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    SubjectRe: [PATCH] kprobes: Enable tracing for mololithic kernel images
    On Wed, Jun 08, 2022 at 10:35:42AM +0800, Guo Ren wrote:
    > .
    >
    > On Wed, Jun 8, 2022 at 8:02 AM Jarkko Sakkinen <jarkko@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.sakkinen@linux.intel.com/

    BR, Jarkko

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