From: Andi Kleen <a...@linux.intel.com>
Add C intrinsics and assembler macros for the new RD/WR FS/GS BASE
instructions.
Very straight forward. Used in followon patch.
[luto: rename the variables from fs and gs to fsbase and gsbase and
make fsgs.h safe to include on 32-bit kernels.]
v2: Use __always_inline
Signed-off-by: Andi Kleen <a...@linux.intel.com>
Signed-off-by: Andy Lutomirski <l...@kernel.org>
[chang: Replace new instruction macros with GAS-compatible and
renaming]
Signed-off-by: Chang S. Bae <chang.seok....@intel.com>
Cc: H. Peter Anvin <h...@zytor.com>
---
arch/x86/include/asm/fsgsbase.h | 102 ++++++++++++++++++++++++++++++++++++++++
1 file changed, 102 insertions(+)
diff --git a/arch/x86/include/asm/fsgsbase.h b/arch/x86/include/asm/fsgsbase.h
index 29249f6..cad2831 100644
--- a/arch/x86/include/asm/fsgsbase.h
+++ b/arch/x86/include/asm/fsgsbase.h
@@ -18,6 +18,44 @@ int write_task_fsbase(struct task_struct *task, unsigned
long fsbase);
int write_task_gsbase(struct task_struct *task, unsigned long gsbase);
/*
+ * Must be protected by X86_FEATURE_FSGSBASE check.
+ */
+
+static __always_inline unsigned long rdfsbase(void)
+{
+ unsigned long fsbase;
+
+ asm volatile(".byte 0xf3, 0x48, 0x0f, 0xae, 0xc0 # rdfsbaseq %%rax"
+ : "=a" (fsbase)
+ :: "memory");
+ return fsbase;
+}
+
+static __always_inline unsigned long rdgsbase(void)
+{
+ unsigned long gsbase;
+
+ asm volatile(".byte 0xf3, 0x48, 0x0f, 0xae, 0xc8 # rdgsbaseq %%rax;"
+ : "=a" (gsbase)
+ :: "memory");
+ return gsbase;
+}
+
+static __always_inline void wrfsbase(unsigned long fsbase)
+{
+ asm volatile(".byte 0xf3, 0x48, 0x0f, 0xae, 0xd0 # wrfsbaseq %%rax"
+ :: "a" (fsbase)
+ : "memory");
+}
+
+static __always_inline void wrgsbase(unsigned long gsbase)
+{
+ asm volatile(".byte 0xf3, 0x48, 0x0f, 0xae, 0xd8 # wrgsbaseq %%rax;"
+ :: "a" (gsbase)
+ : "memory");
+}
+
+/*
* Helper functions for reading/writing FS/GS base
*/
@@ -43,6 +81,70 @@ void write_shadow_gsbase(unsigned long gsbase);
#endif /* CONFIG_X86_64 */
+#else /* __ASSEMBLY__ */
+
+#ifdef CONFIG_X86_64
+
+#include <asm/inst.h>
+
+.macro RDFSBASE opd
+ REG_TYPE rdfsbase_opd_type \opd
+ .if rdfsbase_opd_type == REG_TYPE_R64
+ R64_NUM rdfsbase_opd \opd
+ .byte 0xf3
+ PFX_REX rdfsbase_opd 0 W = 1
+ .else
+ R32_NUM rdfsbase_opd \opd
+ .byte 0xf3
+ .endif
+ .byte 0xf, 0xae
+ MODRM 0xc0 rdfsbase_opd 0
+.endm
+
+.macro WRFSBASE opd
+ REG_TYPE wrfsbase_opd_type \opd
+ .if wrfsbase_opd_type == REG_TYPE_R64
+ R64_NUM wrfsbase_opd \opd
+ .byte 0xf3
+ PFX_REX wrfsbase_opd 0 W = 1
+ .else
+ R32_NUM wrfsbase_opd \opd
+ .byte 0xf3
+ .endif
+ .byte 0xf, 0xae
+ MODRM 0xd0 wrfsbase_opd 0
+.endm
+
+.macro RDGSBASE opd
+ REG_TYPE rdgsbase_opd_type \opd
+ .if rdgsbase_opd_type == REG_TYPE_R64
+ R64_NUM rdgsbase_opd \opd
+ .byte 0xf3
+ PFX_REX rdgsbase_opd 0 W = 1
+ .else
+ R32_NUM rdgsbase_opd \opd
+ .byte 0xf3
+ .endif
+ .byte 0xf, 0xae
+ MODRM 0xc0 rdgsbase_opd 1
+.endm
+
+.macro WRGSBASE opd
+ REG_TYPE wrgsbase_opd_type \opd
+ .if wrgsbase_opd_type == REG_TYPE_R64
+ R64_NUM wrgsbase_opd \opd
+ .byte 0xf3
+ PFX_REX wrgsbase_opd 0 W = 1
+ .else
+ R32_NUM wrgsbase_opd \opd
+ .byte 0xf3
+ .endif
+ .byte 0xf, 0xae
+ MODRM 0xd0 wrgsbase_opd 1
+.endm
+
+#endif /* CONFIG_X86_64 */
+
#endif /* __ASSEMBLY__ */
#endif /* _ASM_FSGSBASE_H */
--
2.7.4
