Em Fri, 26 Apr 2019 23:31:38 +0800
Changbin Du <changbin.du@xxxxxxxxx> escreveu:
> This converts the plain text documentation to reStructuredText format and
> add it to Sphinx TOC tree. No essential content change.
>
> Signed-off-by: Changbin Du <changbin.du@xxxxxxxxx>
Reviewed-by: Mauro Carvalho Chehab <mchehab+samsung@xxxxxxxxxx>
> ---
> Documentation/x86/index.rst | 1 +
> Documentation/x86/{pti.txt => pti.rst} | 17 +++++++++++++----
> 2 files changed, 14 insertions(+), 4 deletions(-)
> rename Documentation/x86/{pti.txt => pti.rst} (96%)
>
> diff --git a/Documentation/x86/index.rst b/Documentation/x86/index.rst
> index a0426ab156bd..1c675cef14d7 100644
> --- a/Documentation/x86/index.rst
> +++ b/Documentation/x86/index.rst
> @@ -21,3 +21,4 @@ Linux x86 Support
> protection-keys
> intel_mpx
> amd-memory-encryption
> + pti
> diff --git a/Documentation/x86/pti.txt b/Documentation/x86/pti.rst
> similarity index 96%
> rename from Documentation/x86/pti.txt
> rename to Documentation/x86/pti.rst
> index 5cd58439ad2d..4b858a9bad8d 100644
> --- a/Documentation/x86/pti.txt
> +++ b/Documentation/x86/pti.rst
> @@ -1,9 +1,15 @@
> +.. SPDX-License-Identifier: GPL-2.0
> +
> +==========================
> +Page Table Isolation (PTI)
> +==========================
> +
> Overview
> ========
>
> -Page Table Isolation (pti, previously known as KAISER[1]) is a
> +Page Table Isolation (pti, previously known as KAISER [1]_) is a
> countermeasure against attacks on the shared user/kernel address
> -space such as the "Meltdown" approach[2].
> +space such as the "Meltdown" approach [2]_.
>
> To mitigate this class of attacks, we create an independent set of
> page tables for use only when running userspace applications. When
> @@ -60,6 +66,7 @@ Protection against side-channel attacks is important. But,
> this protection comes at a cost:
>
> 1. Increased Memory Use
> +
> a. Each process now needs an order-1 PGD instead of order-0.
> (Consumes an additional 4k per process).
> b. The 'cpu_entry_area' structure must be 2MB in size and 2MB
> @@ -68,6 +75,7 @@ this protection comes at a cost:
> is decompressed, but no space in the kernel image itself.
>
> 2. Runtime Cost
> +
> a. CR3 manipulation to switch between the page table copies
> must be done at interrupt, syscall, and exception entry
> and exit (it can be skipped when the kernel is interrupted,
> @@ -142,6 +150,7 @@ ideally doing all of these in parallel:
> interrupted, including nested NMIs. Using "-c" boosts the rate of
> NMIs, and using two -c with separate counters encourages nested NMIs
> and less deterministic behavior.
> + ::
>
> while true; do perf record -c 10000 -e instructions,cycles -a sleep 10; done
>
> @@ -182,5 +191,5 @@ that are worth noting here.
> tended to be TLB invalidation issues. Usually invalidating
> the wrong PCID, or otherwise missing an invalidation.
>
> -1. https://gruss.cc/files/kaiser.pdf
> -2. https://meltdownattack.com/meltdown.pdf
> +.. [1] https://gruss.cc/files/kaiser.pdf
> +.. [2] https://meltdownattack.com/meltdown.pdf
Thanks,
Mauro
