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Filename Latest commit message Latest commit date
James Morse 2f97967503 arm64: kpti: Update arm64_kernel_use_ng_mappings() when forced on
Since commit b89d82ef01 ("arm64: kpti: Avoid rewriting early page
tables when KASLR is enabled"), a kernel built with CONFIG_RANDOMIZE_BASE
can decide early whether to use non-global mappings by checking the
kaslr_offset().

A kernel built without CONFIG_RANDOMIZE_BASE, instead checks the
cpufeature static-key.

This leaves a gap where CONFIG_RANDOMIZE_BASE was enabled, no
kaslr seed was provided, but kpti was forced on using the cmdline
option.

When the decision is made late, kpti_install_ng_mappings() will re-write
the page tables, but arm64_kernel_use_ng_mappings()'s value does not
change as it only tests the cpufeature static-key if
CONFIG_RANDOMIZE_BASE is disabled.
This function influences PROT_DEFAULT via PTE_MAYBE_NG, and causes
pgattr_change_is_safe() to catch nG->G transitions when the unchanged
PROT_DEFAULT is used as part of PAGE_KERNEL_RO:
[    1.942255] alternatives: patching kernel code
[    1.998288] ------------[ cut here ]------------
[    2.000693] kernel BUG at arch/arm64/mm/mmu.c:165!
[    2.019215] Internal error: Oops - BUG: 0 [#1] PREEMPT SMP
[    2.020257] Modules linked in:
[    2.020807] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.0.0-rc2 #51
[    2.021917] Hardware name: linux,dummy-virt (DT)
[    2.022790] pstate: 40000005 (nZcv daif -PAN -UAO)
[    2.023742] pc : __create_pgd_mapping+0x508/0x6d0
[    2.024671] lr : __create_pgd_mapping+0x500/0x6d0

[    2.058059] Process swapper/0 (pid: 1, stack limit = 0x(____ptrval____))
[    2.059369] Call trace:
[    2.059845]  __create_pgd_mapping+0x508/0x6d0
[    2.060684]  update_mapping_prot+0x48/0xd0
[    2.061477]  mark_linear_text_alias_ro+0xdc/0xe4
[    2.070502]  smp_cpus_done+0x90/0x98
[    2.071216]  smp_init+0x100/0x114
[    2.071878]  kernel_init_freeable+0xd4/0x220
[    2.072750]  kernel_init+0x10/0x100
[    2.073455]  ret_from_fork+0x10/0x18

[    2.075414] ---[ end trace 3572f3a7782292de ]---
[    2.076389] Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b

If arm64_kernel_unmapped_at_el0() is true, arm64_kernel_use_ng_mappings()
should also be true.

Signed-off-by: James Morse <james.morse@arm.com>
CC: Ard Biesheuvel <ard.biesheuvel@linaro.org>
CC: John Garry <john.garry@huawei.com>
CC: Will Deacon <will.deacon@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
2019-01-16 11:55:11 +00:00
arch arm64: kpti: Update arm64_kernel_use_ng_mappings() when forced on 2019-01-16 11:55:11 +00:00
block block: fix kerneldoc comment for blk_attempt_plug_merge() 2019-01-09 15:29:08 -07:00
certs
crypto
Documentation ARM: SoC fixes 2019-01-14 10:34:14 +12:00
drivers ARM: SoC fixes 2019-01-14 10:34:14 +12:00
firmware
fs for-5.0-rc1-tag 2019-01-14 05:55:51 +12:00
include ARM: SoC fixes 2019-01-14 10:34:14 +12:00
init
ipc
kernel kernel/sys.c: Clarify that UNAME26 does not generate unique versions anymore 2019-01-14 10:38:03 +12:00
lib Kbuild late updates for v4.21 2019-01-06 16:33:10 -08:00
LICENSES
mm mm/mmu_notifier: mm/rmap.c: Fix a mmu_notifier range bug in try_to_unmap_one 2019-01-10 02:58:21 -08:00
net libceph: allow setting abort_on_full for rbd 2019-01-07 22:47:48 +01:00
samples samples/seccomp: Fix 32-bit build 2019-01-08 07:45:01 +01:00
scripts remove dma_zalloc_coherent 2019-01-12 10:52:40 -08:00
security
sound remove dma_zalloc_coherent 2019-01-12 10:52:40 -08:00
tools Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-01-11 09:44:05 -08:00
usr
virt KVM: validate userspace input in kvm_clear_dirty_log_protect() 2019-01-11 18:38:07 +01:00
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap
COPYING
CREDITS
Kbuild kbuild: use assignment instead of define ... endef for filechk_* rules 2019-01-06 10:22:35 +09:00
Kconfig
MAINTAINERS Staging driver fixes for 5.0-rc2 2019-01-14 05:49:35 +12:00
Makefile Linux 5.0-rc2 2019-01-14 10:41:12 +12:00
README

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.