Re: [PATCH 3/7] x86: Add C intrinsics for new rd/wr fs/gs base instructions

Konrad Rzeszutek Wilk
2014-04-29T14:11:18Z

On Mon, Apr 28, 2014 at 03:12:37PM -0700, Andi Kleen wrote:
> From: Andi Kleen <ak@linux.intel.com>
>
> Plus for swapgs.
>
> Very straight forward. Used in followon patch.

follow on
>
> Signed-off-by: Andi Kleen <ak@linux.intel.com>
> ---
> arch/x86/include/asm/fsgs.h | 43 +++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 43 insertions(+)
> create mode 100644 arch/x86/include/asm/fsgs.h
>
> diff --git a/arch/x86/include/asm/fsgs.h b/arch/x86/include/asm/fsgs.h
> new file mode 100644
> index 0000000..a3a5cd3
> --- /dev/null
> +++ b/arch/x86/include/asm/fsgs.h
> @@ -0,0 +1,43 @@
> +#ifndef _ASM_FSGS_H
> +#define _ASM_FSGS_H 1
> +
> +static inline void swapgs(void)
> +{
> + asm volatile("swapgs" ::: "memory");
> +}
> +
> +/* Must be protected by X86_FEATURE_FSGSBASE check. */
> +
> +static inline unsigned long rdgsbase(void)
> +{
> + unsigned long gs;
> + asm volatile(".byte 0xf3,0x48,0x0f,0xae,0xc8 # rdgsbaseq %%rax"
> + : "=a" (gs)
> + :: "memory");
> + return gs;
> +}
> +
> +static inline unsigned long rdfsbase(void)
> +{
> + unsigned long fs;
> + asm volatile(".byte 0xf3,0x48,0x0f,0xae,0xc0 # rdfsbaseq %%rax"
> + : "=a" (fs)
> + :: "memory");
> + return fs;
> +}
> +
> +static inline void wrgsbase(unsigned long gs)
> +{
> + asm volatile(".byte 0xf3,0x48,0x0f,0xae,0xd8 # wrgsbaseq %%rax"
> + :: "a" (gs)
> + : "memory");
> +}
> +
> +static inline void wrfsbase(unsigned long fs)
> +{
> + asm volatile(".byte 0xf3,0x48,0x0f,0xae,0xd0 # wrfsbaseq %%rax"
> + :: "a" (fs)
> + : "memory");
> +}
> +
> +#endif
> --
> 1.9.0
>
> --
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