Messages in this thread Patch in this message | | | From | "Chang S. Bae" <> | Subject | [PATCH 09/15] x86/fsgsbase/64: Add intrinsics/macros for FSGSBASE instructions | Date | Mon, 19 Mar 2018 10:49:21 -0700 |
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From: Andi Kleen <ak@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 <ak@linux.intel.com> Signed-off-by: Andy Lutomirski <luto@kernel.org> [chang: Replace new instruction macros with GAS-compatible and renaming] Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com> Cc: H. Peter Anvin <hpa@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
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