// SPDX-License-Identifier: GPL-2.0-only
// Copyright (C) 2021 ARM Limited.
// Original author: Mark Brown <broonie@kernel.org>
//
// Trivial syscall overhead benchmark.
//
// This is implemented in asm to ensure that we don't have any issues with
// system libraries using instructions that disrupt the test.

#include <asm/unistd.h>
#include "assembler.h"

.arch_extension sve

.macro test_loop per_loop
        mov     x10, x20
        mov     x8, #__NR_getpid
        mrs     x11, CNTVCT_EL0
1:
        \per_loop
        svc     #0
        sub     x10, x10, #1
        cbnz    x10, 1b

        mrs     x12, CNTVCT_EL0
        sub     x0, x12, x11
        bl      putdec
        puts    "\n"
.endm

// Main program entry point
.globl _start
function _start
        puts    "Iterations per test: "
        mov     x20, #10000
        lsl     x20, x20, #12
        mov     x0, x20
        bl      putdec
        puts    "\n"

        // Test having never used SVE
        puts    "No SVE: "
        test_loop

        // Check for SVE support - should use hwcap but that's hard in asm
        mrs     x0, ID_AA64PFR0_EL1
        ubfx    x0, x0, #32, #4
        cbnz    x0, 1f
        puts    "System does not support SVE\n"
        b       out
1:

        // Execute a SVE instruction
        puts    "SVE VL: "
        rdvl    x0, #8
        bl      putdec
        puts    "\n"

        puts    "SVE used once: "
        test_loop

        // Use SVE per syscall
        puts    "SVE used per syscall: "
        test_loop "rdvl x0, #8"

        // Test non-SVE execution after SVE
        puts    "No SVE after SVE: "
        test_loop

        //  And we're done
out:
        mov     x0, #0
        mov     x8, #__NR_exit
        svc     #0