Messages in this thread |  | | Subject | Re: [PATCH v2] powerpc/uprobes: Validation for prefixed instruction | From | Ravi Bangoria <> | Date | Thu, 4 Feb 2021 16:19:40 +0530 |
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On 2/4/21 4:17 PM, Ravi Bangoria wrote: > Don't allow Uprobe on 2nd word of a prefixed instruction. As per > ISA 3.1, prefixed instruction should not cross 64-byte boundary. > So don't allow Uprobe on such prefixed instruction as well. > > There are two ways probed instruction is changed in mapped pages. > First, when Uprobe is activated, it searches for all the relevant > pages and replace instruction in them. In this case, if we notice > that probe is on the 2nd word of prefixed instruction, error out > directly. Second, when Uprobe is already active and user maps a > relevant page via mmap(), instruction is replaced via mmap() code > path. But because Uprobe is invalid, entire mmap() operation can > not be stopped. In this case just print an error and continue.
@mpe,
arch_uprobe_analyze_insn() can return early if cpu_has_feature(CPU_FTR_ARCH_31) is not set. But that will miss out a rare scenario of user running binary with prefixed instruction on p10 predecessors. Please let me know if I should add cpu_has_feature(CPU_FTR_ARCH_31) or not.
- Ravi
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