Merge branch 'libbpf: auto-resize relocatable LOAD/STORE instructions'

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Andrii Nakryiko says:

====================
Patch set implements logic in libbpf to auto-adjust memory size (1-, 2-, 4-,
8-bytes) of load/store (LD/ST/STX) instructions which have BPF CO-RE field
offset relocation associated with it. In practice this means transparent
handling of 32-bit kernels, both pointer and unsigned integers. Signed
integers are not relocatable with zero-extending loads/stores, so libbpf
poisons them and generates a warning. If/when BPF gets support for
sign-extending loads/stores, it would be possible to automatically relocate
them as well.

All the details are contained in patch #2 comments and commit message.
Patch #3 is a simple change in libbpf to make advanced testing with custom BTF
easier. Patch #4 validates correct uses of auto-resizable loads, as well as
check that libbpf fails invalid uses. Patch #1 skips CO-RE relocation for
programs that had bpf_program__set_autoload(prog, false) set on them, reducing
warnings and noise.

v2->v3:
  - fix copyright (Alexei);
v1->v2:
  - more consistent names for instruction mem size convertion routines (Alexei);
  - extended selftests to use relocatable STX instructions (Alexei);
  - added a fix for skipping CO-RE relocation for non-loadable programs.

Cc: Luka Perkov <luka.perkov@sartura.hr>
Cc: Tony Ambardar <tony.ambardar@gmail.com>
====================

Signed-off-by: Alexei Starovoitov <ast@kernel.org>

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This commit is contained in:

Alexei Starovoitov 2020-10-07 18:50:27 -07:00

parent 80348d8867 888d83b961

commit 1e9259eca8

3 changed files with 539 additions and 9 deletions

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151

tools/lib/bpf/libbpf.c

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225

tools/testing/selftests/bpf/prog_tests/core_autosize.c

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172

tools/testing/selftests/bpf/progs/test_core_autosize.c

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