SIMD-0189: SBPF stricter ELF headers #189
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| @@ -0,0 +1,131 @@ | |||
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| simd: '0187' | |||
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Can you update the SIMD number (and PR title) to match the PR number, per https://github.com/solana-foundation/solana-improvement-documents/blob/main/proposals/0001-simd-process.md#draft
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| - `p_memsz` must fit in 32 bits / be less than `1 << 32` | ||
| - `p_align` is ignored | ||
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| If any check fails `ElfParserError::InvalidProgramHeader` must be thrown. |
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Do you mind specifying where in the program lifecycle this will be thrown? (i.e. will these new checks be enforced at deployment time? when loading into the program cache for execution? both?)
What is the plan for currently deployed programs?
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Or is this SIMD associated with an SBPF version?
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It is associated with a SBPF version (see title), though the specific one is not decided yet.
And these checks will all happen at load time (deployment or feature set change), not at runtime.
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Could we specify in the SIMD where the checks will be performed, and what happens if they fail?
| | stack | PT_GNU_STACK | PF_R, PF_W | 2 << 32 | | ||
| | heap | PT_LOAD | PF_R, PF_W | 3 << 32 | |
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Why do we allow these headers? These regions are configured independently of the ELF. Do we allow these headers just so that we can reduce LLVM modifications? Just curious.
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It is so that the memory regions are correctly reflected in the ELF header. This makes it easier for tooling to detect issues (such as overlap in section allocation) and could simplify the validator implementation in the future.
Also, with the upcoming CPI syscall restrictions (necessary for direct mapping) we will limit pointers provided by the user to come from the stack and heap. Thus their layout will be further solidified.
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| If any check fails `ElfParserError::InvalidProgramHeader` must be thrown. | ||
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| ### Dynamic symbol table |
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Why did you choose the dynamic symbol table entry SHT_DYNAMIC and not the symbol table elf entry SHT_SYMTAB?
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