From d943bc742a6aabc578b6b62a713ceedf8bf16623 Mon Sep 17 00:00:00 2001 From: Ravi Bangoria Date: Thu, 11 Mar 2021 14:45:38 +0530 Subject: [PATCH] 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 Acked-by: Naveen N. Rao Acked-by: Sandipan Das Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20210311091538.368590-1-ravi.bangoria@linux.ibm.com --- arch/powerpc/kernel/uprobes.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/arch/powerpc/kernel/uprobes.c b/arch/powerpc/kernel/uprobes.c index e8a6371..186f69b1 100644 --- a/arch/powerpc/kernel/uprobes.c +++ b/arch/powerpc/kernel/uprobes.c @@ -41,6 +41,13 @@ int arch_uprobe_analyze_insn(struct arch_uprobe *auprobe, if (addr & 0x03) return -EINVAL; + if (cpu_has_feature(CPU_FTR_ARCH_31) && + ppc_inst_prefixed(auprobe->insn) && + (addr & 0x3f) == 60) { + pr_info_ratelimited("Cannot register a uprobe on 64 byte unaligned prefixed instruction\n"); + return -EINVAL; + } + return 0; } -- 2.7.4