[PATCH 13/13] ntdll: Tweak KeUserModeCallback to please Valgrind and GDB.

[Rémi Bernon]

From: Rémi Bernon

This is a hack, but valgrind heuristics are having a hard time with
the stack manipulation around here. This silents some annoying reports.
---
 dlls/ntdll/unix/signal_i386.c   |  3 ++-
 dlls/ntdll/unix/signal_x86_64.c | 23 +++++++++++++++++++++--
 2 files changed, 23 insertions(+), 3 deletions(-)

diff --git a/dlls/ntdll/unix/signal_i386.c b/dlls/ntdll/unix/signal_i386.c
index 9250f863145..484e9c8c72e 100644
--- a/dlls/ntdll/unix/signal_i386.c
+++ b/dlls/ntdll/unix/signal_i386.c
@@ -1605,10 +1605,11 @@ NTSTATUS WINAPI KeUserModeCallback( ULONG id, const void *args, ULONG len, void
         *(--stack) = len;
         *(--stack) = (ULONG_PTR)args_data;
         *(--stack) = id;
-        *(--stack) = 0xdeadbabe;
+        *(--stack) = *(ULONG_PTR *)frame->esp;

callback_frame.frame.esp           = (ULONG_PTR)stack;
         callback_frame.frame.eip           = (ULONG_PTR)pKiUserCallbackDispatcher;
+        callback_frame.frame.ebp           = frame->ebp;
         callback_frame.frame.eflags        = 0x202;
         callback_frame.frame.syscall_flags = frame->syscall_flags;
         callback_frame.frame.syscall_table = frame->syscall_table;
diff --git a/dlls/ntdll/unix/signal_x86_64.c b/dlls/ntdll/unix/signal_x86_64.c
index 98152194e5f..0b7d7bca7bc 100644
--- a/dlls/ntdll/unix/signal_x86_64.c
+++ b/dlls/ntdll/unix/signal_x86_64.c
@@ -64,6 +64,12 @@
 #ifdef __APPLE__
 # include <mach/mach.h>
 #endif
+#ifdef HAVE_VALGRIND_VALGRIND_H
+# include <valgrind/valgrind.h>
+#endif
+#ifdef HAVE_VALGRIND_MEMCHECK_H
+# include <valgrind/memcheck.h>
+#endif

#define NONAMELESSUNION
 #define NONAMELESSSTRUCT
@@ -2404,18 +2410,31 @@ NTSTATUS WINAPI KeUserModeCallback( ULONG id, const void *args, ULONG len, void
     {
         struct syscall_frame *frame = amd64_thread_data()->syscall_frame;
         void *args_data = (void *)((frame->rsp - len) & ~15);
+        ULONG_PTR *stack = args_data;
+
+#if defined(VALGRIND_MAKE_MEM_UNDEFINED)
+        VALGRIND_MAKE_MEM_UNDEFINED( (char *)stack - 0x100, (char *)frame->rsp - (char *)stack + 0x100 );
+#elif defined(VALGRIND_MAKE_WRITABLE)
+        VALGRIND_MAKE_WRITABLE( (char *)stack - 0x100, (char *)frame->rsp - (char *)stack + 0x100 );
+#endif

memcpy( args_data, args, len );
+        *(--stack) = 0;
+        *(--stack) = 0;
+        *(--stack) = 0;
+        *(--stack) = 0;
+        *(--stack) = *(ULONG_PTR *)frame->rsp;

callback_frame.frame.rcx           = id;
-        callback_frame.frame.rdx           = (ULONG_PTR)args;
+        callback_frame.frame.rdx           = (ULONG_PTR)args_data;
         callback_frame.frame.r8            = len;
         callback_frame.frame.cs            = cs64_sel;
         callback_frame.frame.fs            = amd64_thread_data()->fs;
         callback_frame.frame.gs            = ds64_sel;
         callback_frame.frame.ss            = ds64_sel;
-        callback_frame.frame.rsp           = (ULONG_PTR)args_data - 0x28;
+        callback_frame.frame.rsp           = (ULONG_PTR)stack;
         callback_frame.frame.rip           = (ULONG_PTR)pKiUserCallbackDispatcher;
+        callback_frame.frame.rbp           = frame->rbp;
         callback_frame.frame.eflags        = 0x200;
         callback_frame.frame.restore_flags = CONTEXT_CONTROL | CONTEXT_INTEGER;
         callback_frame.frame.prev_frame    = frame;