Add two __failure tests covering the callback return-size checks: - timer_ret_pair_fail: a bpf_timer callback declared to return more than 8 bytes, rejected by check_ld_imm() where the callback's PTR_TO_FUNC is created, with "callback function with >8-byte return value is not supported". - exceptions_ret_pair_fail: an exception callback declared to return more than 8 bytes, rejected by do_check_common() when the callback subprogram is verified, with "exception cb cannot return value larger than 8 bytes". Both callback bodies are written in inline asm so that the tests do not depend on LLVM 23 R0:R2 codegen and run on any compiler. The verifier reads the return type from BTF rather than from the instructions, so the >8 byte return prototype is supplied through __btf_func_path(), pointing at a companion btf__*.c program that exists only to carry that BTF. Signed-off-by: Yonghong Song --- .../selftests/bpf/prog_tests/exceptions.c | 2 + .../testing/selftests/bpf/prog_tests/timer.c | 2 + .../bpf/progs/btf__exceptions_ret_pair_fail.c | 10 ++++ .../bpf/progs/btf__timer_ret_pair_fail.c | 10 ++++ .../bpf/progs/exceptions_ret_pair_fail.c | 30 ++++++++++++ .../selftests/bpf/progs/timer_ret_pair_fail.c | 49 +++++++++++++++++++ 6 files changed, 103 insertions(+) create mode 100644 tools/testing/selftests/bpf/progs/btf__exceptions_ret_pair_fail.c create mode 100644 tools/testing/selftests/bpf/progs/btf__timer_ret_pair_fail.c create mode 100644 tools/testing/selftests/bpf/progs/exceptions_ret_pair_fail.c create mode 100644 tools/testing/selftests/bpf/progs/timer_ret_pair_fail.c diff --git a/tools/testing/selftests/bpf/prog_tests/exceptions.c b/tools/testing/selftests/bpf/prog_tests/exceptions.c index 3588d6f97fd4..71d00c568d80 100644 --- a/tools/testing/selftests/bpf/prog_tests/exceptions.c +++ b/tools/testing/selftests/bpf/prog_tests/exceptions.c @@ -5,6 +5,7 @@ #include "exceptions.skel.h" #include "exceptions_ext.skel.h" #include "exceptions_fail.skel.h" +#include "exceptions_ret_pair_fail.skel.h" #include "exceptions_assert.skel.h" static char log_buf[1024 * 1024]; @@ -12,6 +13,7 @@ static char log_buf[1024 * 1024]; static void test_exceptions_failure(void) { RUN_TESTS(exceptions_fail); + RUN_TESTS(exceptions_ret_pair_fail); } static void test_exceptions_success(void) diff --git a/tools/testing/selftests/bpf/prog_tests/timer.c b/tools/testing/selftests/bpf/prog_tests/timer.c index 09ff21e1ad2f..593e56d8964e 100644 --- a/tools/testing/selftests/bpf/prog_tests/timer.c +++ b/tools/testing/selftests/bpf/prog_tests/timer.c @@ -6,6 +6,7 @@ #include #include "timer.skel.h" #include "timer_failure.skel.h" +#include "timer_ret_pair_fail.skel.h" #include "timer_interrupt.skel.h" #define NUM_THR 8 @@ -285,6 +286,7 @@ void serial_test_timer(void) test_timer(timer); RUN_TESTS(timer_failure); + RUN_TESTS(timer_ret_pair_fail); } void serial_test_timer_stress(void) diff --git a/tools/testing/selftests/bpf/progs/btf__exceptions_ret_pair_fail.c b/tools/testing/selftests/bpf/progs/btf__exceptions_ret_pair_fail.c new file mode 100644 index 000000000000..a45db5d9c1d4 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/btf__exceptions_ret_pair_fail.c @@ -0,0 +1,10 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2026 Meta Platforms, Inc. and affiliates. */ +#include +#include + +unsigned __int128 exception_cb_bad_ret_type3(u64 cookie) +{ + for (;;) + ; +} diff --git a/tools/testing/selftests/bpf/progs/btf__timer_ret_pair_fail.c b/tools/testing/selftests/bpf/progs/btf__timer_ret_pair_fail.c new file mode 100644 index 000000000000..35506c7c5a91 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/btf__timer_ret_pair_fail.c @@ -0,0 +1,10 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2026 Meta Platforms, Inc. and affiliates. */ +#include +#include + +unsigned __int128 timer_cb_ret_pair(void *map, int *key, struct bpf_timer *timer) +{ + for (;;) + ; +} diff --git a/tools/testing/selftests/bpf/progs/exceptions_ret_pair_fail.c b/tools/testing/selftests/bpf/progs/exceptions_ret_pair_fail.c new file mode 100644 index 000000000000..842f86ad8659 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/exceptions_ret_pair_fail.c @@ -0,0 +1,30 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2026 Meta Platforms, Inc. and affiliates. */ +#include +#include +#include + +#include "bpf_misc.h" +#include "bpf_experimental.h" + +__naked __noinline __used +unsigned __int128 exception_cb_bad_ret_type3(u64 cookie) +{ + asm volatile ( + "r0 = r1;" + "r2 = 0;" + "exit;" + ::: __clobber_all); +} + +SEC("?tc") +__exception_cb(exception_cb_bad_ret_type3) +__failure __msg("exception cb cannot return value larger than 8 bytes") +__btf_func_path("btf__exceptions_ret_pair_fail.bpf.o") +int reject_exception_cb_ret_pair(void *ctx) +{ + bpf_throw(0); + return 0; +} + +char _license[] SEC("license") = "GPL"; diff --git a/tools/testing/selftests/bpf/progs/timer_ret_pair_fail.c b/tools/testing/selftests/bpf/progs/timer_ret_pair_fail.c new file mode 100644 index 000000000000..29fd294dfd49 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/timer_ret_pair_fail.c @@ -0,0 +1,49 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2026 Meta Platforms, Inc. and affiliates. */ + +#include +#include +#include +#include +#include "bpf_misc.h" + +char _license[] SEC("license") = "GPL"; + +struct elem { + struct bpf_timer t; +}; + +struct { + __uint(type, BPF_MAP_TYPE_ARRAY); + __uint(max_entries, 1); + __type(key, int); + __type(value, struct elem); +} timer_map SEC(".maps"); + +__naked __noinline __used +static unsigned __int128 timer_cb_ret_pair(void *map, int *key, struct bpf_timer *timer) +{ + asm volatile ( + "r0 = 0;" + "r2 = 0;" + "exit;" + ::: __clobber_all + ); +} + +SEC("fentry/bpf_fentry_test1") +__failure __msg("callback function with >8-byte return value is not supported") +__btf_func_path("btf__timer_ret_pair_fail.bpf.o") +long BPF_PROG2(test_bad_ret_pair, int, a) +{ + int key = 0; + struct bpf_timer *timer; + + timer = bpf_map_lookup_elem(&timer_map, &key); + if (timer) { + bpf_timer_init(timer, &timer_map, CLOCK_BOOTTIME); + bpf_timer_set_callback(timer, timer_cb_ret_pair); + } + + return 0; +} -- 2.53.0-Meta