Commit c2dea5cd authored by Changbin Du's avatar Changbin Du Committed by Jonathan Corbet
Browse files

Documentation: x86: convert entry_64.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: default avatarChangbin Du <changbin.du@gmail.com>
Reviewed-by: default avatarMauro Carvalho Chehab <mchehab+samsung@kernel.org>
Signed-off-by: default avatarJonathan Corbet <corbet@lwn.net>
parent ac2b4687

Documentation/x86/entry_64.txt→Documentation/x86/entry_64.rst

+9 −3
Original line number Original line Diff line number Diff line 
.. SPDX-License-Identifier: GPL-2.0



==============

Kernel Entries

==============



This file documents some of the kernel entries in

This file documents some of the kernel entries in

arch/x86/entry/entry_64.S.  A lot of this explanation is adapted from

arch/x86/entry/entry_64.S.  A lot of this explanation is adapted from

an email from Ingo Molnar:

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.

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

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

	xorl %ebx,%ebx

	testl $3,CS+8(%rsp)

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

	SWAPGS





The expensive (paranoid) way is to read back the MSR_GS_BASE value

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 $1,%ebx

	movl $MSR_GS_BASE,%ecx

	movl $MSR_GS_BASE,%ecx

Documentation/x86/index.rst

+1 −0
Original line number Original line Diff line number Diff line
@@ -12,3 +12,4 @@ x86-specific Documentation 
   topology

   topology

   exception-tables

   exception-tables

   kernel-stacks

   kernel-stacks

   entry_64

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