x86/fpu: Remove fpstate_sanitize_xstate()

No more users.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210623121453.124819167@linutronix.de

arch/x86/include/asm/fpu/internal.h

@@ -86,8 +86,6 @@ extern void fpstate_init_soft(struct swregs_state *soft);
 static inline void fpstate_init_soft(struct swregs_state *soft) {}
 #endif
 
-extern void fpstate_sanitize_xstate(struct fpu *fpu);
-
 #define user_insn(insn, output, input...)				\
 ({									\
 	int err;							\

arch/x86/kernel/fpu/xstate.c

@@ -128,85 +128,6 @@ static bool xfeature_is_supervisor(int xfeature_nr)
 	return ecx & 1;
 }
 
-/*
- * When executing XSAVEOPT (or other optimized XSAVE instructions), if
- * a processor implementation detects that an FPU state component is still
- * (or is again) in its initialized state, it may clear the corresponding
- * bit in the header.xfeatures field, and can skip the writeout of registers
- * to the corresponding memory layout.
- *
- * This means that when the bit is zero, the state component might still contain
- * some previous - non-initialized register state.
- *
- * Before writing xstate information to user-space we sanitize those components,
- * to always ensure that the memory layout of a feature will be in the init state
- * if the corresponding header bit is zero. This is to ensure that user-space doesn't
- * see some stale state in the memory layout during signal handling, debugging etc.
- */
-void fpstate_sanitize_xstate(struct fpu *fpu)
-{
-	struct fxregs_state *fx = &fpu->state.fxsave;
-	int feature_bit;
-	u64 xfeatures;
-
-	if (!use_xsaveopt())
-		return;
-
-	xfeatures = fpu->state.xsave.header.xfeatures;
-
-	/*
-	 * None of the feature bits are in init state. So nothing else
-	 * to do for us, as the memory layout is up to date.
-	 */
-	if ((xfeatures & xfeatures_mask_all) == xfeatures_mask_all)
-		return;
-
-	/*
-	 * FP is in init state
-	 */
-	if (!(xfeatures & XFEATURE_MASK_FP)) {
-		fx->cwd = 0x37f;
-		fx->swd = 0;
-		fx->twd = 0;
-		fx->fop = 0;
-		fx->rip = 0;
-		fx->rdp = 0;
-		memset(fx->st_space, 0, sizeof(fx->st_space));
-	}
-
-	/*
-	 * SSE is in init state
-	 */
-	if (!(xfeatures & XFEATURE_MASK_SSE))
-		memset(fx->xmm_space, 0, sizeof(fx->xmm_space));
-
-	/*
-	 * First two features are FPU and SSE, which above we handled
-	 * in a special way already:
-	 */
-	feature_bit = 0x2;
-	xfeatures = (xfeatures_mask_user() & ~xfeatures) >> 2;
-
-	/*
-	 * Update all the remaining memory layouts according to their
-	 * standard xstate layout, if their header bit is in the init
-	 * state:
-	 */
-	while (xfeatures) {
-		if (xfeatures & 0x1) {
-			int offset = xstate_comp_offsets[feature_bit];
-			int size = xstate_sizes[feature_bit];
-
-			memcpy((void *)fx + offset,
-			       (void *)&init_fpstate.xsave + offset,
-			       size);
-		}
-
-		xfeatures >>= 1;
-		feature_bit++;
-	}
-}
-
 /*
  * Enable the extended processor state save/restore feature.
  * Called once per CPU onlining.