kernel/tools/testing/selftests/bpf/README.rst, branch linux-6.2.y

bpf/docs: Summarize CI system and deny lists

2022-10-19T18:42:01Z

This change adds a brief summary of the BPF continuous integration (CI) to the BPF selftest documentation. The summary focuses not so much on actual workings of the CI, as it is maintained outside of the repository, but aims to document the few bits of it that are sourced from this repository and that developers may want to adjust as part of patch submissions: the BPF kernel configuration and the deny list file(s). Changelog: - v1->v2: - use s390x instead of s390 for consistency Signed-off-by: Daniel Müller Acked-by: David Vernet Link: https://lore.kernel.org/r/20221018164015.1970862-1-deso@posteo.net Signed-off-by: Martin KaFai Lau

bpf/docs: Update README for most recent vmtest.sh

2022-10-18T19:54:05Z

Since commit 40b09653b197 ("selftests/bpf: Adjust vmtest.sh to use local kernel configuration") the vmtest.sh script no longer downloads a kernel configuration but uses the local, in-repository one. This change updates the README, which still mentions the old behavior. Signed-off-by: Daniel Müller Signed-off-by: Daniel Borkmann Link: https://lore.kernel.org/bpf/20221017232458.1272762-1-deso@posteo.net

selftests/bpf: Store BPF object files with .bpf.o extension

2022-09-02T13:55:37Z

BPF object files are, in a way, the final artifact produced as part of the ahead-of-time compilation process. That makes them somewhat special compared to "regular" object files, which are a intermediate build artifacts that can typically be removed safely. As such, it can make sense to name them differently to make it easier to spot this difference at a glance. Among others, libbpf-bootstrap [0] has established the extension .bpf.o for BPF object files. It seems reasonable to follow this example and establish the same denomination for selftest build artifacts. To that end, this change adjusts the corresponding part of the build system and the test programs loading BPF object files to work with .bpf.o files. [0] https://github.com/libbpf/libbpf-bootstrap Suggested-by: Andrii Nakryiko Signed-off-by: Daniel Müller Signed-off-by: Daniel Borkmann Link: https://lore.kernel.org/bpf/20220901222253.1199242-1-deso@posteo.net

bpf/docs: Update list of architectures supported.

2022-03-08T06:27:13Z

vmtest.sh also supports s390x now. Signed-off-by: KP Singh Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20220307133048.1287644-2-kpsingh@kernel.org

bpf/docs: Update vmtest docs for static linking

2022-03-08T06:27:00Z

Dynamic linking when compiling on the host can cause issues when the libc version does not match the one in the VM image. Update the docs to explain how to do this. Before: ./vmtest.sh -- ./test_progs -t test_ima ./test_progs: /usr/lib/libc.so.6: version `GLIBC_2.33' not found (required by ./test_progs) After: LDLIBS=-static ./vmtest.sh -- ./test_progs -t test_ima test_ima:OK Summary: 1/0 PASSED, 0 SKIPPED, 0 FAILED Reported-by: "Geyslan G. Bem" Signed-off-by: KP Singh Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20220307133048.1287644-1-kpsingh@kernel.org

selftests/bpf: specify pahole version requirement for btf_tag test

2022-01-27T20:03:47Z

Specify pahole version requirement (1.23) for btf_tag subtests btf_type_tag_user_{mod1, mod2, vmlinux}. Signed-off-by: Yonghong Song Link: https://lore.kernel.org/r/20220127154622.663337-1-yhs@fb.com Signed-off-by: Alexei Starovoitov

selftests/bpf: Clarify llvm dependency with btf_tag selftest

2021-11-12T01:41:11Z

btf_tag selftest needs certain llvm versions (>= llvm14). Make it clear in the selftests README.rst file. Signed-off-by: Yonghong Song Signed-off-by: Alexei Starovoitov Acked-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20211112012651.1508549-1-yhs@fb.com

bpf: Rename BTF_KIND_TAG to BTF_KIND_DECL_TAG

2021-10-19T01:35:36Z

Patch set [1] introduced BTF_KIND_TAG to allow tagging declarations for struct/union, struct/union field, var, func and func arguments and these tags will be encoded into dwarf. They are also encoded to btf by llvm for the bpf target. After BTF_KIND_TAG is introduced, we intended to use it for kernel __user attributes. But kernel __user is actually a type attribute. Upstream and internal discussion showed it is not a good idea to mix declaration attribute and type attribute. So we proposed to introduce btf_type_tag as a type attribute and existing btf_tag renamed to btf_decl_tag ([2]). This patch renamed BTF_KIND_TAG to BTF_KIND_DECL_TAG and some other declarations with *_tag to *_decl_tag to make it clear the tag is for declaration. In the future, BTF_KIND_TYPE_TAG might be introduced per [3]. [1] https://lore.kernel.org/bpf/20210914223004.244411-1-yhs@fb.com/ [2] https://reviews.llvm.org/D111588 [3] https://reviews.llvm.org/D111199 Fixes: b5ea834dde6b ("bpf: Support for new btf kind BTF_KIND_TAG") Fixes: 5b84bd10363e ("libbpf: Add support for BTF_KIND_TAG") Fixes: 5c07f2fec003 ("bpftool: Add support for BTF_KIND_TAG") Signed-off-by: Yonghong Song Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20211012164838.3345699-1-yhs@fb.com

bpf: selftest: A bpf prog that has a 32bit scalar spill

2021-09-26T20:07:28Z

It is a simplified example that can trigger a 32bit scalar spill. The const scalar is refilled and added to a skb->data later. Since the reg state of the 32bit scalar spill is not saved now, adding the refilled reg to skb->data and then comparing it with skb->data_end cannot verify the skb->data access. With the earlier verifier patch and the llvm patch [1]. The verifier can correctly verify the bpf prog. Here is the snippet of the verifier log that leads to verifier conclusion that the packet data is unsafe to read. The log is from the kerne without the previous verifier patch to save the <8-byte scalar spill. 67: R0=inv1 R1=inv17 R2=invP2 R3=inv1 R4=pkt(id=0,off=68,r=102,imm=0) R5=inv102 R6=pkt(id=0,off=62,r=102,imm=0) R7=pkt(id=0,off=0,r=102,imm=0) R8=pkt_end(id=0,off=0,imm=0) R9=inv17 R10=fp0 67: (63) *(u32 *)(r10 -12) = r5 68: R0=inv1 R1=inv17 R2=invP2 R3=inv1 R4=pkt(id=0,off=68,r=102,imm=0) R5=inv102 R6=pkt(id=0,off=62,r=102,imm=0) R7=pkt(id=0,off=0,r=102,imm=0) R8=pkt_end(id=0,off=0,imm=0) R9=inv17 R10=fp0 fp-16=mmmm???? ... 101: R0_w=map_value_or_null(id=2,off=0,ks=16,vs=1,imm=0) R6_w=pkt(id=0,off=70,r=102,imm=0) R7=pkt(id=0,off=0,r=102,imm=0) R8=pkt_end(id=0,off=0,imm=0) R9=inv17 R10=fp0 fp-16=mmmmmmmm 101: (61) r1 = *(u32 *)(r10 -12) 102: R0_w=map_value_or_null(id=2,off=0,ks=16,vs=1,imm=0) R1_w=inv(id=0,umax_value=4294967295,var_off=(0x0; 0xffffffff)) R6_w=pkt(id=0,off=70,r=102,imm=0) R7=pkt(id=0,off=0,r=102,imm=0) R8=pkt_end(id=0,off=0,imm=0) R9=inv17 R10=fp0 fp-16=mmmmmmmm 102: (bc) w1 = w1 103: R0_w=map_value_or_null(id=2,off=0,ks=16,vs=1,imm=0) R1_w=inv(id=0,umax_value=4294967295,var_off=(0x0; 0xffffffff)) R6_w=pkt(id=0,off=70,r=102,imm=0) R7=pkt(id=0,off=0,r=102,imm=0) R8=pkt_end(id=0,off=0,imm=0) R9=inv17 R10=fp0 fp-16=mmmmmmmm 103: (0f) r7 += r1 last_idx 103 first_idx 67 regs=2 stack=0 before 102: (bc) w1 = w1 regs=2 stack=0 before 101: (61) r1 = *(u32 *)(r10 -12) 104: R0_w=map_value_or_null(id=2,off=0,ks=16,vs=1,imm=0) R1_w=invP(id=0,umax_value=4294967295,var_off=(0x0; 0xffffffff)) R6_w=pkt(id=0,off=70,r=102,imm=0) R7_w=pkt(id=3,off=0,r=0,umax_value=4294967295,var_off=(0x0; 0xffffffff)) R8=pkt_end(id=0,off=0,imm=0) R9=inv17 R10=fp0 fp-16=mmmmmmmm ... 127: R0_w=inv1 R1=invP(id=0,umax_value=4294967295,var_off=(0x0; 0xffffffff)) R6=pkt(id=0,off=70,r=102,imm=0) R7=pkt(id=3,off=0,r=0,umax_value=4294967295,var_off=(0x0; 0xffffffff)) R8=pkt_end(id=0,off=0,imm=0) R9_w=invP17 R10=fp0 fp-16=mmmmmmmm 127: (bf) r1 = r7 128: R0_w=inv1 R1_w=pkt(id=3,off=0,r=0,umax_value=4294967295,var_off=(0x0; 0xffffffff)) R6=pkt(id=0,off=70,r=102,imm=0) R7=pkt(id=3,off=0,r=0,umax_value=4294967295,var_off=(0x0; 0xffffffff)) R8=pkt_end(id=0,off=0,imm=0) R9_w=invP17 R10=fp0 fp-16=mmmmmmmm 128: (07) r1 += 8 129: R0_w=inv1 R1_w=pkt(id=3,off=8,r=0,umax_value=4294967295,var_off=(0x0; 0xffffffff)) R6=pkt(id=0,off=70,r=102,imm=0) R7=pkt(id=3,off=0,r=0,umax_value=4294967295,var_off=(0x0; 0xffffffff)) R8=pkt_end(id=0,off=0,imm=0) R9_w=invP17 R10=fp0 fp-16=mmmmmmmm 129: (b4) w0 = 1 130: R0=inv1 R1=pkt(id=3,off=8,r=0,umax_value=4294967295,var_off=(0x0; 0xffffffff)) R6=pkt(id=0,off=70,r=102,imm=0) R7=pkt(id=3,off=0,r=0,umax_value=4294967295,var_off=(0x0; 0xffffffff)) R8=pkt_end(id=0,off=0,imm=0) R9=invP17 R10=fp0 fp-16=mmmmmmmm 130: (2d) if r1 > r8 goto pc-66 R0=inv1 R1=pkt(id=3,off=8,r=0,umax_value=4294967295,var_off=(0x0; 0xffffffff)) R6=pkt(id=0,off=70,r=102,imm=0) R7=pkt(id=3,off=0,r=0,umax_value=4294967295,var_off=(0x0; 0xffffffff)) R8=pkt_end(id=0,off=0,imm=0) R9=invP17 R10=fp0 fp-16=mmmmmmmm 131: R0=inv1 R1=pkt(id=3,off=8,r=0,umax_value=4294967295,var_off=(0x0; 0xffffffff)) R6=pkt(id=0,off=70,r=102,imm=0) R7=pkt(id=3,off=0,r=0,umax_value=4294967295,var_off=(0x0; 0xffffffff)) R8=pkt_end(id=0,off=0,imm=0) R9=invP17 R10=fp0 fp-16=mmmmmmmm 131: (69) r6 = *(u16 *)(r7 +0) invalid access to packet, off=0 size=2, R7(id=3,off=0,r=0) R7 offset is outside of the packet [1]: https://reviews.llvm.org/D109073 Signed-off-by: Martin KaFai Lau Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20210922004947.626286-1-kafai@fb.com

selftests/bpf: Skip btf_tag test if btf_tag attribute not supported

2021-09-15T15:49:49Z

Commit c240ba287890 ("selftests/bpf: Add a test with a bpf program with btf_tag attributes") added btf_tag selftest to test BTF_KIND_TAG generation from C source code, and to test kernel validation of generated BTF types. But if an old clang (clang 13 or earlier) is used, the following compiler warning may be seen: progs/tag.c:23:20: warning: unknown attribute 'btf_tag' ignored and the test itself is marked OK. The compiler warning is bad and the test itself shouldn't be marked OK. This patch added the check for btf_tag attribute support. If btf_tag is not supported by the clang, the attribute will not be used in the code and the test will be marked as skipped. For example, with clang 13: ./test_progs -t btf_tag #21 btf_tag:SKIP Summary: 1/0 PASSED, 1 SKIPPED, 0 FAILED The selftests/README.rst is updated to clarify when the btf_tag test may be skipped. Signed-off-by: Yonghong Song Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20210915061036.2577971-1-yhs@fb.com