Le 08/06/2022 à 18:12, Song Liu a écrit : > On Wed, Jun 8, 2022 at 7:21 AM Masami Hiramatsu <mhira...@kernel.org> wrote: >> >> Hi Jarkko, >> >> On Wed, 8 Jun 2022 08:25:38 +0300 >> Jarkko Sakkinen <jar...@kernel.org> wrote: >> >>> On Wed, Jun 08, 2022 at 10:35:42AM +0800, Guo Ren wrote: >>>> . >>>> >>>> On Wed, Jun 8, 2022 at 8:02 AM Jarkko Sakkinen <jar...@profian.com> wrote: >>>>> >>>>> Tracing with kprobes while running a monolithic kernel is currently >>>>> impossible because CONFIG_KPROBES is dependent of CONFIG_MODULES. This >>>>> dependency is a result of kprobes code using the module allocator for the >>>>> trampoline code. >>>>> >>>>> Detaching kprobes from modules helps to squeeze down the user space, >>>>> e.g. when developing new core kernel features, while still having all >>>>> the nice tracing capabilities. >>>>> >>>>> For kernel/ and arch/*, move module_alloc() and module_memfree() to >>>>> module_alloc.c, and compile as part of vmlinux when either CONFIG_MODULES >>>>> or CONFIG_KPROBES is enabled. In addition, flag kernel module specific >>>>> code with CONFIG_MODULES. >>>>> >>>>> As the result, kprobes can be used with a monolithic kernel. >>>> It's strange when MODULES is n, but vmlinux still obtains module_alloc. >>>> >>>> Maybe we need a kprobe_alloc, right? >>> >>> Perhaps not the best name but at least it documents the fact that >>> they use the same allocator. >>> >>> Few years ago I carved up something "half-way there" for kprobes, >>> and I used the name text_alloc() [*]. >>> >>> [*] >>> https://lore.kernel.org/all/20200724050553.1724168-1-jarkko.sakki...@linux.intel.com/ >> >> Yeah, I remember that. Thank you for updating your patch! >> I think the idea (split module_alloc() from CONFIG_MODULE) is good to me. >> If module support maintainers think this name is not good, you may be >> able to rename it as text_alloc() and make the module_alloc() as a >> wrapper of it. > > IIUC, most users of module_alloc() use it to allocate memory for text, except > that module code uses it for both text and data. Therefore, I guess calling it > text_alloc() is not 100% accurate until we change the module code (to use > a different API to allocate memory for data).
When CONFIG_ARCH_WANTS_MODULES_DATA_IN_VMALLOC, module code uses module_alloc() for text and vmalloc() for data, see function move_module() in kernel/module/main.c > > Thanks, > Song > >> >> Acked-by: Masami Hiramatsu (Google) <mhira...@kernel.org> >> for kprobe side. >> >> Thank you, >> >> -- >> Masami Hiramatsu (Google) <mhira...@kernel.org>
