Re: [RFC v2 0/4] vmalloc_exec for modules and BPF programs

[Song Liu <songliubraving@meta.com>]

Hi Peter,

> On Oct 7, 2022, at 4:43 PM, Song Liu <song@kernel.org> wrote:
> 
> Changes RFC v1 => RFC v2:
> 1. Major rewrite of the logic of vmalloc_exec and vfree_exec. They now
>   work fine with BPF programs (patch 1, 2, 4). But module side (patch 3)
>   still need some work.
> 
> This set is a prototype that allows dynamic kernel text (modules, bpf
> programs, various trampolines, etc.) to share huge pages. The idea is
> similar to Peter's suggestion in [1]. Please refer to each patch for
> more detais.
> 
> The ultimate goal is to only host kernel text in 2MB pages (for x86_64).
> 
> Please share your comments on this.
> 
> Thanks!
> 
> [1] https://lore.kernel.org/bpf/Ys6cWUMHO8XwyYgr@hirez.programming.kicks-ass.net/
> [2] RFC v1: https://lore.kernel.org/linux-mm/20220818224218.2399791-3-song@kernel.org/T/

Could you please share your comments on this version? Is this the 
right direction to move this work?

Thanks,
Song

> 
> Song Liu (4):
>  vmalloc: introduce vmalloc_exec and vfree_exec
>  bpf: use vmalloc_exec
>  modules, x86: use vmalloc_exec for module core
>  vmalloc_exec: share a huge page with kernel text
> 
> arch/x86/Kconfig              |   1 +
> arch/x86/kernel/alternative.c |  30 +++-
> arch/x86/kernel/module.c      |   1 +
> arch/x86/mm/init_64.c         |   3 +-
> include/linux/vmalloc.h       |   2 +
> kernel/bpf/core.c             | 155 ++----------------
> kernel/module/main.c          |  23 +--
> kernel/module/strict_rwx.c    |   3 -
> kernel/trace/ftrace.c         |   3 +-
> mm/nommu.c                    |   7 +
> mm/vmalloc.c                  | 296 ++++++++++++++++++++++++++++++++++
> 11 files changed, 358 insertions(+), 166 deletions(-)
> 
> --
> 2.30.2