[PATCH v2 12/12] btrace: Extend ptwrite event decoding.

Felix Willgerodt via Gdb-patches
2021-06-14T15:08:47Z

Call the ptwrite listener function whenever a ptwrite event is decoded.
The returned string is written to the aux_data string table and a
corresponding auxiliary instruction is appended to the function segment.

gdb/ChangeLog:
2021-06-14 Felix Willgerodt <felix.willgerodt@intel.com>

* btrace.c (handle_pt_insn_events): Handle ptev_ptwrite.

gdb/testsuite/ChangeLog:
2021-06-14 Felix Willgerodt <felix.willgerodt@intel.com>

* gdb.btrace/ptwrite.c: New file.
* gdb.btrace/ptwrite.exp: New file.
* gdb.btrace/x86_64-ptwrite.S: New file.
* lib/gdb.exp (skip_btrace_ptw_tests): New function.

gdb/doc/ChangeLog:
2021-06-14 Felix Willgerodt <felix.willgerodt@intel.com>

* python.texi (gdb.ptwrite): New documentation.
---
gdb/NEWS | 6 +
gdb/btrace.c | 52 +++
gdb/doc/python.texi | 132 ++++++
gdb/testsuite/gdb.btrace/ptwrite.c | 39 ++
gdb/testsuite/gdb.btrace/ptwrite.exp | 194 +++++++++
gdb/testsuite/gdb.btrace/x86_64-ptwrite.S | 479 ++++++++++++++++++++++
gdb/testsuite/lib/gdb.exp | 82 ++++
7 files changed, 984 insertions(+)
create mode 100644 gdb/testsuite/gdb.btrace/ptwrite.c
create mode 100644 gdb/testsuite/gdb.btrace/ptwrite.exp
create mode 100644 gdb/testsuite/gdb.btrace/x86_64-ptwrite.S

diff --git a/gdb/NEWS b/gdb/NEWS
index 56743fc9aea..c920a5cb8ec 100644
--- a/gdb/NEWS
+++ b/gdb/NEWS
@@ -3,6 +3,12 @@

*** Changes since GDB 10

+* GDB now supports printing of ptwrite payloads from the Intel Processor
+ Trace during 'record instruction-history', 'record function-call-history',
+ all stepping commands and in Python. Printing is customizable via a
+ ptwrite listener function in Python. By default, the raw ptwrite
+ payload is printed for each ptwrite that is encountered.
+
* The 'set disassembler-options' command now supports specifying options
for the ARC target.

diff --git a/gdb/btrace.c b/gdb/btrace.c
index d66c3e21f11..d276de723c0 100644
--- a/gdb/btrace.c
+++ b/gdb/btrace.c
@@ -1247,6 +1247,58 @@ handle_pt_insn_events (struct btrace_thread_info *btinfo,
bfun->insn_offset - 1, offset);

break;
+
+ case ptev_ptwrite:
+ {
+ uint64_t *ip = nullptr;
+ gdb::unique_xmalloc_ptr<char> ptw_string = nullptr;
+ struct btrace_insn ptw_insn;
+ btrace_insn_flags flags;
+
+ /* Lookup the ip if available. */
+ if (event.ip_suppressed == 0)
+ ip = &event.variant.ptwrite.ip;
+ else if (!btinfo->functions.empty ()
+ && !btinfo->functions.back ().insn.empty ())
+ ip = &btinfo->functions.back ().insn.back ().pc;
+
+ if (btinfo->ptw_callback_fun != nullptr)
+ ptw_string = btinfo->ptw_callback_fun (
+ &event.variant.ptwrite.payload, ip,
+ btinfo->ptw_listener);
+
+ if (ptw_string == nullptr)
+ break;
+
+ btinfo->aux_data.emplace_back (ptw_string.get ());
+
+ if (!btinfo->functions.empty ()
+ && !btinfo->functions.back ().insn.empty ())
+ flags = btinfo->functions.back ().insn.back ().flags;
+ else
+ flags = 0;
+
+ /* Update insn list with ptw payload insn. */
+ ptw_insn.aux_data_index = btinfo->aux_data.size () - 1;
+ ptw_insn.flags = flags;
+ ptw_insn.iclass = BTRACE_INSN_AUX;
+ ptw_insn.size = 0;
+
+ if (ip != nullptr)
+ bfun = ftrace_update_function (btinfo, *ip);
+ else
+ {
+ if (btinfo->functions.empty ())
+ bfun = ftrace_new_function (btinfo, NULL, NULL);
+ else
+ bfun = &btinfo->functions.back ();
+ }
+
+ bfun->flags |= BFUN_AUX_DECODED;
+ ftrace_update_insns (bfun, ptw_insn);
+
+ break;
+ }
}
}
#endif /* defined (HAVE_PT_INSN_EVENT) */
diff --git a/gdb/doc/python.texi b/gdb/doc/python.texi
index fa1c69a2283..4436aaa79f8 100644
--- a/gdb/doc/python.texi
+++ b/gdb/doc/python.texi
@@ -6110,6 +6110,7 @@ registering objfile-specific pretty-printers and frame-filters.
* gdb.printing:: Building and registering pretty-printers.
* gdb.types:: Utilities for working with types.
* gdb.prompt:: Utilities for prompt value substitution.
+* gdb.ptwrite:: Utilities for ptwrite listener registration.
@end menu

@node gdb.printing
@@ -6300,3 +6301,134 @@ substitute_prompt ("frame: \f, args: \p@{print frame-arguments@}")
"frame: main, args: scalars"
@end smallexample
@end table
+
+@node gdb.ptwrite
+@subsubsection gdb.ptwrite
+@cindex gdb.ptwrite
+
+This module provides additional functionality for recording programs that make
+use of the PTWRITE instruction. PTWRITE is a x86 instruction that allows to
+write values into the Intel Processor Trace (@pxref{Process Record and Replay}).
+The @value{NGCC} built-in functions for it are:
+@smallexample
+void __builtin_ia32_ptwrite32 (unsigned);
+void __builtin_ia32_ptwrite64 (unsigned long long);
+@end smallexample
+
+If an inferior uses the instruction, @value{GDBN} inserts the raw payload value
+as auxiliary information into the execution history. Auxiliary information
+is by default printed during @code{record instruction-history},
+@code{record function-call-history}, and all stepping commands and is accessible
+in Python as a @code{RecordAuxiliary} object.
+
+@exdent Sample program:
+@smallexample
+@group
+void
+ptwrite64 (unsigned long long value)
+@{
+ __builtin_ia32_ptwrite64 (value);
+@}
+
+int
+main (void)
+@{
+ ptwrite64 (0x42);
+ return 0; /* break here. */
+@}
+@end group
+@end smallexample
+
+
+@exdent @value{GDBN} output after recording the sample program in pt format:
+@smallexample
+@group
+(gdb) record instruction-history 12,14
+12 0x000000000040074c <ptwrite64+16>: ptwrite %rbx
+13 [0x42]
+14 0x0000000000400751 <ptwrite64+21>: mov -0x8(%rbp),%rbx
+(gdb) record function-call-history
+1 main
+2 ptwrite64
+ [0x42]
+3 main
+@end group
+@end smallexample
+
+The @code{gdb.ptwrite} module allows customizing the default output of ptwrite
+auxiliary information. A custom Python function can be registered via
+@code{gdb.ptwrite.register_listener()} as the ptwrite listener function.
+This function will be called with the ptwrite payload and PC as arguments
+during trace decoding.
+
+@findex gdb.ptwrite.register_listener
+@defun register_listener (@var{listener})
+Used to register the ptwrite listener. The listener can be any callable
+object that accepts two arguments. It can return a string, which will be
+printed by @value{GDBN} during the aforementioned commands, or @code{None},
+resulting in no output. @code{None} can also be registered to deactivate
+printing.
+@end defun
+
+@findex gdb.ptwrite.get_listener
+@defun get_listener ()
+Returns the currently active ptwrite listener function.
+@end defun
+
+@findex gdb.ptwrite.default_listener
+@defun default_listener (@var{payload}, @var{ip})
+The listener function active by default.
+@end defun
+
+@value{GDBN} creates a new copy of the listener function for each thread to
+allow for independent internal states. There is no support for registering
+different listeners for different threads. The listener can however
+distinguish between multiple threads with the help of
+@code{gdb.selected_thread().global_num} (@pxref{Threads In Python}) or
+similar. For example:
+
+@smallexample
+@group
+(gdb) python-interactive
+>>> class my_listener(object):
+... def __init__(self):
+... self.variable = 0
+... def __call__(self, payload, ip):
+... if gdb.selected_thread().global_num == 1:
+... self.variable += 1
+... return "payload: @{@}, ip: @{:#x@}".format(self.variable, ip)
+... else:
+... return None
+...
+>>> import gdb.ptwrite
+>>> gdb.ptwrite.register_listener(my_listener())
+>>>
+(gdb) record function-call-history 59,64
+59 pthread_create@@GLIBC_2.2.5
+60 job()
+61 task(void*)
+62 ptwrite64(unsigned long)
+ [payload: 1, ip: 0x401156]
+63 task(void*)
+64 ptwrite32(unsigned int)
+ [payload: 2, ip: 0x40116c]
+(gdb) info threads
+* 1 Thread 0x7ffff7fd8740 (LWP 25796) "ptwrite_threads" task (arg=0x0)
+ at bin/ptwrite/ptwrite_threads.c:45
+ 2 Thread 0x7ffff6eb8700 (LWP 25797) "ptwrite_threads" task (arg=0x0)
+ at bin/ptwrite/ptwrite_threads.c:45
+(gdb) thread 2
+[Switching to thread 2 (Thread 0x7ffff6eb8700 (LWP 25797))]
+#0 task (arg=0x0) at ptwrite_threads.c:45
+45 return NULL;
+(gdb) record function-call-history 10,14
+10 start_thread
+11 task(void*)
+12 ptwrite64(unsigned long)
+13 task(void*)
+14 ptwrite32(unsigned int)
+@end group
+@end smallexample
+
+This GDB feature is dependent on hardware and operating system support and
+requires the Intel Processor Trace decoder library in version 2.0.0 or newer.
diff --git a/gdb/testsuite/gdb.btrace/ptwrite.c b/gdb/testsuite/gdb.btrace/ptwrite.c
new file mode 100644
index 00000000000..f5ead4e7d89
--- /dev/null
+++ b/gdb/testsuite/gdb.btrace/ptwrite.c
@@ -0,0 +1,39 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+ Copyright 2021 Free Software Foundation, Inc.
+
+ 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/>. */
+
+#include <stdint.h>
+
+void
+ptwrite64 (uint64_t value)
+{
+ asm volatile ("PTWRITE %0;" : : "b" (value));
+}
+
+void
+ptwrite32 (uint32_t value)
+{
+ asm volatile ("PTWRITE %0;" : : "b" (value));
+}
+
+int
+main (void)
+{
+ ptwrite64 (0x42);
+ ptwrite32 (0x43);
+
+ return 0;
+}
diff --git a/gdb/testsuite/gdb.btrace/ptwrite.exp b/gdb/testsuite/gdb.btrace/ptwrite.exp
new file mode 100644
index 00000000000..2bbf0f41d3c
--- /dev/null
+++ b/gdb/testsuite/gdb.btrace/ptwrite.exp
@@ -0,0 +1,194 @@
+# This testcase is part of GDB, the GNU debugger.
+#
+# Copyright 2021 Free Software Foundation, Inc.
+#
+# 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/>.
+
+load_lib gdb-python.exp
+
+if { [skip_btrace_pt_tests] } {
+ unsupported "Target does not support record btrace pt."
+ return -1
+}
+
+if { [skip_btrace_ptw_tests] } {
+ unsupported "Hardware does not support ptwrite instructions."
+ return -1
+}
+
+# Test libipt version (must be >= 2.0.0).
+if {[require_libipt_version 2 0 0]} {
+ unsupported "Libipt doesn't support ptwrite decoding."
+ return -1
+}
+
+set opts {}
+
+if [info exists COMPILE] {
+ # make check RUNTESTFLAGS="gdb.btrace/ptwrite.exp COMPILE=1"
+ standard_testfile ptwrite.c
+ lappend opts debug
+} else {
+ if {[is_amd64_regs_target]} {
+ standard_testfile x86_64-ptwrite.S
+ } else {
+ unsupported "target architecture not supported"
+ return -1
+ }
+}
+
+if [prepare_for_testing "failed to prepare" $testfile $srcfile $opts] {
+ return -1
+}
+
+if { ![runto_main] } {
+ untested "failed to run to main"
+ return -1
+}
+
+# This needs to be after runto_main
+if { [skip_python_tests] } {
+ unsupported "Configuration doesn't support python scripting."
+ return -1
+}
+
+
+### 1. Default testrun
+
+# Setup recording
+gdb_test_no_output "set record instruction-history-size unlimited" "Default: set unlimited"
+gdb_test_no_output "record btrace pt" "Default: record btrace pt"
+gdb_test "next" ".*" "Default: first next"
+gdb_test "next" ".*" "Default: second next"
+
+# Test record instruction-history
+gdb_test "record instruction-history 1" [multi_line \
+ ".*\[0-9\]+\t $hex <ptwrite64\\+\[0-9\]+>:\tptwrite %\[a-z\]+" \
+ "\[0-9\]+\t \\\[42\\\]" \
+ ".*\[0-9\]+\t $hex <ptwrite32\\+\[0-9\]+>:\tptwrite %\[a-z\]+" \
+ "\[0-9\]+\t \\\[43\\\].*" \
+ ] "Default: record instruction-history 1"
+
+gdb_test "record instruction-history /a 1" [multi_line \
+ ".*\[0-9\]+\t $hex <ptwrite64\\+\[0-9\]+>:\tptwrite %\[a-z\]+" \
+ ".*\[0-9\]+\t $hex <ptwrite32\\+\[0-9\]+>:\tptwrite %\[a-z\]+.*" \
+ ] "Default: record instruction-history /a 1"
+
+# Test function call history
+gdb_test "record function-call-history 1,4" [multi_line \
+ "1\tmain" \
+ "2\tptwrite64" \
+ "\t\t\\\[42\\\]" \
+ "3\tmain" \
+ "4\tptwrite32" \
+ "\t\t\\\[43\\\]" \
+ ] "Default: record function-call-history 1,4"
+
+gdb_test "record function-call-history /a 1,4" [multi_line \
+ "1\tmain" \
+ "2\tptwrite64" \
+ "3\tmain" \
+ "4\tptwrite32" \
+ ] "Default: record function-call-history /a 1,4"
+
+# Test payload printing during stepping
+gdb_test "record goto 10" "No such instruction\."
+gdb_test "record goto 9" ".*ptwrite64.* at .*ptwrite.c:23.*"
+gdb_test "stepi" ".*\\\[42\\\].*"
+gdb_test "reverse-stepi" ".*\\\[42\\\].*"
+gdb_test "continue" ".*\\\[42\\\].*\\\[43\\\].*"
+gdb_test "reverse-continue" ".*\\\[43\\\].*\\\[42\\\].*"
+
+# Test auxiliary type in python
+gdb_test_multiline "auxiliary type in python" \
+ "python" "" \
+ "h = gdb.current_recording().instruction_history" "" \
+ "for insn in h: print(insn)" "" \
+ "end" [multi_line \
+ ".*RecordAuxiliary.*" \
+ ".*RecordAuxiliary.*" \
+ ]
+
+
+### 2. Test listener registration
+### 2.1 Custom listener
+
+gdb_test_multiline "Custom: register listener in python" \
+ "python" "" \
+ "def my_listener(payload, ip):" "" \
+ " if payload == 66:" "" \
+ " return \"payload: {0}, ip: {1:#x}\".format(payload, ip)" "" \
+ " else:" "" \
+ " return None" "" \
+ "import gdb.ptwrite" "" \
+ "gdb.ptwrite.register_listener(my_listener)" "" \
+ "end" ""
+
+gdb_test "record instruction-history 1" [multi_line \
+ ".*\[0-9\]+\t $hex <ptwrite64\\+\[0-9\]+>:\tptwrite %\[a-z\]+" \
+ "\[0-9\]+\t \\\[payload: 66, ip: $hex\\\]" \
+ ".*\[0-9\]+\t $hex <ptwrite32\\+\[0-9\]+>:\tptwrite %\[a-z\]+" \
+ "\[0-9\]+\t $hex <ptwrite32\\+\[0-9\]+>:.*" \
+ ] "Custom: record instruction-history 1"
+
+### 2.2 None as listener
+
+gdb_test_multiline "None: register listener in python" \
+ "python" "" \
+ "import gdb.ptwrite" "" \
+ "gdb.ptwrite.register_listener(None)" "" \
+ "end" ""
+
+gdb_test "record instruction-history 1" [multi_line \
+ ".*\[0-9\]+\t $hex <ptwrite64\\+\[0-9\]+>:\tptwrite %\[a-z\]+" \
+ "\[0-9\]+\t $hex <ptwrite64\\+\[0-9\]+>:.*" \
+ "\[0-9\]+\t $hex <ptwrite32\\+\[0-9\]+>:\tptwrite %\[a-z\]+" \
+ "\[0-9\]+\t $hex <ptwrite32\\+\[0-9\]+>:.*" \
+ ] "None: record instruction-history 1"
+
+### 2.3 Lambdas as listener
+
+gdb_test_multiline "Lambdas: register listener in python" \
+ "python" "" \
+ "import gdb.ptwrite" "" \
+ "gdb.ptwrite.register_listener(lambda payload, ip: \"{}\".format(payload + 2))" "" \
+ "end" ""
+
+gdb_test "record instruction-history 1" [multi_line \
+ ".*\[0-9\]+\t $hex <ptwrite64\\+\[0-9\]+>:\tptwrite %\[a-z\]+" \
+ "\[0-9\]+\t \\\[68\\\]" \
+ ".*\[0-9\]+\t $hex <ptwrite32\\+\[0-9\]+>:\tptwrite %\[a-z\]+" \
+ "\[0-9\]+\t \\\[69\\\].*" \
+ ] "Lambdas: record instruction-history 1"
+
+### 2.4 Functors as listener
+
+gdb_test_multiline "Functors: register listener in python" \
+ "python" "" \
+ "import gdb.ptwrite" "" \
+ "class foobar(object):" "" \
+ " def __init__(self):" "" \
+ " self.variable = 0" "" \
+ " def __call__(self, payload, ip):" "" \
+ " self.variable += 1" "" \
+ " return \"{}, {}\".format(self.variable, payload)" "" \
+ "gdb.ptwrite.register_listener(foobar())" "" \
+ "end" ""
+
+gdb_test "record instruction-history 1" [multi_line \
+ ".*\[0-9\]+\t $hex <ptwrite64\\+\[0-9\]+>:\tptwrite %\[a-z\]+" \
+ "\[0-9\]+\t \\\[1, 66\\\]" \
+ ".*\[0-9\]+\t $hex <ptwrite32\\+\[0-9\]+>:\tptwrite %\[a-z\]+" \
+ "\[0-9\]+\t \\\[2, 67\\\].*" \
+ ] "Functors: record instruction-history 1"
diff --git a/gdb/testsuite/gdb.btrace/x86_64-ptwrite.S b/gdb/testsuite/gdb.btrace/x86_64-ptwrite.S
new file mode 100644
index 00000000000..0411870eca4
--- /dev/null
+++ b/gdb/testsuite/gdb.btrace/x86_64-ptwrite.S
@@ -0,0 +1,479 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+ Copyright 2021 Free Software Foundation, Inc.
+
+ 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/>.
+
+
+ This file has been generated using gcc version 8.1.1 20180502:
+ gcc -S -dA -g ptwrite.c -o x86_64-ptwrite.S. */
+
+ .file "ptwrite.c"
+ .text
+.Ltext0:
+ .globl ptwrite64
+ .type ptwrite64, @function
+ptwrite64:
+.LFB0:
+ .file 1 "ptwrite.c"
+ # ptwrite.c:22:1
+ .loc 1 22 1
+ .cfi_startproc
+# BLOCK 2 seq:0
+# PRED: ENTRY (FALLTHRU)
+ pushq %rbp
+ .cfi_def_cfa_offset 16
+ .cfi_offset 6, -16
+ movq %rsp, %rbp
+ .cfi_def_cfa_register 6
+ pushq %rbx
+ .cfi_offset 3, -24
+ movq %rdi, -16(%rbp)
+ # ptwrite.c:23:3
+ .loc 1 23 3
+ movq -16(%rbp), %rax
+ movq %rax, %rbx
+#APP
+# 23 "ptwrite.c" 1
+ PTWRITE %rbx;
+# 0 "" 2
+ # ptwrite.c:24:1
+ .loc 1 24 1
+#NO_APP
+ nop
+ popq %rbx
+ popq %rbp
+ .cfi_def_cfa 7, 8
+# SUCC: EXIT [always]
+ ret
+ .cfi_endproc
+.LFE0:
+ .size ptwrite64, .-ptwrite64
+ .globl ptwrite32
+ .type ptwrite32, @function
+ptwrite32:
+.LFB1:
+ # ptwrite.c:28:1
+ .loc 1 28 1
+ .cfi_startproc
+# BLOCK 2 seq:0
+# PRED: ENTRY (FALLTHRU)
+ pushq %rbp
+ .cfi_def_cfa_offset 16
+ .cfi_offset 6, -16
+ movq %rsp, %rbp
+ .cfi_def_cfa_register 6
+ pushq %rbx
+ .cfi_offset 3, -24
+ movl %edi, -12(%rbp)
+ # ptwrite.c:29:3
+ .loc 1 29 3
+ movl -12(%rbp), %eax
+ movl %eax, %ebx
+#APP
+# 29 "ptwrite.c" 1
+ PTWRITE %ebx;
+# 0 "" 2
+ # ptwrite.c:30:1
+ .loc 1 30 1
+#NO_APP
+ nop
+ popq %rbx
+ popq %rbp
+ .cfi_def_cfa 7, 8
+# SUCC: EXIT [always]
+ ret
+ .cfi_endproc
+.LFE1:
+ .size ptwrite32, .-ptwrite32
+ .globl main
+ .type main, @function
+main:
+.LFB2:
+ # ptwrite.c:34:1
+ .loc 1 34 1
+ .cfi_startproc
+# BLOCK 2 seq:0
+# PRED: ENTRY (FALLTHRU)
+ pushq %rbp
+ .cfi_def_cfa_offset 16
+ .cfi_offset 6, -16
+ movq %rsp, %rbp
+ .cfi_def_cfa_register 6
+ # ptwrite.c:36:3
+ .loc 1 36 3
+ movl $66, %edi
+ call ptwrite64
+ # ptwrite.c:37:3
+ .loc 1 37 3
+ movl $67, %edi
+ call ptwrite32
+ # ptwrite.c:39:10
+ .loc 1 39 10
+ movl $0, %eax
+ # ptwrite.c:40:1
+ .loc 1 40 1
+ popq %rbp
+ .cfi_def_cfa 7, 8
+# SUCC: EXIT [always]
+ ret
+ .cfi_endproc
+.LFE2:
+ .size main, .-main
+.Letext0:
+ .file 2 "/usr/include/bits/types.h"
+ .file 3 "/usr/include/bits/stdint-uintn.h"
+ .section .debug_info,"",@progbits
+.Ldebug_info0:
+ .long 0x10f # Length of Compilation Unit Info
+ .value 0x4 # DWARF version number
+ .long .Ldebug_abbrev0 # Offset Into Abbrev. Section
+ .byte 0x8 # Pointer Size (in bytes)
+ .uleb128 0x1 # (DIE (0xb) DW_TAG_compile_unit)
+ .long .LASF13 # DW_AT_producer: "GNU C17 8.1.1 20180502 (Red Hat 8.1.1-1) -mtune=generic -march=x86-64 -g"
+ .byte 0xc # DW_AT_language
+ .long .LASF14 # DW_AT_name: "ptwrite.c"
+ .long .LASF15 # DW_AT_comp_dir: "gdb/gdb/testsuite/gdb.btrace"
+ .quad .Ltext0 # DW_AT_low_pc
+ .quad .Letext0-.Ltext0 # DW_AT_high_pc
+ .long .Ldebug_line0 # DW_AT_stmt_list
+ .uleb128 0x2 # (DIE (0x2d) DW_TAG_base_type)
+ .byte 0x1 # DW_AT_byte_size
+ .byte 0x8 # DW_AT_encoding
+ .long .LASF0 # DW_AT_name: "unsigned char"
+ .uleb128 0x2 # (DIE (0x34) DW_TAG_base_type)
+ .byte 0x2 # DW_AT_byte_size
+ .byte 0x7 # DW_AT_encoding
+ .long .LASF1 # DW_AT_name: "short unsigned int"
+ .uleb128 0x2 # (DIE (0x3b) DW_TAG_base_type)
+ .byte 0x4 # DW_AT_byte_size
+ .byte 0x7 # DW_AT_encoding
+ .long .LASF2 # DW_AT_name: "unsigned int"
+ .uleb128 0x2 # (DIE (0x42) DW_TAG_base_type)
+ .byte 0x8 # DW_AT_byte_size
+ .byte 0x7 # DW_AT_encoding
+ .long .LASF3 # DW_AT_name: "long unsigned int"
+ .uleb128 0x2 # (DIE (0x49) DW_TAG_base_type)
+ .byte 0x1 # DW_AT_byte_size
+ .byte 0x6 # DW_AT_encoding
+ .long .LASF4 # DW_AT_name: "signed char"
+ .uleb128 0x2 # (DIE (0x50) DW_TAG_base_type)
+ .byte 0x2 # DW_AT_byte_size
+ .byte 0x5 # DW_AT_encoding
+ .long .LASF5 # DW_AT_name: "short int"
+ .uleb128 0x3 # (DIE (0x57) DW_TAG_base_type)
+ .byte 0x4 # DW_AT_byte_size
+ .byte 0x5 # DW_AT_encoding
+ .ascii "int\0" # DW_AT_name
+ .uleb128 0x4 # (DIE (0x5e) DW_TAG_typedef)
+ .long .LASF7 # DW_AT_name: "__uint32_t"
+ .byte 0x2 # DW_AT_decl_file (/usr/include/bits/types.h)
+ .byte 0x29 # DW_AT_decl_line
+ .byte 0x16 # DW_AT_decl_column
+ .long 0x3b # DW_AT_type
+ .uleb128 0x2 # (DIE (0x6a) DW_TAG_base_type)
+ .byte 0x8 # DW_AT_byte_size
+ .byte 0x5 # DW_AT_encoding
+ .long .LASF6 # DW_AT_name: "long int"
+ .uleb128 0x4 # (DIE (0x71) DW_TAG_typedef)
+ .long .LASF8 # DW_AT_name: "__uint64_t"
+ .byte 0x2 # DW_AT_decl_file (/usr/include/bits/types.h)
+ .byte 0x2c # DW_AT_decl_line
+ .byte 0x1b # DW_AT_decl_column
+ .long 0x42 # DW_AT_type
+ .uleb128 0x2 # (DIE (0x7d) DW_TAG_base_type)
+ .byte 0x1 # DW_AT_byte_size
+ .byte 0x6 # DW_AT_encoding
+ .long .LASF9 # DW_AT_name: "char"
+ .uleb128 0x4 # (DIE (0x84) DW_TAG_typedef)
+ .long .LASF10 # DW_AT_name: "uint32_t"
+ .byte 0x3 # DW_AT_decl_file (/usr/include/bits/stdint-uintn.h)
+ .byte 0x1a # DW_AT_decl_line
+ .byte 0x14 # DW_AT_decl_column
+ .long 0x5e # DW_AT_type
+ .uleb128 0x4 # (DIE (0x90) DW_TAG_typedef)
+ .long .LASF11 # DW_AT_name: "uint64_t"
+ .byte 0x3 # DW_AT_decl_file (/usr/include/bits/stdint-uintn.h)
+ .byte 0x1b # DW_AT_decl_line
+ .byte 0x14 # DW_AT_decl_column
+ .long 0x71 # DW_AT_type
+ .uleb128 0x5 # (DIE (0x9c) DW_TAG_subprogram)
+ # DW_AT_external
+ .long .LASF16 # DW_AT_name: "main"
+ .byte 0x1 # DW_AT_decl_file (ptwrite.c)
+ .byte 0x21 # DW_AT_decl_line
+ .byte 0x1 # DW_AT_decl_column
+ # DW_AT_prototyped
+ .long 0x57 # DW_AT_type
+ .quad .LFB2 # DW_AT_low_pc
+ .quad .LFE2-.LFB2 # DW_AT_high_pc
+ .uleb128 0x1 # DW_AT_frame_base
+ .byte 0x9c # DW_OP_call_frame_cfa
+ # DW_AT_GNU_all_tail_call_sites
+ .uleb128 0x6 # (DIE (0xba) DW_TAG_subprogram)
+ # DW_AT_external
+ .long .LASF17 # DW_AT_name: "ptwrite32"
+ .byte 0x1 # DW_AT_decl_file (ptwrite.c)
+ .byte 0x1b # DW_AT_decl_line
+ .byte 0x1 # DW_AT_decl_column
+ # DW_AT_prototyped
+ .quad .LFB1 # DW_AT_low_pc
+ .quad .LFE1-.LFB1 # DW_AT_high_pc
+ .uleb128 0x1 # DW_AT_frame_base
+ .byte 0x9c # DW_OP_call_frame_cfa
+ # DW_AT_GNU_all_call_sites
+ .long 0xe8 # DW_AT_sibling
+ .uleb128 0x7 # (DIE (0xd8) DW_TAG_formal_parameter)
+ .long .LASF12 # DW_AT_name: "value"
+ .byte 0x1 # DW_AT_decl_file (ptwrite.c)
+ .byte 0x1b # DW_AT_decl_line
+ .byte 0x15 # DW_AT_decl_column
+ .long 0x84 # DW_AT_type
+ .uleb128 0x2 # DW_AT_location
+ .byte 0x91 # DW_OP_fbreg
+ .sleb128 -28
+ .byte 0 # end of children of DIE 0xba
+ .uleb128 0x8 # (DIE (0xe8) DW_TAG_subprogram)
+ # DW_AT_external
+ .long .LASF18 # DW_AT_name: "ptwrite64"
+ .byte 0x1 # DW_AT_decl_file (ptwrite.c)
+ .byte 0x15 # DW_AT_decl_line
+ .byte 0x1 # DW_AT_decl_column
+ # DW_AT_prototyped
+ .quad .LFB0 # DW_AT_low_pc
+ .quad .LFE0-.LFB0 # DW_AT_high_pc
+ .uleb128 0x1 # DW_AT_frame_base
+ .byte 0x9c # DW_OP_call_frame_cfa
+ # DW_AT_GNU_all_call_sites
+ .uleb128 0x7 # (DIE (0x102) DW_TAG_formal_parameter)
+ .long .LASF12 # DW_AT_name: "value"
+ .byte 0x1 # DW_AT_decl_file (ptwrite.c)
+ .byte 0x15 # DW_AT_decl_line
+ .byte 0x15 # DW_AT_decl_column
+ .long 0x90 # DW_AT_type
+ .uleb128 0x2 # DW_AT_location
+ .byte 0x91 # DW_OP_fbreg
+ .sleb128 -32
+ .byte 0 # end of children of DIE 0xe8
+ .byte 0 # end of children of DIE 0xb
+ .section .debug_abbrev,"",@progbits
+.Ldebug_abbrev0:
+ .uleb128 0x1 # (abbrev code)
+ .uleb128 0x11 # (TAG: DW_TAG_compile_unit)
+ .byte 0x1 # DW_children_yes
+ .uleb128 0x25 # (DW_AT_producer)
+ .uleb128 0xe # (DW_FORM_strp)
+ .uleb128 0x13 # (DW_AT_language)
+ .uleb128 0xb # (DW_FORM_data1)
+ .uleb128 0x3 # (DW_AT_name)
+ .uleb128 0xe # (DW_FORM_strp)
+ .uleb128 0x1b # (DW_AT_comp_dir)
+ .uleb128 0xe # (DW_FORM_strp)
+ .uleb128 0x11 # (DW_AT_low_pc)
+ .uleb128 0x1 # (DW_FORM_addr)
+ .uleb128 0x12 # (DW_AT_high_pc)
+ .uleb128 0x7 # (DW_FORM_data8)
+ .uleb128 0x10 # (DW_AT_stmt_list)
+ .uleb128 0x17 # (DW_FORM_sec_offset)
+ .byte 0
+ .byte 0
+ .uleb128 0x2 # (abbrev code)
+ .uleb128 0x24 # (TAG: DW_TAG_base_type)
+ .byte 0 # DW_children_no
+ .uleb128 0xb # (DW_AT_byte_size)
+ .uleb128 0xb # (DW_FORM_data1)
+ .uleb128 0x3e # (DW_AT_encoding)
+ .uleb128 0xb # (DW_FORM_data1)
+ .uleb128 0x3 # (DW_AT_name)
+ .uleb128 0xe # (DW_FORM_strp)
+ .byte 0
+ .byte 0
+ .uleb128 0x3 # (abbrev code)
+ .uleb128 0x24 # (TAG: DW_TAG_base_type)
+ .byte 0 # DW_children_no
+ .uleb128 0xb # (DW_AT_byte_size)
+ .uleb128 0xb # (DW_FORM_data1)
+ .uleb128 0x3e # (DW_AT_encoding)
+ .uleb128 0xb # (DW_FORM_data1)
+ .uleb128 0x3 # (DW_AT_name)
+ .uleb128 0x8 # (DW_FORM_string)
+ .byte 0
+ .byte 0
+ .uleb128 0x4 # (abbrev code)
+ .uleb128 0x16 # (TAG: DW_TAG_typedef)
+ .byte 0 # DW_children_no
+ .uleb128 0x3 # (DW_AT_name)
+ .uleb128 0xe # (DW_FORM_strp)
+ .uleb128 0x3a # (DW_AT_decl_file)
+ .uleb128 0xb # (DW_FORM_data1)
+ .uleb128 0x3b # (DW_AT_decl_line)
+ .uleb128 0xb # (DW_FORM_data1)
+ .uleb128 0x39 # (DW_AT_decl_column)
+ .uleb128 0xb # (DW_FORM_data1)
+ .uleb128 0x49 # (DW_AT_type)
+ .uleb128 0x13 # (DW_FORM_ref4)
+ .byte 0
+ .byte 0
+ .uleb128 0x5 # (abbrev code)
+ .uleb128 0x2e # (TAG: DW_TAG_subprogram)
+ .byte 0 # DW_children_no
+ .uleb128 0x3f # (DW_AT_external)
+ .uleb128 0x19 # (DW_FORM_flag_present)
+ .uleb128 0x3 # (DW_AT_name)
+ .uleb128 0xe # (DW_FORM_strp)
+ .uleb128 0x3a # (DW_AT_decl_file)
+ .uleb128 0xb # (DW_FORM_data1)
+ .uleb128 0x3b # (DW_AT_decl_line)
+ .uleb128 0xb # (DW_FORM_data1)
+ .uleb128 0x39 # (DW_AT_decl_column)
+ .uleb128 0xb # (DW_FORM_data1)
+ .uleb128 0x27 # (DW_AT_prototyped)
+ .uleb128 0x19 # (DW_FORM_flag_present)
+ .uleb128 0x49 # (DW_AT_type)
+ .uleb128 0x13 # (DW_FORM_ref4)
+ .uleb128 0x11 # (DW_AT_low_pc)
+ .uleb128 0x1 # (DW_FORM_addr)
+ .uleb128 0x12 # (DW_AT_high_pc)
+ .uleb128 0x7 # (DW_FORM_data8)
+ .uleb128 0x40 # (DW_AT_frame_base)
+ .uleb128 0x18 # (DW_FORM_exprloc)
+ .uleb128 0x2116 # (DW_AT_GNU_all_tail_call_sites)
+ .uleb128 0x19 # (DW_FORM_flag_present)
+ .byte 0
+ .byte 0
+ .uleb128 0x6 # (abbrev code)
+ .uleb128 0x2e # (TAG: DW_TAG_subprogram)
+ .byte 0x1 # DW_children_yes
+ .uleb128 0x3f # (DW_AT_external)
+ .uleb128 0x19 # (DW_FORM_flag_present)
+ .uleb128 0x3 # (DW_AT_name)
+ .uleb128 0xe # (DW_FORM_strp)
+ .uleb128 0x3a # (DW_AT_decl_file)
+ .uleb128 0xb # (DW_FORM_data1)
+ .uleb128 0x3b # (DW_AT_decl_line)
+ .uleb128 0xb # (DW_FORM_data1)
+ .uleb128 0x39 # (DW_AT_decl_column)
+ .uleb128 0xb # (DW_FORM_data1)
+ .uleb128 0x27 # (DW_AT_prototyped)
+ .uleb128 0x19 # (DW_FORM_flag_present)
+ .uleb128 0x11 # (DW_AT_low_pc)
+ .uleb128 0x1 # (DW_FORM_addr)
+ .uleb128 0x12 # (DW_AT_high_pc)
+ .uleb128 0x7 # (DW_FORM_data8)
+ .uleb128 0x40 # (DW_AT_frame_base)
+ .uleb128 0x18 # (DW_FORM_exprloc)
+ .uleb128 0x2117 # (DW_AT_GNU_all_call_sites)
+ .uleb128 0x19 # (DW_FORM_flag_present)
+ .uleb128 0x1 # (DW_AT_sibling)
+ .uleb128 0x13 # (DW_FORM_ref4)
+ .byte 0
+ .byte 0
+ .uleb128 0x7 # (abbrev code)
+ .uleb128 0x5 # (TAG: DW_TAG_formal_parameter)
+ .byte 0 # DW_children_no
+ .uleb128 0x3 # (DW_AT_name)
+ .uleb128 0xe # (DW_FORM_strp)
+ .uleb128 0x3a # (DW_AT_decl_file)
+ .uleb128 0xb # (DW_FORM_data1)
+ .uleb128 0x3b # (DW_AT_decl_line)
+ .uleb128 0xb # (DW_FORM_data1)
+ .uleb128 0x39 # (DW_AT_decl_column)
+ .uleb128 0xb # (DW_FORM_data1)
+ .uleb128 0x49 # (DW_AT_type)
+ .uleb128 0x13 # (DW_FORM_ref4)
+ .uleb128 0x2 # (DW_AT_location)
+ .uleb128 0x18 # (DW_FORM_exprloc)
+ .byte 0
+ .byte 0
+ .uleb128 0x8 # (abbrev code)
+ .uleb128 0x2e # (TAG: DW_TAG_subprogram)
+ .byte 0x1 # DW_children_yes
+ .uleb128 0x3f # (DW_AT_external)
+ .uleb128 0x19 # (DW_FORM_flag_present)
+ .uleb128 0x3 # (DW_AT_name)
+ .uleb128 0xe # (DW_FORM_strp)
+ .uleb128 0x3a # (DW_AT_decl_file)
+ .uleb128 0xb # (DW_FORM_data1)
+ .uleb128 0x3b # (DW_AT_decl_line)
+ .uleb128 0xb # (DW_FORM_data1)
+ .uleb128 0x39 # (DW_AT_decl_column)
+ .uleb128 0xb # (DW_FORM_data1)
+ .uleb128 0x27 # (DW_AT_prototyped)
+ .uleb128 0x19 # (DW_FORM_flag_present)
+ .uleb128 0x11 # (DW_AT_low_pc)
+ .uleb128 0x1 # (DW_FORM_addr)
+ .uleb128 0x12 # (DW_AT_high_pc)
+ .uleb128 0x7 # (DW_FORM_data8)
+ .uleb128 0x40 # (DW_AT_frame_base)
+ .uleb128 0x18 # (DW_FORM_exprloc)
+ .uleb128 0x2117 # (DW_AT_GNU_all_call_sites)
+ .uleb128 0x19 # (DW_FORM_flag_present)
+ .byte 0
+ .byte 0
+ .byte 0
+ .section .debug_aranges,"",@progbits
+ .long 0x2c # Length of Address Ranges Info
+ .value 0x2 # DWARF aranges version
+ .long .Ldebug_info0 # Offset of Compilation Unit Info
+ .byte 0x8 # Size of Address
+ .byte 0 # Size of Segment Descriptor
+ .value 0 # Pad to 16 byte boundary
+ .value 0
+ .quad .Ltext0 # Address
+ .quad .Letext0-.Ltext0 # Length
+ .quad 0
+ .quad 0
+ .section .debug_line,"",@progbits
+.Ldebug_line0:
+ .section .debug_str,"MS",@progbits,1
+.LASF2:
+ .string "unsigned int"
+.LASF7:
+ .string "__uint32_t"
+.LASF15:
+ .string "gdb/gdb/testsuite/gdb.btrace"
+.LASF14:
+ .string "ptwrite.c"
+.LASF18:
+ .string "ptwrite64"
+.LASF3:
+ .string "long unsigned int"
+.LASF11:
+ .string "uint64_t"
+.LASF0:
+ .string "unsigned char"
+.LASF16:
+ .string "main"
+.LASF10:
+ .string "uint32_t"
+.LASF6:
+ .string "long int"
+.LASF8:
+ .string "__uint64_t"
+.LASF13:
+ .string "GNU C17 8.1.1 20180502 (Red Hat 8.1.1-1) -mtune=generic -march=x86-64 -g"
+.LASF1:
+ .string "short unsigned int"
+.LASF4:
+ .string "signed char"
+.LASF12:
+ .string "value"
+.LASF5:
+ .string "short int"
+.LASF17:
+ .string "ptwrite32"
+.LASF9:
+ .string "char"
+ .ident "GCC: (GNU) 8.1.1 20180502 (Red Hat 8.1.1-1)"
+ .section .note.GNU-stack,"",@progbits
diff --git a/gdb/testsuite/lib/gdb.exp b/gdb/testsuite/lib/gdb.exp
index d77fac5ae3a..04eed432e03 100644
--- a/gdb/testsuite/lib/gdb.exp
+++ b/gdb/testsuite/lib/gdb.exp
@@ -3457,6 +3457,88 @@ gdb_caching_proc skip_btrace_pt_tests {
return $skip_btrace_tests
}

+# Run a test on the target to see if it supports ptwrite instructions.
+# Return 0 if so, 1 if it does not. Based on 'check_vmx_hw_available'
+# from the GCC testsuite.
+
+gdb_caching_proc skip_btrace_ptw_tests {
+ global srcdir subdir gdb_prompt inferior_exited_re
+ set me "skip_ptw_tests"
+
+ set src {
+ #include <stdbool.h>
+ #include <stdio.h>
+
+ bool
+ linux_supports_ptwrite ()
+ {
+ static const char filename[]
+ = "/sys/bus/event_source/devices/intel_pt/caps/ptwrite";
+ FILE *file = fopen (filename, "r");
+
+ if (file == NULL)
+ return false;
+
+ int status, found = fscanf (file, "%d", &status);
+ fclose (file);
+
+ if (found != 1)
+ return false;
+
+ return status == 1;
+ }
+
+ int
+ main ()
+ {
+ if (linux_supports_ptwrite ())
+ {
+ asm volatile("PTWRITE %0;" : : "b"(0x42));
+ return 1;
+ };
+
+ return 0;
+ }
+ }
+
+ if {![gdb_simple_compile $me $src executable]} {
+ return 1
+ }
+
+ # No error message, compilation succeeded so now run it via gdb.
+
+ gdb_exit
+ gdb_start
+ gdb_reinitialize_dir $srcdir/$subdir
+ gdb_load "$obj"
+ gdb_run_cmd
+
+ gdb_expect {
+ -re ".*Illegal instruction.*${gdb_prompt} $" {
+ verbose -log "$me: ptwrite support not detected."
+ set skip_ptw_tests 1
+ }
+ -re ".*$inferior_exited_re normally.*${gdb_prompt} $" {
+ verbose -log "$me: ptwrite support not detected."
+ set skip_ptw_tests 1
+ }
+ -re ".*exited with code 01.*${gdb_prompt} $" {
+ verbose -log "$me: ptwrite support detected."
+ set skip_ptw_tests 0
+ }
+ default {
+ warning "\n$me: default case taken."
+ set skip_ptw_tests 1
+ }
+ }
+
+ gdb_exit
+ remote_file build delete $obj
+
+ verbose "$me: returning $skip_ptw_tests" 2
+ return $skip_ptw_tests
+}
+
# Run a test on the target to see if we have a minimum libipt version.
# Return 0 if so, 1 if it does not.