text: /*
   * Userspace test harness for load_unaligned_zeropad. Creates two
   * pages and uses mprotect to prevent access to the second page and
   * a SEGV handler that walks the exception tables and runs the fixup
   * routine.
   *
   * The results are compared against a normal load that is that is
   * performed while access to the second page is enabled via mprotect.
   *
   * Copyright (C) 2014 Anton Blanchard <anton@au.ibm.com>, IBM
   *
   * This program is free software; you can redistribute it and/or
   * modify it under the terms of the GNU General Public License
   * as published by the Free Software Foundation; either version
   * 2 of the License, or (at your option) any later version.
   */
  
  #include <stdlib.h>
  #include <string.h>
  #include <stdio.h>
  #include <stdbool.h>
  #include <signal.h>
  #include <unistd.h>
  #include <sys/mman.h>
  
  #define FIXUP_SECTION ".ex_fixup"
  
  #include "word-at-a-time.h"
  
  #include "utils.h"
  
  
  static int page_size;
  static char *mem_region;
  
  static int protect_region(void)
  {
  	if (mprotect(mem_region + page_size, page_size, PROT_NONE)) {
  		perror("mprotect");
  		return 1;
  	}
  
  	return 0;
  }
  
  static int unprotect_region(void)
  {
  	if (mprotect(mem_region + page_size, page_size, PROT_READ|PROT_WRITE)) {
  		perror("mprotect");
  		return 1;
  	}
  
  	return 0;
  }
  
  extern char __start___ex_table[];
  extern char __stop___ex_table[];
  
  #if defined(__powerpc64__)
  #define UCONTEXT_NIA(UC)	(UC)->uc_mcontext.gp_regs[PT_NIP]
  #elif defined(__powerpc__)
  #define UCONTEXT_NIA(UC)	(UC)->uc_mcontext.uc_regs->gregs[PT_NIP]
  #else
  #error implement UCONTEXT_NIA
  #endif
  
  static int segv_error;
  
  static void segv_handler(int signr, siginfo_t *info, void *ptr)
  {
  	ucontext_t *uc = (ucontext_t *)ptr;
  	unsigned long addr = (unsigned long)info->si_addr;
  	unsigned long *ip = &UCONTEXT_NIA(uc);
  	unsigned long *ex_p = (unsigned long *)__start___ex_table;
  
  	while (ex_p < (unsigned long *)__stop___ex_table) {
  		unsigned long insn, fixup;
  
  		insn = *ex_p++;
  		fixup = *ex_p++;
  
  		if (insn == *ip) {
  			*ip = fixup;
  			return;
  		}
  	}
  
  	printf("No exception table match for NIA %lx ADDR %lx\n", *ip, addr);
  	segv_error++;
  }
  
  static void setup_segv_handler(void)
  {
  	struct sigaction action;
  
  	memset(&action, 0, sizeof(action));
  	action.sa_sigaction = segv_handler;
  	action.sa_flags = SA_SIGINFO;
  	sigaction(SIGSEGV, &action, NULL);
  }
  
  static int do_one_test(char *p, int page_offset)
  {
  	unsigned long should;
  	unsigned long got;
  
  	FAIL_IF(unprotect_region());
  	should = *(unsigned long *)p;
  	FAIL_IF(protect_region());
  
  	got = load_unaligned_zeropad(p);
  
  	if (should != got)
  		printf("offset %u load_unaligned_zeropad returned 0x%lx, should be 0x%lx\n", page_offset, got, should);
  
  	return 0;
  }
  
  static int test_body(void)
  {
  	unsigned long i;
  
  	page_size = getpagesize();
  	mem_region = mmap(NULL, page_size * 2, PROT_READ|PROT_WRITE,
  		MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
  
  	FAIL_IF(mem_region == MAP_FAILED);
  
  	for (i = 0; i < page_size; i++)
  		mem_region[i] = i;
  
  	memset(mem_region+page_size, 0, page_size);
  
  	setup_segv_handler();
  
  	for (i = 0; i < page_size; i++)
  		FAIL_IF(do_one_test(mem_region+i, i));
  
  	FAIL_IF(segv_error);
  
  	return 0;
  }
  
  int main(void)
  {
  	return test_harness(test_body, "load_unaligned_zeropad");
  }
  