#include <stdint.h>
#include <stddef.h>

void guest_main(void);
uint64_t guest_hvc_call(uint64_t num, uint64_t a1, uint64_t a2);

static size_t guest_strlen(const char *s)
{
    size_t n = 0;
    while (s[n] != '\0') {
        n++;
    }
    return n;
}

static uint64_t hvc_call(uint64_t num, uint64_t a1, uint64_t a2)
{
    return guest_hvc_call(num, a1, a2);
}

static void console(const char *s)
{
    (void)hvc_call(4u, (uint64_t)(uintptr_t)s, guest_strlen(s));
}

static uint64_t read_midr(void)
{
    uint64_t v;
    __asm__ volatile("mrs %0, midr_el1" : "=r"(v));
    return v;
}

static uint64_t read_pfr0(void)
{
    uint64_t v;
    __asm__ volatile("mrs %0, id_aa64pfr0_el1" : "=r"(v));
    return v;
}

static uint64_t read_cntv_ctl(void)
{
    uint64_t v;
    __asm__ volatile("mrs %0, cntv_ctl_el0" : "=r"(v));
    return v;
}

static void write_sctlr(uint64_t v)
{
    __asm__ volatile("msr sctlr_el1, %0" :: "r"(v) : "memory");
}

static void write_vbar(uint64_t v)
{
    __asm__ volatile("msr vbar_el1, %0" :: "r"(v) : "memory");
}

static void write_ttbr0(uint64_t v)
{
    __asm__ volatile("msr ttbr0_el1, %0" :: "r"(v) : "memory");
}

static void write_tcr(uint64_t v)
{
    __asm__ volatile("msr tcr_el1, %0" :: "r"(v) : "memory");
}

static void write_actlr(uint64_t v)
{
    __asm__ volatile("msr actlr_el1, %0" :: "r"(v) : "memory");
}

static uint64_t attempt_hcr_el2_read(void)
{
    uint64_t v;
    __asm__ volatile("mrs %0, hcr_el2" : "=r"(v));
    return v;
}

static uint64_t read_unknown_sysreg(void)
{
    uint64_t v;
    __asm__ volatile("mrs %0, S3_7_C15_C15_7" : "=r"(v));
    return v;
}

void guest_main(void)
{
    console("diagnostic guest: start");
    uint64_t midr = read_midr();
    (void)midr;
    console("diagnostic guest: read midr_el1");

    uint64_t pfr0 = read_pfr0();
    (void)pfr0;
    console("diagnostic guest: read id_aa64pfr0_el1");

    write_sctlr(0x30d00800u);
    console("diagnostic guest: wrote sctlr_el1 shadow");

    write_vbar(0x40000800u);
    console("diagnostic guest: wrote vbar_el1 vector base");

    write_ttbr0(0u);
    console("diagnostic guest: wrote ttbr0_el1 shadow");

    write_tcr(0u);
    console("diagnostic guest: wrote tcr_el1 shadow");

    uint64_t cntv = read_cntv_ctl();
    (void)cntv;
    console("diagnostic guest: read cntv_ctl_el0");

    (void)hvc_call(0u, 0u, 0u);
    console("diagnostic guest: requested hv id");

    (void)hvc_call(1u, 0u, 0u);
    console("diagnostic guest: requested log dump");

    console("diagnostic guest: attempting denied hcr_el2 read");
    (void)attempt_hcr_el2_read();
    console("diagnostic guest: returned through guest undefined vector");

    __asm__ volatile("brk #0");
    console("diagnostic guest: returned through guest brk vector");

    console("diagnostic guest: attempting unknown sysreg read");
    (void)read_unknown_sysreg();
    console("diagnostic guest: returned from unknown sysreg read");

    console("diagnostic guest: attempting denied actlr_el1 write");
    write_actlr(1u);
    console("diagnostic guest: unexpected return from denied actlr_el1");
    (void)hvc_call(3u, 0u, 0u);
}