tools/testing/selftests/powerpc/primitives/load_unaligned_zeropad.c

   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
  24 static inline unsigned long __fls(unsigned long x);
  25
  26 #include "word-at-a-time.h"
  27
  28 #include "utils.h"
  29
  30 static 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
  38 static int page_size;
  39 static char *mem_region;
  40
  41 static 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
  51 static 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
  61 extern char __start___ex_table[];
  62 extern char __stop___ex_table[];
  63
  64 struct extbl_entry {
  65         int insn;
  66         int fixup;
  67 };
  68
  69 static 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
  92 static 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
 102 static 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
 121 static 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
 144 int main(void)
 145 {
 146         return test_harness(test_body, "load_unaligned_zeropad");
 147 }