BMC/Intel-BMC/linux.git/tools/lib/bpf/bpf.h, branch dev-5.2

libbpf: fix samples/bpf build failure due to undefined UINT32_MAX

2019-04-25T21:34:10+00:00

Currently, building bpf samples will cause the following error. ./tools/lib/bpf/bpf.h:132:27: error: 'UINT32_MAX' undeclared here (not in a function) .. #define BPF_LOG_BUF_SIZE (UINT32_MAX >> 8) /* verifier maximum in kernels <= 5.1 */ ^ ./samples/bpf/bpf_load.h:31:25: note: in expansion of macro 'BPF_LOG_BUF_SIZE' extern char bpf_log_buf[BPF_LOG_BUF_SIZE]; ^~~~~~~~~~~~~~~~ Due to commit 4519efa6f8ea ("libbpf: fix BPF_LOG_BUF_SIZE off-by-one error") hard-coded size of BPF_LOG_BUF_SIZE has been replaced with UINT32_MAX which is defined in header. Even with this change, bpf selftests are running fine since these are built with clang and it includes header(-idirafter) from clang/6.0.0/include. (it has ) clang -I. -I./include/uapi -I../../../include/uapi -idirafter /usr/local/include -idirafter /usr/include \ -idirafter /usr/lib/llvm-6.0/lib/clang/6.0.0/include -idirafter /usr/include/x86_64-linux-gnu \ -Wno-compare-distinct-pointer-types -O2 -target bpf -emit-llvm -c progs/test_sysctl_prog.c -o - | \ llc -march=bpf -mcpu=generic -filetype=obj -o /linux/tools/testing/selftests/bpf/test_sysctl_prog.o But bpf samples are compiled with GCC, and it only searches and includes headers declared at the target file. As '#include ' hasn't been declared in tools/lib/bpf/bpf.h, it causes build failure of bpf samples. gcc -Wp,-MD,./samples/bpf/.sockex3_user.o.d -Wall -Wmissing-prototypes -Wstrict-prototypes \ -O2 -fomit-frame-pointer -std=gnu89 -I./usr/include -I./tools/lib/ -I./tools/testing/selftests/bpf/ \ -I./tools/ lib/ -I./tools/include -I./tools/perf -c -o ./samples/bpf/sockex3_user.o ./samples/bpf/sockex3_user.c; This commit add declaration of '#include ' to tools/lib/bpf/bpf.h to fix this problem. Signed-off-by: Daniel T. Lee Acked-by: Yonghong Song Signed-off-by: Daniel Borkmann

libbpf: fix BPF_LOG_BUF_SIZE off-by-one error

2019-04-20T00:05:48+00:00

The BPF_PROG_LOAD condition for kernel version <= 5.1 is log->len_total > UINT_MAX >> 8 /* (16 * 1024 * 1024) - 1 */ Signed-off-by: McCabe, Robert J Signed-off-by: Alexei Starovoitov

libbpf: add support for ctx_{size, }_{in, out} in BPF_PROG_TEST_RUN

2019-04-11T08:21:41+00:00

Support recently introduced input/output context for test runs. We extend only bpf_prog_test_run_xattr. bpf_prog_test_run is unextendable and left as is. Signed-off-by: Stanislav Fomichev Acked-by: Martin KaFai Lau Signed-off-by: Daniel Borkmann

bpf, libbpf: support global data/bss/rodata sections

2019-04-10T00:05:47+00:00

This work adds BPF loader support for global data sections to libbpf. This allows to write BPF programs in more natural C-like way by being able to define global variables and const data. Back at LPC 2018 [0] we presented a first prototype which implemented support for global data sections by extending BPF syscall where union bpf_attr would get additional memory/size pair for each section passed during prog load in order to later add this base address into the ldimm64 instruction along with the user provided offset when accessing a variable. Consensus from LPC was that for proper upstream support, it would be more desirable to use maps instead of bpf_attr extension as this would allow for introspection of these sections as well as potential live updates of their content. This work follows this path by taking the following steps from loader side: 1) In bpf_object__elf_collect() step we pick up ".data", ".rodata", and ".bss" section information. 2) If present, in bpf_object__init_internal_map() we add maps to the obj's map array that corresponds to each of the present sections. Given section size and access properties can differ, a single entry array map is created with value size that is corresponding to the ELF section size of .data, .bss or .rodata. These internal maps are integrated into the normal map handling of libbpf such that when user traverses all obj maps, they can be differentiated from user-created ones via bpf_map__is_internal(). In later steps when we actually create these maps in the kernel via bpf_object__create_maps(), then for .data and .rodata sections their content is copied into the map through bpf_map_update_elem(). For .bss this is not necessary since array map is already zero-initialized by default. Additionally, for .rodata the map is frozen as read-only after setup, such that neither from program nor syscall side writes would be possible. 3) In bpf_program__collect_reloc() step, we record the corresponding map, insn index, and relocation type for the global data. 4) And last but not least in the actual relocation step in bpf_program__relocate(), we mark the ldimm64 instruction with src_reg = BPF_PSEUDO_MAP_VALUE where in the first imm field the map's file descriptor is stored as similarly done as in BPF_PSEUDO_MAP_FD, and in the second imm field (as ldimm64 is 2-insn wide) we store the access offset into the section. Given these maps have only single element ldimm64's off remains zero in both parts. 5) On kernel side, this special marked BPF_PSEUDO_MAP_VALUE load will then store the actual target address in order to have a 'map-lookup'-free access. That is, the actual map value base address + offset. The destination register in the verifier will then be marked as PTR_TO_MAP_VALUE, containing the fixed offset as reg->off and backing BPF map as reg->map_ptr. Meaning, it's treated as any other normal map value from verification side, only with efficient, direct value access instead of actual call to map lookup helper as in the typical case. Currently, only support for static global variables has been added, and libbpf rejects non-static global variables from loading. This can be lifted until we have proper semantics for how BPF will treat multi-object BPF loads. From BTF side, libbpf will set the value type id of the types corresponding to the ".bss", ".data" and ".rodata" names which LLVM will emit without the object name prefix. The key type will be left as zero, thus making use of the key-less BTF option in array maps. Simple example dump of program using globals vars in each section: # bpftool prog [...] 6784: sched_cls name load_static_dat tag a7e1291567277844 gpl loaded_at 2019-03-11T15:39:34+0000 uid 0 xlated 1776B jited 993B memlock 4096B map_ids 2238,2237,2235,2236,2239,2240 # bpftool map show id 2237 2237: array name test_glo.bss flags 0x0 key 4B value 64B max_entries 1 memlock 4096B # bpftool map show id 2235 2235: array name test_glo.data flags 0x0 key 4B value 64B max_entries 1 memlock 4096B # bpftool map show id 2236 2236: array name test_glo.rodata flags 0x80 key 4B value 96B max_entries 1 memlock 4096B # bpftool prog dump xlated id 6784 int load_static_data(struct __sk_buff * skb): ; int load_static_data(struct __sk_buff *skb) 0: (b7) r6 = 0 ; test_reloc(number, 0, &num0); 1: (63) *(u32 *)(r10 -4) = r6 2: (bf) r2 = r10 ; int load_static_data(struct __sk_buff *skb) 3: (07) r2 += -4 ; test_reloc(number, 0, &num0); 4: (18) r1 = map[id:2238] 6: (18) r3 = map[id:2237][0]+0 <-- direct addr in .bss area 8: (b7) r4 = 0 9: (85) call array_map_update_elem#100464 10: (b7) r1 = 1 ; test_reloc(number, 1, &num1); [...] ; test_reloc(string, 2, str2); 120: (18) r8 = map[id:2237][0]+16 <-- same here at offset +16 122: (18) r1 = map[id:2239] 124: (18) r3 = map[id:2237][0]+16 126: (b7) r4 = 0 127: (85) call array_map_update_elem#100464 128: (b7) r1 = 120 ; str1[5] = 'x'; 129: (73) *(u8 *)(r9 +5) = r1 ; test_reloc(string, 3, str1); 130: (b7) r1 = 3 131: (63) *(u32 *)(r10 -4) = r1 132: (b7) r9 = 3 133: (bf) r2 = r10 ; int load_static_data(struct __sk_buff *skb) 134: (07) r2 += -4 ; test_reloc(string, 3, str1); 135: (18) r1 = map[id:2239] 137: (18) r3 = map[id:2235][0]+16 <-- direct addr in .data area 139: (b7) r4 = 0 140: (85) call array_map_update_elem#100464 141: (b7) r1 = 111 ; __builtin_memcpy(&str2[2], "hello", sizeof("hello")); 142: (73) *(u8 *)(r8 +6) = r1 <-- further access based on .bss data 143: (b7) r1 = 108 144: (73) *(u8 *)(r8 +5) = r1 [...] For Cilium use-case in particular, this enables migrating configuration constants from Cilium daemon's generated header defines into global data sections such that expensive runtime recompilations with LLVM can be avoided altogether. Instead, the ELF file becomes effectively a "template", meaning, it is compiled only once (!) and the Cilium daemon will then rewrite relevant configuration data from the ELF's .data or .rodata sections directly instead of recompiling the program. The updated ELF is then loaded into the kernel and atomically replaces the existing program in the networking datapath. More info in [0]. Based upon recent fix in LLVM, commit c0db6b6bd444 ("[BPF] Don't fail for static variables"). [0] LPC 2018, BPF track, "ELF relocation for static data in BPF", http://vger.kernel.org/lpc-bpf2018.html#session-3 Signed-off-by: Daniel Borkmann Acked-by: Andrii Nakryiko Acked-by: Martin KaFai Lau Signed-off-by: Alexei Starovoitov

libbpf: teach libbpf about log_level bit 2

2019-04-03T23:27:38+00:00

Allow bpf_prog_load_xattr() to specify log_level for program loading. Teach libbpf to accept log_level with bit 2 set. Increase default BPF_LOG_BUF_SIZE from 256k to 16M. There is no downside to increase it to a maximum allowed by old kernels. Existing 256k limit caused ENOSPC errors and users were not able to see verifier error which is printed at the end of the verifier log. If ENOSPC is hit, double the verifier log and try again to capture the verifier error. Signed-off-by: Alexei Starovoitov Signed-off-by: Daniel Borkmann

tools/bpf: add log_level to bpf_load_program_attr

2019-02-08T02:22:31+00:00

The kernel verifier has three levels of logs: 0: no logs 1: logs mostly useful > 1: verbose Current libbpf API functions bpf_load_program_xattr() and bpf_load_program() cannot specify log_level. The bcc, however, provides an interface for user to specify log_level 2 for verbose output. This patch added log_level into structure bpf_load_program_attr, so users, including bcc, can use bpf_load_program_xattr() to change log_level. The supported log_level is 0, 1, and 2. The bpf selftest test_sock.c is modified to enable log_level = 2. If the "verbose" in test_sock.c is changed to true, the test will output logs like below: $ ./test_sock func#0 @0 0: R1=ctx(id=0,off=0,imm=0) R10=fp0,call_-1 0: (bf) r6 = r1 1: R1=ctx(id=0,off=0,imm=0) R6_w=ctx(id=0,off=0,imm=0) R10=fp0,call_-1 1: (61) r7 = *(u32 *)(r6 +28) invalid bpf_context access off=28 size=4 Test case: bind4 load with invalid access: src_ip6 .. [PASS] ... Test case: bind6 allow all .. [PASS] Summary: 16 PASSED, 0 FAILED Some test_sock tests are negative tests and verbose verifier log will be printed out as shown in the above. Signed-off-by: Yonghong Song Signed-off-by: Alexei Starovoitov

libbpf: introduce bpf_map_lookup_elem_flags()

2019-02-01T19:55:39+00:00

Introduce int bpf_map_lookup_elem_flags(int fd, const void *key, void *value, __u64 flags) helper to lookup array/hash/cgroup_local_storage elements with BPF_F_LOCK flag. Signed-off-by: Alexei Starovoitov Signed-off-by: Daniel Borkmann

bpf: libbpf: Add btf_line_info support to libbpf

2018-12-09T21:54:38+00:00

This patch adds bpf_line_info support to libbpf: 1) Parsing the line_info sec from ".BTF.ext" 2) Relocating the line_info. If the main prog *_info relocation fails, it will ignore the remaining subprog line_info and continue. If the subprog *_info relocation fails, it will bail out. 3) BPF_PROG_LOAD a prog with line_info Signed-off-by: Martin KaFai Lau Acked-by: Yonghong Song Signed-off-by: Alexei Starovoitov

libbpf: add bpf_prog_test_run_xattr

2018-12-04T16:18:13+00:00

Add a new function, which encourages safe usage of the test interface. bpf_prog_test_run continues to work as before, but should be considered unsafe. Signed-off-by: Lorenz Bauer Signed-off-by: Alexei Starovoitov

bpf: Add BPF_F_ANY_ALIGNMENT.

2018-12-01T05:38:48+00:00

Often we want to write tests cases that check things like bad context offset accesses. And one way to do this is to use an odd offset on, for example, a 32-bit load. This unfortunately triggers the alignment checks first on platforms that do not set CONFIG_EFFICIENT_UNALIGNED_ACCESS. So the test case see the alignment failure rather than what it was testing for. It is often not completely possible to respect the original intention of the test, or even test the same exact thing, while solving the alignment issue. Another option could have been to check the alignment after the context and other validations are performed by the verifier, but that is a non-trivial change to the verifier. Signed-off-by: David S. Miller Signed-off-by: Alexei Starovoitov