On 1/11/20 8:38 PM, Chip Davis wrote:
January 11, 2020 5:34 PM, "Zebediah Figura" z.figura12@gmail.com wrote:
Hello Chip,
On 1/11/20 4:51 PM, Chip Davis wrote:
This is an assembly function, so we have to do it manually.
Signed-off-by: Chip Davis cdavis@codeweavers.com
Notes: v2: Fix saving EAX. Unfortunately, I need a register because of the 'subl' instruction.
dlls/ntdll/signal_i386.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-)
diff --git a/dlls/ntdll/signal_i386.c b/dlls/ntdll/signal_i386.c index e9dd0de2fc3c..099e10a3ebf2 100644 --- a/dlls/ntdll/signal_i386.c +++ b/dlls/ntdll/signal_i386.c @@ -2548,14 +2548,22 @@ __ASM_STDCALL_FUNC( RtlRaiseException, 4, "movl %esp,%ebp\n\t" __ASM_CFI(".cfi_def_cfa_register %ebp\n\t") "leal -0x2cc(%esp),%esp\n\t" /* sizeof(CONTEXT) */
- "pushl %esp\n\t" /* context */
- "andl $-16,%esp\n\t"
- "subl $16,%esp\n\t"
- "movl %eax,(%esp)\n\t"
- "movl %esp,%eax\n\t"
- "subl $12,%esp\n\t" /* stack alignment */
- "pushl %eax\n\t" /* context */
Out of curiosity, why do you need to align the stack again before calling RtlCaptureContext()? I don't see anything in our implementation that I'm aware relies on an aligned stack.
And if so, perhaps it'd be better to align the stack inside RtlCaptureContext() instead of here?
It isn't needed for RtlCaptureContext(). It's hand-hacked assembly and doesn't have any instructions in it that assume a 16-byte-aligned stack.
I was seeing crashes in send_debug_event(), which I tracked down to the compiler generating an aligned SSE instruction (movaps) on the assumption that the stack was 16-byte aligned. For some reason, adding this here made the crashes go away. These embedded aligned SSE instructions are part of why we compile exported functions with force_align_arg_pointer in the first place. Here we have to do it manually, because of the hand-hacked assembly.
Huh, I'm still confused about how we can get from RtlRaiseException() to send_debug_event() without going through a WINAPI function (which should end up realigning the stack). Am I missing something?
- "movl 16(%esp),%eax\n\t"
"call " __ASM_STDCALL("RtlCaptureContext",4) "\n\t"
- "addl $12,%esp\n\t"
"movl 4(%ebp),%eax\n\t" /* return address */ "movl 8(%ebp),%ecx\n\t" /* rec */ "movl %eax,12(%ecx)\n\t" /* rec->ExceptionAddress */ "leal 12(%ebp),%eax\n\t" "movl %eax,0xc4(%esp)\n\t" /* context->Esp */ "movl %esp,%eax\n\t"
- "subl $8,%esp\n\t" /* stack alignment */
"pushl %eax\n\t" "pushl %ecx\n\t" "call " __ASM_NAME("raise_exception_full_context") "\n\t"
Chip