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Mark Brown 25d4054cc9 mm: make arch_get_unmapped_area() take vm_flags by default 
Patch series "mm: Care about shadow stack guard gap when getting an
unmapped area", v2.

As covered in the commit log for c44357c2e7 ("x86/mm: care about shadow
stack guard gap during placement") our current mmap() implementation does
not take care to ensure that a new mapping isn't placed with existing
mappings inside it's own guard gaps.  This is particularly important for
shadow stacks since if two shadow stacks end up getting placed adjacent to
each other then they can overflow into each other which weakens the
protection offered by the feature.

On x86 there is a custom arch_get_unmapped_area() which was updated by the
above commit to cover this case by specifying a start_gap for allocations
with VM_SHADOW_STACK.  Both arm64 and RISC-V have equivalent features and
use the generic implementation of arch_get_unmapped_area() so let's make
the equivalent change there so they also don't get shadow stack pages
placed without guard pages.  The arm64 and RISC-V shadow stack
implementations are currently on the list:

   https://lore.kernel.org/r/20240829-arm64-gcs-v12-0-42fec94743
   https://lore.kernel.org/lkml/20240403234054.2020347-1-debug@rivosinc.com/

Given the addition of the use of vm_flags in the generic implementation we
also simplify the set of possibilities that have to be dealt with in the
core code by making arch_get_unmapped_area() take vm_flags as standard. 
This is a bit invasive since the prototype change touches quite a few
architectures but since the parameter is ignored the change is
straightforward, the simplification for the generic code seems worth it.


This patch (of 3):

When we introduced arch_get_unmapped_area_vmflags() in 961148704a ("mm:
introduce arch_get_unmapped_area_vmflags()") we did so as part of properly
supporting guard pages for shadow stacks on x86_64, which uses a custom
arch_get_unmapped_area().  Equivalent features are also present on both
arm64 and RISC-V, both of which use the generic implementation of
arch_get_unmapped_area() and will require equivalent modification there. 
Rather than continue to deal with having two versions of the functions
let's bite the bullet and have all implementations of
arch_get_unmapped_area() take vm_flags as a parameter.

The new parameter is currently ignored by all implementations other than
x86.  The only caller that doesn't have a vm_flags available is
mm_get_unmapped_area(), as for the x86 implementation and the wrapper used
on other architectures this is modified to supply no flags.

No functional changes.

Link: https://lkml.kernel.org/r/20240904-mm-generic-shadow-stack-guard-v2-0-a46b8b6dc0ed@kernel.org
Link: https://lkml.kernel.org/r/20240904-mm-generic-shadow-stack-guard-v2-1-a46b8b6dc0ed@kernel.org
Signed-off-by: Mark Brown <broonie@kernel.org>
Acked-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Acked-by: Helge Deller <deller@gmx.de>	[parisc]
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Chris Zankel <chris@zankel.net>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: "Edgecombe, Rick P" <rick.p.edgecombe@intel.com>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Guo Ren <guoren@kernel.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Naveen N Rao <naveen@kernel.org>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Richard Henderson <richard.henderson@linaro.org>
Cc: Rich Felker <dalias@libc.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vineet Gupta <vgupta@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: WANG Xuerui <kernel@xen0n.name>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-09-09 16:39:13 -07:00
arch mm: make arch_get_unmapped_area() take vm_flags by default 2024-09-09 16:39:13 -07:00
block block: fix detection of unsupported WRITE SAME in blkdev_issue_write_zeroes 2024-08-28 08:49:25 -06:00
certs kbuild: use $(src) instead of $(srctree)/$(src) for source directory 2024-05-10 04:34:52 +09:00
crypto crypto: testmgr - generate power-of-2 lengths more often 2024-07-13 11:50:28 +12:00
Documentation zram: support priority parameter in recompression 2024-09-09 16:39:12 -07:00
drivers zram: support priority parameter in recompression 2024-09-09 16:39:12 -07:00
fs mm,tmpfs: consider end of file write in shmem_is_huge 2024-09-09 16:39:12 -07:00
include mm: make arch_get_unmapped_area() take vm_flags by default 2024-09-09 16:39:13 -07:00
init mm: fix typo in Kconfig 2024-09-01 20:25:45 -07:00
io_uring io_uring/kbuf: return correct iovec count from classic buffer peek 2024-08-30 10:45:54 -06:00
ipc ipc/shm, mm: drop do_vma_munmap() 2024-09-03 21:15:52 -07:00
kernel sched/numa: Fix the vma scan starving issue 2024-09-03 21:15:56 -07:00
lib lib: zstd: fix null-deref in ZSTD_createCDict_advanced2() 2024-09-09 16:39:06 -07:00
LICENSES
mm mm: make arch_get_unmapped_area() take vm_flags by default 2024-09-09 16:39:13 -07:00
net Including fixes from bluetooth, wireless and netfilter. 2024-08-30 06:14:39 +12:00
rust Rust fixes for v6.11 2024-08-16 11:24:06 -07:00
samples kmemleak-test: add percpu leak 2024-09-01 20:25:50 -07:00
scripts kasan: simplify and clarify Makefile 2024-09-03 21:15:35 -07:00
security Merge branch 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/groeck/linux-staging 2024-09-01 09:18:48 +12:00
sound sound fixes for 6.11-rc6 2024-08-28 06:24:22 +12:00
tools selftests/mm: relax test to fail after 100 migration failures 2024-09-09 16:39:05 -07:00
usr initramfs: shorten cmd_initfs in usr/Makefile 2024-07-16 01:07:52 +09:00
virt KVM: x86: Disallow read-only memslots for SEV-ES and SEV-SNP (and TDX) 2024-08-14 12:28:24 -04:00
.clang-format Docs: Move clang-format from process/ to dev-tools/ 2024-06-26 16:36:00 -06:00
.cocciconfig
.editorconfig .editorconfig: remove trim_trailing_whitespace option 2024-06-13 16:47:52 +02:00
.get_maintainer.ignore Add Jeff Kirsher to .get_maintainer.ignore 2024-03-08 11:36:54 +00:00
.gitattributes
.gitignore kbuild: add script and target to generate pacman package 2024-07-22 01:24:22 +09:00
.mailmap ARM: SoC fixes for 6.11, part 2 2024-09-01 06:42:13 +12:00
.rustfmt.toml
COPYING
CREDITS tracing: Update of MAINTAINERS and CREDITS file 2024-07-18 14:08:42 -07:00
Kbuild
Kconfig
MAINTAINERS tools: add skeleton code for userland testing of VMA logic 2024-09-01 20:25:55 -07:00
Makefile Linux 6.11-rc6 2024-09-01 19:46:02 +12:00
README README: Fix spelling 2024-03-18 03:36:32 -06:00

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 reStructuredText 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.