On Fri, Oct 8, 2021 at 3:27 PM Andrii Nakryiko
<andrii.nakryiko@xxxxxxxxx> wrote:
>
> On Wed, Oct 6, 2021 at 11:56 AM Yucong Sun <fallentree@xxxxxx> wrote:
> >
> > From: Yucong Sun <sunyucong@xxxxxxxxx>
> >
> > Using same address on different processes of the same binary often fail
> > with EINVAL, this patch make these tests use distinct methods, so they
> > can run in parallel.
> >
> > Signed-off-by: Yucong Sun <sunyucong@xxxxxxxxx>
> > ---
> > tools/testing/selftests/bpf/prog_tests/attach_probe.c | 8 ++++++--
> > tools/testing/selftests/bpf/prog_tests/bpf_cookie.c | 8 ++++++--
> > tools/testing/selftests/bpf/prog_tests/task_pt_regs.c | 8 ++++++--
> > 3 files changed, 18 insertions(+), 6 deletions(-)
> >
> > diff --git a/tools/testing/selftests/bpf/prog_tests/attach_probe.c b/tools/testing/selftests/bpf/prog_tests/attach_probe.c
> > index 6c511dcd1465..eff36ba9c148 100644
> > --- a/tools/testing/selftests/bpf/prog_tests/attach_probe.c
> > +++ b/tools/testing/selftests/bpf/prog_tests/attach_probe.c
> > @@ -5,6 +5,10 @@
> > /* this is how USDT semaphore is actually defined, except volatile modifier */
> > volatile unsigned short uprobe_ref_ctr __attribute__((unused)) __attribute((section(".probes")));
> >
> > +static int method() {
>
> wrong style: { should be on separate line
>
> > + return get_base_addr();
>
> there is nothing special about get_base_addr(), except that it's a
> global function in a different file and won't be inlined, while this
> method() approach has no such guarantee
>
> I've dropped this patch for now.
>
> But I'm surprised that attaching to the same uprobe few times doesn't
> work. Song, is there anything in kernel that could cause this?
libbpf: uprobe perf_event_open() failed: Invalid argument
libbpf: prog 'handle_uprobe': failed to create uprobe
'/proc/self/exe:0x144d59' perf event: Invalid argument
uprobe_subtest:FAIL:link1 unexpected error: -22
The problem only happens when several different processes of the same
binary are trying to attach uprobe on the same function. I am guessing
it is due to address space randomization ?
I traced through the code and the EINVAL is returned right after this warning
[ 1.375901] ref_ctr_offset mismatch. inode: 0x55a0 offset: 0x144d59
ref_ctr_offset(old): 0x554a00 ref_ctr_offset(new): 0x0
This could be easily be reproduced by ./test_progs -t
attach_probe,bpf_cookie,test_pt_regs -j
>
>
> > +}
> > +
> > void test_attach_probe(void)
> > {
> > DECLARE_LIBBPF_OPTS(bpf_uprobe_opts, uprobe_opts);
> > @@ -33,7 +37,7 @@ void test_attach_probe(void)
> > if (CHECK(base_addr < 0, "get_base_addr",
> > "failed to find base addr: %zd", base_addr))
> > return;
> > - uprobe_offset = get_uprobe_offset(&get_base_addr, base_addr);
> > + uprobe_offset = get_uprobe_offset(&method, base_addr);
> >
> > ref_ctr_offset = get_rel_offset((uintptr_t)&uprobe_ref_ctr);
> > if (!ASSERT_GE(ref_ctr_offset, 0, "ref_ctr_offset"))
> > @@ -98,7 +102,7 @@ void test_attach_probe(void)
> > goto cleanup;
> >
> > /* trigger & validate uprobe & uretprobe */
> > - get_base_addr();
> > + method();
> >
> > if (CHECK(skel->bss->uprobe_res != 3, "check_uprobe_res",
> > "wrong uprobe res: %d\n", skel->bss->uprobe_res))
> > diff --git a/tools/testing/selftests/bpf/prog_tests/bpf_cookie.c b/tools/testing/selftests/bpf/prog_tests/bpf_cookie.c
> > index 19c9f7b53cfa..5ebd8ba988e2 100644
> > --- a/tools/testing/selftests/bpf/prog_tests/bpf_cookie.c
> > +++ b/tools/testing/selftests/bpf/prog_tests/bpf_cookie.c
> > @@ -8,6 +8,10 @@
> > #include <test_progs.h>
> > #include "test_bpf_cookie.skel.h"
> >
> > +static int method() {
> > + return get_base_addr();
> > +}
> > +
> > static void kprobe_subtest(struct test_bpf_cookie *skel)
> > {
> > DECLARE_LIBBPF_OPTS(bpf_kprobe_opts, opts);
> > @@ -66,7 +70,7 @@ static void uprobe_subtest(struct test_bpf_cookie *skel)
> > ssize_t base_addr;
> >
> > base_addr = get_base_addr();
> > - uprobe_offset = get_uprobe_offset(&get_base_addr, base_addr);
> > + uprobe_offset = get_uprobe_offset(&method, base_addr);
> >
> > /* attach two uprobes */
> > opts.bpf_cookie = 0x100;
> > @@ -99,7 +103,7 @@ static void uprobe_subtest(struct test_bpf_cookie *skel)
> > goto cleanup;
> >
> > /* trigger uprobe && uretprobe */
> > - get_base_addr();
> > + method();
> >
> > ASSERT_EQ(skel->bss->uprobe_res, 0x100 | 0x200, "uprobe_res");
> > ASSERT_EQ(skel->bss->uretprobe_res, 0x1000 | 0x2000, "uretprobe_res");
> > diff --git a/tools/testing/selftests/bpf/prog_tests/task_pt_regs.c b/tools/testing/selftests/bpf/prog_tests/task_pt_regs.c
> > index 37c20b5ffa70..4d2f1435be90 100644
> > --- a/tools/testing/selftests/bpf/prog_tests/task_pt_regs.c
> > +++ b/tools/testing/selftests/bpf/prog_tests/task_pt_regs.c
> > @@ -3,6 +3,10 @@
> > #include <test_progs.h>
> > #include "test_task_pt_regs.skel.h"
> >
> > +static int method() {
> > + return get_base_addr();
> > +}
> > +
> > void test_task_pt_regs(void)
> > {
> > struct test_task_pt_regs *skel;
> > @@ -14,7 +18,7 @@ void test_task_pt_regs(void)
> > base_addr = get_base_addr();
> > if (!ASSERT_GT(base_addr, 0, "get_base_addr"))
> > return;
> > - uprobe_offset = get_uprobe_offset(&get_base_addr, base_addr);
> > + uprobe_offset = get_uprobe_offset(&method, base_addr);
> >
> > skel = test_task_pt_regs__open_and_load();
> > if (!ASSERT_OK_PTR(skel, "skel_open"))
> > @@ -32,7 +36,7 @@ void test_task_pt_regs(void)
> > skel->links.handle_uprobe = uprobe_link;
> >
> > /* trigger & validate uprobe */
> > - get_base_addr();
> > + method();
> >
> > if (!ASSERT_EQ(skel->bss->uprobe_res, 1, "check_uprobe_res"))
> > goto cleanup;
> > --
> > 2.30.2
> >
