selftests/powerpc: Test the THP bug we fixed in the previous commit

export CC CFLAGS

TARGETS = pmu copyloops

TARGETS = pmu copyloops mm

endif

noarg:

	$(MAKE) -C ../

PROGS := hugetlb_vs_thp_test

all: $(PROGS)

$(PROGS): ../harness.c

run_tests: all

	@-for PROG in $(PROGS); do \

		./$$PROG; \

	done;

clean:

	rm -f $(PROGS)

.PHONY: all run_tests clean

#include <stdio.h>

#include <sys/mman.h>

#include <unistd.h>

#include "utils.h"

/* This must match the huge page & THP size */

#define SIZE	(16 * 1024 * 1024)

static int test_body(void)

{

	void *addr;

	char *p;

	addr = (void *)0xa0000000;

	p = mmap(addr, SIZE, PROT_READ | PROT_WRITE,

		 MAP_HUGETLB | MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);

	if (p != MAP_FAILED) {

		/*

		 * Typically the mmap will fail because no huge pages are

		 * allocated on the system. But if there are huge pages

		 * allocated the mmap will succeed. That's fine too, we just

		 * munmap here before continuing.

		 */

		munmap(addr, SIZE);

	}

	p = mmap(addr, SIZE, PROT_READ | PROT_WRITE,

		 MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);

	if (p == MAP_FAILED) {

		printf("Mapping failed @ %p\n", addr);

		perror("mmap");

		return 1;

	}

	/*

	 * Either a user or kernel access is sufficient to trigger the bug.

	 * A kernel access is easier to spot & debug, as it will trigger the

	 * softlockup or RCU stall detectors, and when the system is kicked

	 * into xmon we get a backtrace in the kernel.

	 *

	 * A good option is:

	 *  getcwd(p, SIZE);

	 *

	 * For the purposes of this testcase it's preferable to spin in

	 * userspace, so the harness can kill us if we get stuck. That way we

	 * see a test failure rather than a dead system.

	 */

	*p = 0xf;

	munmap(addr, SIZE);

	return 0;

}

static int test_main(void)

{

	int i;

	/* 10,000 because it's a "bunch", and completes reasonably quickly */

	for (i = 0; i < 10000; i++)

		if (test_body())

			return 1;

	return 0;

}

int main(void)

{

	return test_harness(test_main, "hugetlb_vs_thp");

}