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

[Song Liu <song@kernel.org>]

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/

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(-)

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2.30.2