[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <YxiXCf1LcFqj5di6@hirez.programming.kicks-ass.net>
Date: Wed, 7 Sep 2022 15:05:13 +0200
From: Peter Zijlstra <peterz@...radead.org>
To: "Masami Hiramatsu (Google)" <mhiramat@...nel.org>
Cc: Steven Rostedt <rostedt@...dmis.org>,
Ingo Molnar <mingo@...nel.org>,
Suleiman Souhlal <suleiman@...gle.com>,
bpf <bpf@...r.kernel.org>, linux-kernel@...r.kernel.org,
Borislav Petkov <bp@...e.de>,
Josh Poimboeuf <jpoimboe@...nel.org>, x86@...nel.org
Subject: Re: [PATCH 1/2] x86/kprobes: Fix kprobes instruction boudary check
with CONFIG_RETHUNK
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.
Powered by blists - more mailing lists