Commit d34b661b authored by Michael Ellerman's avatar Michael Ellerman Committed by Benjamin Herrenschmidt
Browse files

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



Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Reviewed-by: default avatarAneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
parent 09567e7f

tools/testing/selftests/powerpc/Makefile

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@@ -13,7 +13,7 @@ CFLAGS := -Wall -O2 -flto -Wall -Werror -DGIT_VERSION='"$(GIT_VERSION)"' -I$(CUR 


export CC CFLAGS



TARGETS = pmu copyloops

TARGETS = pmu copyloops mm



endif

tools/testing/selftests/powerpc/mm/Makefile

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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

tools/testing/selftests/powerpc/mm/hugetlb_vs_thp_test.c

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#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");

}