Messages in this thread | | | Date | Wed, 7 Sep 2022 15:05:13 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH 1/2] x86/kprobes: Fix kprobes instruction boudary check with CONFIG_RETHUNK |
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On Wed, Sep 07, 2022 at 10:02:41AM +0200, Peter Zijlstra wrote:
> struct queue q; > > start = paddr - offset; > end = start + size; > push(&q, paddr - offset); > > while (start = pop(&q)) { > for_each_insn(&insn, start, end, buf) { > if (insn.kaddr == paddr) > return 1; > > target = insn_get_branch_addr(&insn); > if (target) > push(&q, target); > > if (dead_end_insn(&insn)) > break; > } > }
There is the very rare case of intra-function-calls; but I *think* they're all in noinstr/nokprobe code anyway.
For instance we have RSB stuffing code like:
.rept 16 call 1f; int3 1: .endr add $(BITS_PER_LONG/8) * 16, %_ASM_SP
And the proposed will be horribly confused by that. But like said; it should also never try and untangle it.
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