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Date: Tue, 14 Jul 2020 12:49:28 +0300
From: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
To: Russell King - ARM Linux admin <linux@armlinux.org.uk>
Subject: Re: [PATCH 1/3] module: Rename module_alloc() to text_alloc() and
 move to kernel proper
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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