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mlock tests: Add a regression test
The test tries to trigger creation of a superpage mapping in an mlock()ed region. MFC after: 2 weeks
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@ -28,11 +28,15 @@
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#include <sys/cdefs.h>
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#include <sys/mman.h>
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#include <sys/ptrace.h>
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#include <sys/resource.h>
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#include <sys/wait.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <signal.h>
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#include <stdatomic.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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@ -161,12 +165,122 @@ ATF_TC_BODY(mlock__truncate_and_unlock, tc)
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ATF_REQUIRE(munlock(addr, len) == 0);
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}
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/*
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* Exercise a corner case involving an interaction between mlock() and superpage
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* creation: a truncation of the object backing a mapping results in the
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* truncated region being unmapped by the pmap, but does not affect the logical
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* mapping. In particular, the truncated region remains mlock()ed. If the
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* mapping is later extended, a page fault in the formerly truncated region can
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* result in superpage creation via a call to pmap_enter(psind = 1).
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*/
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ATF_TC(mlock__superpage_fault);
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ATF_TC_HEAD(mlock__superpage_fault, tc)
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{
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atf_tc_set_md_var(tc, "require.user", "root");
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}
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ATF_TC_BODY(mlock__superpage_fault, tc)
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{
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struct rlimit rlim;
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void *addr1, *addr2;
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size_t len, pagesizes[MAXPAGESIZES];
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int count, error, shmfd;
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char vec;
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count = getpagesizes(pagesizes, MAXPAGESIZES);
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ATF_REQUIRE_MSG(count >= 1,
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"failed to get page sizes: %s", strerror(errno));
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if (count == 1)
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atf_tc_skip("system does not support multiple page sizes");
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len = pagesizes[1];
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error = getrlimit(RLIMIT_MEMLOCK, &rlim);
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ATF_REQUIRE_MSG(error == 0, "getrlimit: %s", strerror(errno));
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rlim.rlim_cur += len;
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rlim.rlim_max += len;
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error = setrlimit(RLIMIT_MEMLOCK, &rlim);
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ATF_REQUIRE_MSG(error == 0, "setrlimit: %s", strerror(errno));
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shmfd = shm_open(SHM_ANON, O_RDWR | O_CREAT, 0600);
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ATF_REQUIRE_MSG(shmfd >= 0, "shm_open: %s", strerror(errno));
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error = ftruncate(shmfd, len);
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ATF_REQUIRE_MSG(error == 0, "ftruncate: %s", strerror(errno));
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addr1 = mmap(NULL, len, PROT_READ | PROT_WRITE,
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MAP_SHARED | MAP_ALIGNED_SUPER, shmfd, 0);
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ATF_REQUIRE_MSG(addr1 != MAP_FAILED, "mmap: %s", strerror(errno));
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ATF_REQUIRE_MSG(((uintptr_t)addr1 & (len - 1)) == 0,
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"addr %p is misaligned", addr1);
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addr2 = mmap(NULL, len, PROT_READ,
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MAP_SHARED | MAP_ALIGNED_SUPER, shmfd, 0);
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ATF_REQUIRE_MSG(addr2 != MAP_FAILED, "mmap: %s", strerror(errno));
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ATF_REQUIRE_MSG(((uintptr_t)addr2 & (len - 1)) == 0,
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"addr %p is misaligned", addr2);
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memset(addr1, 0x42, len);
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error = mincore(addr1, pagesizes[0], &vec);
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ATF_REQUIRE_MSG(error == 0, "mincore: %s", strerror(errno));
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if ((vec & MINCORE_SUPER) == 0)
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atf_tc_skip("initial superpage promotion failed");
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error = mlock(addr2, len);
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ATF_REQUIRE_MSG(error == 0, "mlock: %s", strerror(errno));
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error = mincore(addr2, pagesizes[0], &vec);
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ATF_REQUIRE_MSG(error == 0, "mincore: %s", strerror(errno));
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ATF_REQUIRE((vec & MINCORE_SUPER) != 0);
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/*
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* Free a page back to the superpage reservation, demoting both
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* mappings.
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*/
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error = ftruncate(shmfd, len - pagesizes[0]);
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ATF_REQUIRE_MSG(error == 0, "ftruncate: %s", strerror(errno));
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/*
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* Extend the mapping back to its original size.
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*/
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error = ftruncate(shmfd, len);
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ATF_REQUIRE_MSG(error == 0, "ftruncate: %s", strerror(errno));
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/*
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* Trigger re-promotion.
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*/
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error = mincore(addr1, pagesizes[0], &vec);
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ATF_REQUIRE_MSG(error == 0, "mincore: %s", strerror(errno));
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ATF_REQUIRE((vec & MINCORE_SUPER) == 0);
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memset((char *)addr1 + len - pagesizes[0], 0x43, pagesizes[0]);
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error = mincore(addr1, pagesizes[0], &vec);
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ATF_REQUIRE_MSG(error == 0, "mincore: %s", strerror(errno));
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ATF_REQUIRE((vec & MINCORE_SUPER) != 0);
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/*
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* Trigger a read fault, which should install a superpage mapping
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* without promotion.
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*/
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error = mincore(addr2, pagesizes[0], &vec);
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ATF_REQUIRE_MSG(error == 0, "mincore: %s", strerror(errno));
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ATF_REQUIRE((vec & MINCORE_SUPER) == 0);
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(void)atomic_load(
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(_Atomic int *)(void *)((char *)addr2 + len - pagesizes[0]));
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error = mincore(addr2, pagesizes[0], &vec);
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ATF_REQUIRE_MSG(error == 0, "mincore: %s", strerror(errno));
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ATF_REQUIRE((vec & MINCORE_SUPER) != 0);
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/*
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* Trigger demotion of the wired mapping.
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*/
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error = munlock(addr2, pagesizes[0]);
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ATF_REQUIRE_MSG(error == 0, "munlock: %s", strerror(errno));
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ATF_REQUIRE(close(shmfd) == 0);
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}
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ATF_TP_ADD_TCS(tp)
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{
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ATF_TP_ADD_TC(tp, mlock__copy_on_write_anon);
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ATF_TP_ADD_TC(tp, mlock__copy_on_write_vnode);
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ATF_TP_ADD_TC(tp, mlock__truncate_and_resize);
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ATF_TP_ADD_TC(tp, mlock__truncate_and_unlock);
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ATF_TP_ADD_TC(tp, mlock__superpage_fault);
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return (atf_no_error());
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}
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