Paul Gofman : ntdll: Always align stack pointer in __wine_syscall_dispatcher on x64.

[Alexandre Julliard]

Module: wine
Branch: master
Commit: e9b3660e729929f4e09f403d526759d532df03e0
URL:    https://source.winehq.org/git/wine.git/?a=commit;h=e9b3660e729929f4e09f403d5...

Author: Paul Gofman <pgofman(a)codeweavers.com>
Date:   Tue Jul 14 19:06:36 2020 +0300

ntdll: Always align stack pointer in __wine_syscall_dispatcher on x64.

Syscall thunks break stack alignment for dispatcher. Regardless of that,
it is probably better not to assume aligned stack in syscall thunk entry.

Signed-off-by: Paul Gofman <pgofman(a)codeweavers.com>
Signed-off-by: Alexandre Julliard <julliard(a)winehq.org>

---

 tools/winebuild/import.c | 16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/tools/winebuild/import.c b/tools/winebuild/import.c
index 97191ca89e..278de20522 100644
--- a/tools/winebuild/import.c
+++ b/tools/winebuild/import.c
@@ -1497,23 +1497,25 @@ void output_syscalls( DLLSPEC *spec )
              * depends on us returning to it. Adjust the return address accordingly. */
             output( "\tsubq $0xb,0x8(%%rbp)\n" );
             output( "\tcmpq $%u,%%rax\n", count );
-            output( "\tjae 3f\n" );
+            output( "\tjae 4f\n" );
             output( "\tleaq .Lsyscall_args(%%rip),%%rcx\n" );
             output( "\tmovzbl (%%rcx,%%rax),%%ecx\n" );
             output( "\tsubq $0x20,%%rcx\n" );
-            output( "\tjbe 1f\n" );
-            output( "\tsubq %%rcx,%%rsp\n" );
+            output( "\tja 1f\n" );
+            output( "\tandq $~15,%%rsp\n\t" );
+            output( "\tjmp 2f\n" );
+            output( "1:\tsubq %%rcx,%%rsp\n" );
             output( "\tshrq $3,%%rcx\n" );
             output( "\tleaq 0x38(%%rbp),%%rsi\n" );
             output( "\tandq $~15,%%rsp\n\t" );
             output( "\tmovq %%rsp,%%rdi\n" );
             output( "\tcld\n" );
             output( "\trep; movsq\n" );
-            output( "1:\tmovq %%r10,%%rcx\n" );
+            output( "2:\tmovq %%r10,%%rcx\n" );
             output( "\tsubq $0x20,%%rsp\n" );
             output( "\tleaq .Lsyscall_table(%%rip),%%r10\n" );
             output( "\tcallq *(%%r10,%%rax,8)\n" );
-            output( "2:\tleaq -0x10(%%rbp),%%rsp\n" );
+            output( "3:\tleaq -0x10(%%rbp),%%rsp\n" );
             output( "\tpopq %%rdi\n" );
             output_cfi( ".cfi_same_value %%rdi" );
             output( "\tpopq %%rsi\n" );
@@ -1523,8 +1525,8 @@ void output_syscalls( DLLSPEC *spec )
             output_cfi( ".cfi_adjust_cfa_offset -8" );
             output_cfi( ".cfi_same_value %%rbp" );
             output( "\tret\n" );
-            output( "3:\tmovl $0x%x,%%eax\n", invalid_param );
-            output( "\tjmp 2b\n" );
+            output( "4:\tmovl $0x%x,%%eax\n", invalid_param );
+            output( "\tjmp 3b\n" );
             break;
         case CPU_ARM:
             output( "\tldr r1, 4f\n" );