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powerpc/uprobes: Validation for prefixed instruction
As per ISA 3.1, prefixed instruction should not cross 64-byte boundary. So don't allow Uprobe on such prefixed instruction. 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 that probe is on the 64-byte unaligned 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. Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.ibm.com> Acked-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> Acked-by: Sandipan Das <sandipan@linux.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20210311091538.368590-1-ravi.bangoria@linux.ibm.com
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@ -41,6 +41,13 @@ int arch_uprobe_analyze_insn(struct arch_uprobe *auprobe,
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if (addr & 0x03)
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return -EINVAL;
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if (cpu_has_feature(CPU_FTR_ARCH_31) &&
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ppc_inst_prefixed(auprobe->insn) &&
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(addr & 0x3f) == 60) {
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pr_info_ratelimited("Cannot register a uprobe on 64 byte unaligned prefixed instruction\n");
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return -EINVAL;
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}
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return 0;
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}
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