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Subject[PATCH V6 14/49] x86/entry: Add C verion of SWITCH_TO_KERNEL_CR3 as switch_to_kernel_cr3()
Date
From: Lai Jiangshan <laijs@linux.alibaba.com>

The C version switch_to_kernel_cr3() implements SWITCH_TO_KERNEL_CR3().

No functional difference intended.

Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
---
arch/x86/entry/entry64.c | 24 ++++++++++++++++++++++++
1 file changed, 24 insertions(+)

diff --git a/arch/x86/entry/entry64.c b/arch/x86/entry/entry64.c
index 9813a30dbadb..9a5c535b1ddf 100644
--- a/arch/x86/entry/entry64.c
+++ b/arch/x86/entry/entry64.c
@@ -14,3 +14,27 @@
#include <asm/traps.h>

extern unsigned char asm_load_gs_index_gs_change[];
+
+#ifdef CONFIG_PAGE_TABLE_ISOLATION
+static __always_inline void pti_switch_to_kernel_cr3(unsigned long user_cr3)
+{
+ /*
+ * Clear PCID and "PAGE_TABLE_ISOLATION bit", point CR3
+ * at kernel pagetables:
+ */
+ unsigned long cr3 = user_cr3 & ~PTI_USER_PGTABLE_AND_PCID_MASK;
+
+ if (static_cpu_has(X86_FEATURE_PCID))
+ cr3 |= X86_CR3_PCID_NOFLUSH;
+
+ native_write_cr3(cr3);
+}
+
+static __always_inline void switch_to_kernel_cr3(void)
+{
+ if (static_cpu_has(X86_FEATURE_PTI))
+ pti_switch_to_kernel_cr3(__native_read_cr3());
+}
+#else
+static __always_inline void switch_to_kernel_cr3(void) {}
+#endif
--
2.19.1.6.gb485710b
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