From 99bb393f1d107cf2c4016c486f85625d362027a7 Mon Sep 17 00:00:00 2001 From: Hannes Domani Date: Wed, 23 Sep 2020 18:16:24 +0200 Subject: Handle 64bit breakpoints of WOW64 processes as SIGINT When a WOW64 process triggers a breakpoint exception in 64bit code (which happens when a 64bit gdb calls DebugBreakProcess for a 32bit target), gdb ignores the breakpoint (because Wow64GetThreadContext can only report the pc of 32bit code, and there is not int3 at this location). But if these 64bit breakpoint exceptions are handled as SIGINT, gdb doesn't check for int3, and always stops the target. gdb/ChangeLog: 2020-09-23 Hannes Domani * nat/windows-nat.c (handle_exception): Handle 64bit breakpoints in WOW64 processes as SIGINT. * nat/windows-nat.h: Make wow64_process a shared variable. * windows-nat.c: Remove static wow64_process variable. gdbserver/ChangeLog: 2020-09-23 Hannes Domani * win32-low.cc: Remove local wow64_process variable. * win32-low.h: Remove local wow64_process variable. --- gdb/ChangeLog | 7 +++++++ gdb/nat/windows-nat.c | 15 +++++++++++++++ gdb/nat/windows-nat.h | 2 ++ gdb/windows-nat.c | 1 - 4 files changed, 24 insertions(+), 1 deletion(-) (limited to 'gdb') diff --git a/gdb/ChangeLog b/gdb/ChangeLog index 241f3e7..3b851db 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,3 +1,10 @@ +2020-09-23 Hannes Domani + + * nat/windows-nat.c (handle_exception): Handle 64bit breakpoints + in WOW64 processes as SIGINT. + * nat/windows-nat.h: Make wow64_process a shared variable. + * windows-nat.c: Remove static wow64_process variable. + 2020-09-23 Tom Tromey PR symtab/25470: diff --git a/gdb/nat/windows-nat.c b/gdb/nat/windows-nat.c index be6db97..2cbbc0f 100644 --- a/gdb/nat/windows-nat.c +++ b/gdb/nat/windows-nat.c @@ -41,6 +41,7 @@ std::vector pending_stops; EXCEPTION_RECORD siginfo_er; #ifdef __x86_64__ +bool wow64_process = false; bool ignore_first_breakpoint = false; #endif @@ -240,6 +241,20 @@ handle_exception (struct target_waitstatus *ourstatus, bool debug_exceptions) ourstatus->kind = TARGET_WAITKIND_SPURIOUS; ignore_first_breakpoint = false; } + else if (wow64_process) + { + /* This breakpoint exception is triggered for WOW64 processes when + reaching an int3 instruction in 64bit code. + gdb checks for int3 in case of SIGTRAP, this fails because + Wow64GetThreadContext can only report the pc of 32bit code, and + gdb lets the target process continue. + So handle it as SIGINT instead, then the target is stopped + unconditionally. */ + DEBUG_EXCEPTION_SIMPLE ("EXCEPTION_BREAKPOINT"); + rec->ExceptionCode = DBG_CONTROL_C; + ourstatus->value.sig = GDB_SIGNAL_INT; + break; + } #endif /* FALLTHROUGH */ case STATUS_WX86_BREAKPOINT: diff --git a/gdb/nat/windows-nat.h b/gdb/nat/windows-nat.h index f742db2..9bfcb16 100644 --- a/gdb/nat/windows-nat.h +++ b/gdb/nat/windows-nat.h @@ -215,6 +215,8 @@ extern std::vector pending_stops; extern EXCEPTION_RECORD siginfo_er; #ifdef __x86_64__ +/* The target is a WOW64 process */ +extern bool wow64_process; /* Ignore first breakpoint exception of WOW64 process */ extern bool ignore_first_breakpoint; #endif diff --git a/gdb/windows-nat.c b/gdb/windows-nat.c index ba88c33..7fff41d 100644 --- a/gdb/windows-nat.c +++ b/gdb/windows-nat.c @@ -235,7 +235,6 @@ static std::vector thread_list; static int saw_create; static int open_process_used = 0; #ifdef __x86_64__ -static bool wow64_process = false; static void *wow64_dbgbreak; #endif -- cgit v1.1