| Message ID | 20200819224030.1615203-9-haoluo@google.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | bpf: BTF support for ksyms | expand |
On Wed, Aug 19, 2020 at 3:42 PM Hao Luo <haoluo@google.com> wrote: > > Test bpf_per_cpu_ptr(). Test two paths in the kernel. If the base > pointer points to a struct, the returned reg is of type PTR_TO_BTF_ID. > Direct pointer dereference can be applied on the returned variable. > If the base pointer isn't a struct, the returned reg is of type > PTR_TO_MEM, which also supports direct pointer dereference. > > Signed-off-by: Hao Luo <haoluo@google.com> > --- Acked-by: Andrii Nakryiko <andriin@fb.com> > .../testing/selftests/bpf/prog_tests/ksyms_btf.c | 4 ++++ > .../testing/selftests/bpf/progs/test_ksyms_btf.c | 15 ++++++++++++++- > 2 files changed, 18 insertions(+), 1 deletion(-) > > diff --git a/tools/testing/selftests/bpf/prog_tests/ksyms_btf.c b/tools/testing/selftests/bpf/prog_tests/ksyms_btf.c > index 1dad61ba7e99..bdedd4a76b42 100644 > --- a/tools/testing/selftests/bpf/prog_tests/ksyms_btf.c > +++ b/tools/testing/selftests/bpf/prog_tests/ksyms_btf.c > @@ -71,6 +71,10 @@ void test_ksyms_btf(void) > "got %llu, exp %llu\n", data->out__runqueues, runqueues_addr); > CHECK(data->out__bpf_prog_active != bpf_prog_active_addr, "bpf_prog_active", > "got %llu, exp %llu\n", data->out__bpf_prog_active, bpf_prog_active_addr); > + CHECK(data->out__rq_cpu != 1, "rq_cpu", > + "got %u, exp %u\n", data->out__rq_cpu, 1); > + CHECK(data->out__process_counts == -1, "process_counts", > + "got %lu, exp != -1", data->out__process_counts); > > cleanup: > test_ksyms_btf__destroy(skel); > diff --git a/tools/testing/selftests/bpf/progs/test_ksyms_btf.c b/tools/testing/selftests/bpf/progs/test_ksyms_btf.c > index e04e31117f84..78cf1ebb753d 100644 > --- a/tools/testing/selftests/bpf/progs/test_ksyms_btf.c > +++ b/tools/testing/selftests/bpf/progs/test_ksyms_btf.c > @@ -7,16 +7,29 @@ > > __u64 out__runqueues = -1; > __u64 out__bpf_prog_active = -1; > +__u32 out__rq_cpu = -1; > +unsigned long out__process_counts = -1; try to not use long for variables, it is 32-bit integer in user-space but always 64-bit in BPF. This causes problems when using skeleton on 32-bit architecture. > > -extern const struct rq runqueues __ksym; /* struct type global var. */ > +extern const struct rq runqueues __ksym; /* struct type percpu var. */ > extern const int bpf_prog_active __ksym; /* int type global var. */ > +extern const unsigned long process_counts __ksym; /* int type percpu var. */ > > SEC("raw_tp/sys_enter") > int handler(const void *ctx) > { > + struct rq *rq; > + unsigned long *count; > + > out__runqueues = (__u64)&runqueues; > out__bpf_prog_active = (__u64)&bpf_prog_active; > > + rq = (struct rq *)bpf_per_cpu_ptr(&runqueues, 1); > + if (rq) > + out__rq_cpu = rq->cpu; this is awesome! Are there any per-cpu variables that are arrays? Would be nice to test those too. > + count = (unsigned long *)bpf_per_cpu_ptr(&process_counts, 1); > + if (count) > + out__process_counts = *count; > + > return 0; > } > > -- > 2.28.0.220.ged08abb693-goog >
Thanks for taking a look! On Fri, Aug 21, 2020 at 8:30 PM Andrii Nakryiko <andrii.nakryiko@gmail.com> wrote: > > On Wed, Aug 19, 2020 at 3:42 PM Hao Luo <haoluo@google.com> wrote: > > > > Test bpf_per_cpu_ptr(). Test two paths in the kernel. If the base > > pointer points to a struct, the returned reg is of type PTR_TO_BTF_ID. > > Direct pointer dereference can be applied on the returned variable. > > If the base pointer isn't a struct, the returned reg is of type > > PTR_TO_MEM, which also supports direct pointer dereference. > > > > Signed-off-by: Hao Luo <haoluo@google.com> > > --- > > Acked-by: Andrii Nakryiko <andriin@fb.com> > [...] > > > > __u64 out__runqueues = -1; > > __u64 out__bpf_prog_active = -1; > > +__u32 out__rq_cpu = -1; > > +unsigned long out__process_counts = -1; > > try to not use long for variables, it is 32-bit integer in user-space > but always 64-bit in BPF. This causes problems when using skeleton on > 32-bit architecture. > Ack. I will use another variable of type 'int' instead. > > > > -extern const struct rq runqueues __ksym; /* struct type global var. */ > > +extern const struct rq runqueues __ksym; /* struct type percpu var. */ > > extern const int bpf_prog_active __ksym; /* int type global var. */ > > +extern const unsigned long process_counts __ksym; /* int type percpu var. */ > > > > SEC("raw_tp/sys_enter") > > int handler(const void *ctx) > > { > > + struct rq *rq; > > + unsigned long *count; > > + > > out__runqueues = (__u64)&runqueues; > > out__bpf_prog_active = (__u64)&bpf_prog_active; > > > > + rq = (struct rq *)bpf_per_cpu_ptr(&runqueues, 1); > > + if (rq) > > + out__rq_cpu = rq->cpu; > > this is awesome! > > Are there any per-cpu variables that are arrays? Would be nice to test > those too. > > There are currently per-cpu arrays, but not common. There is a 'pmc_prev_left' in arch/x86, I can add that in this test. [...]
On Thu, Aug 27, 2020 at 8:42 PM Hao Luo <haoluo@google.com> wrote: > > Thanks for taking a look! > > On Fri, Aug 21, 2020 at 8:30 PM Andrii Nakryiko > <andrii.nakryiko@gmail.com> wrote: > > > > On Wed, Aug 19, 2020 at 3:42 PM Hao Luo <haoluo@google.com> wrote: > > > > > > Test bpf_per_cpu_ptr(). Test two paths in the kernel. If the base > > > pointer points to a struct, the returned reg is of type PTR_TO_BTF_ID. > > > Direct pointer dereference can be applied on the returned variable. > > > If the base pointer isn't a struct, the returned reg is of type > > > PTR_TO_MEM, which also supports direct pointer dereference. > > > > > > Signed-off-by: Hao Luo <haoluo@google.com> > > > --- > > > > Acked-by: Andrii Nakryiko <andriin@fb.com> > > > [...] > > > > > > __u64 out__runqueues = -1; > > > __u64 out__bpf_prog_active = -1; > > > +__u32 out__rq_cpu = -1; > > > +unsigned long out__process_counts = -1; > > > > try to not use long for variables, it is 32-bit integer in user-space > > but always 64-bit in BPF. This causes problems when using skeleton on > > 32-bit architecture. > > > > Ack. I will use another variable of type 'int' instead. __u64 is fine as well > > > > > > > -extern const struct rq runqueues __ksym; /* struct type global var. */ > > > +extern const struct rq runqueues __ksym; /* struct type percpu var. */ > > > extern const int bpf_prog_active __ksym; /* int type global var. */ > > > +extern const unsigned long process_counts __ksym; /* int type percpu var. */ > > > > > > SEC("raw_tp/sys_enter") > > > int handler(const void *ctx) > > > { > > > + struct rq *rq; > > > + unsigned long *count; > > > + > > > out__runqueues = (__u64)&runqueues; > > > out__bpf_prog_active = (__u64)&bpf_prog_active; > > > > > > + rq = (struct rq *)bpf_per_cpu_ptr(&runqueues, 1); > > > + if (rq) > > > + out__rq_cpu = rq->cpu; > > > > this is awesome! > > > > Are there any per-cpu variables that are arrays? Would be nice to test > > those too. > > > > > > There are currently per-cpu arrays, but not common. There is a > 'pmc_prev_left' in arch/x86, I can add that in this test. arch-specific variables are bad, because selftests will be failing on other architectures; let's not do this then. > > [...]
On Tue, Sep 1, 2020 at 11:12 AM Andrii Nakryiko <andrii.nakryiko@gmail.com> wrote: > > On Thu, Aug 27, 2020 at 8:42 PM Hao Luo <haoluo@google.com> wrote: > > [...] > > > > > > > > -extern const struct rq runqueues __ksym; /* struct type global var. */ > > > > +extern const struct rq runqueues __ksym; /* struct type percpu var. */ > > > > extern const int bpf_prog_active __ksym; /* int type global var. */ > > > > +extern const unsigned long process_counts __ksym; /* int type percpu var. */ > > > > > > > > SEC("raw_tp/sys_enter") > > > > int handler(const void *ctx) > > > > { > > > > + struct rq *rq; > > > > + unsigned long *count; > > > > + > > > > out__runqueues = (__u64)&runqueues; > > > > out__bpf_prog_active = (__u64)&bpf_prog_active; > > > > > > > > + rq = (struct rq *)bpf_per_cpu_ptr(&runqueues, 1); > > > > + if (rq) > > > > + out__rq_cpu = rq->cpu; > > > > > > this is awesome! > > > > > > Are there any per-cpu variables that are arrays? Would be nice to test > > > those too. > > > > > > > > > > There are currently per-cpu arrays, but not common. There is a > > 'pmc_prev_left' in arch/x86, I can add that in this test. > > arch-specific variables are bad, because selftests will be failing on > other architectures; let's not do this then. > Yeah, no problem. Though not going to add this arch-specific variable in the posted patches, I tried array-typed ksyms locally in my test environment. It worked fine, except that the array size is not checked. For instance, if there is a percpu array in kernel as DEFINE_PER_CPU(u32[64], foo); we can declare a ksym of different size and it passes libbpf checks and kernel verification. extern u32 foo[128] __ksyms; It seems that bpf_core_types_are_compat() doesn't check nr_elem. But it seems the kernel verifier does check out-of-bounds accesses, so this may not be a real problem. Just want to list what I saw. > > > > [...]
diff --git a/tools/testing/selftests/bpf/prog_tests/ksyms_btf.c b/tools/testing/selftests/bpf/prog_tests/ksyms_btf.c index 1dad61ba7e99..bdedd4a76b42 100644 --- a/tools/testing/selftests/bpf/prog_tests/ksyms_btf.c +++ b/tools/testing/selftests/bpf/prog_tests/ksyms_btf.c @@ -71,6 +71,10 @@ void test_ksyms_btf(void) "got %llu, exp %llu\n", data->out__runqueues, runqueues_addr); CHECK(data->out__bpf_prog_active != bpf_prog_active_addr, "bpf_prog_active", "got %llu, exp %llu\n", data->out__bpf_prog_active, bpf_prog_active_addr); + CHECK(data->out__rq_cpu != 1, "rq_cpu", + "got %u, exp %u\n", data->out__rq_cpu, 1); + CHECK(data->out__process_counts == -1, "process_counts", + "got %lu, exp != -1", data->out__process_counts); cleanup: test_ksyms_btf__destroy(skel); diff --git a/tools/testing/selftests/bpf/progs/test_ksyms_btf.c b/tools/testing/selftests/bpf/progs/test_ksyms_btf.c index e04e31117f84..78cf1ebb753d 100644 --- a/tools/testing/selftests/bpf/progs/test_ksyms_btf.c +++ b/tools/testing/selftests/bpf/progs/test_ksyms_btf.c @@ -7,16 +7,29 @@ __u64 out__runqueues = -1; __u64 out__bpf_prog_active = -1; +__u32 out__rq_cpu = -1; +unsigned long out__process_counts = -1; -extern const struct rq runqueues __ksym; /* struct type global var. */ +extern const struct rq runqueues __ksym; /* struct type percpu var. */ extern const int bpf_prog_active __ksym; /* int type global var. */ +extern const unsigned long process_counts __ksym; /* int type percpu var. */ SEC("raw_tp/sys_enter") int handler(const void *ctx) { + struct rq *rq; + unsigned long *count; + out__runqueues = (__u64)&runqueues; out__bpf_prog_active = (__u64)&bpf_prog_active; + rq = (struct rq *)bpf_per_cpu_ptr(&runqueues, 1); + if (rq) + out__rq_cpu = rq->cpu; + count = (unsigned long *)bpf_per_cpu_ptr(&process_counts, 1); + if (count) + out__process_counts = *count; + return 0; }
Test bpf_per_cpu_ptr(). Test two paths in the kernel. If the base pointer points to a struct, the returned reg is of type PTR_TO_BTF_ID. Direct pointer dereference can be applied on the returned variable. If the base pointer isn't a struct, the returned reg is of type PTR_TO_MEM, which also supports direct pointer dereference. Signed-off-by: Hao Luo <haoluo@google.com> --- .../testing/selftests/bpf/prog_tests/ksyms_btf.c | 4 ++++ .../testing/selftests/bpf/progs/test_ksyms_btf.c | 15 ++++++++++++++- 2 files changed, 18 insertions(+), 1 deletion(-)