[PATCH v2 0/8] x86/module: use large ROX pages for text allocations

Mike Rapoport
2024-08-26T07:03:43Z

Hi,

These patches add support for using large ROX pages for allocations of
executable memory on x86.

They address Andy's comments [1] about having executable mappings for code
that was not completely formed.

The approach taken is to allocate ROX memory along with writable but not
executable memory and use the writable copy to perform relocations and
alternatives patching. After the module text gets into its final shape, the
contents of the writable memory is copied into the actual ROX location
using text poking.

The allocations of the ROX memory use vmalloc(VMAP_ALLOW_HUGE_MAP) to
allocate PMD aligned memory, fill that memory with invalid instructions and
in the end remap it as ROX. Portions of these large pages are handed out to
execmem_alloc() callers without any changes to the permissions. When the
memory is freed with execmem_free() it is invalidated again so that it
won't contain stale instructions.

The module memory allocation, x86 code dealing with relocations and
alternatives patching take into account the existence of the two copies,
the writable memory and the ROX memory at the actual allocated virtual
address.

The patches are available at git:
https://git.kernel.org/pub/scm/linux/kernel/git/rppt/linux.git/log/?h=execmem/x86-rox/v2

[1] https://lore.kernel.org/all/a17c65c6-863f-4026-9c6f-a04b659e9ab4@app.fastmail.com

Since RFC: https://lore.kernel.org/all/20240411160526.2093408-1-rppt@kernel.org
* update changelog about HUGE_VMAP allocations (Christophe)
* move module_writable_address() from x86 to modules core (Ingo)
* rename execmem_invalidate() to execmem_fill_trapping_insns() (Peter)
* call alternatives_smp_unlock() after module text in-place is up to
date (Nadav)

Mike Rapoport (Microsoft) (7):
mm: vmalloc: group declarations depending on CONFIG_MMU together
mm: vmalloc: don't account for number of nodes for HUGE_VMAP allocations
asm-generic: introduce text-patching.h
module: prepare to handle ROX allocations for text
x86/module: perpare module loading for ROX allocations of text
execmem: add support for cache of large ROX pages
x86/module: enable ROX caches for module text

Song Liu (1):
ftrace: Add swap_func to ftrace_process_locs()

arch/alpha/include/asm/Kbuild | 1 +
arch/arc/include/asm/Kbuild | 1 +
.../include/asm/{patch.h => text-patching.h} | 0
arch/arm/kernel/ftrace.c | 2 +-
arch/arm/kernel/jump_label.c | 2 +-
arch/arm/kernel/kgdb.c | 2 +-
arch/arm/kernel/patch.c | 2 +-
arch/arm/probes/kprobes/core.c | 2 +-
arch/arm/probes/kprobes/opt-arm.c | 2 +-
.../asm/{patching.h => text-patching.h} | 0
arch/arm64/kernel/ftrace.c | 2 +-
arch/arm64/kernel/jump_label.c | 2 +-
arch/arm64/kernel/kgdb.c | 2 +-
arch/arm64/kernel/patching.c | 2 +-
arch/arm64/kernel/probes/kprobes.c | 2 +-
arch/arm64/kernel/traps.c | 2 +-
arch/arm64/net/bpf_jit_comp.c | 2 +-
arch/csky/include/asm/Kbuild | 1 +
arch/hexagon/include/asm/Kbuild | 1 +
arch/loongarch/include/asm/Kbuild | 1 +
arch/m68k/include/asm/Kbuild | 1 +
arch/microblaze/include/asm/Kbuild | 1 +
arch/mips/include/asm/Kbuild | 1 +
arch/nios2/include/asm/Kbuild | 1 +
arch/openrisc/include/asm/Kbuild | 1 +
.../include/asm/{patch.h => text-patching.h} | 0
arch/parisc/kernel/ftrace.c | 2 +-
arch/parisc/kernel/jump_label.c | 2 +-
arch/parisc/kernel/kgdb.c | 2 +-
arch/parisc/kernel/kprobes.c | 2 +-
arch/parisc/kernel/patch.c | 2 +-
arch/powerpc/include/asm/kprobes.h | 2 +-
.../asm/{code-patching.h => text-patching.h} | 0
arch/powerpc/kernel/crash_dump.c | 2 +-
arch/powerpc/kernel/epapr_paravirt.c | 2 +-
arch/powerpc/kernel/jump_label.c | 2 +-
arch/powerpc/kernel/kgdb.c | 2 +-
arch/powerpc/kernel/kprobes.c | 2 +-
arch/powerpc/kernel/module_32.c | 2 +-
arch/powerpc/kernel/module_64.c | 2 +-
arch/powerpc/kernel/optprobes.c | 2 +-
arch/powerpc/kernel/process.c | 2 +-
arch/powerpc/kernel/security.c | 2 +-
arch/powerpc/kernel/setup_32.c | 2 +-
arch/powerpc/kernel/setup_64.c | 2 +-
arch/powerpc/kernel/static_call.c | 2 +-
arch/powerpc/kernel/trace/ftrace.c | 2 +-
arch/powerpc/kernel/trace/ftrace_64_pg.c | 2 +-
arch/powerpc/lib/code-patching.c | 2 +-
arch/powerpc/lib/feature-fixups.c | 2 +-
arch/powerpc/lib/test-code-patching.c | 2 +-
arch/powerpc/lib/test_emulate_step.c | 2 +-
arch/powerpc/mm/book3s32/mmu.c | 2 +-
arch/powerpc/mm/book3s64/hash_utils.c | 2 +-
arch/powerpc/mm/book3s64/slb.c | 2 +-
arch/powerpc/mm/kasan/init_32.c | 2 +-
arch/powerpc/mm/mem.c | 2 +-
arch/powerpc/mm/nohash/44x.c | 2 +-
arch/powerpc/mm/nohash/book3e_pgtable.c | 2 +-
arch/powerpc/mm/nohash/tlb.c | 2 +-
arch/powerpc/net/bpf_jit_comp.c | 2 +-
arch/powerpc/perf/8xx-pmu.c | 2 +-
arch/powerpc/perf/core-book3s.c | 2 +-
arch/powerpc/platforms/85xx/smp.c | 2 +-
arch/powerpc/platforms/86xx/mpc86xx_smp.c | 2 +-
arch/powerpc/platforms/cell/smp.c | 2 +-
arch/powerpc/platforms/powermac/smp.c | 2 +-
arch/powerpc/platforms/powernv/idle.c | 2 +-
arch/powerpc/platforms/powernv/smp.c | 2 +-
arch/powerpc/platforms/pseries/smp.c | 2 +-
arch/powerpc/xmon/xmon.c | 2 +-
arch/riscv/errata/andes/errata.c | 2 +-
arch/riscv/errata/sifive/errata.c | 2 +-
arch/riscv/errata/thead/errata.c | 2 +-
.../include/asm/{patch.h => text-patching.h} | 0
arch/riscv/include/asm/uprobes.h | 2 +-
arch/riscv/kernel/alternative.c | 2 +-
arch/riscv/kernel/cpufeature.c | 3 +-
arch/riscv/kernel/ftrace.c | 2 +-
arch/riscv/kernel/jump_label.c | 2 +-
arch/riscv/kernel/patch.c | 2 +-
arch/riscv/kernel/probes/kprobes.c | 2 +-
arch/riscv/net/bpf_jit_comp64.c | 2 +-
arch/riscv/net/bpf_jit_core.c | 2 +-
arch/sh/include/asm/Kbuild | 1 +
arch/sparc/include/asm/Kbuild | 1 +
arch/um/kernel/um_arch.c | 16 +-
arch/x86/entry/vdso/vma.c | 3 +-
arch/x86/include/asm/alternative.h | 14 +-
arch/x86/include/asm/text-patching.h | 1 +
arch/x86/kernel/alternative.c | 160 ++++++----
arch/x86/kernel/ftrace.c | 41 ++-
arch/x86/kernel/module.c | 45 ++-
arch/x86/mm/init.c | 26 +-
arch/xtensa/include/asm/Kbuild | 1 +
include/asm-generic/text-patching.h | 5 +
include/linux/execmem.h | 25 ++
include/linux/ftrace.h | 2 +
include/linux/module.h | 9 +
include/linux/moduleloader.h | 4 +
include/linux/text-patching.h | 15 +
include/linux/vmalloc.h | 60 ++--
kernel/module/main.c | 77 ++++-
kernel/module/strict_rwx.c | 3 +
kernel/trace/ftrace.c | 13 +-
mm/execmem.c | 301 +++++++++++++++++-
mm/vmalloc.c | 9 +-
107 files changed, 746 insertions(+), 235 deletions(-)
rename arch/arm/include/asm/{patch.h => text-patching.h} (100%)
rename arch/arm64/include/asm/{patching.h => text-patching.h} (100%)
rename arch/parisc/include/asm/{patch.h => text-patching.h} (100%)
rename arch/powerpc/include/asm/{code-patching.h => text-patching.h} (100%)
rename arch/riscv/include/asm/{patch.h => text-patching.h} (100%)
create mode 100644 include/asm-generic/text-patching.h
create mode 100644 include/linux/text-patching.h

base-commit: 47ac09b91befbb6a235ab620c32af719f8208399
--
2.43.0