From 0c6b04823623a6bd121f8c4b80087fe204742b0b Mon Sep 17 00:00:00 2001 From: Pedro Alves Date: Mon, 22 May 2023 17:33:16 +0100 Subject: Windows gdb+gdbserver: Make siginfo_er per-thread state 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. Change-Id: I5d4f1b62f59e8aef3606642c6524df2362b0fb7d --- gdb/nat/windows-nat.c | 2 -- gdb/nat/windows-nat.h | 3 --- gdb/windows-nat.c | 33 ++++++++++++++++----------------- gdbserver/win32-low.cc | 28 +++++++++++++++------------- 4 files changed, 31 insertions(+), 35 deletions(-) diff --git a/gdb/nat/windows-nat.c b/gdb/nat/windows-nat.c index 5760431..d43d549 100644 --- a/gdb/nat/windows-nat.c +++ b/gdb/nat/windows-nat.c @@ -367,8 +367,6 @@ 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 aab76d6..86ad8d0 100644 --- a/gdb/nat/windows-nat.h +++ b/gdb/nat/windows-nat.h @@ -146,9 +146,6 @@ 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 3b01f50..0064444 100644 --- a/gdb/windows-nat.c +++ b/gdb/windows-nat.c @@ -2993,7 +2993,6 @@ 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 (); } @@ -3110,8 +3109,15 @@ 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; @@ -3120,23 +3126,16 @@ 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 40575e3..5560091 100644 --- a/gdbserver/win32-low.cc +++ b/gdbserver/win32-low.cc @@ -675,7 +675,6 @@ win32_clear_inferiors (void) } for_each_thread (delete_thread_info); - windows_process.siginfo_er.ExceptionCode = 0; clear_inferiors (); } @@ -1306,14 +1305,19 @@ 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_ptid ()); + + 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; @@ -1322,17 +1326,15 @@ 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 -- cgit v1.1