// SPDX-License-Identifier: GPL-2.0+
/*
 * Copyright 2005-2020 IBM Corporation.
 *
 * Includes code from librtas (https://github.com/ibm-power-utilities/librtas/)
 */

#include <byteswap.h>
#include <stdint.h>
#include <inttypes.h>
#include <stdio.h>
#include <string.h>
#include <sys/syscall.h>
#include <sys/types.h>
#include <unistd.h>
#include <stdarg.h>
#include <stdlib.h>
#include <fcntl.h>
#include <errno.h>
#include "utils.h"

#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
#define cpu_to_be32(x)          bswap_32(x)
#define be32_to_cpu(x)          bswap_32(x)
#else
#define cpu_to_be32(x)          (x)
#define be32_to_cpu(x)          (x)
#endif

#define RTAS_IO_ASSERT  -1098   /* Unexpected I/O Error */
#define RTAS_UNKNOWN_OP -1099   /* No Firmware Implementation of Function */
#define BLOCK_SIZE 4096
#define PAGE_SIZE 4096
#define MAX_PAGES 64

static const char *ofdt_rtas_path = "/proc/device-tree/rtas";

typedef __be32 uint32_t;
struct rtas_args {
        __be32 token;
        __be32 nargs;
        __be32 nret;
        __be32 args[16];
        __be32 *rets;     /* Pointer to return values in args[]. */
};

struct region {
        uint64_t addr;
        uint32_t size;
        struct region *next;
};

int read_entire_file(int fd, char **buf, size_t *len)
{
        size_t buf_size = 0;
        size_t off = 0;
        int rc;

        *buf = NULL;
        do {
                buf_size += BLOCK_SIZE;
                if (*buf == NULL)
                        *buf = malloc(buf_size);
                else
                        *buf = realloc(*buf, buf_size);

                if (*buf == NULL)
                        return -ENOMEM;

                rc = read(fd, *buf + off, BLOCK_SIZE);
                if (rc < 0)
                        return -EIO;

                off += rc;
        } while (rc == BLOCK_SIZE);

        if (len)
                *len = off;

        return 0;
}

static int open_prop_file(const char *prop_path, const char *prop_name, int *fd)
{
        char *path;
        int len;

        /* allocate enough for two string, a slash and trailing NULL */
        len = strlen(prop_path) + strlen(prop_name) + 1 + 1;
        path = malloc(len);
        if (path == NULL)
                return -ENOMEM;

        snprintf(path, len, "%s/%s", prop_path, prop_name);

        *fd = open(path, O_RDONLY);
        free(path);
        if (*fd < 0)
                return -errno;

        return 0;
}

static int get_property(const char *prop_path, const char *prop_name,
                        char **prop_val, size_t *prop_len)
{
        int rc, fd;

        rc = open_prop_file(prop_path, prop_name, &fd);
        if (rc)
                return rc;

        rc = read_entire_file(fd, prop_val, prop_len);
        close(fd);

        return rc;
}

int rtas_token(const char *call_name)
{
        char *prop_buf = NULL;
        size_t len;
        int rc;

        rc = get_property(ofdt_rtas_path, call_name, &prop_buf, &len);
        if (rc < 0) {
                rc = RTAS_UNKNOWN_OP;
                goto err;
        }

        rc = be32_to_cpu(*(int *)prop_buf);

err:
        free(prop_buf);
        return rc;
}

static int read_kregion_bounds(struct region *kregion)
{
        char *buf;
        int fd;
        int rc;

        fd = open("/proc/ppc64/rtas/rmo_buffer", O_RDONLY);
        if (fd < 0) {
                printf("Could not open rmo_buffer file\n");
                return RTAS_IO_ASSERT;
        }

        rc = read_entire_file(fd, &buf, NULL);
        close(fd);
        if (rc) {
                free(buf);
                return rc;
        }

        sscanf(buf, "%" SCNx64 " %x", &kregion->addr, &kregion->size);
        free(buf);

        if (!(kregion->size && kregion->addr) ||
            (kregion->size > (PAGE_SIZE * MAX_PAGES))) {
                printf("Unexpected kregion bounds\n");
                return RTAS_IO_ASSERT;
        }

        return 0;
}

static int rtas_call(const char *name, int nargs,
                     int nrets, ...)
{
        struct rtas_args args;
        __be32 *rets[16];
        int i, rc, token;
        va_list ap;

        va_start(ap, nrets);

        token = rtas_token(name);
        if (token == RTAS_UNKNOWN_OP) {
                // We don't care if the call doesn't exist
                printf("call '%s' not available, skipping...", name);
                rc = RTAS_UNKNOWN_OP;
                goto err;
        }

        args.token = cpu_to_be32(token);
        args.nargs = cpu_to_be32(nargs);
        args.nret = cpu_to_be32(nrets);

        for (i = 0; i < nargs; i++)
                args.args[i] = (__be32) va_arg(ap, unsigned long);

        for (i = 0; i < nrets; i++)
                rets[i] = (__be32 *) va_arg(ap, unsigned long);

        rc = syscall(__NR_rtas, &args);
        if (rc) {
                rc = -errno;
                goto err;
        }

        if (nrets) {
                *(rets[0]) = be32_to_cpu(args.args[nargs]);

                for (i = 1; i < nrets; i++) {
                        *(rets[i]) = args.args[nargs + i];
                }
        }

err:
        va_end(ap);
        return rc;
}

static int test(void)
{
        struct region rmo_region;
        uint32_t rmo_start;
        uint32_t rmo_end;
        __be32 rets[1];
        int rc;

        // Test a legitimate harmless call
        // Expected: call succeeds
        printf("Test a permitted call, no parameters... ");
        rc = rtas_call("get-time-of-day", 0, 1, rets);
        printf("rc: %d\n", rc);
        FAIL_IF(rc != 0 && rc != RTAS_UNKNOWN_OP);

        // Test a prohibited call
        // Expected: call returns -EINVAL
        printf("Test a prohibited call... ");
        rc = rtas_call("nvram-fetch", 0, 1, rets);
        printf("rc: %d\n", rc);
        FAIL_IF(rc != -EINVAL && rc != RTAS_UNKNOWN_OP);

        // Get RMO
        rc = read_kregion_bounds(&rmo_region);
        if (rc) {
                printf("Couldn't read RMO region bounds, skipping remaining cases\n");
                return 0;
        }
        rmo_start = rmo_region.addr;
        rmo_end = rmo_start + rmo_region.size - 1;
        printf("RMO range: %08x - %08x\n", rmo_start, rmo_end);

        // Test a permitted call, user-supplied size, buffer inside RMO
        // Expected: call succeeds
        printf("Test a permitted call, user-supplied size, buffer inside RMO... ");
        rc = rtas_call("ibm,get-system-parameter", 3, 1, 0, cpu_to_be32(rmo_start),
                       cpu_to_be32(rmo_end - rmo_start + 1), rets);
        printf("rc: %d\n", rc);
        FAIL_IF(rc != 0 && rc != RTAS_UNKNOWN_OP);

        // Test a permitted call, user-supplied size, buffer start outside RMO
        // Expected: call returns -EINVAL
        printf("Test a permitted call, user-supplied size, buffer start outside RMO... ");
        rc = rtas_call("ibm,get-system-parameter", 3, 1, 0, cpu_to_be32(rmo_end + 1),
                       cpu_to_be32(4000), rets);
        printf("rc: %d\n", rc);
        FAIL_IF(rc != -EINVAL && rc != RTAS_UNKNOWN_OP);

        // Test a permitted call, user-supplied size, buffer end outside RMO
        // Expected: call returns -EINVAL
        printf("Test a permitted call, user-supplied size, buffer end outside RMO... ");
        rc = rtas_call("ibm,get-system-parameter", 3, 1, 0, cpu_to_be32(rmo_start),
                       cpu_to_be32(rmo_end - rmo_start + 2), rets);
        printf("rc: %d\n", rc);
        FAIL_IF(rc != -EINVAL && rc != RTAS_UNKNOWN_OP);

        // Test a permitted call, fixed size, buffer end outside RMO
        // Expected: call returns -EINVAL
        printf("Test a permitted call, fixed size, buffer end outside RMO... ");
        rc = rtas_call("ibm,configure-connector", 2, 1, cpu_to_be32(rmo_end - 4000), 0, rets);
        printf("rc: %d\n", rc);
        FAIL_IF(rc != -EINVAL && rc != RTAS_UNKNOWN_OP);

        return 0;
}

int main(int argc, char *argv[])
{
        return test_harness(test, "rtas_filter");
}