Re: [PATCH v6 0/6] MR6866: ntdll: On macOS x86_64, swap GSBASE between the TEB and macOS TSD when entering/leaving PE code.

[Alexandre Julliard (＠julliard)]

Alexandre Julliard (@julliard) commented about dlls/ntdll/unix/signal_x86_64.c:
> -
>               "leaq 0x70(%rcx),%rsp\n\t"      /* %rsp > frame means no longer inside syscall */
>
> +#ifdef __linux__
> -
>               "testl $12,%r14d\n\t"           /* SYSCALL_HAVE_PTHREAD_TEB | SYSCALL_HAVE_WRFSGSBASE */
> -
>               "jz 1f\n\t"
> -
>               "movw %gs:0x338,%fs\n"          /* amd64_thread_data()->fs */
> -
>               "1:\n\t"
>
> +#endif
> +#ifdef __APPLE__
> -
>               "movq 0x88(%rcx),%rsp\n\t"      /* use the user stack for this call */
> -
>               "pushq %rax\n\t"
> -
>               "pushq %rcx\n\t"
> -
>               "movq 0xb8(%rcx),%rdi\n\t"      /* frame->teb */
> -
>               "call " __ASM_NAME("_thread_set_tsd_base") "\n\t"
> -
>               "popq %rcx\n\t"
> -
>               "popq %rax\n\t"
> -
>               "leaq 0x70(%rcx),%rsp\n\t"      /* %rsp > frame means no longer inside syscall */

I don't think we should be touching the user stack at that point.