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| author |   Yonghong Song <yhs@fb.com> | 2022-06-06 23:26:10 -0700 |
|---|---|---|
| committer |   Alexei Starovoitov <ast@kernel.org> | 2022-06-07 10:20:42 -0700 |
| commit | b58b2b3a31228bd9aaed9b96e9452dafd0d46024 (patch) | |
| tree | 1cf5146d57229619708198747aa0af258f80ff2d /tools/lib | |
| parent | libbpf: Permit 64bit relocation value (diff) | |
| download | linux-dev-b58b2b3a31228bd9aaed9b96e9452dafd0d46024.tar.xz linux-dev-b58b2b3a31228bd9aaed9b96e9452dafd0d46024.zip | |
libbpf: Fix an error in 64bit relocation value computation
Currently, the 64bit relocation value in the instruction
is computed as follows:
__u64 imm = insn[0].imm + ((__u64)insn[1].imm << 32)
Suppose insn[0].imm = -1 (0xffffffff) and insn[1].imm = 1.
With the above computation, insn[0].imm will first sign-extend
to 64bit -1 (0xffffffffFFFFFFFF) and then add 0x1FFFFFFFF,
producing incorrect value 0xFFFFFFFF. The correct value
should be 0x1FFFFFFFF.
Changing insn[0].imm to __u32 first will prevent 64bit sign
extension and fix the issue. Merging high and low 32bit values
also changed from '+' to '|' to be consistent with other
similar occurences in kernel and libbpf.
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Dave Marchevsky <davemarchevsky@fb.com>
Signed-off-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/r/20220607062610.3717378-1-yhs@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'tools/lib')
| -rw-r--r-- | tools/lib/bpf/relo_core.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/tools/lib/bpf/relo_core.c b/tools/lib/bpf/relo_core.c index 0dce5644877b..073a54ed7432 100644 --- a/tools/lib/bpf/relo_core.c +++ b/tools/lib/bpf/relo_core.c @@ -1027,7 +1027,7 @@ poison: return -EINVAL; } - imm = insn[0].imm + ((__u64)insn[1].imm << 32); + imm = (__u32)insn[0].imm | ((__u64)insn[1].imm << 32); if (res->validate && imm != orig_val) { pr_warn("prog '%s': relo #%d: unexpected insn #%d (LDIMM64) value: got %llu, exp %llu -> %llu\n", prog_name, relo_idx, |