/*
 * check whether w^x works as one cannot trust /proc/<pid>/maps
 * 2006,2007 lnussel@suse.de, GPL
 */
#include <stdio.h>
#include <string.h>
#include <signal.h>
#include <stdlib.h>
#include <setjmp.h>
#include <sys/mman.h>

static sigjmp_buf jmpbuf;

void segvhandler(int signum)
{
	siglongjmp(jmpbuf, 1);
}

static char staticbuf[] =
#if __i386__
	"\xc7\x00\x01\x00\x00\x00"     // movl   $0x1,(%eax)
	"\xff\xe3"                     // jmp    *%ebx
#else
	"\x48\xc7\x00\x01\x00\x00\x00" // movq   $0x1,(%rax)
	"\xff\xe3"                     // jmpq   *%rbx
#endif
	"\x90\x90\x90\x90"; // some padding

int main(int argc, char* argv[])
{
	int verbose = 1;
	int flag = 0;
	unsigned nonxbits = 0;
	char stackbuf[sizeof(staticbuf)];
	long bufaddr[4];
	char* bufnames[4] = { "static", "stack", "heap", "verify" };
	int i;

	if(argc > 1 && !strcmp(argv[1], "-q"))
		verbose = 0;

	if(verbose)
		puts("If you see any segfault something went wrong.");

	bufaddr[0] = (long)staticbuf;
	bufaddr[1] = (long)stackbuf;
	bufaddr[2] = (long)malloc(sizeof(staticbuf));
	bufaddr[3] = (long)mmap(0, sizeof(staticbuf), PROT_EXEC|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);

	for (i = 1; i < 4; ++i)
	{
		memcpy((void*)bufaddr[i], staticbuf, sizeof(staticbuf));
	}

	signal(SIGSEGV, segvhandler);

	for (i = 0; i < 4; ++i)
	{
		flag = 0;
		if(!sigsetjmp(jmpbuf, 1))
		{
			long faddr = (long)&flag;
			long addr = (long)&&out;

			__asm__ __volatile__(
			#if __i386__
				"movl %2, %%eax\n"\
				"movl %1, %%ebx\n"\
				"jmp *%0\n" \
				:
				: "m"(bufaddr[i]), "m"(addr), "m"(faddr) : "%eax", "%ebx"
			#else
				"movq %2, %%rax\n"\
				"movq %1, %%rbx\n"\
				"jmp *%0\n" \
				:
				: "m"(bufaddr[i]), "m"(addr), "m"(faddr) : "%rax", "%rbx"
			#endif
			);
		}

out:
		nonxbits |= flag<<i;
		if(verbose)
			printf("%6s: NX is%s supported\n", bufnames[i], flag?" not":"");
	}

	if(verbose)
	{
		const char* status = "BUG!, unknown";
		switch(nonxbits)
		{
			case 0x8: status = "full"; break;
			case 0xd: status = "partial"; break;
			case 0xf: status = "no"; break;
		}
		printf("Summary: %s NX support\n", status);
	}

	return !(nonxbits == 0x8);
}