- Linux-kselftest-mirror - lists.linaro.org

[PATCH resend v2 4/5] selftests/vm: add protection_keys_32 / protection_keys_64 to gitignore

by David Hildenbrand

We missed to add two binaries to gitignore. Cc: Andrew Morton <akpm(a)linux-foundation.org> Cc: Michal Hocko <mhocko(a)suse.com> Cc: Oscar Salvador <osalvador(a)suse.de> Cc: Jason Gunthorpe <jgg(a)ziepe.ca> Cc: Peter Xu <peterx(a)redhat.com> Cc: Ram Pai <linuxram(a)us.ibm.com> Cc: Shuah Khan <shuah(a)kernel.org> Cc: linux-kselftest(a)vger.kernel.org Signed-off-by: David Hildenbrand <david(a)redhat.com> --- tools/testing/selftests/vm/.gitignore | 2 ++ 1 file changed, 2 insertions(+) diff --git a/tools/testing/selftests/vm/.gitignore b/tools/testing/selftests/vm/.gitignore index 9a35c3f6a557..b4fc0148360e 100644 --- a/tools/testing/selftests/vm/.gitignore +++ b/tools/testing/selftests/vm/.gitignore @@ -22,3 +22,5 @@ map_fixed_noreplace write_to_hugetlbfs hmm-tests local_config.* +protection_keys_32 +protection_keys_64 -- 2.30.2

4 years, 4 months

1
0
0 0

[PATCH v18 0/9] mm: introduce memfd_secret system call to create "secret" memory areas

by Mike Rapoport

From: Mike Rapoport <rppt(a)linux.ibm.com> Hi, @Andrew, this is based on v5.12-rc1, I can rebase whatever way you prefer. This is an implementation of "secret" mappings backed by a file descriptor. The file descriptor backing secret memory mappings is created using a dedicated memfd_secret system call The desired protection mode for the memory is configured using flags parameter of the system call. The mmap() of the file descriptor created with memfd_secret() will create a "secret" memory mapping. The pages in that mapping will be marked as not present in the direct map and will be present only in the page table of the owning mm. Although normally Linux userspace mappings are protected from other users, such secret mappings are useful for environments where a hostile tenant is trying to trick the kernel into giving them access to other tenants mappings. Additionally, in the future the secret mappings may be used as a mean to protect guest memory in a virtual machine host. For demonstration of secret memory usage we've created a userspace library https://git.kernel.org/pub/scm/linux/kernel/git/jejb/secret-memory-preloade… that does two things: the first is act as a preloader for openssl to redirect all the OPENSSL_malloc calls to secret memory meaning any secret keys get automatically protected this way and the other thing it does is expose the API to the user who needs it. We anticipate that a lot of the use cases would be like the openssl one: many toolkits that deal with secret keys already have special handling for the memory to try to give them greater protection, so this would simply be pluggable into the toolkits without any need for user application modification. Hiding secret memory mappings behind an anonymous file allows usage of the page cache for tracking pages allocated for the "secret" mappings as well as using address_space_operations for e.g. page migration callbacks. The anonymous file may be also used implicitly, like hugetlb files, to implement mmap(MAP_SECRET) and use the secret memory areas with "native" mm ABIs in the future. Removing of the pages from the direct map may cause its fragmentation on architectures that use large pages to map the physical memory which affects the system performance. However, the original Kconfig text for CONFIG_DIRECT_GBPAGES said that gigabyte pages in the direct map "... can improve the kernel's performance a tiny bit ..." (commit 00d1c5e05736 ("x86: add gbpages switches")) and the recent report [1] showed that "... although 1G mappings are a good default choice, there is no compelling evidence that it must be the only choice". Hence, it is sufficient to have secretmem disabled by default with the ability of a system administrator to enable it at boot time. In addition, there is also a long term goal to improve management of the direct map. [1] https://lore.kernel.org/linux-mm/213b4567-46ce-f116-9cdf-bbd0c884eb3c@linux… v18: * rebase on v5.12-rc1 * merge kfence fix into the original patch * massage commit message of the patch introducing the memfd_secret syscall v17: https://lore.kernel.org/lkml/20210208084920.2884-1-rppt@kernel.org * Remove pool of large pages backing secretmem allocations, per Michal Hocko * Add secretmem pages to unevictable LRU, per Michal Hocko * Use GFP_HIGHUSER as secretmem mapping mask, per Michal Hocko * Make secretmem an opt-in feature that is disabled by default v16: https://lore.kernel.org/lkml/20210121122723.3446-1-rppt@kernel.org * Fix memory leak intorduced in v15 * Clean the data left from previous page user before handing the page to the userspace v15: https://lore.kernel.org/lkml/20210120180612.1058-1-rppt@kernel.org * Add riscv/Kconfig update to disable set_memory operations for nommu builds (patch 3) * Update the code around add_to_page_cache() per Matthew's comments (patches 6,7) * Add fixups for build/checkpatch errors discovered by CI systems v14: https://lore.kernel.org/lkml/20201203062949.5484-1-rppt@kernel.org * Finally s/mod_node_page_state/mod_lruvec_page_state/ v13: https://lore.kernel.org/lkml/20201201074559.27742-1-rppt@kernel.org * Added Reviewed-by, thanks Catalin and David * s/mod_node_page_state/mod_lruvec_page_state/ as Shakeel suggested Older history: v12: https://lore.kernel.org/lkml/20201125092208.12544-1-rppt@kernel.org v11: https://lore.kernel.org/lkml/20201124092556.12009-1-rppt@kernel.org v10: https://lore.kernel.org/lkml/20201123095432.5860-1-rppt@kernel.org v9: https://lore.kernel.org/lkml/20201117162932.13649-1-rppt@kernel.org v8: https://lore.kernel.org/lkml/20201110151444.20662-1-rppt@kernel.org v7: https://lore.kernel.org/lkml/20201026083752.13267-1-rppt@kernel.org v6: https://lore.kernel.org/lkml/20200924132904.1391-1-rppt@kernel.org v5: https://lore.kernel.org/lkml/20200916073539.3552-1-rppt@kernel.org v4: https://lore.kernel.org/lkml/20200818141554.13945-1-rppt@kernel.org v3: https://lore.kernel.org/lkml/20200804095035.18778-1-rppt@kernel.org v2: https://lore.kernel.org/lkml/20200727162935.31714-1-rppt@kernel.org v1: https://lore.kernel.org/lkml/20200720092435.17469-1-rppt@kernel.org rfc-v2: https://lore.kernel.org/lkml/20200706172051.19465-1-rppt@kernel.org/ rfc-v1: https://lore.kernel.org/lkml/20200130162340.GA14232@rapoport-lnx/ rfc-v0: https://lore.kernel.org/lkml/1572171452-7958-1-git-send-email-rppt@kernel.o… Mike Rapoport (9): mm: add definition of PMD_PAGE_ORDER mmap: make mlock_future_check() global riscv/Kconfig: make direct map manipulation options depend on MMU set_memory: allow set_direct_map_*_noflush() for multiple pages set_memory: allow querying whether set_direct_map_*() is actually enabled mm: introduce memfd_secret system call to create "secret" memory areas PM: hibernate: disable when there are active secretmem users arch, mm: wire up memfd_secret system call where relevant secretmem: test: add basic selftest for memfd_secret(2) arch/arm64/include/asm/Kbuild | 1 - arch/arm64/include/asm/cacheflush.h | 6 - arch/arm64/include/asm/kfence.h | 2 +- arch/arm64/include/asm/set_memory.h | 17 ++ arch/arm64/include/uapi/asm/unistd.h | 1 + arch/arm64/kernel/machine_kexec.c | 1 + arch/arm64/mm/mmu.c | 6 +- arch/arm64/mm/pageattr.c | 23 +- arch/riscv/Kconfig | 4 +- arch/riscv/include/asm/set_memory.h | 4 +- arch/riscv/include/asm/unistd.h | 1 + arch/riscv/mm/pageattr.c | 8 +- arch/x86/entry/syscalls/syscall_32.tbl | 1 + arch/x86/entry/syscalls/syscall_64.tbl | 1 + arch/x86/include/asm/set_memory.h | 4 +- arch/x86/mm/pat/set_memory.c | 8 +- fs/dax.c | 11 +- include/linux/pgtable.h | 3 + include/linux/secretmem.h | 30 +++ include/linux/set_memory.h | 16 +- include/linux/syscalls.h | 1 + include/uapi/asm-generic/unistd.h | 6 +- include/uapi/linux/magic.h | 1 + kernel/power/hibernate.c | 5 +- kernel/power/snapshot.c | 4 +- kernel/sys_ni.c | 2 + mm/Kconfig | 3 + mm/Makefile | 1 + mm/gup.c | 10 + mm/internal.h | 3 + mm/mlock.c | 3 +- mm/mmap.c | 5 +- mm/secretmem.c | 261 +++++++++++++++++++ mm/vmalloc.c | 5 +- scripts/checksyscalls.sh | 4 + tools/testing/selftests/vm/.gitignore | 1 + tools/testing/selftests/vm/Makefile | 3 +- tools/testing/selftests/vm/memfd_secret.c | 296 ++++++++++++++++++++++ tools/testing/selftests/vm/run_vmtests.sh | 17 ++ 39 files changed, 726 insertions(+), 53 deletions(-) create mode 100644 arch/arm64/include/asm/set_memory.h create mode 100644 include/linux/secretmem.h create mode 100644 mm/secretmem.c create mode 100644 tools/testing/selftests/vm/memfd_secret.c -- 2.28.0

4 years, 4 months

6
20
0 0

[PATCH] kselftest/arm64: Add missing stddef.h include to BTI tests

by Mark Brown

Explicitly include stddef.h when building the BTI tests so that we have a definition of NULL, with at least some toolchains this is not done implicitly by anything else: test.c: In function ‘start’: test.c:214:25: error: ‘NULL’ undeclared (first use in this function) 214 | sigaction(SIGILL, &sa, NULL); | ^~~~ test.c:20:1: note: ‘NULL’ is defined in header ‘<stddef.h>’; did you forget to ‘#include <stddef.h>’? Signed-off-by: Mark Brown <broonie(a)kernel.org> --- tools/testing/selftests/arm64/bti/test.c | 1 + 1 file changed, 1 insertion(+) diff --git a/tools/testing/selftests/arm64/bti/test.c b/tools/testing/selftests/arm64/bti/test.c index 656b04976ccc..67b77ab83c20 100644 --- a/tools/testing/selftests/arm64/bti/test.c +++ b/tools/testing/selftests/arm64/bti/test.c @@ -6,6 +6,7 @@ #include "system.h" +#include <stddef.h> #include <linux/errno.h> #include <linux/auxvec.h> #include <linux/signal.h> -- 2.20.1

4 years, 4 months

2
1
0 0

[PATCH 1/1] mnt: Delete two unneeded bool conversions

by Zhen Lei

The result of an expression consisting of a single relational operator is already of the bool type and does not need to be evaluated explicitly. No functional change. Signed-off-by: Zhen Lei <thunder.leizhen(a)huawei.com> --- tools/testing/selftests/mount/unprivileged-remount-test.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/tools/testing/selftests/mount/unprivileged-remount-test.c b/tools/testing/selftests/mount/unprivileged-remount-test.c index 584dc6bc3b06679..d2917054fe3ae56 100644 --- a/tools/testing/selftests/mount/unprivileged-remount-test.c +++ b/tools/testing/selftests/mount/unprivileged-remount-test.c @@ -204,7 +204,7 @@ bool test_unpriv_remount(const char *fstype, const char *mount_options, if (!WIFEXITED(status)) { die("child did not terminate cleanly\n"); } - return WEXITSTATUS(status) == EXIT_SUCCESS ? true : false; + return WEXITSTATUS(status) == EXIT_SUCCESS; } create_and_enter_userns(); @@ -282,7 +282,7 @@ static bool test_priv_mount_unpriv_remount(void) if (!WIFEXITED(status)) { die("child did not terminate cleanly\n"); } - return WEXITSTATUS(status) == EXIT_SUCCESS ? true : false; + return WEXITSTATUS(status) == EXIT_SUCCESS; } orig_mnt_flags = read_mnt_flags(orig_path); -- 2.26.0.106.g9fadedd

4 years, 4 months

1
0
0 0

[PATCH 1/1] selftests: timers: Remove several unneeded semicolons

by Zhen Lei

The semicolon immediately following '}' is unneeded. Signed-off-by: Zhen Lei <thunder.leizhen(a)huawei.com> --- tools/testing/selftests/timers/alarmtimer-suspend.c | 2 +- tools/testing/selftests/timers/inconsistency-check.c | 2 +- tools/testing/selftests/timers/nanosleep.c | 2 +- tools/testing/selftests/timers/nsleep-lat.c | 2 +- tools/testing/selftests/timers/set-timer-lat.c | 2 +- 5 files changed, 5 insertions(+), 5 deletions(-) diff --git a/tools/testing/selftests/timers/alarmtimer-suspend.c b/tools/testing/selftests/timers/alarmtimer-suspend.c index 4da09dbf83ba8e1..54da4b088f4c898 100644 --- a/tools/testing/selftests/timers/alarmtimer-suspend.c +++ b/tools/testing/selftests/timers/alarmtimer-suspend.c @@ -79,7 +79,7 @@ char *clockstring(int clockid) return "CLOCK_BOOTTIME_ALARM"; case CLOCK_TAI: return "CLOCK_TAI"; - }; + } return "UNKNOWN_CLOCKID"; } diff --git a/tools/testing/selftests/timers/inconsistency-check.c b/tools/testing/selftests/timers/inconsistency-check.c index 022d3ffe3fbffbd..e6756d9c60a7e17 100644 --- a/tools/testing/selftests/timers/inconsistency-check.c +++ b/tools/testing/selftests/timers/inconsistency-check.c @@ -72,7 +72,7 @@ char *clockstring(int clockid) return "CLOCK_BOOTTIME_ALARM"; case CLOCK_TAI: return "CLOCK_TAI"; - }; + } return "UNKNOWN_CLOCKID"; } diff --git a/tools/testing/selftests/timers/nanosleep.c b/tools/testing/selftests/timers/nanosleep.c index 71b5441c2fd9f6f..433a09676aeb8cd 100644 --- a/tools/testing/selftests/timers/nanosleep.c +++ b/tools/testing/selftests/timers/nanosleep.c @@ -72,7 +72,7 @@ char *clockstring(int clockid) return "CLOCK_BOOTTIME_ALARM"; case CLOCK_TAI: return "CLOCK_TAI"; - }; + } return "UNKNOWN_CLOCKID"; } diff --git a/tools/testing/selftests/timers/nsleep-lat.c b/tools/testing/selftests/timers/nsleep-lat.c index eb3e79ed7b4a9eb..a7ca9825e106a68 100644 --- a/tools/testing/selftests/timers/nsleep-lat.c +++ b/tools/testing/selftests/timers/nsleep-lat.c @@ -72,7 +72,7 @@ char *clockstring(int clockid) return "CLOCK_BOOTTIME_ALARM"; case CLOCK_TAI: return "CLOCK_TAI"; - }; + } return "UNKNOWN_CLOCKID"; } diff --git a/tools/testing/selftests/timers/set-timer-lat.c b/tools/testing/selftests/timers/set-timer-lat.c index 50da45437daab0b..d60bbcad487fd11 100644 --- a/tools/testing/selftests/timers/set-timer-lat.c +++ b/tools/testing/selftests/timers/set-timer-lat.c @@ -80,7 +80,7 @@ char *clockstring(int clockid) return "CLOCK_BOOTTIME_ALARM"; case CLOCK_TAI: return "CLOCK_TAI"; - }; + } return "UNKNOWN_CLOCKID"; } -- 2.26.0.106.g9fadedd

4 years, 4 months

1
0
0 0

[PATCH 1/2] kunit: Do not typecheck binary assertions

by David Gow

The use of typecheck() in KUNIT_EXPECT_EQ() and friends is causing more problems than I think it's worth. Things like enums need to have their values explicitly cast, and literals all need to be very precisely typed for the code to compile. While typechecking does have its uses, the additional overhead of having lots of needless casts -- combined with the awkward error messages which don't mention which types are involved -- makes tests less readable and more difficult to write. By removing the typecheck() call, the two arguments still need to be of compatible types, but don't need to be of exactly the same time, which seems a less confusing and more useful compromise. Signed-off-by: David Gow <davidgow(a)google.com> --- I appreciate that this is probably a bit controversial (and, indeed, I was a bit hesitant about sending it out myself), but after sitting on it for a few days, I still think this is probably an improvement overall. The second patch does fix what I think is an actual bug, though, so even if this isn't determined to be a good idea, it (or some equivalent) should probably go through. Cheers, -- David include/kunit/test.h | 1 - 1 file changed, 1 deletion(-) diff --git a/include/kunit/test.h b/include/kunit/test.h index 49601c4b98b8..4c56ffcb7403 100644 --- a/include/kunit/test.h +++ b/include/kunit/test.h @@ -775,7 +775,6 @@ void kunit_do_assertion(struct kunit *test, do { \ typeof(left) __left = (left); \ typeof(right) __right = (right); \ - ((void)__typecheck(__left, __right)); \ \ KUNIT_ASSERTION(test, \ __left op __right, \ -- 2.31.1.607.g51e8a6a459-goog

4 years, 4 months

3
6
0 0

[PATCH v3 0/2] secretmem: optimize page_is_secretmem()

by Mike Rapoport

From: Mike Rapoport <rppt(a)linux.ibm.com> Hi, This is an updated version of page_is_secretmem() changes. This is based on v5.12-rc7-mmots-2021-04-15-16-28. @Andrew, please let me know if you'd like me to rebase it differently or resend the entire set. v3: * add missing put_compound_head() if we are to return NULL from gup_page_range(), thanks David. * add unlikely() to test for page_is_secretmem. v2: * move the check for secretmem page in gup_pte_range after we get a reference to the page, per Matthew. Mike Rapoport (2): secretmem/gup: don't check if page is secretmem without reference secretmem: optimize page_is_secretmem() include/linux/secretmem.h | 26 +++++++++++++++++++++++++- mm/gup.c | 6 +++--- mm/secretmem.c | 12 +----------- 3 files changed, 29 insertions(+), 15 deletions(-) -- 2.28.0 Mike Rapoport (2): secretmem/gup: don't check if page is secretmem without reference secretmem: optimize page_is_secretmem() include/linux/secretmem.h | 26 +++++++++++++++++++++++++- mm/gup.c | 8 +++++--- mm/secretmem.c | 12 +----------- 3 files changed, 31 insertions(+), 15 deletions(-) -- 2.28.0

4 years, 4 months

3
4
0 0

[PATCH v3 1/2] selftests/sgx: Rename 'eenter' and 'sgx_call_vdso'

by Jarkko Sakkinen

Rename symbols for better clarity: * 'eenter' -> 'vdso_sgx_enter_enclave' * 'sgx_call_vdso' -> 'sgx_enter_enclave' Signed-off-by: Jarkko Sakkinen <jarkko(a)kernel.org> --- v2: Refined thh renames just a bit. tools/testing/selftests/sgx/call.S | 6 +++--- tools/testing/selftests/sgx/main.c | 25 +++++++++++++------------ tools/testing/selftests/sgx/main.h | 4 ++-- 3 files changed, 18 insertions(+), 17 deletions(-) diff --git a/tools/testing/selftests/sgx/call.S b/tools/testing/selftests/sgx/call.S index 4ecadc7490f4..b09a25890f3b 100644 --- a/tools/testing/selftests/sgx/call.S +++ b/tools/testing/selftests/sgx/call.S @@ -5,8 +5,8 @@ .text - .global sgx_call_vdso -sgx_call_vdso: + .global sgx_enter_enclave +sgx_enter_enclave: .cfi_startproc push %r15 .cfi_adjust_cfa_offset 8 @@ -27,7 +27,7 @@ sgx_call_vdso: .cfi_adjust_cfa_offset 8 push 0x38(%rsp) .cfi_adjust_cfa_offset 8 - call *eenter(%rip) + call *vdso_sgx_enter_enclave(%rip) add $0x10, %rsp .cfi_adjust_cfa_offset -0x10 pop %rbx diff --git a/tools/testing/selftests/sgx/main.c b/tools/testing/selftests/sgx/main.c index d304a4044eb9..43da68388e25 100644 --- a/tools/testing/selftests/sgx/main.c +++ b/tools/testing/selftests/sgx/main.c @@ -21,7 +21,7 @@ #include "../kselftest.h" static const uint64_t MAGIC = 0x1122334455667788ULL; -vdso_sgx_enter_enclave_t eenter; +vdso_sgx_enter_enclave_t vdso_sgx_enter_enclave; struct vdso_symtab { Elf64_Sym *elf_symtab; @@ -149,7 +149,7 @@ int main(int argc, char *argv[]) { struct sgx_enclave_run run; struct vdso_symtab symtab; - Elf64_Sym *eenter_sym; + Elf64_Sym *sgx_enter_enclave_sym; uint64_t result = 0; struct encl encl; unsigned int i; @@ -194,29 +194,30 @@ int main(int argc, char *argv[]) if (!vdso_get_symtab(addr, &symtab)) goto err; - eenter_sym = vdso_symtab_get(&symtab, "__vdso_sgx_enter_enclave"); - if (!eenter_sym) + sgx_enter_enclave_sym = vdso_symtab_get(&symtab, "__vdso_sgx_enter_enclave"); + if (!sgx_enter_enclave_sym) goto err; - eenter = addr + eenter_sym->st_value; + vdso_sgx_enter_enclave = addr + sgx_enter_enclave_sym->st_value; - ret = sgx_call_vdso((void *)&MAGIC, &result, 0, EENTER, NULL, NULL, &run); - if (!report_results(&run, ret, result, "sgx_call_vdso")) + ret = sgx_enter_enclave((void *)&MAGIC, &result, 0, EENTER, + NULL, NULL, &run); + if (!report_results(&run, ret, result, "sgx_enter_enclave_unclobbered")) goto err; /* Invoke the vDSO directly. */ result = 0; - ret = eenter((unsigned long)&MAGIC, (unsigned long)&result, 0, EENTER, - 0, 0, &run); - if (!report_results(&run, ret, result, "eenter")) + ret = vdso_sgx_enter_enclave((unsigned long)&MAGIC, (unsigned long)&result, + 0, EENTER, 0, 0, &run); + if (!report_results(&run, ret, result, "sgx_enter_enclave")) goto err; /* And with an exit handler. */ run.user_handler = (__u64)user_handler; run.user_data = 0xdeadbeef; - ret = eenter((unsigned long)&MAGIC, (unsigned long)&result, 0, EENTER, - 0, 0, &run); + ret = vdso_sgx_enter_enclave((unsigned long)&MAGIC, (unsigned long)&result, + 0, EENTER, 0, 0, &run); if (!report_results(&run, ret, result, "user_handler")) goto err; diff --git a/tools/testing/selftests/sgx/main.h b/tools/testing/selftests/sgx/main.h index 67211a708f04..68672fd86cf9 100644 --- a/tools/testing/selftests/sgx/main.h +++ b/tools/testing/selftests/sgx/main.h @@ -35,7 +35,7 @@ bool encl_load(const char *path, struct encl *encl); bool encl_measure(struct encl *encl); bool encl_build(struct encl *encl); -int sgx_call_vdso(void *rdi, void *rsi, long rdx, u32 function, void *r8, void *r9, - struct sgx_enclave_run *run); +int sgx_enter_enclave(void *rdi, void *rsi, long rdx, u32 function, void *r8, void *r9, + struct sgx_enclave_run *run); #endif /* MAIN_H */ -- 2.31.1

4 years, 4 months

1
1
0 0

[PATCH v6 00/10] userfaultfd: add minor fault handling for shmem

by Axel Rasmussen

Base ==== This series is based on (and therefore should apply cleanly to) the tag "v5.12-rc8-mmots-2021-04-21-23-08", with the following applied first: 1. Peter's selftest cleanup series: https://lore.kernel.org/patchwork/cover/1412450/ 2. My patch to fix a pre-existing BUG_ON in an edge case: https://lore.kernel.org/patchwork/patch/1419758/ Changelog ========= v5->v6: - Picked up {Reviewed,Acked}-by's. - Rebased onto v5.12-rc8-mmots-2021-04-21-23-08. - Put mistakenly removed delete_from_page_cache() back in the error path in shmem_mfill_atomic_pte(). [Hugh] - Keep shmem_mfill_atomic_pte() naming, instead of shmem_mcopy_... Likewise, rename our new helper to mfill_atomic_install_pte(). [Hugh] - Return directly instead of "goto out" in shmem_mfill_atomic_pte(), saving a couple of lines. [Peter] v4->v5: - Picked up {Reviewed,Acked}-by's. - Fix cleanup in error path in shmem_mcopy_atomic_pte(). [Hugh, Peter] - Mention switching to lru_cache_add() in the commit message of 9/10. [Hugh] - Split + reorder commits, so now we 1) implement the faulting path, 2) implement the CONTINUE ioctl, and 3) advertise the feature. Squash the documentation update into step (3). [Hugh, Peter] - Reorder install_pte() cleanup to come before selftest changes. [Hugh] v3->v4: - Fix handling of the shmem private mcopy case. Previously, I had (incorrectly) assumed that !vma_is_anonymous() was equivalent to "the page will be in the page cache". But, in this case we have an optimization where we allocate a new *anonymous* page. So, use a new "bool page_in_cache" instead, which checks if page->mapping is set. Correct several places with this new check. [Hugh] - Fix calling mm_counter() before page_add_..._rmap(). [Hugh] - When modifying shmem_mcopy_atomic_pte() to use the new install_pte() helper, just use lru_cache_add_inactive_or_unevictable(), no need to branch and maybe use lru_cache_add(). [Hugh] - De-pluralize mcopy_atomic_install_pte(s). [Hugh] - Make "writable" a bool, and initialize consistently. [Hugh] v2->v3: - Picked up {Reviewed,Acked}-by's. - Reorder commits: introduce CONTINUE before MINOR registration. [Hugh, Peter] - Don't try to {unlock,put}_page an xarray value in shmem_getpage_gfp. [Hugh] - Move enum mcopy_atomic_mode forward declare out of CONFIG_HUGETLB_PAGE. [Hugh] - Keep mistakenly removed UFFD_USER_MODE_ONLY in selftest. [Peter] - Cleanup context management in self test (make clear implicit, remove unneeded return values now that we have err()). [Peter] - Correct dst_pte argument to dst_pmd in shmem_mcopy_atomic_pte macro. [Hugh] - Mention the new shmem support feature in documentation. [Hugh] v1->v2: - Pick up Reviewed-by's. - Don't swapin page when a minor fault occurs. Notice that it needs to be swapped in, and just immediately fire the minor fault. Let a future CONTINUE deal with swapping in the page. [Peter] - Clarify comment about i_size checks in mm/userfaultfd.c. [Peter] - Only forward declare once (out of #ifdef) in hugetlb.h. [Peter] Changes since [2]: - Squash the fixes ([2]) in with the original series ([1]). This makes reviewing easier, as we no longer have to sift through deltas undoing what we had done before. [Hugh, Peter] - Modify shmem_mcopy_atomic_pte() to use the new mcopy_atomic_install_ptes() helper, reducing code duplication. [Hugh] - Properly trigger handle_userfault() in the shmem_swapin_page() case. [Hugh] - Use shmem_getpage() instead of find_lock_page() to lookup the existing page in for continue. This properly deals with swapped-out pages. [Hugh] - Unconditionally pte_mkdirty() for anon memory (as before). [Peter] - Don't include userfaultfd_k.h in either hugetlb.h or shmem_fs.h. [Hugh] - Add comment for UFFD_FEATURE_MINOR_SHMEM (to match _HUGETLBFS). [Hugh] - Fix some small cleanup issues (parens, reworded conditionals, reduced plumbing of some parameters, simplify labels/gotos, ...). [Hugh, Peter] Overview ======== See the series which added minor faults for hugetlbfs [3] for a detailed overview of minor fault handling in general. This series adds the same support for shmem-backed areas. This series is structured as follows: - Commits 1 and 2 are cleanups. - Commits 3 and 4 implement the new feature (minor fault handling for shmem). - Commit 5 advertises that the feature is now available since at this point it's fully implemented. - Commit 6 is a final cleanup, modifying an existing code path to re-use a new helper we've introduced. - Commits 7, 8, 9, 10 update the userfaultfd selftest to exercise the feature. Use Case ======== In some cases it is useful to have VM memory backed by tmpfs instead of hugetlbfs. So, this feature will be used to support the same VM live migration use case described in my original series. Additionally, Android folks (Lokesh Gidra <lokeshgidra(a)google.com>) hope to optimize the Android Runtime garbage collector using this feature: "The plan is to use userfaultfd for concurrently compacting the heap. With this feature, the heap can be shared-mapped at another location where the GC-thread(s) could continue the compaction operation without the need to invoke userfault ioctl(UFFDIO_COPY) each time. OTOH, if and when Java threads get faults on the heap, UFFDIO_CONTINUE can be used to resume execution. Furthermore, this feature enables updating references in the 'non-moving' portion of the heap efficiently. Without this feature, uneccessary page copying (ioctl(UFFDIO_COPY)) would be required." [1] https://lore.kernel.org/patchwork/cover/1388144/ [2] https://lore.kernel.org/patchwork/patch/1408161/ [3] https://lore.kernel.org/linux-fsdevel/20210301222728.176417-1-axelrasmussen… Axel Rasmussen (10): userfaultfd/hugetlbfs: avoid including userfaultfd_k.h in hugetlb.h userfaultfd/shmem: combine shmem_{mcopy_atomic,mfill_zeropage}_pte userfaultfd/shmem: support minor fault registration for shmem userfaultfd/shmem: support UFFDIO_CONTINUE for shmem userfaultfd/shmem: advertise shmem minor fault support userfaultfd/shmem: modify shmem_mfill_atomic_pte to use install_pte() userfaultfd/selftests: use memfd_create for shmem test type userfaultfd/selftests: create alias mappings in the shmem test userfaultfd/selftests: reinitialize test context in each test userfaultfd/selftests: exercise minor fault handling shmem support Documentation/admin-guide/mm/userfaultfd.rst | 3 +- fs/userfaultfd.c | 6 +- include/linux/hugetlb.h | 2 +- include/linux/shmem_fs.h | 19 +- include/linux/userfaultfd_k.h | 5 + include/uapi/linux/userfaultfd.h | 7 +- mm/hugetlb.c | 1 + mm/memory.c | 8 +- mm/shmem.c | 120 +++----- mm/userfaultfd.c | 175 ++++++++---- tools/testing/selftests/vm/userfaultfd.c | 274 ++++++++++++------- 11 files changed, 364 insertions(+), 256 deletions(-) -- 2.31.1.527.g47e6f16901-goog

4 years, 4 months

3
12
0 0

[PATCH v3 00/13] Add futex2 syscalls

by André Almeida

Hi, This patch series introduces the futex2 syscalls. * What happened to the current futex()? For some years now, developers have been trying to add new features to futex, but maintainers have been reluctant to accept then, given the multiplexed interface full of legacy features and tricky to do big changes. Some problems that people tried to address with patchsets are: NUMA-awareness[0], smaller sized futexes[1], wait on multiple futexes[2]. NUMA, for instance, just doesn't fit the current API in a reasonable way. Considering that, it's not possible to merge new features into the current futex. ** The NUMA problem At the current implementation, all futex kernel side infrastructure is stored on a single node. Given that, all futex() calls issued by processors that aren't located on that node will have a memory access penalty when doing it. ** The 32bit sized futex problem Embedded systems or anything with memory constrains would benefit of using smaller sizes for the futex userspace integer. Also, a mutex implementation can be done using just three values, so 8 bits is enough for various scenarios. ** The wait on multiple problem The use case lies in the Wine implementation of the Windows NT interface WaitMultipleObjects. This Windows API function allows a thread to sleep waiting on the first of a set of event sources (mutexes, timers, signal, console input, etc) to signal. Considering this is a primitive synchronization operation for Windows applications, being able to quickly signal events on the producer side, and quickly go to sleep on the consumer side is essential for good performance of those running over Wine. [0] https://lore.kernel.org/lkml/20160505204230.932454245@linutronix.de/ [1] https://lore.kernel.org/lkml/20191221155659.3159-2-malteskarupke@web.de/ [2] https://lore.kernel.org/lkml/20200213214525.183689-1-andrealmeid@collabora.… * The solution As proposed by Peter Zijlstra and Florian Weimer[3], a new interface is required to solve this, which must be designed with those features in mind. futex2() is that interface. As opposed to the current multiplexed interface, the new one should have one syscall per operation. This will allow the maintainability of the API if it gets extended, and will help users with type checking of arguments. In particular, the new interface is extended to support the ability to wait on any of a list of futexes at a time, which could be seen as a vectored extension of the FUTEX_WAIT semantics. [3] https://lore.kernel.org/lkml/20200303120050.GC2596@hirez.programming.kicks-… * The interface The new interface can be seen in details in the following patches, but this is a high level summary of what the interface can do: - Supports wake/wait semantics, as in futex() - Supports requeue operations, similarly as FUTEX_CMP_REQUEUE, but with individual flags for each address - Supports waiting for a vector of futexes, using a new syscall named futex_waitv() - Supports variable sized futexes (8bits, 16bits, 32bits and 64bits) - Supports NUMA-awareness operations, where the user can specify on which memory node would like to operate * Implementation The internal implementation follows a similar design to the original futex. Given that we want to replicate the same external behavior of current futex, this should be somewhat expected. For some functions, like the init and the code to get a shared key, I literally copied code and comments from kernel/futex.c. I decided to do so instead of exposing the original function as a public function since in that way we can freely modify our implementation if required, without any impact on old futex. Also, the comments precisely describes the details and corner cases of the implementation. Each patch contains a brief description of implementation, but patch 6 "docs: locking: futex2: Add documentation" adds a more complete document about it. * The patchset This patchset can be also found at my git tree: https://gitlab.collabora.com/tonyk/linux/-/tree/futex2-dev - Patch 1: Implements wait/wake, and the basics foundations of futex2 - Patches 2-4: Implement the remaining features (shared, waitv, requeue). - Patch 5: Adds the x86_x32 ABI handling. I kept it in a separated patch since I'm not sure if x86_x32 is still a thing, or if it should return -ENOSYS. - Patch 6: Add a documentation file which details the interface and the internal implementation. - Patches 7-13: Selftests for all operations along with perf support for futex2. - Patch 14: While working on porting glibc for futex2, I found out that there's a futex_wake() call at the user thread exit path, if that thread was created with clone(..., CLONE_CHILD_SETTID, ...). In order to make pthreads work with futex2, it was required to add this patch. Note that this is more a proof-of-concept of what we will need to do in future, rather than part of the interface and shouldn't be merged as it is. * Testing: This patchset provides selftests for each operation and their flags. Along with that, the following work was done: ** Stability To stress the interface in "real world scenarios": - glibc[4]: nptl's low level locking was modified to use futex2 API (except for robust and PI things). All relevant nptl/ tests passed. - Wine[5]: Proton/Wine was modified in order to use futex2() for the emulation of Windows NT sync mechanisms based on futex, called "fsync". Triple-A games with huge CPU's loads and tons of parallel jobs worked as expected when compared with the previous FUTEX_WAIT_MULTIPLE implementation at futex(). Some games issue 42k futex2() calls per second. - Full GNU/Linux distro: I installed the modified glibc in my host machine, so all pthread's programs would use futex2(). After tweaking systemd[6] to allow futex2() calls at seccomp, everything worked as expected (web browsers do some syscall sandboxing and need some configuration as well). - perf: The perf benchmarks tests can also be used to stress the interface, and they can be found in this patchset. ** Performance - For comparing futex() and futex2() performance, I used the artificial benchmarks implemented at perf (wake, wake-parallel, hash and requeue). The setup was 200 runs for each test and using 8, 80, 800, 8000 for the number of threads, Note that for this test, I'm not using patch 14 ("kernel: Enable waitpid() for futex2") , for reasons explained at "The patchset" section. - For the first three ones, I measured an average of 4% gain in performance. This is not a big step, but it shows that the new interface is at least comparable in performance with the current one. - For requeue, I measured an average of 21% decrease in performance compared to the original futex implementation. This is expected given the new design with individual flags. The performance trade-offs are explained at patch 4 ("futex2: Implement requeue operation"). [4] https://gitlab.collabora.com/tonyk/glibc/-/tree/futex2 [5] https://gitlab.collabora.com/tonyk/wine/-/tree/proton_5.13 [6] https://gitlab.collabora.com/tonyk/systemd * FAQ ** "Where's the code for NUMA and FUTEX_8/16/64?" The current code is already complex enough to take some time for review, so I believe it's better to split that work out to a future iteration of this patchset. Besides that, this RFC is the core part of the infrastructure, and the following features will not pose big design changes to it, the work will be more about wiring up the flags and modifying some functions. ** "Where's the PI/robust stuff?" As said by Peter Zijlstra at [3], all those new features are related to the "simple" futex interface, that doesn't use PI or robust. Do we want to have this complexity at futex2() and if so, should it be part of this patchset or can it be future work? Thanks, André * Changelog Changes from v2: - API now supports 64bit futexes, in addition to 8, 16 and 32. - This API change will break the glibc[4] and Proton[5] ports for now. - Refactored futex2_wait and futex2_waitv selftests v2: https://lore.kernel.org/lkml/20210304004219.134051-1-andrealmeid@collabora.… Changes from v1: - Unified futex_set_timer_and_wait and __futex_wait code - Dropped _carefull from linked list function calls - Fixed typos on docs patch - uAPI flags are now added as features are introduced, instead of all flags in patch 1 - Removed struct futex_single_waiter in favor of an anon struct v1: https://lore.kernel.org/lkml/20210215152404.250281-1-andrealmeid@collabora.… André Almeida (13): futex2: Implement wait and wake functions futex2: Add support for shared futexes futex2: Implement vectorized wait futex2: Implement requeue operation futex2: Add compatibility entry point for x86_x32 ABI docs: locking: futex2: Add documentation selftests: futex2: Add wake/wait test selftests: futex2: Add timeout test selftests: futex2: Add wouldblock test selftests: futex2: Add waitv test selftests: futex2: Add requeue test perf bench: Add futex2 benchmark tests kernel: Enable waitpid() for futex2 Documentation/locking/futex2.rst | 198 +++ Documentation/locking/index.rst | 1 + MAINTAINERS | 2 +- arch/arm/tools/syscall.tbl | 4 + arch/arm64/include/asm/unistd.h | 2 +- arch/arm64/include/asm/unistd32.h | 8 + arch/x86/entry/syscalls/syscall_32.tbl | 4 + arch/x86/entry/syscalls/syscall_64.tbl | 4 + fs/inode.c | 1 + include/linux/compat.h | 26 + include/linux/fs.h | 1 + include/linux/syscalls.h | 17 + include/uapi/asm-generic/unistd.h | 14 +- include/uapi/linux/futex.h | 31 + init/Kconfig | 7 + kernel/Makefile | 1 + kernel/fork.c | 2 + kernel/futex2.c | 1252 +++++++++++++++++ kernel/sys_ni.c | 9 + tools/arch/x86/include/asm/unistd_64.h | 12 + tools/include/uapi/asm-generic/unistd.h | 11 +- .../arch/x86/entry/syscalls/syscall_64.tbl | 4 + tools/perf/bench/bench.h | 4 + tools/perf/bench/futex-hash.c | 24 +- tools/perf/bench/futex-requeue.c | 57 +- tools/perf/bench/futex-wake-parallel.c | 41 +- tools/perf/bench/futex-wake.c | 37 +- tools/perf/bench/futex.h | 47 + tools/perf/builtin-bench.c | 18 +- .../selftests/futex/functional/.gitignore | 3 + .../selftests/futex/functional/Makefile | 6 +- .../futex/functional/futex2_requeue.c | 164 +++ .../selftests/futex/functional/futex2_wait.c | 195 +++ .../selftests/futex/functional/futex2_waitv.c | 154 ++ .../futex/functional/futex_wait_timeout.c | 58 +- .../futex/functional/futex_wait_wouldblock.c | 33 +- .../testing/selftests/futex/functional/run.sh | 6 + .../selftests/futex/include/futex2test.h | 112 ++ 38 files changed, 2518 insertions(+), 52 deletions(-) create mode 100644 Documentation/locking/futex2.rst create mode 100644 kernel/futex2.c create mode 100644 tools/testing/selftests/futex/functional/futex2_requeue.c create mode 100644 tools/testing/selftests/futex/functional/futex2_wait.c create mode 100644 tools/testing/selftests/futex/functional/futex2_waitv.c create mode 100644 tools/testing/selftests/futex/include/futex2test.h -- 2.31.1

4 years, 4 months

3
16
0 0

2025

2024

2023

2022

2021

2020

2019

2018

2017

Linux-kselftest-mirror