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8008342853
When a tracing BPF program attempts to read memory without using the bpf_probe_read() helper, the verifier marks the load instruction with the BPF_PROBE_MEM flag. Since the arm64 JIT does not currently recognize this flag it falls back to the interpreter. Add support for BPF_PROBE_MEM, by appending an exception table to the BPF program. If the load instruction causes a data abort, the fixup infrastructure finds the exception table and fixes up the fault, by clearing the destination register and jumping over the faulting instruction. To keep the compact exception table entry format, inspect the pc in fixup_exception(). A more generic solution would add a "handler" field to the table entry, like on x86 and s390. Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Song Liu <songliubraving@fb.com> Link: https://lore.kernel.org/bpf/20200728152122.1292756-2-jean-philippe@linaro.org |
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| Makefile | ||
| bpf_jit.h | ||
| bpf_jit_comp.c | ||