Jacek Caban : ntdll: Get TEB from signal stack pointer in init_handler.

[Alexandre Julliard]

Module: wine
Branch: master
Commit: e7accd7c0f9d8aa7c8c52a7d48c3374da49e32f5
URL:    https://gitlab.winehq.org/wine/wine/-/commit/e7accd7c0f9d8aa7c8c52a7d48c3374...

Author: Jacek Caban <jacek(a)codeweavers.com>
Date:   Mon Nov 28 18:06:18 2022 +0100

ntdll: Get TEB from signal stack pointer in init_handler.

We can't use NtCurrentTeb before setting %fs base.

---

 dlls/ntdll/unix/signal_x86_64.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/dlls/ntdll/unix/signal_x86_64.c b/dlls/ntdll/unix/signal_x86_64.c
index cc070dda5ae..8541dc9ccaf 100644
--- a/dlls/ntdll/unix/signal_x86_64.c
+++ b/dlls/ntdll/unix/signal_x86_64.c
@@ -440,6 +440,13 @@ static inline struct amd64_thread_data *amd64_thread_data(void)
     return (struct amd64_thread_data *)ntdll_get_thread_data()->cpu_data;
 }
 
+static inline TEB *get_current_teb(void)
+{
+    unsigned long rsp;
+    __asm__( "movq %%rsp,%0" : "=r" (rsp) );
+    return (TEB *)(rsp & ~signal_stack_mask);
+}
+
 static BOOL is_inside_syscall( const ucontext_t *sigcontext )
 {
     return ((char *)RSP_sig(sigcontext) >= (char *)ntdll_get_thread_data()->kernel_stack &&
@@ -806,7 +813,11 @@ static inline void set_sigcontext( const CONTEXT *context, ucontext_t *sigcontex
 static inline void init_handler( const ucontext_t *sigcontext )
 {
 #ifdef __linux__
-    if (fs32_sel) arch_prctl( ARCH_SET_FS, amd64_thread_data()->pthread_teb );
+    if (fs32_sel)
+    {
+        struct ntdll_thread_data *thread_data = (struct ntdll_thread_data *)&get_current_teb()->GdiTebBatch;
+        arch_prctl( ARCH_SET_FS, ((struct amd64_thread_data *)thread_data->cpu_data)->pthread_teb );
+    }
 #endif
 }