From 7b5e70a921a6c168459002e7a3a464791ae75cc2 Mon Sep 17 00:00:00 2001 From: Tom Tromey Date: Thu, 31 Mar 2022 07:55:09 -0600 Subject: [PATCH] Fix regression on Windows with WOW64 Internally at AdaCore, we recently started testing a 64-bit gdb debugging 32-bit processes. This failed with gdb head, but not with gdb 11. The tests fail like this: Starting program: [...].exe warning: Could not load shared library symbols for WOW64_IMAGE_SECTION. Do you need "set solib-search-path" or "set sysroot"? warning: Could not load shared library symbols for WOW64_IMAGE_SECTION. Do you need "set solib-search-path" or "set sysroot"? warning: Could not load shared library symbols for NOT_AN_IMAGE. Do you need "set solib-search-path" or "set sysroot"? warning: Could not load shared library symbols for NOT_AN_IMAGE. Do you need "set solib-search-path" or "set sysroot"? After some debugging and bisecting, to my surprise the bug was introduced by commit 183be222 ("gdb, gdbserver: make target_waitstatus safe"). The problem occurs in handle_exception. Previously the code did: - ourstatus->kind = TARGET_WAITKIND_STOPPED; [...] case EXCEPTION_BREAKPOINT: [...] - ourstatus->kind = TARGET_WAITKIND_SPURIOUS; [...] /* FALLTHROUGH */ case STATUS_WX86_BREAKPOINT: DEBUG_EXCEPTION_SIMPLE ("EXCEPTION_BREAKPOINT"); - ourstatus->value.sig = GDB_SIGNAL_TRAP; [...] - last_sig = ourstatus->value.sig; However, in the new code, the fallthrough case does: + ourstatus->set_stopped (GDB_SIGNAL_TRAP); ... which changes the 'kind' in 'ourstatus' after falling through. This patch rearranges the 'last_sig' setting to more closely match what was done before (this is probably not strictly needed but also seemed harmless), and removes the fall-through in the 'ignore_first_breakpoint' case when __x86_64__ is defined. --- gdb/nat/windows-nat.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/gdb/nat/windows-nat.c b/gdb/nat/windows-nat.c index 21445f3f859..27d7911a30e 100644 --- a/gdb/nat/windows-nat.c +++ b/gdb/nat/windows-nat.c @@ -201,6 +201,8 @@ handle_exception (struct target_waitstatus *ourstatus, bool debug_exceptions) thread_rec (ptid_t (current_event.dwProcessId, current_event.dwThreadId, 0), DONT_SUSPEND); + last_sig = GDB_SIGNAL_0; + switch (code) { case EXCEPTION_ACCESS_VIOLATION: @@ -261,8 +263,10 @@ handle_exception (struct target_waitstatus *ourstatus, bool debug_exceptions) on startup, first a BREAKPOINT for the 64bit ntdll.dll, then a WX86_BREAKPOINT for the 32bit ntdll.dll. Here we only care about the WX86_BREAKPOINT's. */ + DEBUG_EXCEPTION_SIMPLE ("EXCEPTION_BREAKPOINT - ignore_first_breakpoint"); ourstatus->set_spurious (); ignore_first_breakpoint = false; + break; } else if (wow64_process) { @@ -273,7 +277,7 @@ handle_exception (struct target_waitstatus *ourstatus, bool debug_exceptions) gdb lets the target process continue. So handle it as SIGINT instead, then the target is stopped unconditionally. */ - DEBUG_EXCEPTION_SIMPLE ("EXCEPTION_BREAKPOINT"); + DEBUG_EXCEPTION_SIMPLE ("EXCEPTION_BREAKPOINT - wow64_process"); rec->ExceptionCode = DBG_CONTROL_C; ourstatus->set_stopped (GDB_SIGNAL_INT); break; -- 2.47.2