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| author | Yonghong Song <yhs@fb.com> | 2017-04-29 22:52:42 -0700 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2017-05-01 11:40:23 -0400 |
| commit | 332270fdc8b6fba07d059a9ad44df9e1a2ad4529 (patch) | |
| tree | 95e4cf412f1691c5ac9063c64989337fc80a278e /Documentation/fpga | |
| parent | 2faf26575350e49c1e242b7a464e9302f78b9b15 (diff) | |
bpf: enhance verifier to understand stack pointer arithmetic
llvm 4.0 and above generates the code like below:
....
440: (b7) r1 = 15
441: (05) goto pc+73
515: (79) r6 = *(u64 *)(r10 -152)
516: (bf) r7 = r10
517: (07) r7 += -112
518: (bf) r2 = r7
519: (0f) r2 += r1
520: (71) r1 = *(u8 *)(r8 +0)
521: (73) *(u8 *)(r2 +45) = r1
....
and the verifier complains "R2 invalid mem access 'inv'" for insn #521.
This is because verifier marks register r2 as unknown value after #519
where r2 is a stack pointer and r1 holds a constant value.
Teach verifier to recognize "stack_ptr + imm" and
"stack_ptr + reg with const val" as valid stack_ptr with new offset.
Signed-off-by: Yonghong Song <yhs@fb.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'Documentation/fpga')
0 files changed, 0 insertions, 0 deletions