hf_call.c

// SPDX-License-Identifier: Apache-2.0
/*
 * Copyright 2019 The Hafnium Authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "hf/call.h"
#include "hf/types.h"

int64_t hf_call(uint64_t arg0, uint64_t arg1, uint64_t arg2, uint64_t arg3)
{
	register uint64_t r0 __asm__("x0") = arg0;
	register uint64_t r1 __asm__("x1") = arg1;
	register uint64_t r2 __asm__("x2") = arg2;
	register uint64_t r3 __asm__("x3") = arg3;

	/*
	 * We currently implement SMCCC 1.0, which specifies that the callee can
	 * use x4–x17 as scratch registers. If we move to SMCCC 1.1 then this
	 * will change.
	 */
	__asm__ volatile(
		"hvc #0"
		: /* Output registers, also used as inputs ('+' constraint). */
		"+r"(r0), "+r"(r1), "+r"(r2), "+r"(r3)
		:
		: /* Clobber registers. */
		"x4", "x5", "x6", "x7", "x8", "x9", "x10", "x11", "x12", "x13",
		"x14", "x15", "x16", "x17");

	return r0;
}