On Wed, Aug 16, 2023 at 09:58:13AM -0700, Dave Marchevsky wrote: > This patch adds selftests that exercise kfunc flavor relocation > functionality added in the previous patch. The actual kfunc defined in > kernel/bpf/helpers.c is > > struct task_struct *bpf_task_acquire(struct task_struct *p) > > The following relocation behaviors are checked: > > struct task_struct *bpf_task_acquire___one(struct task_struct *name) > * Should succeed despite differing param name > > struct task_struct *bpf_task_acquire___two(struct task_struct *p, void *ctx) > * Should fail because there is no two-param bpf_task_acquire > > struct task_struct *bpf_task_acquire___three(void *ctx) > * Should fail because, despite vmlinux's bpf_task_acquire having one param, > the types don't match > > Changelog: > v1 -> v2: https://lore.kernel.org/bpf/20230811201346.3240403-2-davemarchevsky@xxxxxx/ > * Change comment on bpf_task_acquire___two to more accurately reflect > that it fails in same codepath as bpf_task_acquire___three, and to > not mention dead code elimination as thats an implementation detail > (Yonghong) > > Signed-off-by: Dave Marchevsky <davemarchevsky@xxxxxx> > --- > .../selftests/bpf/prog_tests/task_kfunc.c | 1 + > .../selftests/bpf/progs/task_kfunc_success.c | 37 +++++++++++++++++++ > 2 files changed, 38 insertions(+) > > diff --git a/tools/testing/selftests/bpf/prog_tests/task_kfunc.c b/tools/testing/selftests/bpf/prog_tests/task_kfunc.c > index 740d5f644b40..99abb0350154 100644 > --- a/tools/testing/selftests/bpf/prog_tests/task_kfunc.c > +++ b/tools/testing/selftests/bpf/prog_tests/task_kfunc.c > @@ -79,6 +79,7 @@ static const char * const success_tests[] = { > "test_task_from_pid_current", > "test_task_from_pid_invalid", > "task_kfunc_acquire_trusted_walked", > + "test_task_kfunc_flavor_relo", > }; > > void test_task_kfunc(void) > diff --git a/tools/testing/selftests/bpf/progs/task_kfunc_success.c b/tools/testing/selftests/bpf/progs/task_kfunc_success.c > index b09371bba204..ffbe3ff72639 100644 > --- a/tools/testing/selftests/bpf/progs/task_kfunc_success.c > +++ b/tools/testing/selftests/bpf/progs/task_kfunc_success.c Do you think it's worth it to also add a failure case for if there's no correct bpf_taks_acquire___one(), to verify e.g. that we can't resolve bpf_task_acquire___three(void *ctx) __ksym __weak? > @@ -18,6 +18,13 @@ int err, pid; > */ > > struct task_struct *bpf_task_acquire(struct task_struct *p) __ksym __weak; > + > +struct task_struct *bpf_task_acquire___one(struct task_struct *task) __ksym __weak; > +/* The two-param bpf_task_acquire doesn't exist */ > +struct task_struct *bpf_task_acquire___two(struct task_struct *p, void *ctx) __ksym __weak; > +/* Incorrect type for first param */ > +struct task_struct *bpf_task_acquire___three(void *ctx) __ksym __weak; > + > void invalid_kfunc(void) __ksym __weak; > void bpf_testmod_test_mod_kfunc(int i) __ksym __weak; > > @@ -55,6 +62,36 @@ static int test_acquire_release(struct task_struct *task) > return 0; > } > > +SEC("tp_btf/task_newtask") > +int BPF_PROG(test_task_kfunc_flavor_relo, struct task_struct *task, u64 clone_flags) > +{ > + struct task_struct *acquired = NULL; > + int fake_ctx = 42; > + > + if (bpf_ksym_exists(bpf_task_acquire___one)) { > + acquired = bpf_task_acquire___one(task); > + } else if (bpf_ksym_exists(bpf_task_acquire___two)) { > + /* Here, bpf_object__resolve_ksym_func_btf_id's find_ksym_btf_id > + * call will find vmlinux's bpf_task_acquire, but subsequent > + * bpf_core_types_are_compat will fail > + */ > + acquired = bpf_task_acquire___two(task, &fake_ctx); > + err = 3; > + return 0; > + } else if (bpf_ksym_exists(bpf_task_acquire___three)) { > + /* bpf_core_types_are_compat will fail similarly to above case */ > + acquired = bpf_task_acquire___three(&fake_ctx); > + err = 4; > + return 0; > + } > + > + if (acquired) > + bpf_task_release(acquired); Might be slightly simpler to do the release + return immediately in the bpf_task_acquire___one branch, and then to just do the following here without the if / else: err = 5; return 0; What do you think? > + else > + err = 5; > + return 0; > +} > + > SEC("tp_btf/task_newtask") > int BPF_PROG(test_task_acquire_release_argument, struct task_struct *task, u64 clone_flags) > { > -- > 2.34.1 > >
