arm64: signal: nofpsimd: Handle fp/simd context for signal frames

Make sure we try to save/restore the vfp/fpsimd context for signal
handling only when the fp/simd support is available. Otherwise, skip
the frames.

Cc: Will Deacon <will@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>

arch/arm64/kernel/signal.c

@@ -371,6 +371,8 @@ static int parse_user_sigframe(struct user_ctxs *user,
 			goto done;
 
 		case FPSIMD_MAGIC:
+			if (!system_supports_fpsimd())
+				goto invalid;
 			if (user->fpsimd)
 				goto invalid;
 
@@ -506,7 +508,7 @@ static int restore_sigframe(struct pt_regs *regs,
 	if (err == 0)
 		err = parse_user_sigframe(&user, sf);
 
-	if (err == 0) {
+	if (err == 0 && system_supports_fpsimd()) {
 		if (!user.fpsimd)
 			return -EINVAL;
 
@@ -623,7 +625,7 @@ static int setup_sigframe(struct rt_sigframe_user_layout *user,
 
 	err |= __copy_to_user(&sf->uc.uc_sigmask, set, sizeof(*set));
 
-	if (err == 0) {
+	if (err == 0 && system_supports_fpsimd()) {
 		struct fpsimd_context __user *fpsimd_ctx =
 			apply_user_offset(user, user->fpsimd_offset);
 		err |= preserve_fpsimd_context(fpsimd_ctx);

arch/arm64/kernel/signal32.c

@@ -223,7 +223,7 @@ static int compat_restore_sigframe(struct pt_regs *regs,
 	err |= !valid_user_regs(&regs->user_regs, current);
 
 	aux = (struct compat_aux_sigframe __user *) sf->uc.uc_regspace;
-	if (err == 0)
+	if (err == 0 && system_supports_fpsimd())
 		err |= compat_restore_vfp_context(&aux->vfp);
 
 	return err;
@@ -419,7 +419,7 @@ static int compat_setup_sigframe(struct compat_sigframe __user *sf,
 
 	aux = (struct compat_aux_sigframe __user *) sf->uc.uc_regspace;
 
-	if (err == 0)
+	if (err == 0 && system_supports_fpsimd())
 		err |= compat_preserve_vfp_context(&aux->vfp);
 	__put_user_error(0, &aux->end_magic, err);