On Mon, 8 Jan 2018, Willy Tarreau wrote:
> This allows to report the current state of the PTI protection and to
> enable or disable it for the current task.
>
> Signed-off-by: Willy Tarreau <[email protected]>
> ---
> arch/x86/include/uapi/asm/prctl.h | 3 +++
> arch/x86/kernel/process_64.c | 24 ++++++++++++++++++++++++
> 2 files changed, 27 insertions(+)
>
> diff --git a/arch/x86/include/uapi/asm/prctl.h
> b/arch/x86/include/uapi/asm/prctl.h
> index 5a6aac9..1f1b5bc 100644
> --- a/arch/x86/include/uapi/asm/prctl.h
> +++ b/arch/x86/include/uapi/asm/prctl.h
> @@ -10,6 +10,9 @@
> #define ARCH_GET_CPUID 0x1011
> #define ARCH_SET_CPUID 0x1012
>
> +#define ARCH_GET_NOPTI 0x1021
> +#define ARCH_SET_NOPTI 0x1022
> +
> #define ARCH_MAP_VDSO_X32 0x2001
> #define ARCH_MAP_VDSO_32 0x2002
> #define ARCH_MAP_VDSO_64 0x2003
> diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
> index c754662..1686d3d 100644
> --- a/arch/x86/kernel/process_64.c
> +++ b/arch/x86/kernel/process_64.c
> @@ -654,6 +654,30 @@ long do_arch_prctl_64(struct task_struct *task, int
> option, unsigned long arg2)
> ret = put_user(base, (unsigned long __user *)arg2);
> break;
> }
> + case ARCH_GET_NOPTI: {
> + unsigned long flag;
> +
> + printk(KERN_DEBUG "get1: task=%p ti=%p fl=%16lx\n", task,
> task_thread_info(task), task_thread_info(task)->flags);
> + flag = !!(task_thread_info(task)->flags & _TIF_NOPTI);
> + ret = put_user(flag, (unsigned long __user *)arg2);
> + break;
Per task is really an odd choice. That should be per process I think, but
that of course needs synchronization of some form. Aside of that we need to
think about fork().
Thanks,
tglx
