Messages in this thread | | | Date | Fri, 7 Jun 2019 10:52:59 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH 12/15] x86/static_call: Add out-of-line static call implementation |
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On Fri, Jun 07, 2019 at 10:38:46AM +0200, Peter Zijlstra wrote: > On Fri, Jun 07, 2019 at 06:13:58AM +0000, Nadav Amit wrote: > > > On Jun 5, 2019, at 6:08 AM, Peter Zijlstra <peterz@infradead.org> wrote: > > > > +void arch_static_call_transform(void *site, void *tramp, void *func) > > > +{ > > > + unsigned char opcodes[CALL_INSN_SIZE]; > > > + unsigned char insn_opcode; > > > + unsigned long insn; > > > + s32 dest_relative; > > > + > > > + mutex_lock(&text_mutex); > > > + > > > + insn = (unsigned long)tramp; > > > + > > > + insn_opcode = *(unsigned char *)insn; > > > + if (insn_opcode != 0xE9) { > > > + WARN_ONCE(1, "unexpected static call insn opcode 0x%x at %pS", > > > + insn_opcode, (void *)insn); > > > + goto unlock; > > > > This might happen if a kprobe is installed on the call, no? > > > > I don’t know if you want to be more gentle handling of this case (or perhaps > > modify can_probe() to prevent such a case). > > > > yuck.. yes, that's something that needs consideration.
For jump_label this is avoided by jump_label_text_reserved(), I'm thinking static_call should do the same.
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