On Thu 14-03-19 09:51:42, Dave Hansen wrote:
[...]
> From: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
>
> MPX is being removed from the kernel due to a lack of support
> in the toolchain going forward (gcc).
>
> The first thing we need to do is remove the userspace-visible
> ABIs so that applications will stop using it. The most visible
> one are the enable/disable prctl()s. Remove them first.
>
> This is the most minimal and least invasive patch needed to
> start removing MPX.
Is this something we _want_ to push to stable trees?
>
> Signed-off-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
> ---
>
> b/include/uapi/linux/prctl.h | 2 +-
> b/kernel/sys.c | 16 ++--------------
> 2 files changed, 3 insertions(+), 15 deletions(-)
>
> diff -puN include/uapi/linux/prctl.h~mpx-remove-apis include/uapi/linux/prctl.h
> --- a/include/uapi/linux/prctl.h~mpx-remove-apis 2019-01-04 14:40:06.853514089 -0800
> +++ b/include/uapi/linux/prctl.h 2019-01-04 14:40:06.860514089 -0800
> @@ -181,7 +181,7 @@ struct prctl_mm_map {
> #define PR_GET_THP_DISABLE 42
>
> /*
> - * Tell the kernel to start/stop helping userspace manage bounds tables.
> + * No longer implemented, but left here to ensure the numbers stay reserved:
> */
> #define PR_MPX_ENABLE_MANAGEMENT 43
> #define PR_MPX_DISABLE_MANAGEMENT 44
> diff -puN kernel/sys.c~mpx-remove-apis kernel/sys.c
> --- a/kernel/sys.c~mpx-remove-apis 2019-01-04 14:40:06.857514089 -0800
> +++ b/kernel/sys.c 2019-01-04 14:40:06.860514089 -0800
> @@ -103,12 +103,6 @@
> #ifndef SET_TSC_CTL
> # define SET_TSC_CTL(a) (-EINVAL)
> #endif
> -#ifndef MPX_ENABLE_MANAGEMENT
> -# define MPX_ENABLE_MANAGEMENT() (-EINVAL)
> -#endif
> -#ifndef MPX_DISABLE_MANAGEMENT
> -# define MPX_DISABLE_MANAGEMENT() (-EINVAL)
> -#endif
> #ifndef GET_FP_MODE
> # define GET_FP_MODE(a) (-EINVAL)
> #endif
> @@ -2448,15 +2442,9 @@ SYSCALL_DEFINE5(prctl, int, option, unsi
> up_write(&me->mm->mmap_sem);
> break;
> case PR_MPX_ENABLE_MANAGEMENT:
> - if (arg2 || arg3 || arg4 || arg5)
> - return -EINVAL;
> - error = MPX_ENABLE_MANAGEMENT();
> - break;
> case PR_MPX_DISABLE_MANAGEMENT:
> - if (arg2 || arg3 || arg4 || arg5)
> - return -EINVAL;
> - error = MPX_DISABLE_MANAGEMENT();
> - break;
> + /* No longer implemented: */
> + return -EINVAL;
> case PR_SET_FP_MODE:
> error = SET_FP_MODE(me, arg2);
> break;
> _
--
Michal Hocko
SUSE Labs
