Thread (55 messages) 55 messages, 10 authors, 2023-07-20

Re: [PATCH 12/13] x86/jitalloc: prepare to allocate exectuatble memory as ROX

From: Kent Overstreet <kent.overstreet@linux.dev>
Date: 2023-06-04 21:47:51
Also in: bpf, linux-arm-kernel, linux-mips, linux-modules, linux-riscv, linux-s390, linux-trace-kernel, linuxppc-dev, lkml, loongarch, sparclinux

On Thu, Jun 01, 2023 at 08:50:39PM +0000, Edgecombe, Rick P wrote:
quoted
Ahh! Thanks for that; perhaps the comment in text_poke() about IPIs
could be a bit clearer.

What is it (if anything) you don't like about text_poke() then? It
looks
like it's doing broadly similar things to kmap_local(), so should be
in the same ballpark from a performance POV?
The way text_poke() is used here, it is creating a new writable alias
and flushing it for *each* write to the module (like for each write of
an individual relocation, etc). I was just thinking it might warrant
some batching or something.
Ah, I see. A kmap_local type interface might get us that kind of
batching, if it supported mapping compound pages - currently kmap_local
still only maps single pages, but with folios getting plumbed around I
assume someone will make it handle compound pages eventually.
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