Hi Jisheng, On Wed, 14 Apr 2021 15:27:28 +0800 Jisheng Zhang <jisheng.zh...@synaptics.com> wrote:
\ > > > > On Tue, 13 Apr 2021 18:03:24 +0800 > > Jisheng Zhang <jisheng.zh...@synaptics.com> wrote: > > > > > Use the __vmalloc_node_range() to simplify x86's alloc_insn_page() > > > implementation. > > > > Have you checked this is equivarent to the original code on all > > architecture? IIRC, some arch has a special module_alloc(), > > > Indeed, this isn't equivarent to the original code. FWICT, the differences > > on x86 are: > > > 1) module_alloc() allocates a special vmalloc range > > 2) module_alloc() randomizes the return address via. module_load_offset() > > 3) module_alloc() also supports kasan instrumentation by > > kasan_module_alloc() > > > But I'm not sure whether the above differences are useful for kprobes ss > > insn slot page or not. Take 1) for example, special range in module_alloc > > is due to relative jump limitation, modules need to call kernel .text. does > > kprobes ss ins slot needs this limitation too? > > Oops, I found this wonderful thread: > https://www.lkml.org/lkml/2020/7/28/1413 > > So kprobes ss ins slot page "must be in the range of relative branching only > for x86 and arm" Yes, at this moment. (Not sure we can introduce similar feature on other arch too) > > And Jarkko's "arch/x86: kprobes: Remove MODULES dependency" series look > much better. The last version is v5, I'm not sure whether Jarkko will > send new version to mainline the series. I hope so. If module_alloc() itself is implemented on the generic text_alloc(), I can replace the module_alloc() with text_alloc(). Thank you, -- Masami Hiramatsu <mhira...@kernel.org>
