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

   1/*
   2 * Userspace test harness for load_unaligned_zeropad. Creates two
   3 * pages and uses mprotect to prevent access to the second page and
   4 * a SEGV handler that walks the exception tables and runs the fixup
   5 * routine.
   6 *
   7 * The results are compared against a normal load that is that is
   8 * performed while access to the second page is enabled via mprotect.
   9 *
  10 * Copyright (C) 2014 Anton Blanchard <anton@au.ibm.com>, IBM
  11 *
  12 * This program is free software; you can redistribute it and/or
  13 * modify it under the terms of the GNU General Public License
  14 * as published by the Free Software Foundation; either version
  15 * 2 of the License, or (at your option) any later version.
  16 */
  17
  18#include <stdlib.h>
  19#include <string.h>
  20#include <stdio.h>
  21#include <stdbool.h>
  22#include <signal.h>
  23#include <unistd.h>
  24#include <sys/mman.h>
  25
  26#define FIXUP_SECTION ".ex_fixup"
  27
  28static inline unsigned long __fls(unsigned long x);
  29
  30#include "word-at-a-time.h"
  31
  32#include "utils.h"
  33
  34static inline unsigned long __fls(unsigned long x)
  35{
  36        int lz;
  37
  38        asm (PPC_CNTLZL "%0,%1" : "=r" (lz) : "r" (x));
  39        return sizeof(unsigned long) - 1 - lz;
  40}
  41
  42static int page_size;
  43static char *mem_region;
  44
  45static int protect_region(void)
  46{
  47        if (mprotect(mem_region + page_size, page_size, PROT_NONE)) {
  48                perror("mprotect");
  49                return 1;
  50        }
  51
  52        return 0;
  53}
  54
  55static int unprotect_region(void)
  56{
  57        if (mprotect(mem_region + page_size, page_size, PROT_READ|PROT_WRITE)) {
  58                perror("mprotect");
  59                return 1;
  60        }
  61
  62        return 0;
  63}
  64
  65extern char __start___ex_table[];
  66extern char __stop___ex_table[];
  67
  68#if defined(__powerpc64__)
  69#define UCONTEXT_NIA(UC)        (UC)->uc_mcontext.gp_regs[PT_NIP]
  70#elif defined(__powerpc__)
  71#define UCONTEXT_NIA(UC)        (UC)->uc_mcontext.uc_regs->gregs[PT_NIP]
  72#else
  73#error implement UCONTEXT_NIA
  74#endif
  75
  76struct extbl_entry {
  77        int insn;
  78        int fixup;
  79};
  80
  81static void segv_handler(int signr, siginfo_t *info, void *ptr)
  82{
  83        ucontext_t *uc = (ucontext_t *)ptr;
  84        unsigned long addr = (unsigned long)info->si_addr;
  85        unsigned long *ip = &UCONTEXT_NIA(uc);
  86        struct extbl_entry *entry = (struct extbl_entry *)__start___ex_table;
  87
  88        while (entry < (struct extbl_entry *)__stop___ex_table) {
  89                unsigned long insn, fixup;
  90
  91                insn  = (unsigned long)&entry->insn + entry->insn;
  92                fixup = (unsigned long)&entry->fixup + entry->fixup;
  93
  94                if (insn == *ip) {
  95                        *ip = fixup;
  96                        return;
  97                }
  98        }
  99
 100        printf("No exception table match for NIA %lx ADDR %lx\n", *ip, addr);
 101        abort();
 102}
 103
 104static void setup_segv_handler(void)
 105{
 106        struct sigaction action;
 107
 108        memset(&action, 0, sizeof(action));
 109        action.sa_sigaction = segv_handler;
 110        action.sa_flags = SA_SIGINFO;
 111        sigaction(SIGSEGV, &action, NULL);
 112}
 113
 114static int do_one_test(char *p, int page_offset)
 115{
 116        unsigned long should;
 117        unsigned long got;
 118
 119        FAIL_IF(unprotect_region());
 120        should = *(unsigned long *)p;
 121        FAIL_IF(protect_region());
 122
 123        got = load_unaligned_zeropad(p);
 124
 125        if (should != got) {
 126                printf("offset %u load_unaligned_zeropad returned 0x%lx, should be 0x%lx\n", page_offset, got, should);
 127                return 1;
 128        }
 129
 130        return 0;
 131}
 132
 133static int test_body(void)
 134{
 135        unsigned long i;
 136
 137        page_size = getpagesize();
 138        mem_region = mmap(NULL, page_size * 2, PROT_READ|PROT_WRITE,
 139                MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
 140
 141        FAIL_IF(mem_region == MAP_FAILED);
 142
 143        for (i = 0; i < page_size; i++)
 144                mem_region[i] = i;
 145
 146        memset(mem_region+page_size, 0, page_size);
 147
 148        setup_segv_handler();
 149
 150        for (i = 0; i < page_size; i++)
 151                FAIL_IF(do_one_test(mem_region+i, i));
 152
 153        return 0;
 154}
 155
 156int main(void)
 157{
 158        return test_harness(test_body, "load_unaligned_zeropad");
 159}
 160