From: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
To: Russell King - ARM Linux admin <linux@armlinux.org.uk>
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Subject: Re: [PATCH 1/3] module: Rename module_alloc() to text_alloc() and move to kernel proper
Date: Tue, 14 Jul 2020 12:49:28 +0300 [thread overview]
Message-ID: <20200714094928.GA1442951@linux.intel.com> (raw)
In-Reply-To: <20200713183410.GY1551@shell.armlinux.org.uk>
On Mon, Jul 13, 2020 at 07:34:10PM +0100, Russell King - ARM Linux admin wrote:
> On Mon, Jul 13, 2020 at 09:19:37PM +0300, Jarkko Sakkinen wrote:
> > Rename module_alloc() to text_alloc() and module_memfree() to
> > text_memfree(), and move them to kernel/text.c, which is unconditionally
> > compiled to the kernel proper. This allows kprobes, ftrace and bpf to
> > allocate space for executable code without requiring to compile the modules
> > support (CONFIG_MODULES=y) in.
>
> I'm not sure this is a good idea for 32-bit ARM. The code you are
> moving for 32-bit ARM is quite specific to module use in that it also
> supports allocating from the vmalloc area, where the module code
> knows to add PLT entries.
>
> If the other proposed users of this text_alloc() do not have the logic
> to add PLT entries when branches between kernel code and this
> allocation are not reachable by, e.g. a 26-bit signed offset for 32-bit
> ARM code, then this code is not suitable for that use.
My intention is to use this in kprobes code in the place of
module_alloc(). I'm not sure why moving this code out of the module
subsystem could possibly break anything. Unfortunately I forgot to add
covere letter to my series. Sending v2 with that to explain my use case
for this.
/Jarkko
next prev parent reply other threads:[~2020-07-14 10:41 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-13 18:19 [PATCH 1/3] module: Rename module_alloc() to text_alloc() and move to kernel proper Jarkko Sakkinen
2020-07-13 18:34 ` Russell King - ARM Linux admin
2020-07-14 9:49 ` Jarkko Sakkinen [this message]
2020-07-14 9:53 ` Russell King - ARM Linux admin
2020-07-14 11:43 ` Jarkko Sakkinen
2020-07-13 19:49 ` Ard Biesheuvel
2020-07-14 2:04 ` Steven Rostedt
2020-07-14 6:35 ` Ard Biesheuvel
2020-07-14 9:52 ` Jarkko Sakkinen
2020-07-14 10:17 ` Ard Biesheuvel
2020-07-14 10:33 ` Russell King - ARM Linux admin
2020-07-14 11:45 ` Peter Zijlstra
2020-07-14 12:11 ` Jarkko Sakkinen
2020-07-14 11:55 ` Jarkko Sakkinen
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