Messages in this thread | | | Date | Thu, 19 May 2022 12:43:18 -0700 | Subject | Re: [PATCH bpf v4 3/3] libbpf, selftests/bpf: pass array of u64 values in kprobe_multi.addrs | From | Yonghong Song <> |
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On 5/19/22 11:14 AM, Eugene Syromiatnikov wrote: > With the interface as defined, it is impossible to pass 64-bit kernel > addresses from a 32-bit userspace process in BPF_LINK_TYPE_KPROBE_MULTI, > which severly limits the useability of the interface, change the API > to accept an array of u64 values instead of (kernel? user?) longs. > This patch implements the user space part of the change (without > the relevant kernel changes, since, as of now, an attempt to add > kprobe_multi link will fail with -EOPNOTSUPP), to avoid changing > the interface after a release. > > Fixes: 5117c26e877352bc ("libbpf: Add bpf_link_create support for multi kprobes") > Fixes: ddc6b04989eb0993 ("libbpf: Add bpf_program__attach_kprobe_multi_opts function") > Fixes: f7a11eeccb111854 ("selftests/bpf: Add kprobe_multi attach test") > Fixes: 9271a0c7ae7a9147 ("selftests/bpf: Add attach test for bpf_program__attach_kprobe_multi_opts") > Fixes: 2c6401c966ae1fbe ("selftests/bpf: Add kprobe_multi bpf_cookie test") > Signed-off-by: Eugene Syromiatnikov <esyr@redhat.com> > --- > tools/lib/bpf/bpf.h | 2 +- > tools/lib/bpf/libbpf.c | 8 ++++---- > tools/lib/bpf/libbpf.h | 2 +- > tools/testing/selftests/bpf/prog_tests/bpf_cookie.c | 2 +- > tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c | 8 ++++---- > 5 files changed, 11 insertions(+), 11 deletions(-) > > diff --git a/tools/lib/bpf/bpf.h b/tools/lib/bpf/bpf.h > index f4b4afb..f677602 100644 > --- a/tools/lib/bpf/bpf.h > +++ b/tools/lib/bpf/bpf.h > @@ -417,7 +417,7 @@ struct bpf_link_create_opts { > __u32 flags; > __u32 cnt; > const char **syms; > - const unsigned long *addrs; > + const __u64 *addrs;
Patch 2 and 3 will prevent supporting 64-bit kernel, 32-bit userspace for kprobe_multi. So effectively, kprobe_multi only supports 64-bit kernel and 64-bit user space. This is definitely an option, but it would be great if other people can chime in as well for whether this choice is best or not.
> const __u64 *cookies; > } kprobe_multi; > }; > diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c > index 809fe20..03a14a6 100644 > --- a/tools/lib/bpf/libbpf.c > +++ b/tools/lib/bpf/libbpf.c > @@ -10279,7 +10279,7 @@ static bool glob_match(const char *str, const char *pat) > > struct kprobe_multi_resolve { > const char *pattern; > - unsigned long *addrs; > + __u64 *addrs; > size_t cap; > size_t cnt; > }; > @@ -10294,12 +10294,12 @@ resolve_kprobe_multi_cb(unsigned long long sym_addr, char sym_type, > if (!glob_match(sym_name, res->pattern)) > return 0; > > - err = libbpf_ensure_mem((void **) &res->addrs, &res->cap, sizeof(unsigned long), > + err = libbpf_ensure_mem((void **) &res->addrs, &res->cap, sizeof(__u64), > res->cnt + 1); > if (err) > return err; > > - res->addrs[res->cnt++] = (unsigned long) sym_addr; > + res->addrs[res->cnt++] = sym_addr; > return 0; > } > > @@ -10314,7 +10314,7 @@ bpf_program__attach_kprobe_multi_opts(const struct bpf_program *prog, > }; > struct bpf_link *link = NULL; > char errmsg[STRERR_BUFSIZE]; > - const unsigned long *addrs; > + const __u64 *addrs; > int err, link_fd, prog_fd; > const __u64 *cookies; > const char **syms; > diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h > index 05dde85..ec1cb61 100644 > --- a/tools/lib/bpf/libbpf.h > +++ b/tools/lib/bpf/libbpf.h > @@ -431,7 +431,7 @@ struct bpf_kprobe_multi_opts { > /* array of function symbols to attach */ > const char **syms; > /* array of function addresses to attach */ > - const unsigned long *addrs; > + const __u64 *addrs; > /* array of user-provided values fetchable through bpf_get_attach_cookie */ > const __u64 *cookies; > /* number of elements in syms/addrs/cookies arrays */ > diff --git a/tools/testing/selftests/bpf/prog_tests/bpf_cookie.c b/tools/testing/selftests/bpf/prog_tests/bpf_cookie.c > index 923a613..5aa482a 100644 > --- a/tools/testing/selftests/bpf/prog_tests/bpf_cookie.c > +++ b/tools/testing/selftests/bpf/prog_tests/bpf_cookie.c > @@ -137,7 +137,7 @@ static void kprobe_multi_link_api_subtest(void) > cookies[6] = 7; > cookies[7] = 8; > > - opts.kprobe_multi.addrs = (const unsigned long *) &addrs; > + opts.kprobe_multi.addrs = (const __u64 *) &addrs; > opts.kprobe_multi.cnt = ARRAY_SIZE(addrs); > opts.kprobe_multi.cookies = (const __u64 *) &cookies; > prog_fd = bpf_program__fd(skel->progs.test_kprobe); > diff --git a/tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c b/tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c > index b9876b5..fbf4cf2 100644 > --- a/tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c > +++ b/tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c > @@ -105,7 +105,7 @@ static void test_link_api_addrs(void) > GET_ADDR("bpf_fentry_test7", addrs[6]); > GET_ADDR("bpf_fentry_test8", addrs[7]); > > - opts.kprobe_multi.addrs = (const unsigned long*) addrs; > + opts.kprobe_multi.addrs = (const __u64 *) addrs; > opts.kprobe_multi.cnt = ARRAY_SIZE(addrs); > test_link_api(&opts); > } > @@ -183,7 +183,7 @@ static void test_attach_api_addrs(void) > GET_ADDR("bpf_fentry_test7", addrs[6]); > GET_ADDR("bpf_fentry_test8", addrs[7]); > > - opts.addrs = (const unsigned long *) addrs; > + opts.addrs = (const __u64 *) addrs; > opts.cnt = ARRAY_SIZE(addrs); > test_attach_api(NULL, &opts); > } > @@ -241,7 +241,7 @@ static void test_attach_api_fails(void) > goto cleanup; > > /* fail_2 - both addrs and syms set */ > - opts.addrs = (const unsigned long *) addrs; > + opts.addrs = (const __u64 *) addrs; > opts.syms = syms; > opts.cnt = ARRAY_SIZE(syms); > opts.cookies = NULL; > @@ -255,7 +255,7 @@ static void test_attach_api_fails(void) > goto cleanup; > > /* fail_3 - pattern and addrs set */ > - opts.addrs = (const unsigned long *) addrs; > + opts.addrs = (const __u64 *) addrs; > opts.syms = NULL; > opts.cnt = ARRAY_SIZE(syms); > opts.cookies = NULL;
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