LXR linux/tools/testing/selftests/powerpc/primitives/load_unaligned

   1// SPDX-License-Identifier: GPL-2.0-or-later
   2/*
   3 * Userspace test harness for load_unaligned_zeropad. Creates two
   4 * pages and uses mprotect to prevent access to the second page and
   5 * a SEGV handler that walks the exception tables and runs the fixup
   6 * routine.
   7 *
   8 * The results are compared against a normal load that is that is
   9 * performed while access to the second page is enabled via mprotect.
  10 *
  11 * Copyright (C) 2014 Anton Blanchard <anton@au.ibm.com>, IBM
  12 */
  13
  14#include <stdlib.h>
  15#include <string.h>
  16#include <stdio.h>
  17#include <stdbool.h>
  18#include <signal.h>
  19#include <unistd.h>
  20#include <sys/mman.h>
  21
  22#define FIXUP_SECTION ".ex_fixup"
  23
  24static inline unsigned long __fls(unsigned long x);
  25
  26#include "word-at-a-time.h"
  27
  28#include "utils.h"
  29
  30static inline unsigned long __fls(unsigned long x)
  31{
  32        int lz;
  33
  34        asm (PPC_CNTLZL "%0,%1" : "=r" (lz) : "r" (x));
  35        return sizeof(unsigned long) - 1 - lz;
  36}
  37
  38static int page_size;
  39static char *mem_region;
  40
  41static int protect_region(void)
  42{
  43        if (mprotect(mem_region + page_size, page_size, PROT_NONE)) {
  44                perror("mprotect");
  45                return 1;
  46        }
  47
  48        return 0;
  49}
  50
  51static int unprotect_region(void)
  52{
  53        if (mprotect(mem_region + page_size, page_size, PROT_READ|PROT_WRITE)) {
  54                perror("mprotect");
  55                return 1;
  56        }
  57
  58        return 0;
  59}
  60
  61extern char __start___ex_table[];
  62extern char __stop___ex_table[];
  63
  64struct extbl_entry {
  65        int insn;
  66        int fixup;
  67};
  68
  69static void segv_handler(int signr, siginfo_t *info, void *ptr)
  70{
  71        ucontext_t *uc = (ucontext_t *)ptr;
  72        unsigned long addr = (unsigned long)info->si_addr;
  73        unsigned long *ip = &UCONTEXT_NIA(uc);
  74        struct extbl_entry *entry = (struct extbl_entry *)__start___ex_table;
  75
  76        while (entry < (struct extbl_entry *)__stop___ex_table) {
  77                unsigned long insn, fixup;
  78
  79                insn  = (unsigned long)&entry->insn + entry->insn;
  80                fixup = (unsigned long)&entry->fixup + entry->fixup;
  81
  82                if (insn == *ip) {
  83                        *ip = fixup;
  84                        return;
  85                }
  86        }
  87
  88        printf("No exception table match for NIA %lx ADDR %lx\n", *ip, addr);
  89        abort();
  90}
  91
  92static void setup_segv_handler(void)
  93{
  94        struct sigaction action;
  95
  96        memset(&action, 0, sizeof(action));
  97        action.sa_sigaction = segv_handler;
  98        action.sa_flags = SA_SIGINFO;
  99        sigaction(SIGSEGV, &action, NULL);
 100}
 101
 102static int do_one_test(char *p, int page_offset)
 103{
 104        unsigned long should;
 105        unsigned long got;
 106
 107        FAIL_IF(unprotect_region());
 108        should = *(unsigned long *)p;
 109        FAIL_IF(protect_region());
 110
 111        got = load_unaligned_zeropad(p);
 112
 113        if (should != got) {
 114                printf("offset %u load_unaligned_zeropad returned 0x%lx, should be 0x%lx\n", page_offset, got, should);
 115                return 1;
 116        }
 117
 118        return 0;
 119}
 120
 121static int test_body(void)
 122{
 123        unsigned long i;
 124
 125        page_size = getpagesize();
 126        mem_region = mmap(NULL, page_size * 2, PROT_READ|PROT_WRITE,
 127                MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
 128
 129        FAIL_IF(mem_region == MAP_FAILED);
 130
 131        for (i = 0; i < page_size; i++)
 132                mem_region[i] = i;
 133
 134        memset(mem_region+page_size, 0, page_size);
 135
 136        setup_segv_handler();
 137
 138        for (i = 0; i < page_size; i++)
 139                FAIL_IF(do_one_test(mem_region+i, i));
 140
 141        return 0;
 142}
 143
 144int main(void)
 145{
 146        return test_harness(test_body, "load_unaligned_zeropad");
 147}
 148