Commit 97f404ad authored by Kirill A. Shutemov's avatar Kirill A. Shutemov Committed by Thomas Gleixner
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x86/selftests: Add test for mapping placement for 5-level paging 



5-level paging provides a 56-bit virtual address space for user space
application. But the kernel defaults to mappings below the 47-bit address
space boundary, which is the upper bound for 4-level paging, unless an
application explicitely request it by using a mmap(2) address hint above
the 47-bit boundary. The kernel prevents mappings which spawn across the
47-bit boundary unless mmap(2) was invoked with MAP_FIXED.

Add a self-test that covers the corner cases of the interface and validates
the correctness of the implementation.

[ tglx: Massaged changelog once more ]

Signed-off-by: default avatarKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: linux-mm@kvack.org
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lkml.kernel.org/r/20171115143607.81541-2-kirill.shutemov@linux.intel.com
parent 1e0f25db

tools/testing/selftests/x86/5lvl.c

0 → 100644
+177 −0
Original line number Diff line number Diff line 
#include <stdio.h>

#include <sys/mman.h>



#define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]))



#define PAGE_SIZE	4096

#define LOW_ADDR	((void *) (1UL << 30))

#define HIGH_ADDR	((void *) (1UL << 50))



struct testcase {

	void *addr;

	unsigned long size;

	unsigned long flags;

	const char *msg;

	unsigned int low_addr_required:1;

	unsigned int keep_mapped:1;

};



static struct testcase testcases[] = {

	{

		.addr = NULL,

		.size = 2 * PAGE_SIZE,

		.flags = MAP_PRIVATE | MAP_ANONYMOUS,

		.msg = "mmap(NULL)",

		.low_addr_required = 1,

	},

	{

		.addr = LOW_ADDR,

		.size = 2 * PAGE_SIZE,

		.flags = MAP_PRIVATE | MAP_ANONYMOUS,

		.msg = "mmap(LOW_ADDR)",

		.low_addr_required = 1,

	},

	{

		.addr = HIGH_ADDR,

		.size = 2 * PAGE_SIZE,

		.flags = MAP_PRIVATE | MAP_ANONYMOUS,

		.msg = "mmap(HIGH_ADDR)",

		.keep_mapped = 1,

	},

	{

		.addr = HIGH_ADDR,

		.size = 2 * PAGE_SIZE,

		.flags = MAP_PRIVATE | MAP_ANONYMOUS,

		.msg = "mmap(HIGH_ADDR) again",

		.keep_mapped = 1,

	},

	{

		.addr = HIGH_ADDR,

		.size = 2 * PAGE_SIZE,

		.flags = MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED,

		.msg = "mmap(HIGH_ADDR, MAP_FIXED)",

	},

	{

		.addr = (void*) -1,

		.size = 2 * PAGE_SIZE,

		.flags = MAP_PRIVATE | MAP_ANONYMOUS,

		.msg = "mmap(-1)",

		.keep_mapped = 1,

	},

	{

		.addr = (void*) -1,

		.size = 2 * PAGE_SIZE,

		.flags = MAP_PRIVATE | MAP_ANONYMOUS,

		.msg = "mmap(-1) again",

	},

	{

		.addr = (void *)((1UL << 47) - PAGE_SIZE),

		.size = 2 * PAGE_SIZE,

		.flags = MAP_PRIVATE | MAP_ANONYMOUS,

		.msg = "mmap((1UL << 47), 2 * PAGE_SIZE)",

		.low_addr_required = 1,

		.keep_mapped = 1,

	},

	{

		.addr = (void *)((1UL << 47) - PAGE_SIZE / 2),

		.size = 2 * PAGE_SIZE,

		.flags = MAP_PRIVATE | MAP_ANONYMOUS,

		.msg = "mmap((1UL << 47), 2 * PAGE_SIZE / 2)",

		.low_addr_required = 1,

		.keep_mapped = 1,

	},

	{

		.addr = (void *)((1UL << 47) - PAGE_SIZE),

		.size = 2 * PAGE_SIZE,

		.flags = MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED,

		.msg = "mmap((1UL << 47) - PAGE_SIZE, 2 * PAGE_SIZE, MAP_FIXED)",

	},

	{

		.addr = NULL,

		.size = 2UL << 20,

		.flags = MAP_HUGETLB | MAP_PRIVATE | MAP_ANONYMOUS,

		.msg = "mmap(NULL, MAP_HUGETLB)",

		.low_addr_required = 1,

	},

	{

		.addr = LOW_ADDR,

		.size = 2UL << 20,

		.flags = MAP_HUGETLB | MAP_PRIVATE | MAP_ANONYMOUS,

		.msg = "mmap(LOW_ADDR, MAP_HUGETLB)",

		.low_addr_required = 1,

	},

	{

		.addr = HIGH_ADDR,

		.size = 2UL << 20,

		.flags = MAP_HUGETLB | MAP_PRIVATE | MAP_ANONYMOUS,

		.msg = "mmap(HIGH_ADDR, MAP_HUGETLB)",

		.keep_mapped = 1,

	},

	{

		.addr = HIGH_ADDR,

		.size = 2UL << 20,

		.flags = MAP_HUGETLB | MAP_PRIVATE | MAP_ANONYMOUS,

		.msg = "mmap(HIGH_ADDR, MAP_HUGETLB) again",

		.keep_mapped = 1,

	},

	{

		.addr = HIGH_ADDR,

		.size = 2UL << 20,

		.flags = MAP_HUGETLB | MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED,

		.msg = "mmap(HIGH_ADDR, MAP_FIXED | MAP_HUGETLB)",

	},

	{

		.addr = (void*) -1,

		.size = 2UL << 20,

		.flags = MAP_HUGETLB | MAP_PRIVATE | MAP_ANONYMOUS,

		.msg = "mmap(-1, MAP_HUGETLB)",

		.keep_mapped = 1,

	},

	{

		.addr = (void*) -1,

		.size = 2UL << 20,

		.flags = MAP_HUGETLB | MAP_PRIVATE | MAP_ANONYMOUS,

		.msg = "mmap(-1, MAP_HUGETLB) again",

	},

	{

		.addr = (void *)((1UL << 47) - PAGE_SIZE),

		.size = 4UL << 20,

		.flags = MAP_HUGETLB | MAP_PRIVATE | MAP_ANONYMOUS,

		.msg = "mmap((1UL << 47), 4UL << 20, MAP_HUGETLB)",

		.low_addr_required = 1,

		.keep_mapped = 1,

	},

	{

		.addr = (void *)((1UL << 47) - (2UL << 20)),

		.size = 4UL << 20,

		.flags = MAP_HUGETLB | MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED,

		.msg = "mmap((1UL << 47) - (2UL << 20), 4UL << 20, MAP_FIXED | MAP_HUGETLB)",

	},

};



int main(int argc, char **argv)

{

	int i;

	void *p;



	for (i = 0; i < ARRAY_SIZE(testcases); i++) {

		struct testcase *t = testcases + i;



		p = mmap(t->addr, t->size, PROT_NONE, t->flags, -1, 0);



		printf("%s: %p - ", t->msg, p);



		if (p == MAP_FAILED) {

			printf("FAILED\n");

			continue;

		}



		if (t->low_addr_required && p >= (void *)(1UL << 47))

			printf("FAILED\n");

		else

			printf("OK\n");

		if (!t->keep_mapped)

			munmap(p, t->size);

	}

	return 0;

}

tools/testing/selftests/x86/Makefile

+1 −1
Original line number Diff line number Diff line
@@ -11,7 +11,7 @@ TARGETS_C_BOTHBITS := single_step_syscall sysret_ss_attrs syscall_nt ptrace_sysc 
TARGETS_C_32BIT_ONLY := entry_from_vm86 syscall_arg_fault test_syscall_vdso unwind_vdso \

			test_FCMOV test_FCOMI test_FISTTP \

			vdso_restorer

TARGETS_C_64BIT_ONLY := fsgsbase sysret_rip

TARGETS_C_64BIT_ONLY := fsgsbase sysret_rip 5lvl



TARGETS_C_32BIT_ALL := $(TARGETS_C_BOTHBITS) $(TARGETS_C_32BIT_ONLY)

TARGETS_C_64BIT_ALL := $(TARGETS_C_BOTHBITS) $(TARGETS_C_64BIT_ONLY)

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