Re: [PATCH 7/7] x86/entry/64: extend register clearing on syscall entry to lower registers

[Ingo Molnar]

* Dominik Brodowski <li...@dominikbrodowski.net> wrote:

>       .endif
>       pushq   \rdx            /* pt_regs->dx */
> +     xorl    %edx, %edx      /* nosepc   dx */
>       pushq   %rcx            /* pt_regs->cx */
> +     xorl    %ecx, %ecx      /* nosepc   cx */
>       pushq   \rax            /* pt_regs->ax */
>       pushq   %r8             /* pt_regs->r8 */
>       xorl    %r8d, %r8d      /* nospec   r8 */
> diff --git a/arch/x86/entry/entry_64_compat.S 
> b/arch/x86/entry/entry_64_compat.S
> index 08425c42f8b7..23e0945959e5 100644
> --- a/arch/x86/entry/entry_64_compat.S
> +++ b/arch/x86/entry/entry_64_compat.S
> @@ -220,8 +220,11 @@ GLOBAL(entry_SYSCALL_compat_after_hwframe)
>       pushq   %rax                    /* pt_regs->orig_ax */
>       pushq   %rdi                    /* pt_regs->di */
>       pushq   %rsi                    /* pt_regs->si */
> +     xorl    %esi, %esi              /* nosepc   si */
>       pushq   %rdx                    /* pt_regs->dx */
> +     xorl    %edx, %edx              /* nosepc   dx */
>       pushq   %rbp                    /* pt_regs->cx (stashed in bp) */
> +     xorl    %ecx, %ecx              /* nosepc   cx */
>       pushq   $-ENOSYS                /* pt_regs->ax */
>       pushq   $0                      /* pt_regs->r8  = 0 */
>       xorl    %r8d, %r8d              /* nospec   r8 */
> @@ -365,8 +368,11 @@ ENTRY(entry_INT80_compat)
>  
>       pushq   (%rdi)                  /* pt_regs->di */
>       pushq   %rsi                    /* pt_regs->si */
> +     xorl    %esi, %esi              /* nosepc   si */
>       pushq   %rdx                    /* pt_regs->dx */
> +     xorl    %edx, %edx              /* nosepc   dx */
>       pushq   %rcx                    /* pt_regs->cx */
> +     xorl    %ecx, %ecx              /* nosepc   cx */
>       pushq   $-ENOSYS                /* pt_regs->ax */
>       pushq   $0                      /* pt_regs->r8  = 0 */
>       xorl    %r8d, %r8d              /* nospec   r8 */

s/nosepc
 /nospec

Thanks,

        Ingo