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/*
* 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"
static inline unsigned long __fls(unsigned long x);
#include "word-at-a-time.h"
#include "utils.h"
static inline unsigned long __fls(unsigned long x)
{
int lz;
asm (PPC_CNTLZL "%0,%1" : "=r" (lz) : "r" (x));
return sizeof(unsigned long) - 1 - lz;
}
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
struct extbl_entry {
int insn;
int fixup;
};
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);
struct extbl_entry *entry = (struct extbl_entry *)__start___ex_table;
while (entry < (struct extbl_entry *)__stop___ex_table) {
unsigned long insn, fixup;
insn = (unsigned long)&entry->insn + entry->insn;
fixup = (unsigned long)&entry->fixup + entry->fixup;
if (insn == *ip) {
*ip = fixup;
return;
}
}
printf("No exception table match for NIA %lx ADDR %lx\n", *ip, addr);
abort();
}
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 1;
}
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));
return 0;
}
int main(void)
{
return test_harness(test_body, "load_unaligned_zeropad");
}
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