b9d2ccc54e
We fail to see what CONFIG_KAISER_REAL_SWITCH is for: it seems to be left over from early development, and now just obscures tricky parts of the code. Delete it before adding PCIDs, or nokaiser boot option. (Or if there is some good reason to keep the option, then it needs a help text - and a "depends on KAISER", so that all those without KAISER are not asked the question.) Signed-off-by: Hugh Dickins <hughd@google.com> Acked-by: Jiri Kosina <jkosina@suse.cz> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
115 lines
3.2 KiB
C
115 lines
3.2 KiB
C
#ifndef _ASM_X86_KAISER_H
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#define _ASM_X86_KAISER_H
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/*
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* This file includes the definitions for the KAISER feature.
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* KAISER is a counter measure against x86_64 side channel attacks on
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* the kernel virtual memory. It has a shadow pgd for every process: the
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* shadow pgd has a minimalistic kernel-set mapped, but includes the whole
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* user memory. Within a kernel context switch, or when an interrupt is handled,
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* the pgd is switched to the normal one. When the system switches to user mode,
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* the shadow pgd is enabled. By this, the virtual memory caches are freed,
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* and the user may not attack the whole kernel memory.
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*
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* A minimalistic kernel mapping holds the parts needed to be mapped in user
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* mode, such as the entry/exit functions of the user space, or the stacks.
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*/
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#define KAISER_SHADOW_PGD_OFFSET 0x1000
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#ifdef __ASSEMBLY__
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#ifdef CONFIG_KAISER
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.macro _SWITCH_TO_KERNEL_CR3 reg
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movq %cr3, \reg
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andq $(~KAISER_SHADOW_PGD_OFFSET), \reg
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movq \reg, %cr3
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.endm
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.macro _SWITCH_TO_USER_CR3 reg
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movq %cr3, \reg
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orq $(KAISER_SHADOW_PGD_OFFSET), \reg
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movq \reg, %cr3
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.endm
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.macro SWITCH_KERNEL_CR3
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pushq %rax
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_SWITCH_TO_KERNEL_CR3 %rax
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popq %rax
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.endm
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.macro SWITCH_USER_CR3
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pushq %rax
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_SWITCH_TO_USER_CR3 %rax
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popq %rax
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.endm
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.macro SWITCH_KERNEL_CR3_NO_STACK
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movq %rax, PER_CPU_VAR(unsafe_stack_register_backup)
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_SWITCH_TO_KERNEL_CR3 %rax
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movq PER_CPU_VAR(unsafe_stack_register_backup), %rax
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.endm
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.macro SWITCH_USER_CR3_NO_STACK
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movq %rax, PER_CPU_VAR(unsafe_stack_register_backup)
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_SWITCH_TO_USER_CR3 %rax
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movq PER_CPU_VAR(unsafe_stack_register_backup), %rax
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.endm
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#else /* CONFIG_KAISER */
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.macro SWITCH_KERNEL_CR3 reg
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.endm
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.macro SWITCH_USER_CR3 reg
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.endm
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.macro SWITCH_USER_CR3_NO_STACK
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.endm
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.macro SWITCH_KERNEL_CR3_NO_STACK
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.endm
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#endif /* CONFIG_KAISER */
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#else /* __ASSEMBLY__ */
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#ifdef CONFIG_KAISER
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/*
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* Upon kernel/user mode switch, it may happen that the address
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* space has to be switched before the registers have been
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* stored. To change the address space, another register is
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* needed. A register therefore has to be stored/restored.
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*/
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DECLARE_PER_CPU_USER_MAPPED(unsigned long, unsafe_stack_register_backup);
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/**
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* kaiser_add_mapping - map a virtual memory part to the shadow (user) mapping
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* @addr: the start address of the range
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* @size: the size of the range
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* @flags: The mapping flags of the pages
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*
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* The mapping is done on a global scope, so no bigger
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* synchronization has to be done. the pages have to be
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* manually unmapped again when they are not needed any longer.
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*/
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extern int kaiser_add_mapping(unsigned long addr, unsigned long size, unsigned long flags);
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/**
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* kaiser_remove_mapping - unmap a virtual memory part of the shadow mapping
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* @addr: the start address of the range
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* @size: the size of the range
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*/
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extern void kaiser_remove_mapping(unsigned long start, unsigned long size);
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/**
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* kaiser_init - Initialize the shadow mapping
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*
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* Most parts of the shadow mapping can be mapped upon boot
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* time. Only per-process things like the thread stacks
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* or a new LDT have to be mapped at runtime. These boot-
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* time mappings are permanent and never unmapped.
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*/
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extern void kaiser_init(void);
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#endif /* CONFIG_KAISER */
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#endif /* __ASSEMBLY */
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#endif /* _ASM_X86_KAISER_H */
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