Refactor - Restrict callx to registered functions
#397
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alessandrod
reviewed
Oct 30, 2022
| if *offset == call_unsupported_instruction { | ||
| *offset = callx_unsupported_instruction; | ||
| if self.config.static_syscalls { | ||
| let mut prev_pc = 0; |
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wouldn't it be faster to memset the pc_section slice when we mmap, before we set the valid entries?
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During compilation the pc_section is used for relocation of jumps & calls. Only at the end it is steamrolled for the most part to be used at runtime.
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Depends on
Config::static_syscalls, because it needs function symbols to be registered by their PC not their hash.In the interpreter, simply throw
EbpfError::UnsupportedInstructionincallxif thelookup_bpf_functionof thetarget_pcfails. In the JIT, mark all instructions which are not a function symbol asANCHOR_CALLX_UNSUPPORTED_INSTRUCTIONinjit.result.pc_section.Unfortunately, that also means that the host to guest PC translation (
ANCHOR_TRANSLATE_PC) used byANCHOR_MEMORY_ACCESS_VIOLATIONwon't work anymore and needs to be replaced by an explicit push of the guest / vm PC (resulting in more instructions emitted per memory access, thus longer executables produced by the JIT).