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From 7bb8f481c84ef1755e442700593f0ef10857c108 Mon Sep 17 00:00:00 2001
From: Hugh Dickins <hughd@google.com>
Date: Sun, 3 Sep 2017 19:18:07 -0700
Subject: [PATCH 013/103] kaiser: tidied up asm/kaiser.h somewhat
Mainly deleting a surfeit of blank lines, and reflowing header comment.
Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/x86/include/asm/kaiser.h | 32 +++++++++++++-------------------
1 file changed, 13 insertions(+), 19 deletions(-)
diff --git a/arch/x86/include/asm/kaiser.h b/arch/x86/include/asm/kaiser.h
index 0703f48..7394ba9 100644
--- a/arch/x86/include/asm/kaiser.h
+++ b/arch/x86/include/asm/kaiser.h
@@ -1,15 +1,17 @@
#ifndef _ASM_X86_KAISER_H
#define _ASM_X86_KAISER_H
-
-/* This file includes the definitions for the KAISER feature.
- * KAISER is a counter measure against x86_64 side channel attacks on the kernel virtual memory.
- * It has a shodow-pgd for every process. the shadow-pgd has a minimalistic kernel-set mapped,
- * but includes the whole user memory. Within a kernel context switch, or when an interrupt is handled,
- * the pgd is switched to the normal one. When the system switches to user mode, the shadow pgd is enabled.
- * By this, the virtual memory chaches are freed, and the user may not attack the whole kernel memory.
+/*
+ * This file includes the definitions for the KAISER feature.
+ * KAISER is a counter measure against x86_64 side channel attacks on
+ * the kernel virtual memory. It has a shadow pgd for every process: the
+ * shadow pgd has a minimalistic kernel-set mapped, but includes the whole
+ * user memory. Within a kernel context switch, or when an interrupt is handled,
+ * the pgd is switched to the normal one. When the system switches to user mode,
+ * the shadow pgd is enabled. By this, the virtual memory caches are freed,
+ * and the user may not attack the whole kernel memory.
*
- * A minimalistic kernel mapping holds the parts needed to be mapped in user mode, as the entry/exit functions
- * of the user space, or the stacks.
+ * A minimalistic kernel mapping holds the parts needed to be mapped in user
+ * mode, such as the entry/exit functions of the user space, or the stacks.
*/
#ifdef __ASSEMBLY__
#ifdef CONFIG_KAISER
@@ -48,13 +50,10 @@ _SWITCH_TO_KERNEL_CR3 %rax
movq PER_CPU_VAR(unsafe_stack_register_backup), %rax
.endm
-
.macro SWITCH_USER_CR3_NO_STACK
-
movq %rax, PER_CPU_VAR(unsafe_stack_register_backup)
_SWITCH_TO_USER_CR3 %rax
movq PER_CPU_VAR(unsafe_stack_register_backup), %rax
-
.endm
#else /* CONFIG_KAISER */
@@ -72,7 +71,6 @@ movq PER_CPU_VAR(unsafe_stack_register_backup), %rax
#else /* __ASSEMBLY__ */
-
#ifdef CONFIG_KAISER
/*
* Upon kernel/user mode switch, it may happen that the address
@@ -80,7 +78,6 @@ movq PER_CPU_VAR(unsafe_stack_register_backup), %rax
* stored. To change the address space, another register is
* needed. A register therefore has to be stored/restored.
*/
-
DECLARE_PER_CPU_USER_MAPPED(unsigned long, unsafe_stack_register_backup);
/**
@@ -95,7 +92,6 @@ DECLARE_PER_CPU_USER_MAPPED(unsigned long, unsafe_stack_register_backup);
*/
extern int kaiser_add_mapping(unsigned long addr, unsigned long size, unsigned long flags);
-
/**
* kaiser_remove_mapping - unmap a virtual memory part of the shadow mapping
* @addr: the start address of the range
@@ -104,12 +100,12 @@ extern int kaiser_add_mapping(unsigned long addr, unsigned long size, unsigned l
extern void kaiser_remove_mapping(unsigned long start, unsigned long size);
/**
- * kaiser_initialize_mapping - Initalize the shadow mapping
+ * kaiser_init - Initialize the shadow mapping
*
* Most parts of the shadow mapping can be mapped upon boot
* time. Only per-process things like the thread stacks
* or a new LDT have to be mapped at runtime. These boot-
- * time mappings are permanent and nevertunmapped.
+ * time mappings are permanent and never unmapped.
*/
extern void kaiser_init(void);
@@ -117,6 +113,4 @@ extern void kaiser_init(void);
#endif /* __ASSEMBLY */
-
-
#endif /* _ASM_X86_KAISER_H */
--
2.7.4
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