linux/tools/lib
Martynas Pumputis 97eb31384a libbpf: Fix reuse of pinned map on older kernel
When loading a BPF program with a pinned map, the loader checks whether
the pinned map can be reused, i.e. their properties match. To derive
such of the pinned map, the loader invokes BPF_OBJ_GET_INFO_BY_FD and
then does the comparison.

Unfortunately, on < 4.12 kernels the BPF_OBJ_GET_INFO_BY_FD is not
available, so loading the program fails with the following error:

	libbpf: failed to get map info for map FD 5: Invalid argument
	libbpf: couldn't reuse pinned map at
		'/sys/fs/bpf/tc/globals/cilium_call_policy': parameter
		mismatch"
	libbpf: map 'cilium_call_policy': error reusing pinned map
	libbpf: map 'cilium_call_policy': failed to create:
		Invalid argument(-22)
	libbpf: failed to load object 'bpf_overlay.o'

To fix this, fallback to derivation of the map properties via
/proc/$PID/fdinfo/$MAP_FD if BPF_OBJ_GET_INFO_BY_FD fails with EINVAL,
which can be used as an indicator that the kernel doesn't support
the latter.

Signed-off-by: Martynas Pumputis <m@lambda.lt>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20210712125552.58705-1-m@lambda.lt
2021-07-12 16:15:27 -07:00
..
api tools api fs: Cache cgroupfs mount point 2021-02-17 15:09:08 -03:00
bpf libbpf: Fix reuse of pinned map on older kernel 2021-07-12 16:15:27 -07:00
lockdep .gitignore: add SPDX License Identifier 2020-03-25 11:50:48 +01:00
perf perf jit: Let convert_timestamp() to be backwards-compatible 2021-04-29 10:31:00 -03:00
subcmd tools: Avoid comma separated statements 2020-10-02 10:36:36 -06:00
symbol libsymbols kallsyms: Move hex2u64 out of header 2020-05-05 16:35:32 -03:00
traceevent KVM: x86/mmu: Rename "nxe" role bit to "efer_nx" for macro shenanigans 2021-06-24 18:00:41 -04:00
argv_split.c tools lib: Move argv_{split,free} from tools/perf/util/ 2019-07-01 22:50:40 -03:00
bitmap.c tools: bitmap: sync function declarations with the kernel 2021-05-06 19:24:11 -07:00
ctype.c tools perf: Move from sane_ctype.h obtained from git to the Linux's original 2019-06-25 21:02:47 -03:00
find_bit.c tools: sync lib/find_bit implementation 2021-05-06 19:24:12 -07:00
hweight.c
rbtree.c tools/: replace HTTP links with HTTPS ones 2020-08-07 11:33:21 -07:00
str_error_r.c objtool, perf: Fix GCC 8 -Wrestrict error 2018-03-19 13:51:54 -03:00
string.c tools lib: Adopt memchr_inv() from kernel 2020-11-27 08:34:52 -03:00
vsprintf.c perf script: Pad DSO name for --call-trace 2019-05-28 18:37:44 -03:00
zalloc.c tools lib: Adopt zalloc()/zfree() from tools/perf 2019-07-09 10:13:26 -03:00