diff options
| author | Changbin Du <changbin.du@gmail.com> | 2019-05-08 23:21:29 +0800 |
|---|---|---|
| committer | Jonathan Corbet <corbet@lwn.net> | 2019-05-08 14:34:10 -0600 |
| commit | ea0765e835e084707abb7e14d84b572f5ffe4242 (patch) | |
| tree | efff70d7e4b6a449476508d3233d9a9802034cb9 /Documentation/x86 | |
| parent | 0c7180f2e4e6fc02f268e18c4f753d9f9cdfb5ad (diff) | |
Documentation: x86: convert pti.txt to reST
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@gmail.com>
Reviewed-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Diffstat (limited to 'Documentation/x86')
| -rw-r--r-- | Documentation/x86/index.rst | 1 | ||||
| -rw-r--r-- | Documentation/x86/pti.rst (renamed from Documentation/x86/pti.txt) | 17 |
2 files changed, 14 insertions, 4 deletions
diff --git a/Documentation/x86/index.rst b/Documentation/x86/index.rst index 85f1f44cc8ac..6719defc16f8 100644 --- a/Documentation/x86/index.rst +++ b/Documentation/x86/index.rst @@ -21,3 +21,4 @@ x86-specific Documentation protection-keys intel_mpx amd-memory-encryption + pti diff --git a/Documentation/x86/pti.txt b/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 |