Since it is the current behaviour, this new option is also
the new default.
One caveat is that when resuming a thread that is at the end of its execution
history, record btrace implicitly stops replaying other threads and resumes
the entire process. This is a convenience feature to not require the user
to explicitly move all other threads to the end of their execution histories
before being able to resume the process.
We mimick this behaviour with scheduler-locking replay and move it from
record-btrace into infrun. With all-stop on top of non-stop, we can't do
this in record-btrace anymore.
Record full does not really support multi-threading and is therefore not
impacted. If it were extended to support multi-threading, it would 'benefit'
from this change. The good thing is that all record targets will behave the
same with respect to scheduler-locking.
I put the code for this into clear_proceed_status. It also sends the
about_to_proceed notification.
gdb/
* NEWS: Announce new scheduler-locking mode.
* infrun.c (schedlock_replay): New.
(scheduler_enums): Add schedlock_replay.
(scheduler_mode): Change default to schedlock_replay.
(user_visible_resume_ptid): Handle schedlock_replay.
(clear_proceed_status_thread): Stop replaying if resumed thread is
not replaying.
(schedlock_applies): Handle schedlock_replay.
(_initialize_infrun): Document new scheduler-locking mode.
* record-btrace.c (record_btrace_resume): Remove code to stop other
threads when not replaying the resumed thread.
doc/
* gdb.texinfo (All-Stop Mode): Describe new scheduler-locking mode.
Add a new target method to_record_will_replay to query if there is a record
target that will replay at least one thread matching the argument PTID if it
were executed in the argument execution direction.
gdb/
* record-btrace.c ((record_btrace_will_replay): New.
(init_record_btrace_ops): Initialize to_record_will_replay.
* record-full.c ((record_full_will_replay): New.
(init_record_full_ops): Initialize to_record_will_replay.
* target-delegates.c: Regenerated.
* target.c (target_record_will_replay): New.
* target.h (struct target_ops) <to_record_will_replay>: New.
(target_record_will_replay): New.
Signed-off-by: Markus Metzger <markus.t.metzger@intel.com>
The record btrace target does not allow accessing memory and storing registers
while replaying. For multi-threaded applications, this prevents those
accesses also for threads that are at the end of their execution history as
long as at least one thread is replaying.
Change this to only check if the selected thread is replaying. This allows
threads that are at the end of their execution history to read and write
memory and to store registers.
Also change the error message to reflect this change.
gdb/
* record-btrace.c (record_btrace_xfer_partial)
(record_btrace_store_registers, record_btrace_prepare_to_store):
Call record_btrace_is_replaying with inferior_ptid instead of
minus_one_ptid.
(record_btrace_store_registers): Change error message.
The to_record_is_replaying target method is used to query record targets if
they are replaying. This is currently interpreted as "is any thread being
replayed".
Add a PTID argument and change the interpretation to "is any thread matching
PTID being replayed".
Change all users to pass minus_one_ptid to preserve the old meaning.
The record full target does not really support multi-threading and ignores
the PTID argument.
gdb/
* record-btrace.c (record_btrace_is_replaying): Add ptid argument.
Update users to pass minus_one_ptid.
* record-full.c (record_full_is_replaying): Add ptid argument (ignored).
* record.c (cmd_record_delete): Pass inferior_ptid to
target_record_is_replaying.
* target-delegates.c: Regenerated.
* target.c (target_record_is_replaying): Add ptid argument.
* target.h (struct target_ops) <to_record_is_replaying>: Add ptid
argument.
(target_record_is_replaying): Add ptid argument.
A thread that runs out of its execution history is stopped. We already set
stop_pc and call stop_waiting. But we do not switch to the stopped thread.
In normal_stop, we call finish_thread_state_cleanup to set a thread's running
state. In all-stop mode, we call it with minus_one_ptid; in non-stop mode, we
only call it for inferior_ptid.
If in non-stop mode normal_stop is called on behalf of a thread that is not
inferior_ptid, that other thread will still be reported as running. If it is
actually stopped it can't be resumed again.
Record targets traditionally don't support non-stop and only resume
inferior_ptid. So this has not been a problem, so far.
Switch to the eventing thread for NO_HISTORY events as preparation to support
non-stop for the record btrace target.
gdb/
* infrun.c (handle_inferior_event_1): Switch to the eventing thread
in the TARKET_WAITKIND_NO_HISTORY case.
The record btrace target runs synchronous with GDB. That is, GDB steps
resumed threads in record btrace's to_wait method. Without GDB calling
to_wait, nothing happens 'on the target'.
Check for further expected events in to_wait before reporting the current
event and mark record btrace's async event handler in async mode.
gdb/
* record-btrace.c (record_btrace_maybe_mark_async_event): New.
(record_btrace_wait): Call record_btrace_maybe_mark_async_event.
Get_current_frame uses inferior_ptid. In record_btrace_start_replaying,
we need to get the current frame of the argument thread. So far, this
has always been inferior_ptid. With non-stop, this is not guaranteed.
Temporarily set inferior_ptid to the ptid of the argument thread.
We already temporarily set the argument thread's executing flag to false.
Move both into a new function get_thread_current_frame that does the temporary
adjustments, calls get_current_frame, and restores the previous values.
gdb/
* record-btrace.c (get_thread_current_frame): New.
(record_btrace_start_replaying): Call get_thread_current_frame.
The record targets are implicitly schedlocked. They only step the current
thread and keep other threads where they are.
Change record btrace to step all requested threads in to_resume.
For maintenance and debugging, we keep the old behaviour when the target below
is not non-stop. Enable with "maint set target-non-stop on".
gdb/
* record-btrace.c (record_btrace_resume_thread): A move request
overwrites a previous move request.
(record_btrace_find_resume_thread): Removed.
(record_btrace_resume): Resume all requested threads.
Record btrace's to_wait method picks a single thread to step. When passed
minus_one_ptid, it picks the current thread. All other threads remain where
they are.
Change this to step all resumed threads together, one step at a time, until
the first thread reports an event.
We do delay reporting NO_HISTORY events until there are no other events to
report to prevent threads at the end of their execution history from starving
other threads.
We keep threads at the end of their execution history moving and replaying
until we announce their stop in to_wait. This shouldn't really be user-visible
but its a detail worth mentioning.
Since record btrace's to_resume method also picks only a single thread to
resume, there shouldn't be a difference with the current all-stop.
With non-stop or all-stop on top of non-stop, we will see differences. The
behaviour should be more natural as we're moving all threads.
gdb/
* record-btrace.c: Include vec.h.
(record_btrace_find_thread_to_move): Removed.
(btrace_step_no_resumed, btrace_step_again)
(record_btrace_stop_replaying_at_end): New.
(record_btrace_cancel_resume): Call record_btrace_stop_replaying_at_end.
(record_btrace_single_step_forward): Remove calls to
record_btrace_stop_replaying.
(record_btrace_step_thread): Do only one step for BTHR_CONT and
BTHR_RCONT. Keep threads at the end of their history moving.
(record_btrace_wait): Call record_btrace_step_thread for all threads
until one reports an event. Call record_btrace_stop_replaying_at_end
for the eventing thread.
If a single-step ended right at the end of the execution history, we forgot
to announce that. Fix it.
gdb/
* record-btrace.c (record_btrace_single_step_forward): Return
NO_HISTORY if a step brings us to the end of the execution history.
Breakpoints are only checked for BTHR_CONT and BTHR_RCONT stepping requests.
A BTHR_STEP and BTHR_RSTEP request will always report stopped without reason.
Since breakpoints are reported correctly, I assume infrun is handling this.
Move the breakpoint check into the btrace single stepping functions. This
will cause us to report breakpoint hits now also for single-step requests.
One thing to notice is that
- when executing forwards, the breakpoint is checked before 'executing'
the instruction, i.e. before moving the PC to the next instruction.
- when executing backwards, the breakpoint is checked after 'executing'
the instruction, i.e. after moving the PC to the preceding instruction
in the recorded execution.
There is code in infrun (see, for example proceed and adjust_pc_after_break)
that handles this and also depends on this behaviour.
gdb/
* record-btrace.c (record_btrace_step_thread): Move breakpoint check
to ...
(record_btrace_single_step_forward): ... here and
(record_btrace_single_step_backward): ... here.
The code for BTHR_STEP and BTHR_CONT is fairly similar. Extract the common
parts into a new function record_btrace_single_step_forward. The function
returns TARGET_WAITKIND_SPURIOUS to indicate that the single-step completed
without triggering a trap.
Same for BTHR_RSTEP and BTHR_RCONT.
gdb/
* record-btrace.c (btrace_step_spurious)
(record_btrace_single_step_forward)
(record_btrace_single_step_backward): New.
(record_btrace_step_thread): Call record_btrace_single_step_forward
and record_btrace_single_step_backward.
There are two places where record_btrace_step_thread checks for a breakpoint
at the current replay position. Move this code into its own function.
gdb/
* record-btrace.c (record_btrace_replay_at_breakpoint): New.
(record_btrace_step_thread): Call record_btrace_replay_at_breakpoint.
H.J. Lu