/*
 * Copyright IBM Corp.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of version 2.1 of the GNU Lesser General Public License
 * as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it would be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 *
 */

#include <assert.h>
#include <errno.h>
#include <fcntl.h>
#include <signal.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/mman.h>
#include <sys/ptrace.h>
#include <sys/syscall.h>
#include <ucontext.h>
#include <unistd.h>

#include "utils.h"

char *file_name;

int in_test;
volatile int faulted;
volatile void *dar;
int errors;

static void segv(int signum, siginfo_t *info, void *ctxt_v)
{
        ucontext_t *ctxt = (ucontext_t *)ctxt_v;
        struct pt_regs *regs = ctxt->uc_mcontext.regs;

        if (!in_test) {
                fprintf(stderr, "Segfault outside of test !\n");
                exit(1);
        }

        faulted = 1;
        dar = (void *)regs->dar;
        regs->nip += 4;
}

static inline void do_read(const volatile void *addr)
{
        int ret;

        asm volatile("lwz %0,0(%1); twi 0,%0,0; isync;\n"
                     : "=r" (ret) : "r" (addr) : "memory");
}

static inline void do_write(const volatile void *addr)
{
        int val = 0x1234567;

        asm volatile("stw %0,0(%1); sync; \n"
                     : : "r" (val), "r" (addr) : "memory");
}

static inline void check_faulted(void *addr, long page, long subpage, int write)
{
        int want_fault = (subpage == ((page + 3) % 16));

        if (write)
                want_fault |= (subpage == ((page + 1) % 16));

        if (faulted != want_fault) {
                printf("Failed at %p (p=%ld,sp=%ld,w=%d), want=%s, got=%s !\n",
                       addr, page, subpage, write,
                       want_fault ? "fault" : "pass",
                       faulted ? "fault" : "pass");
                ++errors;
        }

        if (faulted) {
                if (dar != addr) {
                        printf("Fault expected at %p and happened at %p !\n",
                               addr, dar);
                }
                faulted = 0;
                asm volatile("sync" : : : "memory");
        }
}

static int run_test(void *addr, unsigned long size)
{
        unsigned int *map;
        long i, j, pages, err;

        pages = size / 0x10000;
        map = malloc(pages * 4);
        assert(map);

        /*
         * for each page, mark subpage i % 16 read only and subpage
         * (i + 3) % 16 inaccessible
         */
        for (i = 0; i < pages; i++) {
                map[i] = (0x40000000 >> (((i + 1) * 2) % 32)) |
                        (0xc0000000 >> (((i + 3) * 2) % 32));
        }

        err = syscall(__NR_subpage_prot, addr, size, map);
        if (err) {
                perror("subpage_perm");
                return 1;
        }
        free(map);

        in_test = 1;
        errors = 0;
        for (i = 0; i < pages; i++) {
                for (j = 0; j < 16; j++, addr += 0x1000) {
                        do_read(addr);
                        check_faulted(addr, i, j, 0);
                        do_write(addr);
                        check_faulted(addr, i, j, 1);
                }
        }

        in_test = 0;
        if (errors) {
                printf("%d errors detected\n", errors);
                return 1;
        }

        return 0;
}

static int syscall_available(void)
{
        int rc;

        errno = 0;
        rc = syscall(__NR_subpage_prot, 0, 0, 0);

        return rc == 0 || (errno != ENOENT && errno != ENOSYS);
}

int test_anon(void)
{
        unsigned long align;
        struct sigaction act = {
                .sa_sigaction = segv,
                .sa_flags = SA_SIGINFO
        };
        void *mallocblock;
        unsigned long mallocsize;

        SKIP_IF(!syscall_available());

        if (getpagesize() != 0x10000) {
                fprintf(stderr, "Kernel page size must be 64K!\n");
                return 1;
        }

        sigaction(SIGSEGV, &act, NULL);

        mallocsize = 4 * 16 * 1024 * 1024;

        FAIL_IF(posix_memalign(&mallocblock, 64 * 1024, mallocsize));

        align = (unsigned long)mallocblock;
        if (align & 0xffff)
                align = (align | 0xffff) + 1;

        mallocblock = (void *)align;

        printf("allocated malloc block of 0x%lx bytes at %p\n",
               mallocsize, mallocblock);

        printf("testing malloc block...\n");

        return run_test(mallocblock, mallocsize);
}

int test_file(void)
{
        struct sigaction act = {
                .sa_sigaction = segv,
                .sa_flags = SA_SIGINFO
        };
        void *fileblock;
        off_t filesize;
        int fd;

        SKIP_IF(!syscall_available());

        fd = open(file_name, O_RDWR);
        if (fd == -1) {
                perror("failed to open file");
                return 1;
        }
        sigaction(SIGSEGV, &act, NULL);

        filesize = lseek(fd, 0, SEEK_END);
        if (filesize & 0xffff)
                filesize &= ~0xfffful;

        fileblock = mmap(NULL, filesize, PROT_READ | PROT_WRITE,
                         MAP_SHARED, fd, 0);
        if (fileblock == MAP_FAILED) {
                perror("failed to map file");
                return 1;
        }
        printf("allocated %s for 0x%llx bytes at %p\n",
               file_name, (long long)filesize, fileblock);

        printf("testing file map...\n");

        return run_test(fileblock, filesize);
}

int main(int argc, char *argv[])
{
        int rc;

        rc = test_harness(test_anon, "subpage_prot_anon");
        if (rc)
                return rc;

        if (argc > 1)
                file_name = argv[1];
        else
                file_name = "tempfile";

        return test_harness(test_file, "subpage_prot_file");
}