Toolchain/binutils-gdb
1
0
Fork 0
forked from Imagelibrary/binutils-gdb
Code Pull Requests Activity

Fix regression on Windows with WOW64

Browse Source 
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.
This commit is contained in:
Tom Tromey
2022-03-31 07:55:09 -06:00
parent 74f8cb8887
commit 7b5e70a921
1 changed files with 5 additions and 1 deletions
Download Patch File Download Diff File Expand all files Collapse all files

6
gdb/nat/windows-nat.c
View File

@@ -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;