Merge branch 'stable-3.2' into pandora-3.2

[pandora-kernel.git] / arch / x86 / include / asm / kaiser.h

diff --git a/arch/x86/include/asm/kaiser.h b/arch/x86/include/asm/kaiser.h
new file mode 100644 (file)
index 0000000..de6fd81
--- /dev/null
+++ b/arch/x86/include/asm/kaiser.h
@@ -0,0 +1,141 @@
+#ifndef _ASM_X86_KAISER_H
+#define _ASM_X86_KAISER_H
+
+#include <asm/processor-flags.h> /* For PCID constants */
+
+/*
+ * 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, such as the entry/exit functions of the user space, or the stacks.
+ */
+
+#define KAISER_SHADOW_PGD_OFFSET 0x1000
+
+#ifdef __ASSEMBLY__
+#ifdef CONFIG_PAGE_TABLE_ISOLATION
+
+.macro _SWITCH_TO_KERNEL_CR3 reg
+movq %cr3, \reg
+andq $(~(X86_CR3_PCID_ASID_MASK | KAISER_SHADOW_PGD_OFFSET)), \reg
+/* If PCID enabled, set X86_CR3_PCID_NOFLUSH_BIT */
+ALTERNATIVE "", "bts $63, \reg", X86_FEATURE_PCID
+movq \reg, %cr3
+.endm
+
+.macro _SWITCH_TO_USER_CR3 reg regb
+/*
+ * regb must be the low byte portion of reg: because we have arranged
+ * for the low byte of the user PCID to serve as the high byte of NOFLUSH
+ * (0x80 for each when PCID is enabled, or 0x00 when PCID and NOFLUSH are
+ * not enabled): so that the one register can update both memory and cr3.
+ */
+movq %cr3, \reg
+orq  PER_CPU_VAR(x86_cr3_pcid_user), \reg
+js   9f
+/* If PCID enabled, FLUSH this time, reset to NOFLUSH for next time */
+movb \regb, PER_CPU_VAR(x86_cr3_pcid_user+7)
+9:
+movq \reg, %cr3
+.endm
+
+.macro SWITCH_KERNEL_CR3
+ALTERNATIVE "jmp 8f", "pushq %rax", X86_FEATURE_KAISER
+_SWITCH_TO_KERNEL_CR3 %rax
+popq %rax
+8:
+.endm
+
+.macro SWITCH_USER_CR3
+ALTERNATIVE "jmp 8f", "pushq %rax", X86_FEATURE_KAISER
+_SWITCH_TO_USER_CR3 %rax %al
+popq %rax
+8:
+.endm
+
+.macro SWITCH_KERNEL_CR3_NO_STACK
+ALTERNATIVE "jmp 8f", \
+       __stringify(movq %rax, PER_CPU_VAR(unsafe_stack_register_backup)), \
+       X86_FEATURE_KAISER
+_SWITCH_TO_KERNEL_CR3 %rax
+movq PER_CPU_VAR(unsafe_stack_register_backup), %rax
+8:
+.endm
+
+#else /* CONFIG_PAGE_TABLE_ISOLATION */
+
+.macro SWITCH_KERNEL_CR3
+.endm
+.macro SWITCH_USER_CR3
+.endm
+.macro SWITCH_KERNEL_CR3_NO_STACK
+.endm
+
+#endif /* CONFIG_PAGE_TABLE_ISOLATION */
+
+#else /* __ASSEMBLY__ */
+
+#ifdef CONFIG_PAGE_TABLE_ISOLATION
+/*
+ * Upon kernel/user mode switch, it may happen that the address
+ * space has to be switched before the registers have been
+ * 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);
+
+DECLARE_PER_CPU(unsigned long, x86_cr3_pcid_user);
+
+extern char __per_cpu_user_mapped_start[], __per_cpu_user_mapped_end[];
+
+extern int kaiser_enabled;
+extern void __init kaiser_check_boottime_disable(void);
+#else
+#define kaiser_enabled 0
+static inline void __init kaiser_check_boottime_disable(void) {}
+#endif /* CONFIG_PAGE_TABLE_ISOLATION */
+
+/*
+ * Kaiser function prototypes are needed even when CONFIG_PAGE_TABLE_ISOLATION is not set,
+ * so as to build with tests on kaiser_enabled instead of #ifdefs.
+ */
+
+/**
+ *  kaiser_add_mapping - map a virtual memory part to the shadow (user) mapping
+ *  @addr: the start address of the range
+ *  @size: the size of the range
+ *  @flags: The mapping flags of the pages
+ *
+ *  The mapping is done on a global scope, so no bigger
+ *  synchronization has to be done.  the pages have to be
+ *  manually unmapped again when they are not needed any longer.
+ */
+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
+ *  @size: the size of the range
+ */
+extern void kaiser_remove_mapping(unsigned long start, unsigned long size);
+
+/**
+ *  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 never unmapped.
+ */
+extern void kaiser_init(void);
+
+#endif /* __ASSEMBLY */
+
+#endif /* _ASM_X86_KAISER_H */