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| author | Andrii Nakryiko <andriin@fb.com> | 2020-08-13 13:49:44 -0700 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2020-08-13 16:45:41 -0700 |
| commit | 0f993845d723c87656552837b412994d6086f086 (patch) | |
| tree | bf9c93f669615a61b4dbdcfa2e400fee402bdc73 /tools | |
| parent | 5705d705832f74395c5465ce93192688f543006a (diff) | |
| download | linux-0f993845d723c87656552837b412994d6086f086.tar.bz2 | |
tools/bpftool: Generate data section struct with conservative alignment
The comment in the code describes this in good details. Generate such a memory
layout that would work both on 32-bit and 64-bit architectures for user-space.
Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200813204945.1020225-9-andriin@fb.com
Diffstat (limited to 'tools')
| -rw-r--r-- | tools/bpf/bpftool/gen.c | 14 |
1 files changed, 14 insertions, 0 deletions
diff --git a/tools/bpf/bpftool/gen.c b/tools/bpf/bpftool/gen.c index db80e836816e..f61184653633 100644 --- a/tools/bpf/bpftool/gen.c +++ b/tools/bpf/bpftool/gen.c @@ -143,6 +143,20 @@ static int codegen_datasec_def(struct bpf_object *obj, var_name, align); return -EINVAL; } + /* Assume 32-bit architectures when generating data section + * struct memory layout. Given bpftool can't know which target + * host architecture it's emitting skeleton for, we need to be + * conservative and assume 32-bit one to ensure enough padding + * bytes are generated for pointer and long types. This will + * still work correctly for 64-bit architectures, because in + * the worst case we'll generate unnecessary padding field, + * which on 64-bit architectures is not strictly necessary and + * would be handled by natural 8-byte alignment. But it still + * will be a correct memory layout, based on recorded offsets + * in BTF. + */ + if (align > 4) + align = 4; align_off = (off + align - 1) / align * align; if (align_off != need_off) { |