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Fri, 24 Apr 2026 13:46:15 -0700 (PDT) Received: from localhost ([2001:8a0:facb:a800:7315:8865:c664:fc06]) by smtp.gmail.com with UTF8SMTPSA id 5b1f17b1804b1-48a59816b71sm134639715e9.1.2026.04.24.13.46.14 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 24 Apr 2026 13:46:15 -0700 (PDT) From: Pedro Alves To: gdb-patches@sourceware.org Cc: Tom Tromey Subject: [pushed 21/28] Windows gdb+gdbserver: Make siginfo_er per-thread state Date: Fri, 24 Apr 2026 21:45:01 +0100 Message-ID: <20260424204508.1343973-22-pedro@palves.net> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260424204508.1343973-1-pedro@palves.net> References: <20260424204508.1343973-1-pedro@palves.net> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-BeenThere: gdb-patches@sourceware.org X-Mailman-Version: 2.1.30 Precedence: list List-Id: Gdb-patches mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: gdb-patches-bounces~public-inbox=simark.ca@sourceware.org With non-stop mode support, each thread has its own "last event", and so printing $_siginfo should print the siginfo of the selected thread. Likewise, with all-stop and scheduler-locking. This patch reworks the siginfo functions in gdb/windows-nat.c and gdbserver/win32-low.cc to reuse the exception record already saved within each thread's 'last_event' field. Here's an example of what you'll see after the whole non-stop series: (gdb) thread apply all p -pretty -- $_siginfo Thread 3 (Thread 2612.0x1470): $1 = { ExceptionCode = DBG_CONTROL_C, ExceptionFlags = 0, ExceptionRecord = 0x0, ExceptionAddress = 0x7ffd0583e929 , NumberParameters = 0, { ExceptionInformation = {0 }, AccessViolationInformation = { Type = READ_ACCESS_VIOLATION, Address = 0x0 } } } Thread 2 (Thread 2612.0x1704): $2 = { ExceptionCode = SINGLE_STEP, ExceptionFlags = 0, ExceptionRecord = 0x0, ExceptionAddress = 0x7ffd080ad6e4 , NumberParameters = 0, { ExceptionInformation = {0 }, AccessViolationInformation = { Type = READ_ACCESS_VIOLATION, Address = 0x0 } } } Thread 1 (Thread 2612.0x434): $3 = { ExceptionCode = BREAKPOINT, ExceptionFlags = 0, ExceptionRecord = 0x0, ExceptionAddress = 0x7ff6f691174c , NumberParameters = 1, { ExceptionInformation = {0 }, AccessViolationInformation = { Type = READ_ACCESS_VIOLATION, Address = 0x0 } } } (gdb) This was in non-stop mode, and the program originally had two threads. Thread 1 stopped for a breakpoint, then thread 2 was manually interrupted/paused and then single-stepped. And then I typed Ctrl-C in the inferior's terminal, which made Windows inject thread 3 in the inferior, and report a DBG_CONTROL_C exception for it. Approved-By: Tom Tromey Change-Id: I5d4f1b62f59e8aef3606642c6524df2362b0fb7d commit-id:e0f75dea --- gdb/nat/windows-nat.c | 2 -- gdb/nat/windows-nat.h | 3 --- gdb/windows-nat.c | 33 ++++++++++++++++----------------- gdbserver/win32-low.cc | 27 ++++++++++++++------------- 4 files changed, 30 insertions(+), 35 deletions(-) diff --git a/gdb/nat/windows-nat.c b/gdb/nat/windows-nat.c index 7eff99170fc..1f8967dcd8d 100644 --- a/gdb/nat/windows-nat.c +++ b/gdb/nat/windows-nat.c @@ -357,8 +357,6 @@ windows_process_info::handle_exception (DEBUG_EVENT ¤t_event, DWORD code = rec->ExceptionCode; handle_exception_result result = HANDLE_EXCEPTION_HANDLED; - memcpy (&siginfo_er, rec, sizeof siginfo_er); - switch (code) { case EXCEPTION_ACCESS_VIOLATION: diff --git a/gdb/nat/windows-nat.h b/gdb/nat/windows-nat.h index 8555085c9f7..152410580f0 100644 --- a/gdb/nat/windows-nat.h +++ b/gdb/nat/windows-nat.h @@ -152,9 +152,6 @@ struct windows_process_info DWORD process_id = 0; DWORD main_thread_id = 0; - /* Contents of $_siginfo */ - EXCEPTION_RECORD siginfo_er {}; - #ifdef __x86_64__ /* The target is a WOW64 process */ bool wow64_process = false; diff --git a/gdb/windows-nat.c b/gdb/windows-nat.c index b5e80139c26..1593524f900 100644 --- a/gdb/windows-nat.c +++ b/gdb/windows-nat.c @@ -2336,7 +2336,6 @@ windows_nat_target::mourn_inferior () CHECK (CloseHandle (windows_process->handle)); windows_process->open_process_used = 0; } - windows_process->siginfo_er.ExceptionCode = 0; inf_child_target::mourn_inferior (); } @@ -2453,8 +2452,15 @@ static enum target_xfer_status windows_xfer_siginfo (gdb_byte *readbuf, ULONGEST offset, ULONGEST len, ULONGEST *xfered_len) { - char *buf = (char *) &windows_process->siginfo_er; - size_t bufsize = sizeof (windows_process->siginfo_er); + windows_thread_info *th = windows_process->find_thread (inferior_ptid); + + if (th->last_event.dwDebugEventCode != EXCEPTION_DEBUG_EVENT) + return TARGET_XFER_E_IO; + + EXCEPTION_RECORD &er = th->last_event.u.Exception.ExceptionRecord; + + char *buf = (char *) &er; + size_t bufsize = sizeof (er); #ifdef __x86_64__ EXCEPTION_RECORD32 er32; @@ -2463,23 +2469,16 @@ windows_xfer_siginfo (gdb_byte *readbuf, ULONGEST offset, ULONGEST len, buf = (char *) &er32; bufsize = sizeof (er32); - er32.ExceptionCode = windows_process->siginfo_er.ExceptionCode; - er32.ExceptionFlags = windows_process->siginfo_er.ExceptionFlags; - er32.ExceptionRecord - = (uintptr_t) windows_process->siginfo_er.ExceptionRecord; - er32.ExceptionAddress - = (uintptr_t) windows_process->siginfo_er.ExceptionAddress; - er32.NumberParameters = windows_process->siginfo_er.NumberParameters; - int i; - for (i = 0; i < EXCEPTION_MAXIMUM_PARAMETERS; i++) - er32.ExceptionInformation[i] - = windows_process->siginfo_er.ExceptionInformation[i]; + er32.ExceptionCode = er.ExceptionCode; + er32.ExceptionFlags = er.ExceptionFlags; + er32.ExceptionRecord = (uintptr_t) er.ExceptionRecord; + er32.ExceptionAddress = (uintptr_t) er.ExceptionAddress; + er32.NumberParameters = er.NumberParameters; + for (int i = 0; i < EXCEPTION_MAXIMUM_PARAMETERS; i++) + er32.ExceptionInformation[i] = er.ExceptionInformation[i]; } #endif - if (windows_process->siginfo_er.ExceptionCode == 0) - return TARGET_XFER_E_IO; - if (readbuf == nullptr) return TARGET_XFER_E_IO; diff --git a/gdbserver/win32-low.cc b/gdbserver/win32-low.cc index 5e09779082c..cc4a63319ef 100644 --- a/gdbserver/win32-low.cc +++ b/gdbserver/win32-low.cc @@ -643,7 +643,6 @@ win32_clear_process () } for_each_thread (delete_thread_info); - windows_process.siginfo_er.ExceptionCode = 0; } /* Implementation of target_ops::kill. */ @@ -1271,14 +1270,18 @@ win32_process_target::qxfer_siginfo (const char *annex, unsigned const char *writebuf, CORE_ADDR offset, int len) { - if (windows_process.siginfo_er.ExceptionCode == 0) + windows_thread_info *th = windows_process.find_thread (current_thread->id); + + if (th->last_event.dwDebugEventCode != EXCEPTION_DEBUG_EVENT) return -1; if (readbuf == nullptr) return -1; - char *buf = (char *) &windows_process.siginfo_er; - size_t bufsize = sizeof (windows_process.siginfo_er); + EXCEPTION_RECORD &er = th->last_event.u.Exception.ExceptionRecord; + + char *buf = (char *) &er; + size_t bufsize = sizeof (er); #ifdef __x86_64__ EXCEPTION_RECORD32 er32; @@ -1287,17 +1290,15 @@ win32_process_target::qxfer_siginfo (const char *annex, buf = (char *) &er32; bufsize = sizeof (er32); - er32.ExceptionCode = windows_process.siginfo_er.ExceptionCode; - er32.ExceptionFlags = windows_process.siginfo_er.ExceptionFlags; + er32.ExceptionCode = er.ExceptionCode; + er32.ExceptionFlags = er.ExceptionFlags; er32.ExceptionRecord - = (uintptr_t) windows_process.siginfo_er.ExceptionRecord; + = (uintptr_t) er.ExceptionRecord; er32.ExceptionAddress - = (uintptr_t) windows_process.siginfo_er.ExceptionAddress; - er32.NumberParameters = windows_process.siginfo_er.NumberParameters; - int i; - for (i = 0; i < EXCEPTION_MAXIMUM_PARAMETERS; i++) - er32.ExceptionInformation[i] - = windows_process.siginfo_er.ExceptionInformation[i]; + = (uintptr_t) er.ExceptionAddress; + er32.NumberParameters = er.NumberParameters; + for (int i = 0; i < EXCEPTION_MAXIMUM_PARAMETERS; i++) + er32.ExceptionInformation[i] = er.ExceptionInformation[i]; } #endif -- 2.53.0