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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: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: Thomas 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
178 lines
4.0 KiB
C
178 lines
4.0 KiB
C
#include <stdio.h>
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#include <sys/mman.h>
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#define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]))
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#define PAGE_SIZE 4096
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#define LOW_ADDR ((void *) (1UL << 30))
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#define HIGH_ADDR ((void *) (1UL << 50))
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struct testcase {
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void *addr;
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unsigned long size;
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unsigned long flags;
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const char *msg;
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unsigned int low_addr_required:1;
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unsigned int keep_mapped:1;
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};
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static struct testcase testcases[] = {
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{
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.addr = NULL,
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.size = 2 * PAGE_SIZE,
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.flags = MAP_PRIVATE | MAP_ANONYMOUS,
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.msg = "mmap(NULL)",
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.low_addr_required = 1,
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},
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{
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.addr = LOW_ADDR,
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.size = 2 * PAGE_SIZE,
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.flags = MAP_PRIVATE | MAP_ANONYMOUS,
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.msg = "mmap(LOW_ADDR)",
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.low_addr_required = 1,
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},
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{
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.addr = HIGH_ADDR,
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.size = 2 * PAGE_SIZE,
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.flags = MAP_PRIVATE | MAP_ANONYMOUS,
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.msg = "mmap(HIGH_ADDR)",
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.keep_mapped = 1,
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},
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{
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.addr = HIGH_ADDR,
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.size = 2 * PAGE_SIZE,
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.flags = MAP_PRIVATE | MAP_ANONYMOUS,
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.msg = "mmap(HIGH_ADDR) again",
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.keep_mapped = 1,
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},
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{
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.addr = HIGH_ADDR,
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.size = 2 * PAGE_SIZE,
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.flags = MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED,
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.msg = "mmap(HIGH_ADDR, MAP_FIXED)",
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},
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{
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.addr = (void*) -1,
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.size = 2 * PAGE_SIZE,
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.flags = MAP_PRIVATE | MAP_ANONYMOUS,
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.msg = "mmap(-1)",
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.keep_mapped = 1,
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},
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{
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.addr = (void*) -1,
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.size = 2 * PAGE_SIZE,
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.flags = MAP_PRIVATE | MAP_ANONYMOUS,
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.msg = "mmap(-1) again",
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},
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{
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.addr = (void *)((1UL << 47) - PAGE_SIZE),
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.size = 2 * PAGE_SIZE,
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.flags = MAP_PRIVATE | MAP_ANONYMOUS,
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.msg = "mmap((1UL << 47), 2 * PAGE_SIZE)",
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.low_addr_required = 1,
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.keep_mapped = 1,
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},
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{
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.addr = (void *)((1UL << 47) - PAGE_SIZE / 2),
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.size = 2 * PAGE_SIZE,
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.flags = MAP_PRIVATE | MAP_ANONYMOUS,
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.msg = "mmap((1UL << 47), 2 * PAGE_SIZE / 2)",
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.low_addr_required = 1,
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.keep_mapped = 1,
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},
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{
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.addr = (void *)((1UL << 47) - PAGE_SIZE),
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.size = 2 * PAGE_SIZE,
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.flags = MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED,
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.msg = "mmap((1UL << 47) - PAGE_SIZE, 2 * PAGE_SIZE, MAP_FIXED)",
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},
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{
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.addr = NULL,
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.size = 2UL << 20,
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.flags = MAP_HUGETLB | MAP_PRIVATE | MAP_ANONYMOUS,
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.msg = "mmap(NULL, MAP_HUGETLB)",
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.low_addr_required = 1,
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},
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{
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.addr = LOW_ADDR,
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.size = 2UL << 20,
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.flags = MAP_HUGETLB | MAP_PRIVATE | MAP_ANONYMOUS,
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.msg = "mmap(LOW_ADDR, MAP_HUGETLB)",
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.low_addr_required = 1,
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},
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{
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.addr = HIGH_ADDR,
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.size = 2UL << 20,
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.flags = MAP_HUGETLB | MAP_PRIVATE | MAP_ANONYMOUS,
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.msg = "mmap(HIGH_ADDR, MAP_HUGETLB)",
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.keep_mapped = 1,
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},
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{
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.addr = HIGH_ADDR,
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.size = 2UL << 20,
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.flags = MAP_HUGETLB | MAP_PRIVATE | MAP_ANONYMOUS,
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.msg = "mmap(HIGH_ADDR, MAP_HUGETLB) again",
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.keep_mapped = 1,
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},
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{
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.addr = HIGH_ADDR,
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.size = 2UL << 20,
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.flags = MAP_HUGETLB | MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED,
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.msg = "mmap(HIGH_ADDR, MAP_FIXED | MAP_HUGETLB)",
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},
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{
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.addr = (void*) -1,
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.size = 2UL << 20,
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.flags = MAP_HUGETLB | MAP_PRIVATE | MAP_ANONYMOUS,
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.msg = "mmap(-1, MAP_HUGETLB)",
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.keep_mapped = 1,
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},
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{
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.addr = (void*) -1,
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.size = 2UL << 20,
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.flags = MAP_HUGETLB | MAP_PRIVATE | MAP_ANONYMOUS,
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.msg = "mmap(-1, MAP_HUGETLB) again",
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},
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{
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.addr = (void *)((1UL << 47) - PAGE_SIZE),
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.size = 4UL << 20,
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.flags = MAP_HUGETLB | MAP_PRIVATE | MAP_ANONYMOUS,
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.msg = "mmap((1UL << 47), 4UL << 20, MAP_HUGETLB)",
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.low_addr_required = 1,
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.keep_mapped = 1,
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},
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{
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.addr = (void *)((1UL << 47) - (2UL << 20)),
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.size = 4UL << 20,
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.flags = MAP_HUGETLB | MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED,
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.msg = "mmap((1UL << 47) - (2UL << 20), 4UL << 20, MAP_FIXED | MAP_HUGETLB)",
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},
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};
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int main(int argc, char **argv)
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{
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int i;
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void *p;
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for (i = 0; i < ARRAY_SIZE(testcases); i++) {
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struct testcase *t = testcases + i;
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p = mmap(t->addr, t->size, PROT_NONE, t->flags, -1, 0);
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printf("%s: %p - ", t->msg, p);
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if (p == MAP_FAILED) {
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printf("FAILED\n");
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continue;
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}
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if (t->low_addr_required && p >= (void *)(1UL << 47))
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printf("FAILED\n");
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else
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printf("OK\n");
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if (!t->keep_mapped)
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munmap(p, t->size);
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}
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return 0;
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}
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