| Message ID | 20241024074815.1255066-2-namhyung@kernel.org (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [v2,bpf-next,1/2] bpf: Add open coded version of kmem_cache iterator | expand |
On Thu, Oct 24, 2024 at 12:48 AM Namhyung Kim <namhyung@kernel.org> wrote: > > The new subtest is attached to sleepable fentry of syncfs() syscall. > It iterates the kmem_cache using bpf_for_each loop and count the number > of entries. Finally it checks it with the number of entries from the > regular iterator. > > $ ./vmtest.sh -- ./test_progs -t kmem_cache_iter > ... > #130/1 kmem_cache_iter/check_task_struct:OK > #130/2 kmem_cache_iter/check_slabinfo:OK > #130/3 kmem_cache_iter/open_coded_iter:OK > #130 kmem_cache_iter:OK > Summary: 1/3 PASSED, 0 SKIPPED, 0 FAILED > > Also simplify the code by using attach routine of the skeleton. > > Signed-off-by: Namhyung Kim <namhyung@kernel.org> > --- > v2) > * remove unnecessary detach (Martin) > * check pid in syncfs to prevent surprise (Martin) > * remove unnecessary local variable (Andrii) > > .../testing/selftests/bpf/bpf_experimental.h | 6 ++++ > .../bpf/prog_tests/kmem_cache_iter.c | 28 +++++++++++-------- > .../selftests/bpf/progs/kmem_cache_iter.c | 28 +++++++++++++++++++ > 3 files changed, 50 insertions(+), 12 deletions(-) > > diff --git a/tools/testing/selftests/bpf/bpf_experimental.h b/tools/testing/selftests/bpf/bpf_experimental.h > index b0668f29f7b394eb..cd8ecd39c3f3c68d 100644 > --- a/tools/testing/selftests/bpf/bpf_experimental.h > +++ b/tools/testing/selftests/bpf/bpf_experimental.h > @@ -582,4 +582,10 @@ extern int bpf_wq_set_callback_impl(struct bpf_wq *wq, > unsigned int flags__k, void *aux__ign) __ksym; > #define bpf_wq_set_callback(timer, cb, flags) \ > bpf_wq_set_callback_impl(timer, cb, flags, NULL) > + > +struct bpf_iter_kmem_cache; > +extern int bpf_iter_kmem_cache_new(struct bpf_iter_kmem_cache *it) __weak __ksym; > +extern struct kmem_cache *bpf_iter_kmem_cache_next(struct bpf_iter_kmem_cache *it) __weak __ksym; > +extern void bpf_iter_kmem_cache_destroy(struct bpf_iter_kmem_cache *it) __weak __ksym; > + > #endif > diff --git a/tools/testing/selftests/bpf/prog_tests/kmem_cache_iter.c b/tools/testing/selftests/bpf/prog_tests/kmem_cache_iter.c > index 848d8fc9171fae45..778b55bc1f912b98 100644 > --- a/tools/testing/selftests/bpf/prog_tests/kmem_cache_iter.c > +++ b/tools/testing/selftests/bpf/prog_tests/kmem_cache_iter.c > @@ -68,12 +68,20 @@ static void subtest_kmem_cache_iter_check_slabinfo(struct kmem_cache_iter *skel) > fclose(fp); > } > > +static void subtest_kmem_cache_iter_open_coded(struct kmem_cache_iter *skel) > +{ > + skel->bss->tgid = getpid(); > + > + /* To trigger the open coded iterator attached to the syscall */ > + syncfs(0); > + > + /* It should be same as we've seen from the explicit iterator */ > + ASSERT_EQ(skel->bss->open_coded_seen, skel->bss->kmem_cache_seen, "open_code_seen_eq"); > +} > + > void test_kmem_cache_iter(void) > { > - DECLARE_LIBBPF_OPTS(bpf_iter_attach_opts, opts); > struct kmem_cache_iter *skel = NULL; > - union bpf_iter_link_info linfo = {}; > - struct bpf_link *link; > char buf[256]; > int iter_fd; > > @@ -81,16 +89,12 @@ void test_kmem_cache_iter(void) > if (!ASSERT_OK_PTR(skel, "kmem_cache_iter__open_and_load")) > return; > > - opts.link_info = &linfo; > - opts.link_info_len = sizeof(linfo); > - > - link = bpf_program__attach_iter(skel->progs.slab_info_collector, &opts); > - if (!ASSERT_OK_PTR(link, "attach_iter")) > + if (!ASSERT_OK(kmem_cache_iter__attach(skel), "skel_attach")) > goto destroy; > > - iter_fd = bpf_iter_create(bpf_link__fd(link)); > + iter_fd = bpf_iter_create(bpf_link__fd(skel->links.slab_info_collector)); > if (!ASSERT_GE(iter_fd, 0, "iter_create")) > - goto free_link; > + goto destroy; > > memset(buf, 0, sizeof(buf)); > while (read(iter_fd, buf, sizeof(buf) > 0)) { > @@ -105,11 +109,11 @@ void test_kmem_cache_iter(void) > subtest_kmem_cache_iter_check_task_struct(skel); > if (test__start_subtest("check_slabinfo")) > subtest_kmem_cache_iter_check_slabinfo(skel); > + if (test__start_subtest("open_coded_iter")) > + subtest_kmem_cache_iter_open_coded(skel); > > close(iter_fd); > > -free_link: > - bpf_link__destroy(link); > destroy: > kmem_cache_iter__destroy(skel); > } > diff --git a/tools/testing/selftests/bpf/progs/kmem_cache_iter.c b/tools/testing/selftests/bpf/progs/kmem_cache_iter.c > index 72c9dafecd98406b..e62807caa7593604 100644 > --- a/tools/testing/selftests/bpf/progs/kmem_cache_iter.c > +++ b/tools/testing/selftests/bpf/progs/kmem_cache_iter.c > @@ -2,6 +2,8 @@ > /* Copyright (c) 2024 Google */ > > #include "bpf_iter.h" > +#include "bpf_experimental.h" > +#include "bpf_misc.h" > #include <bpf/bpf_helpers.h> > #include <bpf/bpf_tracing.h> > > @@ -30,9 +32,12 @@ struct { > > extern struct kmem_cache *bpf_get_kmem_cache(u64 addr) __ksym; > > +unsigned int tgid; > + > /* Result, will be checked by userspace */ > int task_struct_found; > int kmem_cache_seen; > +int open_coded_seen; > > SEC("iter/kmem_cache") > int slab_info_collector(struct bpf_iter__kmem_cache *ctx) > @@ -85,3 +90,26 @@ int BPF_PROG(check_task_struct) > task_struct_found = -2; > return 0; > } > + > +SEC("fentry.s/" SYS_PREFIX "sys_syncfs") > +int open_coded_iter(const void *ctx) > +{ > + struct kmem_cache *s; > + > + if (tgid != bpf_get_current_pid_tgid() >> 32) > + return 0; Pls use syscall prog type and prog_run() it. No need to attach to exotic syscalls and filter by pid. > + > + bpf_for_each(kmem_cache, s) { > + struct kmem_cache_result *r; > + > + r = bpf_map_lookup_elem(&slab_result, &open_coded_seen); > + if (!r) > + break; > + > + open_coded_seen++; > + > + if (r->obj_size != s->size) > + break; The order of 'if' and ++ should probably be changed ? Otherwise the last object isn't sufficiently checked. pw-bot: cr
Hello, On Thu, Oct 24, 2024 at 11:08:00AM -0700, Alexei Starovoitov wrote: > On Thu, Oct 24, 2024 at 12:48 AM Namhyung Kim <namhyung@kernel.org> wrote: > > > > The new subtest is attached to sleepable fentry of syncfs() syscall. > > It iterates the kmem_cache using bpf_for_each loop and count the number > > of entries. Finally it checks it with the number of entries from the > > regular iterator. > > > > $ ./vmtest.sh -- ./test_progs -t kmem_cache_iter > > ... > > #130/1 kmem_cache_iter/check_task_struct:OK > > #130/2 kmem_cache_iter/check_slabinfo:OK > > #130/3 kmem_cache_iter/open_coded_iter:OK > > #130 kmem_cache_iter:OK > > Summary: 1/3 PASSED, 0 SKIPPED, 0 FAILED > > > > Also simplify the code by using attach routine of the skeleton. > > > > Signed-off-by: Namhyung Kim <namhyung@kernel.org> > > --- > > v2) > > * remove unnecessary detach (Martin) > > * check pid in syncfs to prevent surprise (Martin) > > * remove unnecessary local variable (Andrii) > > > > .../testing/selftests/bpf/bpf_experimental.h | 6 ++++ > > .../bpf/prog_tests/kmem_cache_iter.c | 28 +++++++++++-------- > > .../selftests/bpf/progs/kmem_cache_iter.c | 28 +++++++++++++++++++ > > 3 files changed, 50 insertions(+), 12 deletions(-) > > > > diff --git a/tools/testing/selftests/bpf/bpf_experimental.h b/tools/testing/selftests/bpf/bpf_experimental.h > > index b0668f29f7b394eb..cd8ecd39c3f3c68d 100644 > > --- a/tools/testing/selftests/bpf/bpf_experimental.h > > +++ b/tools/testing/selftests/bpf/bpf_experimental.h > > @@ -582,4 +582,10 @@ extern int bpf_wq_set_callback_impl(struct bpf_wq *wq, > > unsigned int flags__k, void *aux__ign) __ksym; > > #define bpf_wq_set_callback(timer, cb, flags) \ > > bpf_wq_set_callback_impl(timer, cb, flags, NULL) > > + > > +struct bpf_iter_kmem_cache; > > +extern int bpf_iter_kmem_cache_new(struct bpf_iter_kmem_cache *it) __weak __ksym; > > +extern struct kmem_cache *bpf_iter_kmem_cache_next(struct bpf_iter_kmem_cache *it) __weak __ksym; > > +extern void bpf_iter_kmem_cache_destroy(struct bpf_iter_kmem_cache *it) __weak __ksym; > > + > > #endif > > diff --git a/tools/testing/selftests/bpf/prog_tests/kmem_cache_iter.c b/tools/testing/selftests/bpf/prog_tests/kmem_cache_iter.c > > index 848d8fc9171fae45..778b55bc1f912b98 100644 > > --- a/tools/testing/selftests/bpf/prog_tests/kmem_cache_iter.c > > +++ b/tools/testing/selftests/bpf/prog_tests/kmem_cache_iter.c > > @@ -68,12 +68,20 @@ static void subtest_kmem_cache_iter_check_slabinfo(struct kmem_cache_iter *skel) > > fclose(fp); > > } > > > > +static void subtest_kmem_cache_iter_open_coded(struct kmem_cache_iter *skel) > > +{ > > + skel->bss->tgid = getpid(); > > + > > + /* To trigger the open coded iterator attached to the syscall */ > > + syncfs(0); > > + > > + /* It should be same as we've seen from the explicit iterator */ > > + ASSERT_EQ(skel->bss->open_coded_seen, skel->bss->kmem_cache_seen, "open_code_seen_eq"); > > +} > > + > > void test_kmem_cache_iter(void) > > { > > - DECLARE_LIBBPF_OPTS(bpf_iter_attach_opts, opts); > > struct kmem_cache_iter *skel = NULL; > > - union bpf_iter_link_info linfo = {}; > > - struct bpf_link *link; > > char buf[256]; > > int iter_fd; > > > > @@ -81,16 +89,12 @@ void test_kmem_cache_iter(void) > > if (!ASSERT_OK_PTR(skel, "kmem_cache_iter__open_and_load")) > > return; > > > > - opts.link_info = &linfo; > > - opts.link_info_len = sizeof(linfo); > > - > > - link = bpf_program__attach_iter(skel->progs.slab_info_collector, &opts); > > - if (!ASSERT_OK_PTR(link, "attach_iter")) > > + if (!ASSERT_OK(kmem_cache_iter__attach(skel), "skel_attach")) > > goto destroy; > > > > - iter_fd = bpf_iter_create(bpf_link__fd(link)); > > + iter_fd = bpf_iter_create(bpf_link__fd(skel->links.slab_info_collector)); > > if (!ASSERT_GE(iter_fd, 0, "iter_create")) > > - goto free_link; > > + goto destroy; > > > > memset(buf, 0, sizeof(buf)); > > while (read(iter_fd, buf, sizeof(buf) > 0)) { > > @@ -105,11 +109,11 @@ void test_kmem_cache_iter(void) > > subtest_kmem_cache_iter_check_task_struct(skel); > > if (test__start_subtest("check_slabinfo")) > > subtest_kmem_cache_iter_check_slabinfo(skel); > > + if (test__start_subtest("open_coded_iter")) > > + subtest_kmem_cache_iter_open_coded(skel); > > > > close(iter_fd); > > > > -free_link: > > - bpf_link__destroy(link); > > destroy: > > kmem_cache_iter__destroy(skel); > > } > > diff --git a/tools/testing/selftests/bpf/progs/kmem_cache_iter.c b/tools/testing/selftests/bpf/progs/kmem_cache_iter.c > > index 72c9dafecd98406b..e62807caa7593604 100644 > > --- a/tools/testing/selftests/bpf/progs/kmem_cache_iter.c > > +++ b/tools/testing/selftests/bpf/progs/kmem_cache_iter.c > > @@ -2,6 +2,8 @@ > > /* Copyright (c) 2024 Google */ > > > > #include "bpf_iter.h" > > +#include "bpf_experimental.h" > > +#include "bpf_misc.h" > > #include <bpf/bpf_helpers.h> > > #include <bpf/bpf_tracing.h> > > > > @@ -30,9 +32,12 @@ struct { > > > > extern struct kmem_cache *bpf_get_kmem_cache(u64 addr) __ksym; > > > > +unsigned int tgid; > > + > > /* Result, will be checked by userspace */ > > int task_struct_found; > > int kmem_cache_seen; > > +int open_coded_seen; > > > > SEC("iter/kmem_cache") > > int slab_info_collector(struct bpf_iter__kmem_cache *ctx) > > @@ -85,3 +90,26 @@ int BPF_PROG(check_task_struct) > > task_struct_found = -2; > > return 0; > > } > > + > > +SEC("fentry.s/" SYS_PREFIX "sys_syncfs") > > +int open_coded_iter(const void *ctx) > > +{ > > + struct kmem_cache *s; > > + > > + if (tgid != bpf_get_current_pid_tgid() >> 32) > > + return 0; > > Pls use syscall prog type and prog_run() it. > No need to attach to exotic syscalls and filter by pid. Sure, will update in v3. > > > + > > + bpf_for_each(kmem_cache, s) { > > + struct kmem_cache_result *r; > > + > > + r = bpf_map_lookup_elem(&slab_result, &open_coded_seen); > > + if (!r) > > + break; > > + > > + open_coded_seen++; > > + > > + if (r->obj_size != s->size) > > + break; > > The order of 'if' and ++ should probably be changed ? > Otherwise the last object isn't sufficiently checked. I don't think so. The last element should be an actual slab cache and then the iterator will return NULL to break the loop. I don't expect it will hit the if statement. Thanks, Namhyung
On Tue, Oct 29, 2024 at 06:40:46PM -0700, Namhyung Kim wrote: > Hello, > > On Thu, Oct 24, 2024 at 11:08:00AM -0700, Alexei Starovoitov wrote: > > On Thu, Oct 24, 2024 at 12:48 AM Namhyung Kim <namhyung@kernel.org> wrote: > > > > > > The new subtest is attached to sleepable fentry of syncfs() syscall. > > > It iterates the kmem_cache using bpf_for_each loop and count the number > > > of entries. Finally it checks it with the number of entries from the > > > regular iterator. > > > > > > $ ./vmtest.sh -- ./test_progs -t kmem_cache_iter > > > ... > > > #130/1 kmem_cache_iter/check_task_struct:OK > > > #130/2 kmem_cache_iter/check_slabinfo:OK > > > #130/3 kmem_cache_iter/open_coded_iter:OK > > > #130 kmem_cache_iter:OK > > > Summary: 1/3 PASSED, 0 SKIPPED, 0 FAILED > > > > > > Also simplify the code by using attach routine of the skeleton. > > > > > > Signed-off-by: Namhyung Kim <namhyung@kernel.org> > > > --- [SNIP] > > > +SEC("fentry.s/" SYS_PREFIX "sys_syncfs") > > > +int open_coded_iter(const void *ctx) > > > +{ > > > + struct kmem_cache *s; > > > + > > > + if (tgid != bpf_get_current_pid_tgid() >> 32) > > > + return 0; > > > > Pls use syscall prog type and prog_run() it. > > No need to attach to exotic syscalls and filter by pid. > > Sure, will update in v3. > > > > > > + > > > + bpf_for_each(kmem_cache, s) { > > > + struct kmem_cache_result *r; > > > + > > > + r = bpf_map_lookup_elem(&slab_result, &open_coded_seen); > > > + if (!r) > > > + break; > > > + > > > + open_coded_seen++; > > > + > > > + if (r->obj_size != s->size) > > > + break; > > > > The order of 'if' and ++ should probably be changed ? > > Otherwise the last object isn't sufficiently checked. > > I don't think so. The last element should be an actual slab cache and > then the iterator will return NULL to break the loop. I don't expect it > will hit the if statement. Oh, it seems you meant checking the obj_size. Ok then, I can move the increment after the check. Thanks, Namhyung
diff --git a/tools/testing/selftests/bpf/bpf_experimental.h b/tools/testing/selftests/bpf/bpf_experimental.h index b0668f29f7b394eb..cd8ecd39c3f3c68d 100644 --- a/tools/testing/selftests/bpf/bpf_experimental.h +++ b/tools/testing/selftests/bpf/bpf_experimental.h @@ -582,4 +582,10 @@ extern int bpf_wq_set_callback_impl(struct bpf_wq *wq, unsigned int flags__k, void *aux__ign) __ksym; #define bpf_wq_set_callback(timer, cb, flags) \ bpf_wq_set_callback_impl(timer, cb, flags, NULL) + +struct bpf_iter_kmem_cache; +extern int bpf_iter_kmem_cache_new(struct bpf_iter_kmem_cache *it) __weak __ksym; +extern struct kmem_cache *bpf_iter_kmem_cache_next(struct bpf_iter_kmem_cache *it) __weak __ksym; +extern void bpf_iter_kmem_cache_destroy(struct bpf_iter_kmem_cache *it) __weak __ksym; + #endif diff --git a/tools/testing/selftests/bpf/prog_tests/kmem_cache_iter.c b/tools/testing/selftests/bpf/prog_tests/kmem_cache_iter.c index 848d8fc9171fae45..778b55bc1f912b98 100644 --- a/tools/testing/selftests/bpf/prog_tests/kmem_cache_iter.c +++ b/tools/testing/selftests/bpf/prog_tests/kmem_cache_iter.c @@ -68,12 +68,20 @@ static void subtest_kmem_cache_iter_check_slabinfo(struct kmem_cache_iter *skel) fclose(fp); } +static void subtest_kmem_cache_iter_open_coded(struct kmem_cache_iter *skel) +{ + skel->bss->tgid = getpid(); + + /* To trigger the open coded iterator attached to the syscall */ + syncfs(0); + + /* It should be same as we've seen from the explicit iterator */ + ASSERT_EQ(skel->bss->open_coded_seen, skel->bss->kmem_cache_seen, "open_code_seen_eq"); +} + void test_kmem_cache_iter(void) { - DECLARE_LIBBPF_OPTS(bpf_iter_attach_opts, opts); struct kmem_cache_iter *skel = NULL; - union bpf_iter_link_info linfo = {}; - struct bpf_link *link; char buf[256]; int iter_fd; @@ -81,16 +89,12 @@ void test_kmem_cache_iter(void) if (!ASSERT_OK_PTR(skel, "kmem_cache_iter__open_and_load")) return; - opts.link_info = &linfo; - opts.link_info_len = sizeof(linfo); - - link = bpf_program__attach_iter(skel->progs.slab_info_collector, &opts); - if (!ASSERT_OK_PTR(link, "attach_iter")) + if (!ASSERT_OK(kmem_cache_iter__attach(skel), "skel_attach")) goto destroy; - iter_fd = bpf_iter_create(bpf_link__fd(link)); + iter_fd = bpf_iter_create(bpf_link__fd(skel->links.slab_info_collector)); if (!ASSERT_GE(iter_fd, 0, "iter_create")) - goto free_link; + goto destroy; memset(buf, 0, sizeof(buf)); while (read(iter_fd, buf, sizeof(buf) > 0)) { @@ -105,11 +109,11 @@ void test_kmem_cache_iter(void) subtest_kmem_cache_iter_check_task_struct(skel); if (test__start_subtest("check_slabinfo")) subtest_kmem_cache_iter_check_slabinfo(skel); + if (test__start_subtest("open_coded_iter")) + subtest_kmem_cache_iter_open_coded(skel); close(iter_fd); -free_link: - bpf_link__destroy(link); destroy: kmem_cache_iter__destroy(skel); } diff --git a/tools/testing/selftests/bpf/progs/kmem_cache_iter.c b/tools/testing/selftests/bpf/progs/kmem_cache_iter.c index 72c9dafecd98406b..e62807caa7593604 100644 --- a/tools/testing/selftests/bpf/progs/kmem_cache_iter.c +++ b/tools/testing/selftests/bpf/progs/kmem_cache_iter.c @@ -2,6 +2,8 @@ /* Copyright (c) 2024 Google */ #include "bpf_iter.h" +#include "bpf_experimental.h" +#include "bpf_misc.h" #include <bpf/bpf_helpers.h> #include <bpf/bpf_tracing.h> @@ -30,9 +32,12 @@ struct { extern struct kmem_cache *bpf_get_kmem_cache(u64 addr) __ksym; +unsigned int tgid; + /* Result, will be checked by userspace */ int task_struct_found; int kmem_cache_seen; +int open_coded_seen; SEC("iter/kmem_cache") int slab_info_collector(struct bpf_iter__kmem_cache *ctx) @@ -85,3 +90,26 @@ int BPF_PROG(check_task_struct) task_struct_found = -2; return 0; } + +SEC("fentry.s/" SYS_PREFIX "sys_syncfs") +int open_coded_iter(const void *ctx) +{ + struct kmem_cache *s; + + if (tgid != bpf_get_current_pid_tgid() >> 32) + return 0; + + bpf_for_each(kmem_cache, s) { + struct kmem_cache_result *r; + + r = bpf_map_lookup_elem(&slab_result, &open_coded_seen); + if (!r) + break; + + open_coded_seen++; + + if (r->obj_size != s->size) + break; + } + return 0; +}
The new subtest is attached to sleepable fentry of syncfs() syscall. It iterates the kmem_cache using bpf_for_each loop and count the number of entries. Finally it checks it with the number of entries from the regular iterator. $ ./vmtest.sh -- ./test_progs -t kmem_cache_iter ... #130/1 kmem_cache_iter/check_task_struct:OK #130/2 kmem_cache_iter/check_slabinfo:OK #130/3 kmem_cache_iter/open_coded_iter:OK #130 kmem_cache_iter:OK Summary: 1/3 PASSED, 0 SKIPPED, 0 FAILED Also simplify the code by using attach routine of the skeleton. Signed-off-by: Namhyung Kim <namhyung@kernel.org> --- v2) * remove unnecessary detach (Martin) * check pid in syncfs to prevent surprise (Martin) * remove unnecessary local variable (Andrii) .../testing/selftests/bpf/bpf_experimental.h | 6 ++++ .../bpf/prog_tests/kmem_cache_iter.c | 28 +++++++++++-------- .../selftests/bpf/progs/kmem_cache_iter.c | 28 +++++++++++++++++++ 3 files changed, 50 insertions(+), 12 deletions(-)