Re: [patch V2 16/52] x86/fpu: Use copy_uabi_xstate_to_membuf() in fpregs_get()

Borislav Petkov
2021-06-17T11:50:46Z

On Mon, Jun 14, 2021 at 05:44:24PM +0200, Thomas Gleixner wrote:
> Use the new functionality of copy_uabi_xstate_to_membuf() to retrieve the
> FX state when XSAVE* is in use. This avoids to overwrite the FPU state
> buffer with fpstate_sanitize_xstate() which is error prone and duplicated
> code.
>
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> ---
> V2: New patch
> ---
> arch/x86/kernel/fpu/regset.c | 30 ++++++++++++++++++++----------
> 1 file changed, 20 insertions(+), 10 deletions(-)
>
> --- a/arch/x86/kernel/fpu/regset.c
> +++ b/arch/x86/kernel/fpu/regset.c
> @@ -211,10 +211,10 @@ static inline u32 twd_fxsr_to_i387(struc
> * FXSR floating point environment conversions.
> */
>
> -void
> -convert_from_fxsr(struct user_i387_ia32_struct *env, struct task_struct *tsk)
> +static void __convert_from_fxsr(struct user_i387_ia32_struct *env,
> + struct task_struct *tsk,
> + struct fxregs_state *fxsave)
> {
> - struct fxregs_state *fxsave = &tsk->thread.fpu.state.fxsave;
> struct _fpreg *to = (struct _fpreg *) &env->st_space[0];
> struct _fpxreg *from = (struct _fpxreg *) &fxsave->st_space[0];
> int i;
> @@ -248,6 +248,12 @@ convert_from_fxsr(struct user_i387_ia32_
> memcpy(&to[i], &from[i], sizeof(to[0]));
> }
>
> +void
> +convert_from_fxsr(struct user_i387_ia32_struct *env, struct task_struct *tsk)
> +{
> + __convert_from_fxsr(env, tsk, &tsk->thread.fpu.state.fxsave);
> +}
> +
> void convert_to_fxsr(struct fxregs_state *fxsave,
> const struct user_i387_ia32_struct *env)
>
> @@ -280,25 +286,29 @@ int fpregs_get(struct task_struct *targe
> {
> struct fpu *fpu = &target->thread.fpu;
> struct user_i387_ia32_struct env;
> + struct fxregs_state fxsave, *fx;
>
> fpu__prepare_read(fpu);
>
> - if (!boot_cpu_has(X86_FEATURE_FPU))
> + if (!static_cpu_has(X86_FEATURE_FPU))
> return fpregs_soft_get(target, regset, to);
>
> - if (!boot_cpu_has(X86_FEATURE_FXSR)) {
> + if (!static_cpu_has(X86_FEATURE_FXSR)) {

both: cpu_feature_enabled

With that:

Reviewed-by: Borislav Petkov <bp@suse.de>

--
Regards/Gruss,
Boris.

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