[PATCH v4 42/63] Documentation: x86: convert entry_64.txt to reST

Changbin Du
2019-04-23T16:29:11Z

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>
---
Documentation/x86/{entry_64.txt => entry_64.rst} | 12 +++++++++---
Documentation/x86/index.rst | 1 +
2 files changed, 10 insertions(+), 3 deletions(-)
rename Documentation/x86/{entry_64.txt => entry_64.rst} (95%)

diff --git a/Documentation/x86/entry_64.txt b/Documentation/x86/entry_64.rst
similarity index 95%
rename from Documentation/x86/entry_64.txt
rename to Documentation/x86/entry_64.rst
index c1df8eba9dfd..a48b3f6ebbe8 100644
--- a/Documentation/x86/entry_64.txt
+++ b/Documentation/x86/entry_64.rst
@@ -1,3 +1,9 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+==============
+Kernel Entries
+==============
+
This file documents some of the kernel entries in
arch/x86/entry/entry_64.S. A lot of this explanation is adapted from
an email from Ingo Molnar:
@@ -59,7 +65,7 @@ Now, there's a secondary complication: there's a cheap way to test
which mode the CPU is in and an expensive way.

The cheap way is to pick this info off the entry frame on the kernel
-stack, from the CS of the ptregs area of the kernel stack:
+stack, from the CS of the ptregs area of the kernel stack::

xorl %ebx,%ebx
testl $3,CS+8(%rsp)
@@ -67,7 +73,7 @@ stack, from the CS of the ptregs area of the kernel stack:
SWAPGS

The expensive (paranoid) way is to read back the MSR_GS_BASE value
-(which is what SWAPGS modifies):
+(which is what SWAPGS modifies)::

movl $1,%ebx
movl $MSR_GS_BASE,%ecx
@@ -76,7 +82,7 @@ The expensive (paranoid) way is to read back the MSR_GS_BASE value
js 1f /* negative -> in kernel */
SWAPGS
xorl %ebx,%ebx
-1: ret
+ 1: ret

If we are at an interrupt or user-trap/gate-alike boundary then we can
use the faster check: the stack will be a reliable indicator of
diff --git a/Documentation/x86/index.rst b/Documentation/x86/index.rst
index 489f4f4179c4..8a666c5abc85 100644
--- a/Documentation/x86/index.rst
+++ b/Documentation/x86/index.rst
@@ -12,3 +12,4 @@ Linux x86 Support
topology
exception-tables
kernel-stacks
+ entry_64
--
2.20.1