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

[bpf-next] selftests/bpf: clean-up fmod_ret in bench_rename test script

by Yipeng Zou

[root@localhost bpf]# ./benchs/run_bench_rename.sh base : 0.819 ± 0.012M/s kprobe : 0.538 ± 0.009M/s kretprobe : 0.503 ± 0.004M/s rawtp : 0.779 ± 0.020M/s fentry : 0.726 ± 0.007M/s fexit : 0.691 ± 0.007M/s benchmark 'rename-fmodret' not found The bench_rename_fmod_ret has been removed in the commit [1], clean-up it in test script. [1] b000def2e052 ("selftests: Remove fmod_ret from test_overhead"). Fixes: b000def2e052 ("selftests: Remove fmod_ret from test_overhead") Signed-off-by: Yipeng Zou <zouyipeng(a)huawei.com> --- tools/testing/selftests/bpf/benchs/run_bench_rename.sh | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/tools/testing/selftests/bpf/benchs/run_bench_rename.sh b/tools/testing/selftests/bpf/benchs/run_bench_rename.sh index 16f774b1cdbe..7b281dbe4165 100755 --- a/tools/testing/selftests/bpf/benchs/run_bench_rename.sh +++ b/tools/testing/selftests/bpf/benchs/run_bench_rename.sh @@ -2,7 +2,7 @@ set -eufo pipefail -for i in base kprobe kretprobe rawtp fentry fexit fmodret +for i in base kprobe kretprobe rawtp fentry fexit do summary=$(sudo ./bench -w2 -d5 -a rename-$i | tail -n1 | cut -d'(' -f1 | cut -d' ' -f3-) printf "%-10s: %s\n" $i "$summary" -- 2.34.1

2 years, 1 month

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[bpf-next] selftests/bpf: fix repeat option when kfunc_call verify fail

by Yipeng Zou

There is no way to set topts.repeat=1 when tc_test going to verify fail. Maybe it's clerical error, fix it directly. Fixes: fb66223a244f ("selftests/bpf: add test for accessing ctx from syscall program type") Signed-off-by: Yipeng Zou <zouyipeng(a)huawei.com> Reviewed-by: Li Zetao <lizetao1(a)huawei.com> --- tools/testing/selftests/bpf/prog_tests/kfunc_call.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/tools/testing/selftests/bpf/prog_tests/kfunc_call.c b/tools/testing/selftests/bpf/prog_tests/kfunc_call.c index a543742cd7bd..2eb71559713c 100644 --- a/tools/testing/selftests/bpf/prog_tests/kfunc_call.c +++ b/tools/testing/selftests/bpf/prog_tests/kfunc_call.c @@ -173,8 +173,8 @@ static void verify_fail(struct kfunc_test_params *param) case tc_test: topts.data_in = &pkt_v4; topts.data_size_in = sizeof(pkt_v4); - break; topts.repeat = 1; + break; } skel = kfunc_call_fail__open_opts(&opts); -- 2.34.1

2 years, 1 month

2
1
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[PATCH] selftests: cgroup: fix test_kmem_memcg_deletion false positives

by Lucas Karpinski

The test allocates dcache inside a cgroup, then destroys the cgroups and then checks the sanity of numbers on the parent level. The reason it fails is because dentries are freed with an RCU delay - a debugging sleep shows that usage drops as expected shortly after. Insert a 1s sleep after completing the cgroup creation/deletions. This should be good enough, assuming that machines running those tests are otherwise not very busy. This commit is directly inspired by Johannes over at the link below. Link: https://lore.kernel.org/all/20230801135632.1768830-1-hannes@cmpxchg.org/ Signed-off-by: Lucas Karpinski <lkarpins(a)redhat.com> --- tools/testing/selftests/cgroup/test_kmem.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/tools/testing/selftests/cgroup/test_kmem.c b/tools/testing/selftests/cgroup/test_kmem.c index 67cc0182058d..7ac384bbfdd5 100644 --- a/tools/testing/selftests/cgroup/test_kmem.c +++ b/tools/testing/selftests/cgroup/test_kmem.c @@ -183,6 +183,9 @@ static int test_kmem_memcg_deletion(const char *root) if (cg_run_in_subcgroups(parent, alloc_kmem_smp, NULL, 100)) goto cleanup; + /* wait for RCU freeing */ + sleep(1); + current = cg_read_long(parent, "memory.current"); slab = cg_read_key_long(parent, "memory.stat", "slab "); anon = cg_read_key_long(parent, "memory.stat", "anon "); -- 2.41.0

2 years, 1 month

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[PATCH net-next v3 0/6] tls: implement key updates for TLS1.3

by Sabrina Dubroca

This adds support for receiving KeyUpdate messages (RFC 8446, 4.6.3 [1]). A sender transmits a KeyUpdate message and then changes its TX key. The receiver should react by updating its RX key before processing the next message. This patchset implements key updates by: 1. pausing decryption when a KeyUpdate message is received, to avoid attempting to use the old key to decrypt a record encrypted with the new key 2. returning -EKEYEXPIRED to syscalls that cannot receive the KeyUpdate message, until the rekey has been performed by userspace 3. passing the KeyUpdate message to userspace as a control message 4. allowing updates of the crypto_info via the TLS_TX/TLS_RX setsockopts This API has been tested with gnutls to make sure that it allows userspace libraries to implement key updates [2]. Thanks to Frantisek Krenzelok <fkrenzel(a)redhat.com> for providing the implementation in gnutls and testing the kernel patches. ======================================================================= Discussions around v2 of this patchset focused on how HW offload would interact with rekey. RX - The existing SW path will handle all records between the KeyUpdate message signaling the change of key and the new key becoming known to the kernel -- those will be queued encrypted, and decrypted in SW as they are read by userspace (once the key is provided, ie same as this patchset) - Call ->tls_dev_del + ->tls_dev_add immediately during setsockopt(TLS_RX) TX - After setsockopt(TLS_TX), switch to the existing SW path (not the current device_fallback) until we're able to re-enable HW offload - tls_device_sendmsg will call into tls_sw_sendmsg under lock_sock to avoid changing socket ops during the rekey while another thread might be waiting on the lock - We only re-enable HW offload (call ->tls_dev_add to install the new key in HW) once all records sent with the old key have been ACKed. At this point, all unacked records are SW-encrypted with the new key, and the old key is unused by both HW and retransmissions. - If there are no unacked records when userspace does setsockopt(TLS_TX), we can (try to) install the new key in HW immediately. - If yet another key has been provided via setsockopt(TLS_TX), we don't install intermediate keys, only the latest. - TCP notifies ktls of ACKs via the icsk_clean_acked callback. In case of a rekey, tls_icsk_clean_acked will record when all data sent with the most recent past key has been sent. The next call to sendmsg will install the new key in HW. - We close and push the current SW record before reenabling offload. If ->tls_dev_add fails to install the new key in HW, we stay in SW mode. We can add a counter to keep track of this. In addition: Because we can't change socket ops during a rekey, we'll also have to modify do_tls_setsockopt_conf to check ctx->tx_conf and only call either tls_set_device_offload or tls_set_sw_offload. RX already uses the same ops for both TLS_HW and TLS_SW, so we could switch between HW and SW mode on rekey. An alternative would be to have a common sendmsg which locks the socket and then calls the correct implementation. We'll need that anyway for the offload under rekey case, so that would only add a test to the SW path's ops (compared to the current code). That should allow us to simplify build_protos a bit, but might have a performance impact - we'll need to check it if we want to go that route. ======================================================================= Note: in a future series, I'll clean up tls_set_sw_offload and eliminate the per-cipher copy-paste using tls_cipher_size_desc. [1] https://www.rfc-editor.org/rfc/rfc8446#section-4.6.3 [2] https://gitlab.com/gnutls/gnutls/-/merge_requests/1625 Sabrina Dubroca (6): tls: remove tls_context argument from tls_set_sw_offload tls: block decryption when a rekey is pending tls: implement rekey for TLS1.3 docs: tls: document TLS1.3 key updates selftests: tls: add key_generation argument to tls_crypto_info_init selftests: tls: add rekey tests Documentation/networking/tls.rst | 21 ++ include/net/tls.h | 3 + net/tls/tls.h | 3 +- net/tls/tls_device.c | 2 +- net/tls/tls_main.c | 47 ++- net/tls/tls_sw.c | 184 +++++++++--- tools/testing/selftests/net/tls.c | 466 +++++++++++++++++++++++++++++- 7 files changed, 661 insertions(+), 65 deletions(-) -- 2.40.1

2 years, 1 month

3
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[PATCH] selftests/mm: fix uffd-stress help information

by Rong Tao

From: Rong Tao <rongtao(a)cestc.cn> commit 686a8bb72349("selftests/mm: split uffd tests into uffd-stress and uffd-unit-tests") split uffd tests into uffd-stress and uffd-unit-tests, obviously we need to modify the help information synchronously. Also modify code indentation. Signed-off-by: Rong Tao <rongtao(a)cestc.cn> --- tools/testing/selftests/mm/uffd-stress.c | 24 ++++++++++++------------ 1 file changed, 12 insertions(+), 12 deletions(-) diff --git a/tools/testing/selftests/mm/uffd-stress.c b/tools/testing/selftests/mm/uffd-stress.c index 995ff13e74c7..e40b6d7d2c0e 100644 --- a/tools/testing/selftests/mm/uffd-stress.c +++ b/tools/testing/selftests/mm/uffd-stress.c @@ -53,21 +53,21 @@ pthread_attr_t attr; do { typeof(a) __tmp = (a); (a) = (b); (b) = __tmp; } while (0) const char *examples = - "# Run anonymous memory test on 100MiB region with 99999 bounces:\n" - "./userfaultfd anon 100 99999\n\n" - "# Run share memory test on 1GiB region with 99 bounces:\n" - "./userfaultfd shmem 1000 99\n\n" - "# Run hugetlb memory test on 256MiB region with 50 bounces:\n" - "./userfaultfd hugetlb 256 50\n\n" - "# Run the same hugetlb test but using private file:\n" - "./userfaultfd hugetlb-private 256 50\n\n" - "# 10MiB-~6GiB 999 bounces anonymous test, " - "continue forever unless an error triggers\n" - "while ./userfaultfd anon $[RANDOM % 6000 + 10] 999; do true; done\n\n"; + "# Run anonymous memory test on 100MiB region with 99999 bounces:\n" + "./uffd-stress anon 100 99999\n\n" + "# Run share memory test on 1GiB region with 99 bounces:\n" + "./uffd-stress shmem 1000 99\n\n" + "# Run hugetlb memory test on 256MiB region with 50 bounces:\n" + "./uffd-stress hugetlb 256 50\n\n" + "# Run the same hugetlb test but using private file:\n" + "./uffd-stress hugetlb-private 256 50\n\n" + "# 10MiB-~6GiB 999 bounces anonymous test, " + "continue forever unless an error triggers\n" + "while ./uffd-stress anon $[RANDOM % 6000 + 10] 999; do true; done\n\n"; static void usage(void) { - fprintf(stderr, "\nUsage: ./userfaultfd <test type> <MiB> <bounces>\n\n"); + fprintf(stderr, "\nUsage: ./uffd-stress <test type> <MiB> <bounces>\n\n"); fprintf(stderr, "Supported <test type>: anon, hugetlb, " "hugetlb-private, shmem, shmem-private\n\n"); fprintf(stderr, "Examples:\n\n"); -- 2.39.3

2 years, 1 month

1
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[PATCH] kunit: replace KUNIT_TRIGGER_STATIC_STUB macro with KUNIT_STATIC_STUB_REDIRECT

by Kemeng Shi

We mix up KUNIT_TRIGGER_STATIC_STUB and KUNIT_STATIC_STUB_REDIRECT in static_stub header. Just correct KUNIT_TRIGGER_STATIC_STUB to KUNIT_STATIC_STUB_REDIRECT which is documented. Signed-off-by: Kemeng Shi <shikemeng(a)huaweicloud.com> Fixes: e047c5eaa763 ("kunit: Expose 'static stub' API to redirect functions") Reviewed-by: David Gow <davidgow(a)google.com> --- v1->v2: -Fix typo -Add Fixes tag. -Collect RVB from David --- include/kunit/static_stub.h | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/include/kunit/static_stub.h b/include/kunit/static_stub.h index 9b80150a5d62..85315c80b303 100644 --- a/include/kunit/static_stub.h +++ b/include/kunit/static_stub.h @@ -11,7 +11,7 @@ #if !IS_ENABLED(CONFIG_KUNIT) /* If CONFIG_KUNIT is not enabled, these stubs quietly disappear. */ -#define KUNIT_TRIGGER_STATIC_STUB(real_fn_name, args...) do {} while (0) +#define KUNIT_STATIC_STUB_REDIRECT(real_fn_name, args...) do {} while (0) #else @@ -30,7 +30,7 @@ * This is a function prologue which is used to allow calls to the current * function to be redirected by a KUnit test. KUnit tests can call * kunit_activate_static_stub() to pass a replacement function in. The - * replacement function will be called by KUNIT_TRIGGER_STATIC_STUB(), which + * replacement function will be called by KUNIT_STATIC_STUB_REDIRECT(), which * will then return from the function. If the caller is not in a KUnit context, * the function will continue execution as normal. * @@ -87,7 +87,7 @@ void __kunit_activate_static_stub(struct kunit *test, * When activated, calls to real_fn_addr from within this test (even if called * indirectly) will instead call replacement_addr. The function pointed to by * real_fn_addr must begin with the static stub prologue in - * KUNIT_TRIGGER_STATIC_STUB() for this to work. real_fn_addr and + * KUNIT_STATIC_STUB_REDIRECT() for this to work. real_fn_addr and * replacement_addr must have the same type. * * The redirection can be disabled again with kunit_deactivate_static_stub(). -- 2.30.0

2 years, 1 month

1
0
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[PATCH v2 0/7] selftests/nolibc: customize CROSS_COMPILE for all supported architectures

by Zhangjin Wu

Hi, Willy Here is v2 of the customized CROSS_COMPILE support, this helps a lot during the testing of the other cross-arch nolibc changes: $ ARCHS="i386 x86_64 arm64 arm mips ppc ppc64 ppc64le riscv s390" $ for arch in ${ARCHS[@]}; do printf "%9s: " $arch; make run-user XARCH=$arch | grep status; done Based on your suggestion, we did this changes: - The qemu notes patch [1] is removed, welcome your doc file ;-) - Arnd's crosstools are customized by default - Import cc-cross-prefix to support local cross toolchains too - Use mips64 toolchains for mips like x86_64 toolchains for i386, allow download less toolchains - Use HOSTCC for libc-test compiling Changes from v1 --> v2: * selftests/nolibc: allow use x86_64 toolchain for i386 No change. * selftests/nolibc: allow use mips64 toolchain for mips Allow download less toolchains, save time save storage space * selftests/nolibc: libc-test: use HOSTCC instead of CC libc-test is mainly for local test, use HOSTCC * selftests/nolibc: allow customize CROSS_COMPILE by architecture Moved the ../../../scripts/Makefile.include after our customized CROSS_COMPILE, to let it prefix CC with $(CROSS_COMPILE) for us. * selftests/nolibc: customize CROSS_COMPILE for all architectures Use Arnd's crosstools as the default ones * selftests/nolibc: import cc-cross-prefix macro selftests/nolibc: allow use cross toolchains from software repository Import cc-cross-prefix to allow customize a list of the cross compilers, the ones from local repositories are appended in. If already installed ones from local repos, why not use them, let's do it. Willy, since this series is really important to test the coming patchsets, I send it here before the others to simplify the testing, but we can delay its review, it is not urgent. And here [2] is the simple script I wrote to download, decompress and configure the PATH variable for Anrd's crosstools, hope it helps. Best regards, Zhangjin Wu --- [1]: https://lore.kernel.org/lkml/6de680acbc2d87e13a680d4453ef022568bf489b.16912… [2]: https://gitee.com/tinylab/linux-lab/blob/next/tools/nolibc/crosstool.sh v1: https://lore.kernel.org/lkml/cover.1691263493.git.falcon@tinylab.org/ Zhangjin Wu (7): selftests/nolibc: allow use x86_64 toolchain for i386 selftests/nolibc: allow use mips64 toolchain for mips selftests/nolibc: libc-test: use HOSTCC instead of CC selftests/nolibc: allow customize CROSS_COMPILE by architecture selftests/nolibc: customize CROSS_COMPILE for all architectures selftests/nolibc: import cc-cross-prefix macro selftests/nolibc: allow use cross toolchains from software repository tools/testing/selftests/nolibc/Makefile | 38 +++++++++++++++++++++---- 1 file changed, 33 insertions(+), 5 deletions(-) -- 2.25.1

2 years, 1 month

2
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[PATCH] kunit: replace KUNIT_TRIGGER_STATIC_STUB maro with KUNIT_STATIC_STUB_REDIRECT

by Kemeng Shi

We mix up KUNIT_TRIGGER_STATIC_STUB and KUNIT_STATIC_STUB_REDIRECT in static_stub header. Just correct KUNIT_TRIGGER_STATIC_STUB to KUNIT_STATIC_STUB_REDIRECT which is documented. Signed-off-by: Kemeng Shi <shikemeng(a)huaweicloud.com> --- include/kunit/static_stub.h | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/include/kunit/static_stub.h b/include/kunit/static_stub.h index 9b80150a5d62..85315c80b303 100644 --- a/include/kunit/static_stub.h +++ b/include/kunit/static_stub.h @@ -11,7 +11,7 @@ #if !IS_ENABLED(CONFIG_KUNIT) /* If CONFIG_KUNIT is not enabled, these stubs quietly disappear. */ -#define KUNIT_TRIGGER_STATIC_STUB(real_fn_name, args...) do {} while (0) +#define KUNIT_STATIC_STUB_REDIRECT(real_fn_name, args...) do {} while (0) #else @@ -30,7 +30,7 @@ * This is a function prologue which is used to allow calls to the current * function to be redirected by a KUnit test. KUnit tests can call * kunit_activate_static_stub() to pass a replacement function in. The - * replacement function will be called by KUNIT_TRIGGER_STATIC_STUB(), which + * replacement function will be called by KUNIT_STATIC_STUB_REDIRECT(), which * will then return from the function. If the caller is not in a KUnit context, * the function will continue execution as normal. * @@ -87,7 +87,7 @@ void __kunit_activate_static_stub(struct kunit *test, * When activated, calls to real_fn_addr from within this test (even if called * indirectly) will instead call replacement_addr. The function pointed to by * real_fn_addr must begin with the static stub prologue in - * KUNIT_TRIGGER_STATIC_STUB() for this to work. real_fn_addr and + * KUNIT_STATIC_STUB_REDIRECT() for this to work. real_fn_addr and * replacement_addr must have the same type. * * The redirection can be disabled again with kunit_deactivate_static_stub(). -- 2.30.0

2 years, 1 month

2
3
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[PATCH] rcutorture: Copy out ftrace into its own console file

by Joel Fernandes (Google)

From: Joel <agnel.joel(a)gmail.com> Often times it is difficult to jump to the ftrace buffers and treat it independently during debugging. Copy the contents of the buffers into its own file. Signed-off-by: Joel Fernandes (Google) <joel(a)joelfernandes.org> --- .../selftests/rcutorture/bin/functions.sh | 24 +++++++++++++++++++ .../selftests/rcutorture/bin/parse-console.sh | 7 ++++++ 2 files changed, 31 insertions(+) mode change 100644 => 100755 tools/testing/selftests/rcutorture/bin/functions.sh diff --git a/tools/testing/selftests/rcutorture/bin/functions.sh b/tools/testing/selftests/rcutorture/bin/functions.sh old mode 100644 new mode 100755 index b8e2ea23cb3f..2ec4ab87a7f0 --- a/tools/testing/selftests/rcutorture/bin/functions.sh +++ b/tools/testing/selftests/rcutorture/bin/functions.sh @@ -331,3 +331,27 @@ specify_qemu_net () { echo $1 -net none fi } + +# Extract the ftrace output from the console log output +# The ftrace output looks in the logs looks like: +# Dumping ftrace buffer: +# --------------------------------- +# [...] +# --------------------------------- +extract_ftrace_from_console() { + awk ' + /Dumping ftrace buffer:/ { + capture = 1 + next + } + /---------------------------------/ { + if(capture == 1) { + capture = 2 + next + } else if(capture == 2) { + capture = 0 + } + } + capture == 2 + ' "$1"; +} diff --git a/tools/testing/selftests/rcutorture/bin/parse-console.sh b/tools/testing/selftests/rcutorture/bin/parse-console.sh index 9ab0f6bc172c..e3d2f69ec0fb 100755 --- a/tools/testing/selftests/rcutorture/bin/parse-console.sh +++ b/tools/testing/selftests/rcutorture/bin/parse-console.sh @@ -182,3 +182,10 @@ if ! test -s $file.diags then rm -f $file.diags fi + +# Call extract_ftrace_from_console function, if the output is empty, +# don't create $file.ftrace. Otherwise output the results to $file.ftrace +extract_ftrace_from_console $file > $file.ftrace +if [ ! -s $file.ftrace ]; then + rm -f $file.ftrace +fi -- 2.41.0.640.ga95def55d0-goog

2 years, 1 month

3
2
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[PATCH v29 0/6] Implement IOCTL to get and optionally clear info about PTEs

by Muhammad Usama Anjum

*Changes in v29:* - Polish IOCTL and improve documentation *Changes in v28:* - Fix walk_end and add 17 test cases in selftests patch *Changes in v27:* - Handle review comments and minor improvements - Add performance improvement patch on top with test for easy review *Changes in v26:* - Code re-structurring and API changes in PAGEMAP_IOCTL *Changes in v25*: - Do proper filtering on hole as well (hole got missed earlier) *Changes in v24*: - Rebase on top of next-20230710 - Place WP markers in case of hole as well *Changes in v23*: - Set vec_buf_index in loop only when vec_buf_index is set - Return -EFAULT instead of -EINVAL if vec is NULL - Correctly return the walk ending address to the page granularity *Changes in v22*: - Interface change: - Replace [start start + len) with [start, end) - Return the ending address of the address walk in start *Changes in v21*: - Abort walk instead of returning error if WP is to be performed on partial hugetlb *Changes in v20* - Correct PAGE_IS_FILE and add PAGE_IS_PFNZERO *Changes in v19* - Minor changes and interface updates *Changes in v18* - Rebase on top of next-20230613 - Minor updates *Changes in v17* - Rebase on top of next-20230606 - Minor improvements in PAGEMAP_SCAN IOCTL patch *Changes in v16* - Fix a corner case - Add exclusive PM_SCAN_OP_WP back *Changes in v15* - Build fix (Add missed build fix in RESEND) *Changes in v14* - Fix build error caused by #ifdef added at last minute in some configs *Changes in v13* - Rebase on top of next-20230414 - Give-up on using uffd_wp_range() and write new helpers, flush tlb only once *Changes in v12* - Update and other memory types to UFFD_FEATURE_WP_ASYNC - Rebaase on top of next-20230406 - Review updates *Changes in v11* - Rebase on top of next-20230307 - Base patches on UFFD_FEATURE_WP_UNPOPULATED - Do a lot of cosmetic changes and review updates - Remove ENGAGE_WP + !GET operation as it can be performed with UFFDIO_WRITEPROTECT *Changes in v10* - Add specific condition to return error if hugetlb is used with wp async - Move changes in tools/include/uapi/linux/fs.h to separate patch - Add documentation *Changes in v9:* - Correct fault resolution for userfaultfd wp async - Fix build warnings and errors which were happening on some configs - Simplify pagemap ioctl's code *Changes in v8:* - Update uffd async wp implementation - Improve PAGEMAP_IOCTL implementation *Changes in v7:* - Add uffd wp async - Update the IOCTL to use uffd under the hood instead of soft-dirty flags *Motivation* The real motivation for adding PAGEMAP_SCAN IOCTL is to emulate Windows GetWriteWatch() and ResetWriteWatch() syscalls [1]. The GetWriteWatch() retrieves the addresses of the pages that are written to in a region of virtual memory. This syscall is used in Windows applications and games etc. This syscall is being emulated in pretty slow manner in userspace. Our purpose is to enhance the kernel such that we translate it efficiently in a better way. Currently some out of tree hack patches are being used to efficiently emulate it in some kernels. We intend to replace those with these patches. So the whole gaming on Linux can effectively get benefit from this. It means there would be tons of users of this code. CRIU use case [2] was mentioned by Andrei and Danylo: > Use cases for migrating sparse VMAs are binaries sanitized with ASAN, > MSAN or TSAN [3]. All of these sanitizers produce sparse mappings of > shadow memory [4]. Being able to migrate such binaries allows to highly > reduce the amount of work needed to identify and fix post-migration > crashes, which happen constantly. Andrei's defines the following uses of this code: * it is more granular and allows us to track changed pages more effectively. The current interface can clear dirty bits for the entire process only. In addition, reading info about pages is a separate operation. It means we must freeze the process to read information about all its pages, reset dirty bits, only then we can start dumping pages. The information about pages becomes more and more outdated, while we are processing pages. The new interface solves both these downsides. First, it allows us to read pte bits and clear the soft-dirty bit atomically. It means that CRIU will not need to freeze processes to pre-dump their memory. Second, it clears soft-dirty bits for a specified region of memory. It means CRIU will have actual info about pages to the moment of dumping them. * The new interface has to be much faster because basic page filtering is happening in the kernel. With the old interface, we have to read pagemap for each page. *Implementation Evolution (Short Summary)* From the definition of GetWriteWatch(), we feel like kernel's soft-dirty feature can be used under the hood with some additions like: * reset soft-dirty flag for only a specific region of memory instead of clearing the flag for the entire process * get and clear soft-dirty flag for a specific region atomically So we decided to use ioctl on pagemap file to read or/and reset soft-dirty flag. But using soft-dirty flag, sometimes we get extra pages which weren't even written. They had become soft-dirty because of VMA merging and VM_SOFTDIRTY flag. This breaks the definition of GetWriteWatch(). We were able to by-pass this short coming by ignoring VM_SOFTDIRTY until David reported that mprotect etc messes up the soft-dirty flag while ignoring VM_SOFTDIRTY [5]. This wasn't happening until [6] got introduced. We discussed if we can revert these patches. But we could not reach to any conclusion. So at this point, I made couple of tries to solve this whole VM_SOFTDIRTY issue by correcting the soft-dirty implementation: * [7] Correct the bug fixed wrongly back in 2014. It had potential to cause regression. We left it behind. * [8] Keep a list of soft-dirty part of a VMA across splits and merges. I got the reply don't increase the size of the VMA by 8 bytes. At this point, we left soft-dirty considering it is too much delicate and userfaultfd [9] seemed like the only way forward. From there onward, we have been basing soft-dirty emulation on userfaultfd wp feature where kernel resolves the faults itself when WP_ASYNC feature is used. It was straight forward to add WP_ASYNC feature in userfautlfd. Now we get only those pages dirty or written-to which are really written in reality. (PS There is another WP_UNPOPULATED userfautfd feature is required which is needed to avoid pre-faulting memory before write-protecting [9].) All the different masks were added on the request of CRIU devs to create interface more generic and better. [1] https://learn.microsoft.com/en-us/windows/win32/api/memoryapi/nf-memoryapi-… [2] https://lore.kernel.org/all/20221014134802.1361436-1-mdanylo@google.com [3] https://github.com/google/sanitizers [4] https://github.com/google/sanitizers/wiki/AddressSanitizerAlgorithm#64-bit [5] https://lore.kernel.org/all/bfcae708-db21-04b4-0bbe-712badd03071@redhat.com [6] https://lore.kernel.org/all/20220725142048.30450-1-peterx@redhat.com/ [7] https://lore.kernel.org/all/20221122115007.2787017-1-usama.anjum@collabora.… [8] https://lore.kernel.org/all/20221220162606.1595355-1-usama.anjum@collabora.… [9] https://lore.kernel.org/all/20230306213925.617814-1-peterx@redhat.com [10] https://lore.kernel.org/all/20230125144529.1630917-1-mdanylo@google.com * Original Cover letter from v8* Hello, Note: Soft-dirty pages and pages which have been written-to are synonyms. As kernel already has soft-dirty feature inside which we have given up to use, we are using written-to terminology while using UFFD async WP under the hood. It is possible to find and clear soft-dirty pages entirely in userspace. But it isn't efficient: - The mprotect and SIGSEGV handler for bookkeeping - The userfaultfd wp (synchronous) with the handler for bookkeeping Some benchmarks can be seen here[1]. This series adds features that weren't present earlier: - There is no atomic get soft-dirty/Written-to status and clear present in the kernel. - The pages which have been written-to can not be found in accurate way. (Kernel's soft-dirty PTE bit + sof_dirty VMA bit shows more soft-dirty pages than there actually are.) Historically, soft-dirty PTE bit tracking has been used in the CRIU project. The procfs interface is enough for finding the soft-dirty bit status and clearing the soft-dirty bit of all the pages of a process. We have the use case where we need to track the soft-dirty PTE bit for only specific pages on-demand. We need this tracking and clear mechanism of a region of memory while the process is running to emulate the getWriteWatch() syscall of Windows. *(Moved to using UFFD instead of soft-dirty feature to find pages which have been written-to from v7 patch series)*: Stop using the soft-dirty flags for finding which pages have been written to. It is too delicate and wrong as it shows more soft-dirty pages than the actual soft-dirty pages. There is no interest in correcting it [2][3] as this is how the feature was written years ago. It shouldn't be updated to changed behaviour. Peter Xu has suggested using the async version of the UFFD WP [4] as it is based inherently on the PTEs. So in this patch series, I've added a new mode to the UFFD which is asynchronous version of the write protect. When this variant of the UFFD WP is used, the page faults are resolved automatically by the kernel. The pages which have been written-to can be found by reading pagemap file (!PM_UFFD_WP). This feature can be used successfully to find which pages have been written to from the time the pages were write protected. This works just like the soft-dirty flag without showing any extra pages which aren't soft-dirty in reality. The information related to pages if the page is file mapped, present and swapped is required for the CRIU project [5][6]. The addition of the required mask, any mask, excluded mask and return masks are also required for the CRIU project [5]. The IOCTL returns the addresses of the pages which match the specific masks. The page addresses are returned in struct page_region in a compact form. The max_pages is needed to support a use case where user only wants to get a specific number of pages. So there is no need to find all the pages of interest in the range when max_pages is specified. The IOCTL returns when the maximum number of the pages are found. The max_pages is optional. If max_pages is specified, it must be equal or greater than the vec_size. This restriction is needed to handle worse case when one page_region only contains info of one page and it cannot be compacted. This is needed to emulate the Windows getWriteWatch() syscall. The patch series include the detailed selftest which can be used as an example for the uffd async wp test and PAGEMAP_IOCTL. It shows the interface usages as well. [1] https://lore.kernel.org/lkml/54d4c322-cd6e-eefd-b161-2af2b56aae24@collabora… [2] https://lore.kernel.org/all/20221220162606.1595355-1-usama.anjum@collabora.… [3] https://lore.kernel.org/all/20221122115007.2787017-1-usama.anjum@collabora.… [4] https://lore.kernel.org/all/Y6Hc2d+7eTKs7AiH@x1n [5] https://lore.kernel.org/all/YyiDg79flhWoMDZB@gmail.com/ [6] https://lore.kernel.org/all/20221014134802.1361436-1-mdanylo@google.com/ Regards, Muhammad Usama Anjum Muhammad Usama Anjum (5): fs/proc/task_mmu: Implement IOCTL to get and optionally clear info about PTEs fs/proc/task_mmu: Add fast paths to get/clear PAGE_IS_WRITTEN flag tools headers UAPI: Update linux/fs.h with the kernel sources mm/pagemap: add documentation of PAGEMAP_SCAN IOCTL selftests: mm: add pagemap ioctl tests Peter Xu (1): userfaultfd: UFFD_FEATURE_WP_ASYNC Documentation/admin-guide/mm/pagemap.rst | 89 + Documentation/admin-guide/mm/userfaultfd.rst | 35 + fs/proc/task_mmu.c | 709 ++++++++ fs/userfaultfd.c | 26 +- include/linux/hugetlb.h | 1 + include/linux/userfaultfd_k.h | 21 +- include/uapi/linux/fs.h | 59 + include/uapi/linux/userfaultfd.h | 9 +- mm/hugetlb.c | 34 +- mm/memory.c | 27 +- tools/include/uapi/linux/fs.h | 59 + tools/testing/selftests/mm/.gitignore | 2 + tools/testing/selftests/mm/Makefile | 3 +- tools/testing/selftests/mm/config | 1 + tools/testing/selftests/mm/pagemap_ioctl.c | 1660 ++++++++++++++++++ tools/testing/selftests/mm/run_vmtests.sh | 4 + 16 files changed, 2715 insertions(+), 24 deletions(-) create mode 100644 tools/testing/selftests/mm/pagemap_ioctl.c -- 2.40.1

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