| Age | Commit message (Collapse) | Author |
|---|
|
bpf_check_attach_target() rejects a freplace whose target is a static
function, using the subprog "unreliable" flag as a proxy for "static".
That flag is raised whenever a subprogram's BTF prototype disagrees with
the registers at its call site.
`147400e9c27c ("bpf: Compute parameters liveness in
bpf_compute_live_registers()")` made that work for static callees: a
static function with an unused argument no longer matches its BTF
prototype at the call site and is marked unreliable.
Since LLVM commit `29b36a16f111 ("[BPF] Emit ABI-accurate BTF
prototypes for DW_CC_nocall")` in 23.1 [1] that premise is gone:
BTFDebug may now drop arguments removed by the optimizer, so for
__noinline static int subprog(struct __sk_buff *ctx)
{
return bpf_ktime_get_ns();
}
compiled with clang 23 the BTF describes subprog() as
[75] FUNC_PROTO '(anon)' ret_type_id=2 vlen=0
[76] FUNC 'subprog' type_id=75 linkage=static
There is then no argument left to compare, the subprog stays reliable,
and the check in bpf_check_attach_target() is skipped. The freplace is
then rejected by the later linkage check instead, reporting "subprog()
is not a global function", and the selftest "exceptions" fails.
Determine staticness from the BTF linkage instead, and keep the
unreliable check for global functions whose BTF does not match their
call site.
There is no functional change: freplacing a static function was rejected
before and is still rejected with the same -EINVAL. Selftest "exceptions"
is updated to match.
[1] https://github.com/llvm/llvm-project/pull/198426
Fixes: 147400e9c27c ("bpf: Compute parameters liveness in bpf_compute_live_registers()")
Signed-off-by: KaFai Wan <kafai.wan@linux.dev>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://patch.msgid.link/20261018005348.2195130-2-kafai.wan@linux.dev
|
|
This computes exact liveness for the arguments of a call to a
subprogram instead of assuming that r1..r5 are read:
- For static subprograms compute use registers at the
bpf_compute_live_registers() fixpoint phase.
- For global subprograms use BTF information.
Add a separate pass doing try_btf_prepare_func_args() in order for
bpf_subprog_info->arg_slot_cnt to be available during
bpf_compute_live_registers().
The conservative liveness marks hindered SCEV widening logic on a set
of production programs.
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://patch.msgid.link/20261009-scev-minimal-rebase-v3-11-bcba9bc53ac9@gmail.com
|
|
Add a test where a static subprogram only called from dead code sits in
front of the exception callback, so that its removal compacts
subprog_info[] underneath the callback's index.
# LDLIBS=-static PKG_CONFIG='pkg-config --static' ./vmtest.sh -- ./test_progs -t exceptions
[...]
#129/119 exceptions/exception_cb_behind_dead_subprog:OK
#129 exceptions:OK
Summary: 1/119 PASSED, 0 SKIPPED, 0/0 FAILED
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://patch.msgid.link/20260925175244.1136329-17-daniel@iogearbox.net
|
|
The existing exception tests do not reach a callback that materializes
BPF_REG_FP into a register. They either throw from the main program,
where BPF_REG_FP already holds the value the callback needs, or use a
callback whose only stack accesses are frame pointer relative, which the
arm64 JIT rewrites to be stack pointer relative.
Add a test that throws from a subprogram using its own BPF stack, with a
callback that hands the address of a local variable to
bpf_probe_read_kernel(). The helper and the callback have to name the
same slot for the value read back to be the one the helper stored.
Signed-off-by: Donggeun Yoo <donggeunyoo.kernel@gmail.com>
Link: https://lore.kernel.org/r/20260907130624.611942-3-donggeunyoo.kernel@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
|
|
Add tests to verify that bpf_throw() correctly unwinds the stack
when the program uses outgoing stack arguments (functions with >5
args). Without the preceding x86 fix, these tests crash the kernel
on x86 due to corrupted callee-saved register restore. There is
no change for arm64 to support exception with stack arguments.
Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20260517150707.289273-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
|
|
The fsession attach type is missed in the verifier log in
check_get_func_ip(), bpf_check_attach_target() and check_attach_btf_id().
Update them to make the verifier log proper. Meanwhile, update the
corresponding selftests.
Acked-by: Leon Hwang <leon.hwang@linux.dev>
Signed-off-by: Menglong Dong <dongml2@chinatelecom.cn>
Link: https://lore.kernel.org/r/20260412060346.142007-2-dongml2@chinatelecom.cn
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
|
|
Add additional testing for void global functions. The tests
ensure that calls to void global functions properly keep
R0 invalid. Also make sure that exception callbacks still
require a return value.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Emil Tsalapatis <emil@etsalapatis.com>
Link: https://lore.kernel.org/r/20260228184759.108145-6-emil@etsalapatis.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
|
|
Alexei reported seeing log messages for some test cases even though we
just wanted to match the error string from the verifier. Move the
printing of the log buffer to a guarded condition so that we only print
it when we fail to match on the expected string in the log buffer,
preventing unneeded output when running the test.
Reported-by: Alexei Starovoitov <ast@kernel.org>
Fixes: d2a93715bfb0 ("selftests/bpf: Add tests for BPF exceptions")
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20230918155233.297024-2-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
|
|
Add selftests to cover success and failure cases of API usage, runtime
behavior and invariants that need to be maintained for implementation
correctness.
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20230912233214.1518551-18-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
|
