x86/fpu: Use copy_xstate_to_uabi_buf() in xfpregs_get()

Use the new functionality of copy_xstate_to_uabi_buf() to retrieve the
FX state when XSAVE* is in use. This avoids overwriting the FPU state
buffer with fpstate_sanitize_xstate() which is error prone and duplicated
code.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210623121452.901736860@linutronix.de

diff --git a/arch/x86/kernel/fpu/regset.c b/arch/x86/kernel/fpu/regset.c
index 783f84d..ccbe25f 100644 (file)
--- a/arch/x86/kernel/fpu/regset.c
+++ b/arch/x86/kernel/fpu/regset.c
@@ -33,13 +33,18 @@ int xfpregs_get(struct task_struct *target, const struct user_regset *regset,
 {
        struct fpu *fpu = &target->thread.fpu;
 
-       if (!boot_cpu_has(X86_FEATURE_FXSR))
+       if (!cpu_feature_enabled(X86_FEATURE_FXSR))
                return -ENODEV;
 
        fpu__prepare_read(fpu);
-       fpstate_sanitize_xstate(fpu);
 
-       return membuf_write(&to, &fpu->state.fxsave, sizeof(struct fxregs_state));
+       if (!use_xsave()) {
+               return membuf_write(&to, &fpu->state.fxsave,
+                                   sizeof(fpu->state.fxsave));
+       }
+
+       copy_xstate_to_uabi_buf(to, &fpu->state.xsave, XSTATE_COPY_FX);
+       return 0;
 }
 
 int xfpregs_set(struct task_struct *target, const struct user_regset *regset,