diff mbox series

[PATCHv3,bpf-next,2/2] selftests/bpf: Add uprobe multi consumers test

Message ID 20240722202758.3889061-3-jolsa@kernel.org (mailing list archive)
State Accepted
Commit c5ec71c325e7190bf4981877a89f0c5f79780050
Delegated to: BPF
Headers show
Series selftests/bpf: Add more uprobe multi tests | expand

Checks

Context Check Description
netdev/series_format success Posting correctly formatted
netdev/tree_selection success Clearly marked for bpf-next, async
netdev/ynl success Generated files up to date; no warnings/errors; no diff in generated;
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 661 this patch: 661
netdev/build_tools success Errors and warnings before: 0 this patch: 0
netdev/cc_maintainers warning 8 maintainers not CCed: kpsingh@kernel.org shuah@kernel.org linux-kselftest@vger.kernel.org yonghong.song@linux.dev martin.lau@linux.dev mykolal@fb.com song@kernel.org eddyz87@gmail.com
netdev/build_clang success Errors and warnings before: 663 this patch: 663
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 667 this patch: 667
netdev/checkpatch warning CHECK: Alignment should match open parenthesis WARNING: Missing a blank line after declarations WARNING: Prefer using '"%s...", __func__' to using 'consumer_test', this function's name, in a string WARNING: added, moved or deleted file(s), does MAINTAINERS need updating? WARNING: line length of 86 exceeds 80 columns WARNING: line length of 88 exceeds 80 columns WARNING: line length of 89 exceeds 80 columns WARNING: line length of 94 exceeds 80 columns WARNING: line length of 96 exceeds 80 columns WARNING: line length of 98 exceeds 80 columns
netdev/build_clang_rust success No Rust files in patch. Skipping build
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0
bpf/vmtest-bpf-next-PR success PR summary
bpf/vmtest-bpf-next-VM_Test-11 success Logs for s390x-gcc / build / build for s390x with gcc
bpf/vmtest-bpf-next-VM_Test-17 success Logs for s390x-gcc / veristat
bpf/vmtest-bpf-next-VM_Test-18 success Logs for set-matrix
bpf/vmtest-bpf-next-VM_Test-19 success Logs for x86_64-gcc / build / build for x86_64 with gcc
bpf/vmtest-bpf-next-VM_Test-20 success Logs for x86_64-gcc / build-release
bpf/vmtest-bpf-next-VM_Test-28 success Logs for x86_64-llvm-17 / build / build for x86_64 with llvm-17
bpf/vmtest-bpf-next-VM_Test-34 success Logs for x86_64-llvm-17 / veristat
bpf/vmtest-bpf-next-VM_Test-35 success Logs for x86_64-llvm-18 / build / build for x86_64 with llvm-18
bpf/vmtest-bpf-next-VM_Test-36 success Logs for x86_64-llvm-18 / build-release / build for x86_64 with llvm-18-O2
bpf/vmtest-bpf-next-VM_Test-42 success Logs for x86_64-llvm-18 / veristat
bpf/vmtest-bpf-next-VM_Test-6 success Logs for aarch64-gcc / test (test_maps, false, 360) / test_maps on aarch64 with gcc
bpf/vmtest-bpf-next-VM_Test-7 success Logs for aarch64-gcc / test (test_progs, false, 360) / test_progs on aarch64 with gcc
bpf/vmtest-bpf-next-VM_Test-8 success Logs for aarch64-gcc / test (test_progs_no_alu32, false, 360) / test_progs_no_alu32 on aarch64 with gcc
bpf/vmtest-bpf-next-VM_Test-16 success Logs for s390x-gcc / test (test_verifier, false, 360) / test_verifier on s390x with gcc
bpf/vmtest-bpf-next-VM_Test-21 success Logs for x86_64-gcc / test (test_maps, false, 360) / test_maps on x86_64 with gcc
bpf/vmtest-bpf-next-VM_Test-22 success Logs for x86_64-gcc / test (test_progs, false, 360) / test_progs on x86_64 with gcc
bpf/vmtest-bpf-next-VM_Test-25 success Logs for x86_64-gcc / test (test_progs_parallel, true, 30) / test_progs_parallel on x86_64 with gcc
bpf/vmtest-bpf-next-VM_Test-27 success Logs for x86_64-gcc / veristat / veristat on x86_64 with gcc
bpf/vmtest-bpf-next-VM_Test-26 success Logs for x86_64-gcc / test (test_verifier, false, 360) / test_verifier on x86_64 with gcc
bpf/vmtest-bpf-next-VM_Test-32 success Logs for x86_64-llvm-17 / test (test_progs_no_alu32, false, 360) / test_progs_no_alu32 on x86_64 with llvm-17
bpf/vmtest-bpf-next-VM_Test-33 success Logs for x86_64-llvm-17 / test (test_verifier, false, 360) / test_verifier on x86_64 with llvm-17
bpf/vmtest-bpf-next-VM_Test-38 success Logs for x86_64-llvm-18 / test (test_progs, false, 360) / test_progs on x86_64 with llvm-18
bpf/vmtest-bpf-next-VM_Test-39 success Logs for x86_64-llvm-18 / test (test_progs_cpuv4, false, 360) / test_progs_cpuv4 on x86_64 with llvm-18
bpf/vmtest-bpf-next-VM_Test-40 success Logs for x86_64-llvm-18 / test (test_progs_no_alu32, false, 360) / test_progs_no_alu32 on x86_64 with llvm-18
bpf/vmtest-bpf-next-VM_Test-41 success Logs for x86_64-llvm-18 / test (test_verifier, false, 360) / test_verifier on x86_64 with llvm-18
bpf/vmtest-bpf-next-VM_Test-3 success Logs for Validate matrix.py
bpf/vmtest-bpf-next-VM_Test-1 success Logs for ShellCheck
bpf/vmtest-bpf-next-VM_Test-0 success Logs for Lint
bpf/vmtest-bpf-next-VM_Test-2 success Logs for Unittests
bpf/vmtest-bpf-next-VM_Test-13 success Logs for set-matrix
bpf/vmtest-bpf-next-VM_Test-4 success Logs for aarch64-gcc / build / build for aarch64 with gcc
bpf/vmtest-bpf-next-VM_Test-5 success Logs for aarch64-gcc / build-release
bpf/vmtest-bpf-next-VM_Test-10 success Logs for aarch64-gcc / veristat
bpf/vmtest-bpf-next-VM_Test-24 success Logs for x86_64-llvm-17 / build-release / build for x86_64 with llvm-17-O2
bpf/vmtest-bpf-next-VM_Test-9 success Logs for aarch64-gcc / test (test_verifier, false, 360) / test_verifier on aarch64 with gcc
bpf/vmtest-bpf-next-VM_Test-14 success Logs for x86_64-gcc / build / build for x86_64 with gcc
bpf/vmtest-bpf-next-VM_Test-12 success Logs for s390x-gcc / build-release
bpf/vmtest-bpf-next-VM_Test-29 success Logs for x86_64-llvm-17 / veristat
bpf/vmtest-bpf-next-VM_Test-23 success Logs for x86_64-llvm-17 / build / build for x86_64 with llvm-17
bpf/vmtest-bpf-next-VM_Test-30 success Logs for x86_64-llvm-18 / build / build for x86_64 with llvm-18
bpf/vmtest-bpf-next-VM_Test-15 success Logs for x86_64-gcc / build-release
bpf/vmtest-bpf-next-VM_Test-37 success Logs for x86_64-llvm-18 / veristat
bpf/vmtest-bpf-next-VM_Test-31 success Logs for x86_64-llvm-18 / build-release / build for x86_64 with llvm-18-O2

Commit Message

Jiri Olsa July 22, 2024, 8:27 p.m. UTC 
Adding test that attaches/detaches multiple consumers on
single uprobe and verifies all were hit as expected.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
 .../bpf/prog_tests/uprobe_multi_test.c        | 213 ++++++++++++++++++
 .../bpf/progs/uprobe_multi_consumers.c        |  39 ++++
 2 files changed, 252 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/progs/uprobe_multi_consumers.c

Comments

Andrii Nakryiko July 23, 2024, 8:23 p.m. UTC | #1 
On Mon, Jul 22, 2024 at 1:28 PM Jiri Olsa <jolsa@kernel.org> wrote:
>
> Adding test that attaches/detaches multiple consumers on
> single uprobe and verifies all were hit as expected.
>
> Signed-off-by: Jiri Olsa <jolsa@kernel.org>
> ---
>  .../bpf/prog_tests/uprobe_multi_test.c        | 213 ++++++++++++++++++
>  .../bpf/progs/uprobe_multi_consumers.c        |  39 ++++
>  2 files changed, 252 insertions(+)
>  create mode 100644 tools/testing/selftests/bpf/progs/uprobe_multi_consumers.c
>

[...]

> +               } else {
> +                       /*
> +                        * uprobe return is tricky ;-)
> +                        *
> +                        * to trigger uretprobe consumer, the uretprobe needs to be installed,
> +                        * which means one of the 'return' uprobes was alive when probe was hit:
> +                        *
> +                        *   idxs: 2/3 uprobe return in 'installed' mask
> +                        *
> +                        * in addition if 'after' state removes everything that was installed in
> +                        * 'before' state, then uprobe kernel object goes away and return uprobe
> +                        * is not installed and we won't hit it even if it's in 'after' state.
> +                        */
> +                       unsigned long had_uretprobes  = before & 0b1100; // is uretprobe installed
> +                       unsigned long probe_preserved = before & after;  // did uprobe go away

fixed C++-style comments, pushed to bpf-next


> +
> +                       if (had_uretprobes && probe_preserved && test_bit(idx, after))
> +                               val++;
> +                       fmt = "idx 2/3: uretprobe";
> +               }
> +
> +               ASSERT_EQ(skel->bss->uprobe_result[idx], val, fmt);
> +               skel->bss->uprobe_result[idx] = 0;
> +       }
> +
> +cleanup:
> +       for (idx = 0; idx < 4; idx++)
> +               uprobe_detach(skel, idx);
> +}

[...]
Ihor Solodrai Sept. 24, 2024, 12:33 a.m. UTC | #2 
On Monday, July 22nd, 2024 at 1:27 PM, Jiri Olsa <jolsa@kernel.org> wrote:

> 
> 
> Adding test that attaches/detaches multiple consumers on
> single uprobe and verifies all were hit as expected.
> 
> Signed-off-by: Jiri Olsa jolsa@kernel.org
> 
> ---
> .../bpf/prog_tests/uprobe_multi_test.c | 213 ++++++++++++++++++
> .../bpf/progs/uprobe_multi_consumers.c | 39 ++++
> 2 files changed, 252 insertions(+)
> create mode 100644 tools/testing/selftests/bpf/progs/uprobe_multi_consumers.c
> 
> diff --git a/tools/testing/selftests/bpf/prog_tests/uprobe_multi_test.c b/tools/testing/selftests/bpf/prog_tests/uprobe_multi_test.c
> index e6255d4df81d..27708110ea20 100644
> --- a/tools/testing/selftests/bpf/prog_tests/uprobe_multi_test.c
> +++ b/tools/testing/selftests/bpf/prog_tests/uprobe_multi_test.c
> @@ -6,6 +6,7 @@
> #include "uprobe_multi.skel.h"
> #include "uprobe_multi_bench.skel.h"
> #include "uprobe_multi_usdt.skel.h"
> +#include "uprobe_multi_consumers.skel.h"
> #include "bpf/libbpf_internal.h"
> #include "testing_helpers.h"
> #include "../sdt.h"
> @@ -731,6 +732,216 @@ static void test_link_api(void)
> __test_link_api(child);
> }
> 

[...]

> +
> +static void consumer_test(struct uprobe_multi_consumers skel,
> + unsigned long before, unsigned long after)
> +{
> + int err, idx;
> +
> + printf("consumer_test before %lu after %lu\n", before, after);
> +
> + / 'before' is each, we attach uprobe for every set idx */
> + for (idx = 0; idx < 4; idx++) {
> + if (test_bit(idx, before)) {
> + if (!ASSERT_OK(uprobe_attach(skel, idx), "uprobe_attach_before"))
> + goto cleanup;
> + }
> + }
> +
> + err = uprobe_consumer_test(skel, before, after);
> + if (!ASSERT_EQ(err, 0, "uprobe_consumer_test"))
> + goto cleanup;
> +
> + for (idx = 0; idx < 4; idx++) {
> + const char fmt = "BUG";
> + __u64 val = 0;
> +
> + if (idx < 2) {
> + /
> + * uprobe entry
> + * +1 if define in 'before'
> + /
> + if (test_bit(idx, before))
> + val++;
> + fmt = "prog 0/1: uprobe";
> + } else {
> + /
> + * uprobe return is tricky ;-)
> + *
> + * to trigger uretprobe consumer, the uretprobe needs to be installed,
> + * which means one of the 'return' uprobes was alive when probe was hit:
> + *
> + * idxs: 2/3 uprobe return in 'installed' mask
> + *
> + * in addition if 'after' state removes everything that was installed in
> + * 'before' state, then uprobe kernel object goes away and return uprobe
> + * is not installed and we won't hit it even if it's in 'after' state.
> + */
> + unsigned long had_uretprobes = before & 0b1100; // is uretprobe installed
> + unsigned long probe_preserved = before & after; // did uprobe go away
> +
> + if (had_uretprobes && probe_preserved && test_bit(idx, after))
> + val++;
> + fmt = "idx 2/3: uretprobe";
> + }

Jiri, Andrii,

This test case started failing since upstream got merged into bpf-next,
starting from commit https://git.kernel.org/bpf/bpf-next/c/440b65232829

A snippet from the test log:

    consumer_test before 4 after 8
    uprobe_attach:PASS:bpf_program__attach_uprobe_multi 0 nsec
    consumer_test:PASS:uprobe_attach_before 0 nsec
    uprobe_attach:PASS:bpf_program__attach_uprobe_multi 0 nsec
    uprobe_consumer_test:PASS:uprobe_attach_after 0 nsec
    consumer_test:PASS:uprobe_consumer_test 0 nsec
    consumer_test:PASS:prog 0/1: uprobe 0 nsec
    consumer_test:PASS:prog 0/1: uprobe 0 nsec
    consumer_test:PASS:idx 2/3: uretprobe 0 nsec
    consumer_test:FAIL:idx 2/3: uretprobe unexpected idx 2/3: uretprobe: actual 1 != expected 0
    consumer_test before 4 after 9
    uprobe_attach:PASS:bpf_program__attach_uprobe_multi 0 nsec
    consumer_test:PASS:uprobe_attach_before 0 nsec
    uprobe_attach:PASS:bpf_program__attach_uprobe_multi 0 nsec
    uprobe_consumer_test:PASS:uprobe_attach_after 0 nsec
    uprobe_attach:PASS:bpf_program__attach_uprobe_multi 0 nsec
    uprobe_consumer_test:PASS:uprobe_attach_after 0 nsec
    consumer_test:PASS:uprobe_consumer_test 0 nsec
    consumer_test:PASS:prog 0/1: uprobe 0 nsec
    consumer_test:PASS:prog 0/1: uprobe 0 nsec
    consumer_test:PASS:idx 2/3: uretprobe 0 nsec
    consumer_test:FAIL:idx 2/3: uretprobe unexpected idx 2/3: uretprobe: actual 1 != expected 0
    consumer_test before 4 after 10
    uprobe_attach:PASS:bpf_program__attach_uprobe_multi 0 nsec
    consumer_test:PASS:uprobe_attach_before 0 nsec
    uprobe_attach:PASS:bpf_program__attach_uprobe_multi 0 nsec
    uprobe_consumer_test:PASS:uprobe_attach_after 0 nsec
    uprobe_attach:PASS:bpf_program__attach_uprobe_multi 0 nsec
    uprobe_consumer_test:PASS:uprobe_attach_after 0 nsec
    consumer_test:PASS:uprobe_consumer_test 0 nsec
    consumer_test:PASS:prog 0/1: uprobe 0 nsec
    consumer_test:PASS:prog 0/1: uprobe 0 nsec
    consumer_test:PASS:idx 2/3: uretprobe 0 nsec
    consumer_test:FAIL:idx 2/3: uretprobe unexpected idx 2/3: uretprobe: actual 1 != expected 0


I couldn't figure out the reason as I have very shallow understanding
of what's happening in the test.

Jiri, could you please look into it?

I excluded this test from BPF CI for now.

Thank you!

> +
> + ASSERT_EQ(skel->bss->uprobe_result[idx], val, fmt);
> 
> + skel->bss->uprobe_result[idx] = 0;
> 
> + }
> +
> +cleanup:
> + for (idx = 0; idx < 4; idx++)
> + uprobe_detach(skel, idx);
> +}

[...]
Andrii Nakryiko Sept. 24, 2024, 5:44 a.m. UTC | #3 
On Tue, Sep 24, 2024 at 2:33 AM Ihor Solodrai <ihor.solodrai@pm.me> wrote:
>
> On Monday, July 22nd, 2024 at 1:27 PM, Jiri Olsa <jolsa@kernel.org> wrote:
>
> >
> >
> > Adding test that attaches/detaches multiple consumers on
> > single uprobe and verifies all were hit as expected.
> >
> > Signed-off-by: Jiri Olsa jolsa@kernel.org
> >
> > ---
> > .../bpf/prog_tests/uprobe_multi_test.c | 213 ++++++++++++++++++
> > .../bpf/progs/uprobe_multi_consumers.c | 39 ++++
> > 2 files changed, 252 insertions(+)
> > create mode 100644 tools/testing/selftests/bpf/progs/uprobe_multi_consumers.c
> >
> > diff --git a/tools/testing/selftests/bpf/prog_tests/uprobe_multi_test.c b/tools/testing/selftests/bpf/prog_tests/uprobe_multi_test.c
> > index e6255d4df81d..27708110ea20 100644
> > --- a/tools/testing/selftests/bpf/prog_tests/uprobe_multi_test.c
> > +++ b/tools/testing/selftests/bpf/prog_tests/uprobe_multi_test.c
> > @@ -6,6 +6,7 @@
> > #include "uprobe_multi.skel.h"
> > #include "uprobe_multi_bench.skel.h"
> > #include "uprobe_multi_usdt.skel.h"
> > +#include "uprobe_multi_consumers.skel.h"
> > #include "bpf/libbpf_internal.h"
> > #include "testing_helpers.h"
> > #include "../sdt.h"
> > @@ -731,6 +732,216 @@ static void test_link_api(void)
> > __test_link_api(child);
> > }
> >
>
> [...]
>
> > +
> > +static void consumer_test(struct uprobe_multi_consumers skel,
> > + unsigned long before, unsigned long after)
> > +{
> > + int err, idx;
> > +
> > + printf("consumer_test before %lu after %lu\n", before, after);
> > +
> > + / 'before' is each, we attach uprobe for every set idx */
> > + for (idx = 0; idx < 4; idx++) {
> > + if (test_bit(idx, before)) {
> > + if (!ASSERT_OK(uprobe_attach(skel, idx), "uprobe_attach_before"))
> > + goto cleanup;
> > + }
> > + }
> > +
> > + err = uprobe_consumer_test(skel, before, after);
> > + if (!ASSERT_EQ(err, 0, "uprobe_consumer_test"))
> > + goto cleanup;
> > +
> > + for (idx = 0; idx < 4; idx++) {
> > + const char fmt = "BUG";
> > + __u64 val = 0;
> > +
> > + if (idx < 2) {
> > + /
> > + * uprobe entry
> > + * +1 if define in 'before'
> > + /
> > + if (test_bit(idx, before))
> > + val++;
> > + fmt = "prog 0/1: uprobe";
> > + } else {
> > + /
> > + * uprobe return is tricky ;-)
> > + *
> > + * to trigger uretprobe consumer, the uretprobe needs to be installed,
> > + * which means one of the 'return' uprobes was alive when probe was hit:
> > + *
> > + * idxs: 2/3 uprobe return in 'installed' mask
> > + *
> > + * in addition if 'after' state removes everything that was installed in
> > + * 'before' state, then uprobe kernel object goes away and return uprobe
> > + * is not installed and we won't hit it even if it's in 'after' state.
> > + */
> > + unsigned long had_uretprobes = before & 0b1100; // is uretprobe installed
> > + unsigned long probe_preserved = before & after; // did uprobe go away
> > +
> > + if (had_uretprobes && probe_preserved && test_bit(idx, after))
> > + val++;
> > + fmt = "idx 2/3: uretprobe";
> > + }
>
> Jiri, Andrii,
>
> This test case started failing since upstream got merged into bpf-next,
> starting from commit https://git.kernel.org/bpf/bpf-next/c/440b65232829
>
> A snippet from the test log:
>
>     consumer_test before 4 after 8
>     uprobe_attach:PASS:bpf_program__attach_uprobe_multi 0 nsec
>     consumer_test:PASS:uprobe_attach_before 0 nsec
>     uprobe_attach:PASS:bpf_program__attach_uprobe_multi 0 nsec
>     uprobe_consumer_test:PASS:uprobe_attach_after 0 nsec
>     consumer_test:PASS:uprobe_consumer_test 0 nsec
>     consumer_test:PASS:prog 0/1: uprobe 0 nsec
>     consumer_test:PASS:prog 0/1: uprobe 0 nsec
>     consumer_test:PASS:idx 2/3: uretprobe 0 nsec
>     consumer_test:FAIL:idx 2/3: uretprobe unexpected idx 2/3: uretprobe: actual 1 != expected 0
>     consumer_test before 4 after 9
>     uprobe_attach:PASS:bpf_program__attach_uprobe_multi 0 nsec
>     consumer_test:PASS:uprobe_attach_before 0 nsec
>     uprobe_attach:PASS:bpf_program__attach_uprobe_multi 0 nsec
>     uprobe_consumer_test:PASS:uprobe_attach_after 0 nsec
>     uprobe_attach:PASS:bpf_program__attach_uprobe_multi 0 nsec
>     uprobe_consumer_test:PASS:uprobe_attach_after 0 nsec
>     consumer_test:PASS:uprobe_consumer_test 0 nsec
>     consumer_test:PASS:prog 0/1: uprobe 0 nsec
>     consumer_test:PASS:prog 0/1: uprobe 0 nsec
>     consumer_test:PASS:idx 2/3: uretprobe 0 nsec
>     consumer_test:FAIL:idx 2/3: uretprobe unexpected idx 2/3: uretprobe: actual 1 != expected 0
>     consumer_test before 4 after 10
>     uprobe_attach:PASS:bpf_program__attach_uprobe_multi 0 nsec
>     consumer_test:PASS:uprobe_attach_before 0 nsec
>     uprobe_attach:PASS:bpf_program__attach_uprobe_multi 0 nsec
>     uprobe_consumer_test:PASS:uprobe_attach_after 0 nsec
>     uprobe_attach:PASS:bpf_program__attach_uprobe_multi 0 nsec
>     uprobe_consumer_test:PASS:uprobe_attach_after 0 nsec
>     consumer_test:PASS:uprobe_consumer_test 0 nsec
>     consumer_test:PASS:prog 0/1: uprobe 0 nsec
>     consumer_test:PASS:prog 0/1: uprobe 0 nsec
>     consumer_test:PASS:idx 2/3: uretprobe 0 nsec
>     consumer_test:FAIL:idx 2/3: uretprobe unexpected idx 2/3: uretprobe: actual 1 != expected 0
>
>
> I couldn't figure out the reason as I have very shallow understanding
> of what's happening in the test.
>
> Jiri, could you please look into it?
>
> I excluded this test from BPF CI for now.

Thanks for the mitigation! I think this is due to my recent RCU and
refcounting changes to uprobes/uretprobes, which went through
tip/perf/core initially. And now that tip and bpf-next trees
converged, this condition:

  > unsigned long probe_preserved = before & after; // did uprobe go away

is no longer correct, and uretprobe can be activated if there was
*any* uretprobe installed before.

So the test needs adjustment, but I don't think anything really broke.
I don't remember exactly (and given the conferencing schedule and
quite bad internet can't test quickly), but I think the condition
should now be:

unsigned long probe_preserved = after & 0x1100;

(though we might want to also rename the variable to be a bit more
meaningful now).

Anyways, I don't think this is critical and we can address this later.
But if anyone is willing to send a fix, I'd appreciate it, of course!

>
> Thank you!
>
> > +
> > + ASSERT_EQ(skel->bss->uprobe_result[idx], val, fmt);
> >
> > + skel->bss->uprobe_result[idx] = 0;
> >
> > + }
> > +
> > +cleanup:
> > + for (idx = 0; idx < 4; idx++)
> > + uprobe_detach(skel, idx);
> > +}
>
> [...]
>
Jiri Olsa Sept. 24, 2024, 11:13 a.m. UTC | #4 
On Tue, Sep 24, 2024 at 07:44:50AM +0200, Andrii Nakryiko wrote:

SNIP

> > > + /
> > > + * uprobe return is tricky ;-)
> > > + *
> > > + * to trigger uretprobe consumer, the uretprobe needs to be installed,
> > > + * which means one of the 'return' uprobes was alive when probe was hit:
> > > + *
> > > + * idxs: 2/3 uprobe return in 'installed' mask
> > > + *
> > > + * in addition if 'after' state removes everything that was installed in
> > > + * 'before' state, then uprobe kernel object goes away and return uprobe
> > > + * is not installed and we won't hit it even if it's in 'after' state.
> > > + */
> > > + unsigned long had_uretprobes = before & 0b1100; // is uretprobe installed
> > > + unsigned long probe_preserved = before & after; // did uprobe go away
> > > +
> > > + if (had_uretprobes && probe_preserved && test_bit(idx, after))
> > > + val++;
> > > + fmt = "idx 2/3: uretprobe";
> > > + }
> >
> > Jiri, Andrii,
> >
> > This test case started failing since upstream got merged into bpf-next,
> > starting from commit https://git.kernel.org/bpf/bpf-next/c/440b65232829

thanks for the report

SNIP

> 
> Thanks for the mitigation! I think this is due to my recent RCU and
> refcounting changes to uprobes/uretprobes, which went through
> tip/perf/core initially. And now that tip and bpf-next trees
> converged, this condition:
> 
>   > unsigned long probe_preserved = before & after; // did uprobe go away
> 
> is no longer correct, and uretprobe can be activated if there was
> *any* uretprobe installed before.
> 
> So the test needs adjustment, but I don't think anything really broke.
> I don't remember exactly (and given the conferencing schedule and
> quite bad internet can't test quickly), but I think the condition
> should now be:
> 
> unsigned long probe_preserved = after & 0x1100;
> 
> (though we might want to also rename the variable to be a bit more
> meaningful now).
> 
> Anyways, I don't think this is critical and we can address this later.
> But if anyone is willing to send a fix, I'd appreciate it, of course!

I think we can remove that check completely.. I sent the patch, let's discuss there ;-)

thanks,
jirka
diff mbox series

Patch

diff --git a/tools/testing/selftests/bpf/prog_tests/uprobe_multi_test.c b/tools/testing/selftests/bpf/prog_tests/uprobe_multi_test.c
index e6255d4df81d..27708110ea20 100644
--- a/tools/testing/selftests/bpf/prog_tests/uprobe_multi_test.c
+++ b/tools/testing/selftests/bpf/prog_tests/uprobe_multi_test.c
@@ -6,6 +6,7 @@ 
 #include "uprobe_multi.skel.h"
 #include "uprobe_multi_bench.skel.h"
 #include "uprobe_multi_usdt.skel.h"
+#include "uprobe_multi_consumers.skel.h"
 #include "bpf/libbpf_internal.h"
 #include "testing_helpers.h"
 #include "../sdt.h"
@@ -731,6 +732,216 @@  static void test_link_api(void)
 	__test_link_api(child);
 }
 
+static struct bpf_program *
+get_program(struct uprobe_multi_consumers *skel, int prog)
+{
+	switch (prog) {
+	case 0:
+		return skel->progs.uprobe_0;
+	case 1:
+		return skel->progs.uprobe_1;
+	case 2:
+		return skel->progs.uprobe_2;
+	case 3:
+		return skel->progs.uprobe_3;
+	default:
+		ASSERT_FAIL("get_program");
+		return NULL;
+	}
+}
+
+static struct bpf_link **
+get_link(struct uprobe_multi_consumers *skel, int link)
+{
+	switch (link) {
+	case 0:
+		return &skel->links.uprobe_0;
+	case 1:
+		return &skel->links.uprobe_1;
+	case 2:
+		return &skel->links.uprobe_2;
+	case 3:
+		return &skel->links.uprobe_3;
+	default:
+		ASSERT_FAIL("get_link");
+		return NULL;
+	}
+}
+
+static int uprobe_attach(struct uprobe_multi_consumers *skel, int idx)
+{
+	struct bpf_program *prog = get_program(skel, idx);
+	struct bpf_link **link = get_link(skel, idx);
+	LIBBPF_OPTS(bpf_uprobe_multi_opts, opts);
+
+	if (!prog || !link)
+		return -1;
+
+	/*
+	 * bit/prog: 0,1 uprobe entry
+	 * bit/prog: 2,3 uprobe return
+	 */
+	opts.retprobe = idx == 2 || idx == 3;
+
+	*link = bpf_program__attach_uprobe_multi(prog, 0, "/proc/self/exe",
+						"uprobe_consumer_test",
+						&opts);
+	if (!ASSERT_OK_PTR(*link, "bpf_program__attach_uprobe_multi"))
+		return -1;
+	return 0;
+}
+
+static void uprobe_detach(struct uprobe_multi_consumers *skel, int idx)
+{
+	struct bpf_link **link = get_link(skel, idx);
+
+	bpf_link__destroy(*link);
+	*link = NULL;
+}
+
+static bool test_bit(int bit, unsigned long val)
+{
+	return val & (1 << bit);
+}
+
+noinline int
+uprobe_consumer_test(struct uprobe_multi_consumers *skel,
+		     unsigned long before, unsigned long after)
+{
+	int idx;
+
+	/* detach uprobe for each unset programs in 'before' state ... */
+	for (idx = 0; idx < 4; idx++) {
+		if (test_bit(idx, before) && !test_bit(idx, after))
+			uprobe_detach(skel, idx);
+	}
+
+	/* ... and attach all new programs in 'after' state */
+	for (idx = 0; idx < 4; idx++) {
+		if (!test_bit(idx, before) && test_bit(idx, after)) {
+			if (!ASSERT_OK(uprobe_attach(skel, idx), "uprobe_attach_after"))
+				return -1;
+		}
+	}
+	return 0;
+}
+
+static void consumer_test(struct uprobe_multi_consumers *skel,
+			  unsigned long before, unsigned long after)
+{
+	int err, idx;
+
+	printf("consumer_test before %lu after %lu\n", before, after);
+
+	/* 'before' is each, we attach uprobe for every set idx */
+	for (idx = 0; idx < 4; idx++) {
+		if (test_bit(idx, before)) {
+			if (!ASSERT_OK(uprobe_attach(skel, idx), "uprobe_attach_before"))
+				goto cleanup;
+		}
+	}
+
+	err = uprobe_consumer_test(skel, before, after);
+	if (!ASSERT_EQ(err, 0, "uprobe_consumer_test"))
+		goto cleanup;
+
+	for (idx = 0; idx < 4; idx++) {
+		const char *fmt = "BUG";
+		__u64 val = 0;
+
+		if (idx < 2) {
+			/*
+			 * uprobe entry
+			 *   +1 if define in 'before'
+			 */
+			if (test_bit(idx, before))
+				val++;
+			fmt = "prog 0/1: uprobe";
+		} else {
+			/*
+			 * uprobe return is tricky ;-)
+			 *
+			 * to trigger uretprobe consumer, the uretprobe needs to be installed,
+			 * which means one of the 'return' uprobes was alive when probe was hit:
+			 *
+			 *   idxs: 2/3 uprobe return in 'installed' mask
+			 *
+			 * in addition if 'after' state removes everything that was installed in
+			 * 'before' state, then uprobe kernel object goes away and return uprobe
+			 * is not installed and we won't hit it even if it's in 'after' state.
+			 */
+			unsigned long had_uretprobes  = before & 0b1100; // is uretprobe installed
+			unsigned long probe_preserved = before & after;  // did uprobe go away
+
+			if (had_uretprobes && probe_preserved && test_bit(idx, after))
+				val++;
+			fmt = "idx 2/3: uretprobe";
+		}
+
+		ASSERT_EQ(skel->bss->uprobe_result[idx], val, fmt);
+		skel->bss->uprobe_result[idx] = 0;
+	}
+
+cleanup:
+	for (idx = 0; idx < 4; idx++)
+		uprobe_detach(skel, idx);
+}
+
+static void test_consumers(void)
+{
+	struct uprobe_multi_consumers *skel;
+	int before, after;
+
+	skel = uprobe_multi_consumers__open_and_load();
+	if (!ASSERT_OK_PTR(skel, "uprobe_multi_consumers__open_and_load"))
+		return;
+
+	/*
+	 * The idea of this test is to try all possible combinations of
+	 * uprobes consumers attached on single function.
+	 *
+	 *  - 2 uprobe entry consumer
+	 *  - 2 uprobe exit consumers
+	 *
+	 * The test uses 4 uprobes attached on single function, but that
+	 * translates into single uprobe with 4 consumers in kernel.
+	 *
+	 * The before/after values present the state of attached consumers
+	 * before and after the probed function:
+	 *
+	 *  bit/prog 0,1 : uprobe entry
+	 *  bit/prog 2,3 : uprobe return
+	 *
+	 * For example for:
+	 *
+	 *   before = 0b0101
+	 *   after  = 0b0110
+	 *
+	 * it means that before we call 'uprobe_consumer_test' we attach
+	 * uprobes defined in 'before' value:
+	 *
+	 *   - bit/prog 0: uprobe entry
+	 *   - bit/prog 2: uprobe return
+	 *
+	 * uprobe_consumer_test is called and inside it we attach and detach
+	 * uprobes based on 'after' value:
+	 *
+	 *   - bit/prog 0: stays untouched
+	 *   - bit/prog 2: uprobe return is detached
+	 *
+	 * uprobe_consumer_test returns and we check counters values increased
+	 * by bpf programs on each uprobe to match the expected count based on
+	 * before/after bits.
+	 */
+
+	for (before = 0; before < 16; before++) {
+		for (after = 0; after < 16; after++)
+			consumer_test(skel, before, after);
+	}
+
+	uprobe_multi_consumers__destroy(skel);
+}
+
 static void test_bench_attach_uprobe(void)
 {
 	long attach_start_ns = 0, attach_end_ns = 0;
@@ -821,4 +1032,6 @@  void test_uprobe_multi_test(void)
 		test_attach_api_fails();
 	if (test__start_subtest("attach_uprobe_fails"))
 		test_attach_uprobe_fails();
+	if (test__start_subtest("consumers"))
+		test_consumers();
 }
diff --git a/tools/testing/selftests/bpf/progs/uprobe_multi_consumers.c b/tools/testing/selftests/bpf/progs/uprobe_multi_consumers.c
new file mode 100644
index 000000000000..7e0fdcbbd242
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/uprobe_multi_consumers.c
@@ -0,0 +1,39 @@ 
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+#include <stdbool.h>
+#include "bpf_kfuncs.h"
+#include "bpf_misc.h"
+
+char _license[] SEC("license") = "GPL";
+
+__u64 uprobe_result[4];
+
+SEC("uprobe.multi")
+int uprobe_0(struct pt_regs *ctx)
+{
+	uprobe_result[0]++;
+	return 0;
+}
+
+SEC("uprobe.multi")
+int uprobe_1(struct pt_regs *ctx)
+{
+	uprobe_result[1]++;
+	return 0;
+}
+
+SEC("uprobe.multi")
+int uprobe_2(struct pt_regs *ctx)
+{
+	uprobe_result[2]++;
+	return 0;
+}
+
+SEC("uprobe.multi")
+int uprobe_3(struct pt_regs *ctx)
+{
+	uprobe_result[3]++;
+	return 0;
+}