From 3c591de2854381e313ec149bc1bbd8360f9ed53b Mon Sep 17 00:00:00 2001 From: Eric Long Date: Wed, 2 Oct 2024 14:25:07 +0800 Subject: [PATCH] selftests/bpf: Test linking with duplicate extern functions Previously when multiple BPF object files referencing the same extern function (usually kfunc) are statically linked using `bpftool gen object`, libbpf tries to get the nonexistent size of BTF_KIND_FUNC_PROTO and fails. This test ensures it is fixed. Signed-off-by: Eric Long Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20241002-libbpf-dup-extern-funcs-v4-2-560eb460ff90@hack3r.moe --- tools/testing/selftests/bpf/progs/linked_funcs1.c | 8 ++++++++ tools/testing/selftests/bpf/progs/linked_funcs2.c | 8 ++++++++ 2 files changed, 16 insertions(+) diff --git a/tools/testing/selftests/bpf/progs/linked_funcs1.c b/tools/testing/selftests/bpf/progs/linked_funcs1.c index cc79dddac182..049a1f78de3f 100644 --- a/tools/testing/selftests/bpf/progs/linked_funcs1.c +++ b/tools/testing/selftests/bpf/progs/linked_funcs1.c @@ -63,6 +63,8 @@ extern int set_output_val2(int x); /* here we'll force set_output_ctx2() to be __hidden in the final obj file */ __hidden extern void set_output_ctx2(__u64 *ctx); +void *bpf_cast_to_kern_ctx(void *obj) __ksym; + SEC("?raw_tp/sys_enter") int BPF_PROG(handler1, struct pt_regs *regs, long id) { @@ -86,4 +88,10 @@ int BPF_PROG(handler1, struct pt_regs *regs, long id) return 0; } +/* Generate BTF FUNC record and test linking with duplicate extern functions */ +void kfunc_gen1(void) +{ + bpf_cast_to_kern_ctx(0); +} + char LICENSE[] SEC("license") = "GPL"; diff --git a/tools/testing/selftests/bpf/progs/linked_funcs2.c b/tools/testing/selftests/bpf/progs/linked_funcs2.c index 942cc5526ddf..96850759fd8d 100644 --- a/tools/testing/selftests/bpf/progs/linked_funcs2.c +++ b/tools/testing/selftests/bpf/progs/linked_funcs2.c @@ -63,6 +63,8 @@ extern int set_output_val1(int x); /* here we'll force set_output_ctx1() to be __hidden in the final obj file */ __hidden extern void set_output_ctx1(__u64 *ctx); +void *bpf_cast_to_kern_ctx(void *obj) __ksym; + SEC("?raw_tp/sys_enter") int BPF_PROG(handler2, struct pt_regs *regs, long id) { @@ -86,4 +88,10 @@ int BPF_PROG(handler2, struct pt_regs *regs, long id) return 0; } +/* Generate BTF FUNC record and test linking with duplicate extern functions */ +void kfunc_gen2(void) +{ + bpf_cast_to_kern_ctx(0); +} + char LICENSE[] SEC("license") = "GPL"; -- 2.50.1