All of lore.kernel.org
 help / color / mirror / Atom feed
* [PATCH 0/6] arch, mm/execmem: resolve confusion about set_direct_map_valid_noflush()
@ 2026-08-16 10:59 ` Mike Rapoport (Microsoft)
  0 siblings, 0 replies; 20+ messages in thread
From: Mike Rapoport (Microsoft) @ 2026-08-16 10:59 UTC (permalink / raw)
  To: Andrew Morton
  Cc: Adrian Barnaś, Albert Ou, Alexander Gordeev, Alexandre Ghiti,
	Andy Lutomirski, Borislav Petkov, Brendan Jackman,
	Catalin Marinas, Christian Borntraeger, Dave Hansen,
	David Hildenbrand, Gerald Schaefer, Heiko Carstens, Huacai Chen,
	Ingo Molnar, Len Brown, Mike Rapoport, Palmer Dabbelt,
	Paul Walmsley, Pavel Machek, Peter Zijlstra, H. Peter Anvin,
	Rafael J. Wysocki, Ryan Roberts, Sven Schnelle, Thomas Gleixner,
	Uladzislau Rezki, Vasily Gorbik, WANG Xuerui, Will Deacon, x86,
	linux-arm-kernel, linux-kernel, linux-mm, linux-pm, linux-riscv,
	linux-s390, loongarch

Recent discussion about implementation of execmem's ROX caches on arm64
revealed a confusion about how set_direct_map_valid_noflush()
implemented on different architectures.

On arm64 it sets or clears the PTE_VALID bit marking a PTE as present or
not present.

On other architectures it's a range version of
set_direct_map_invalid_noflush() and set_direct_map_default_noflush()

Unlike arm64::set_direct_map_valid_noflush(),
set_direct_map_default_noflush() not only marks PTE as present, but also
sets its default protection mode.

Other than that, initial design of execmem ROX caches didn't rely on
restoration of large mappings that's now available on x86, but
completely removed the memory allocated for the ROX cache from the
direct map to ensure that large mappings are not split. This precluded
usage of VM_FLUSH_RESET_PERMS for the ROX cache allocations and required
execmem to implement manipulation of the direct map alias.

Current implementation of ROX caches does not remove the direct map
alias but simply calls set_memory_rox() that updates the permissions in
both vmalloc address space and the direct map and relies on
collapse_large_pages() in x86 CPA to keep large mappings.

This allow using VM_FLUSH_RESET_PERMS for execmem ROX cache allocations
with small adjustments to set_direct_map APIs and vmalloc::reset_perms()
behaviour: adding number of pages parameter to set_direct_map APIs and
making resetting of the direct map permissions in vmalloc VMAP_HUGE
friendly.

Implement these adjustments, make execmem always use
VM_FLUSH_RESET_PERMS and revert set_direct_map_valid_noflush() changes.

[1] https://lore.kernel.org/all/20260611130144.1385343-4-abarnas@google.com

---
Mike Rapoport (Microsoft) (6):
      set_memory: add number of pages parameter to set_direct_map APIs
      mm/vmalloc: set area's page_order after allocation succeeds
      mm/vmalloc: constify vm parameter of get_vm_area_page_order()
      mm/vmalloc: make set_area_direct_map HUGE_VMAP friendly
      mm/execmem: use VM_FLUSH_RESET_PERMS for ROX cache allocations
      Revert "arch: introduce set_direct_map_valid_noflush()"

 arch/arm64/include/asm/set_memory.h     |  5 ++--
 arch/arm64/mm/pageattr.c                | 24 ++++---------------
 arch/loongarch/include/asm/set_memory.h |  5 ++--
 arch/loongarch/mm/pageattr.c            | 27 ++++-----------------
 arch/riscv/include/asm/set_memory.h     |  5 ++--
 arch/riscv/mm/pageattr.c                | 23 ++++--------------
 arch/s390/include/asm/set_memory.h      |  5 ++--
 arch/s390/mm/pageattr.c                 | 20 ++++------------
 arch/x86/include/asm/set_memory.h       |  5 ++--
 arch/x86/mm/pat/set_memory.c            | 16 ++++---------
 include/linux/set_memory.h              | 12 ++++------
 kernel/power/snapshot.c                 |  4 ++--
 mm/execmem.c                            | 42 ++++++---------------------------
 mm/secretmem.c                          |  6 ++---
 mm/vmalloc.c                            | 31 ++++++++++++++++--------
 mm/vmalloc.h                            |  2 +-
 16 files changed, 68 insertions(+), 164 deletions(-)
---
base-commit: 1029098ee3275ea5b78e329ce132262affa2f8cc
change-id: 20260816-execmem-set-vm-perms-v0-2-bae847a4f64f

--
Sincerely yours,
Mike.


^ permalink raw reply	[flat|nested] 20+ messages in thread

end of thread, other threads:[~2026-08-16 11:17 UTC | newest]

Thread overview: 20+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2026-08-16 10:59 [PATCH 0/6] arch, mm/execmem: resolve confusion about set_direct_map_valid_noflush() Mike Rapoport (Microsoft)
2026-08-16 10:59 ` Mike Rapoport (Microsoft)
2026-08-16 10:59 ` [PATCH 1/6] set_memory: add number of pages parameter to set_direct_map APIs Mike Rapoport (Microsoft)
2026-08-16 10:59   ` Mike Rapoport (Microsoft)
2026-08-16 11:12   ` sashiko-bot
2026-08-16 10:59 ` [PATCH 2/6] mm/vmalloc: set area's page_order after allocation succeeds Mike Rapoport (Microsoft)
2026-08-16 10:59   ` Mike Rapoport (Microsoft)
2026-08-16 11:08   ` sashiko-bot
2026-08-16 10:59 ` [PATCH 3/6] mm/vmalloc: constify vm parameter of get_vm_area_page_order() Mike Rapoport (Microsoft)
2026-08-16 10:59   ` Mike Rapoport (Microsoft)
2026-08-16 11:03   ` sashiko-bot
2026-08-16 10:59 ` [PATCH 4/6] mm/vmalloc: make set_area_direct_map HUGE_VMAP friendly Mike Rapoport (Microsoft)
2026-08-16 10:59   ` Mike Rapoport (Microsoft)
2026-08-16 11:10   ` sashiko-bot
2026-08-16 10:59 ` [PATCH 5/6] mm/execmem: use VM_FLUSH_RESET_PERMS for ROX cache allocations Mike Rapoport (Microsoft)
2026-08-16 10:59   ` Mike Rapoport (Microsoft)
2026-08-16 11:17   ` sashiko-bot
2026-08-16 10:59 ` [PATCH 6/6] Revert "arch: introduce set_direct_map_valid_noflush()" Mike Rapoport (Microsoft)
2026-08-16 10:59   ` Mike Rapoport (Microsoft)
2026-08-16 11:03   ` sashiko-bot

This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.