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Add the listns() system call to all architectures.
Link: https://patch.msgid.link/20251029-work-namespace-nstree-listns-v4-20-2e6f823ebdc0@kernel.org
Tested-by: syzbot@syzkaller.appspotmail.com
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Introduce file_getattr() and file_setattr() syscalls to manipulate inode
extended attributes. The syscalls takes pair of file descriptor and
pathname. Then it operates on inode opened accroding to openat()
semantics. The struct file_attr is passed to obtain/change extended
attributes.
This is an alternative to FS_IOC_FSSETXATTR ioctl with a difference
that file don't need to be open as we can reference it with a path
instead of fd. By having this we can manipulated inode extended
attributes not only on regular files but also on special ones. This
is not possible with FS_IOC_FSSETXATTR ioctl as with special files
we can not call ioctl() directly on the filesystem inode using fd.
This patch adds two new syscalls which allows userspace to get/set
extended inode attributes on special files by using parent directory
and a path - *at() like syscall.
CC: linux-api@vger.kernel.org
CC: linux-fsdevel@vger.kernel.org
CC: linux-xfs@vger.kernel.org
Signed-off-by: Andrey Albershteyn <aalbersh@kernel.org>
Link: https://lore.kernel.org/20250630-xattrat-syscall-v6-6-c4e3bc35227b@kernel.org
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Add open_tree_attr() which allow to atomically create a detached mount
tree and set mount options on it. If OPEN_TREE_CLONE is used this will
allow the creation of a detached mount with a new set of mount options
without it ever being exposed to userspace without that set of mount
options applied.
Link: https://lore.kernel.org/r/20250128-work-mnt_idmap-update-v2-v1-3-c25feb0d2eb3@kernel.org
Reviewed-by: "Seth Forshee (DigitalOcean)" <sforshee@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Add the four syscalls setxattrat(), getxattrat(), listxattrat() and
removexattrat(). Those can be used to operate on extended attributes,
especially security related ones, either relative to a pinned directory
or on a file descriptor without read access, avoiding a
/proc/<pid>/fd/<fd> detour, requiring a mounted procfs.
One use case will be setfiles(8) setting SELinux file contexts
("security.selinux") without race conditions and without a file
descriptor opened with read access requiring SELinux read permission.
Use the do_{name}at() pattern from fs/open.c.
Pass the value of the extended attribute, its length, and for
setxattrat(2) the command (XATTR_CREATE or XATTR_REPLACE) via an added
struct xattr_args to not exceed six syscall arguments and not
merging the AT_* and XATTR_* flags.
[AV: fixes by Christian Brauner folded in, the entire thing rebased on
top of {filename,file}_...xattr() primitives, treatment of empty
pathnames regularized. As the result, AT_EMPTY_PATH+NULL handling
is cheap, so f...(2) can use it]
Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
Link: https://lore.kernel.org/r/20240426162042.191916-1-cgoettsche@seltendoof.de
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Christian Brauner <brauner@kernel.org>
CC: x86@kernel.org
CC: linux-alpha@vger.kernel.org
CC: linux-kernel@vger.kernel.org
CC: linux-arm-kernel@lists.infradead.org
CC: linux-ia64@vger.kernel.org
CC: linux-m68k@lists.linux-m68k.org
CC: linux-mips@vger.kernel.org
CC: linux-parisc@vger.kernel.org
CC: linuxppc-dev@lists.ozlabs.org
CC: linux-s390@vger.kernel.org
CC: linux-sh@vger.kernel.org
CC: sparclinux@vger.kernel.org
CC: linux-fsdevel@vger.kernel.org
CC: audit@vger.kernel.org
CC: linux-arch@vger.kernel.org
CC: linux-api@vger.kernel.org
CC: linux-security-module@vger.kernel.org
CC: selinux@vger.kernel.org
[brauner: slight tweaks]
Signed-off-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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syscall*.tbl files were added to make it easier to check which system
calls are supported on each architecture and to check for their numbers.
Arm and x86 files lack Linux-syscall-note license exception present in
files for all other architectures.
Signed-off-by: Marcin Juszkiewicz <marcin@juszkiewicz.com.pl>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Cc: linux-arm-kernel@lists.infradead.org
Link: https://lore.kernel.org/r/20240229145101.553998-1-marcin@juszkiewicz.com.pl
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Patch series "Introduce mseal", v10.
This patchset proposes a new mseal() syscall for the Linux kernel.
In a nutshell, mseal() protects the VMAs of a given virtual memory range
against modifications, such as changes to their permission bits.
Modern CPUs support memory permissions, such as the read/write (RW) and
no-execute (NX) bits. Linux has supported NX since the release of kernel
version 2.6.8 in August 2004 [1]. The memory permission feature improves
the security stance on memory corruption bugs, as an attacker cannot
simply write to arbitrary memory and point the code to it. The memory
must be marked with the X bit, or else an exception will occur.
Internally, the kernel maintains the memory permissions in a data
structure called VMA (vm_area_struct). mseal() additionally protects the
VMA itself against modifications of the selected seal type.
Memory sealing is useful to mitigate memory corruption issues where a
corrupted pointer is passed to a memory management system. For example,
such an attacker primitive can break control-flow integrity guarantees
since read-only memory that is supposed to be trusted can become writable
or .text pages can get remapped. Memory sealing can automatically be
applied by the runtime loader to seal .text and .rodata pages and
applications can additionally seal security critical data at runtime. A
similar feature already exists in the XNU kernel with the
VM_FLAGS_PERMANENT [3] flag and on OpenBSD with the mimmutable syscall
[4]. Also, Chrome wants to adopt this feature for their CFI work [2] and
this patchset has been designed to be compatible with the Chrome use case.
Two system calls are involved in sealing the map: mmap() and mseal().
The new mseal() is an syscall on 64 bit CPU, and with following signature:
int mseal(void addr, size_t len, unsigned long flags)
addr/len: memory range.
flags: reserved.
mseal() blocks following operations for the given memory range.
1> Unmapping, moving to another location, and shrinking the size,
via munmap() and mremap(), can leave an empty space, therefore can
be replaced with a VMA with a new set of attributes.
2> Moving or expanding a different VMA into the current location,
via mremap().
3> Modifying a VMA via mmap(MAP_FIXED).
4> Size expansion, via mremap(), does not appear to pose any specific
risks to sealed VMAs. It is included anyway because the use case is
unclear. In any case, users can rely on merging to expand a sealed VMA.
5> mprotect() and pkey_mprotect().
6> Some destructive madvice() behaviors (e.g. MADV_DONTNEED) for anonymous
memory, when users don't have write permission to the memory. Those
behaviors can alter region contents by discarding pages, effectively a
memset(0) for anonymous memory.
The idea that inspired this patch comes from Stephen Röttger’s work in
V8 CFI [5]. Chrome browser in ChromeOS will be the first user of this
API.
Indeed, the Chrome browser has very specific requirements for sealing,
which are distinct from those of most applications. For example, in the
case of libc, sealing is only applied to read-only (RO) or read-execute
(RX) memory segments (such as .text and .RELRO) to prevent them from
becoming writable, the lifetime of those mappings are tied to the lifetime
of the process.
Chrome wants to seal two large address space reservations that are managed
by different allocators. The memory is mapped RW- and RWX respectively
but write access to it is restricted using pkeys (or in the future ARM
permission overlay extensions). The lifetime of those mappings are not
tied to the lifetime of the process, therefore, while the memory is
sealed, the allocators still need to free or discard the unused memory.
For example, with madvise(DONTNEED).
However, always allowing madvise(DONTNEED) on this range poses a security
risk. For example if a jump instruction crosses a page boundary and the
second page gets discarded, it will overwrite the target bytes with zeros
and change the control flow. Checking write-permission before the discard
operation allows us to control when the operation is valid. In this case,
the madvise will only succeed if the executing thread has PKEY write
permissions and PKRU changes are protected in software by control-flow
integrity.
Although the initial version of this patch series is targeting the Chrome
browser as its first user, it became evident during upstream discussions
that we would also want to ensure that the patch set eventually is a
complete solution for memory sealing and compatible with other use cases.
The specific scenario currently in mind is glibc's use case of loading and
sealing ELF executables. To this end, Stephen is working on a change to
glibc to add sealing support to the dynamic linker, which will seal all
non-writable segments at startup. Once this work is completed, all
applications will be able to automatically benefit from these new
protections.
In closing, I would like to formally acknowledge the valuable
contributions received during the RFC process, which were instrumental in
shaping this patch:
Jann Horn: raising awareness and providing valuable insights on the
destructive madvise operations.
Liam R. Howlett: perf optimization.
Linus Torvalds: assisting in defining system call signature and scope.
Theo de Raadt: sharing the experiences and insight gained from
implementing mimmutable() in OpenBSD.
MM perf benchmarks
==================
This patch adds a loop in the mprotect/munmap/madvise(DONTNEED) to
check the VMAs’ sealing flag, so that no partial update can be made,
when any segment within the given memory range is sealed.
To measure the performance impact of this loop, two tests are developed.
[8]
The first is measuring the time taken for a particular system call,
by using clock_gettime(CLOCK_MONOTONIC). The second is using
PERF_COUNT_HW_REF_CPU_CYCLES (exclude user space). Both tests have
similar results.
The tests have roughly below sequence:
for (i = 0; i < 1000, i++)
create 1000 mappings (1 page per VMA)
start the sampling
for (j = 0; j < 1000, j++)
mprotect one mapping
stop and save the sample
delete 1000 mappings
calculates all samples.
Below tests are performed on Intel(R) Pentium(R) Gold 7505 @ 2.00GHz,
4G memory, Chromebook.
Based on the latest upstream code:
The first test (measuring time)
syscall__ vmas t t_mseal delta_ns per_vma %
munmap__ 1 909 944 35 35 104%
munmap__ 2 1398 1502 104 52 107%
munmap__ 4 2444 2594 149 37 106%
munmap__ 8 4029 4323 293 37 107%
munmap__ 16 6647 6935 288 18 104%
munmap__ 32 11811 12398 587 18 105%
mprotect 1 439 465 26 26 106%
mprotect 2 1659 1745 86 43 105%
mprotect 4 3747 3889 142 36 104%
mprotect 8 6755 6969 215 27 103%
mprotect 16 13748 14144 396 25 103%
mprotect 32 27827 28969 1142 36 104%
madvise_ 1 240 262 22 22 109%
madvise_ 2 366 442 76 38 121%
madvise_ 4 623 751 128 32 121%
madvise_ 8 1110 1324 215 27 119%
madvise_ 16 2127 2451 324 20 115%
madvise_ 32 4109 4642 534 17 113%
The second test (measuring cpu cycle)
syscall__ vmas cpu cmseal delta_cpu per_vma %
munmap__ 1 1790 1890 100 100 106%
munmap__ 2 2819 3033 214 107 108%
munmap__ 4 4959 5271 312 78 106%
munmap__ 8 8262 8745 483 60 106%
munmap__ 16 13099 14116 1017 64 108%
munmap__ 32 23221 24785 1565 49 107%
mprotect 1 906 967 62 62 107%
mprotect 2 3019 3203 184 92 106%
mprotect 4 6149 6569 420 105 107%
mprotect 8 9978 10524 545 68 105%
mprotect 16 20448 21427 979 61 105%
mprotect 32 40972 42935 1963 61 105%
madvise_ 1 434 497 63 63 115%
madvise_ 2 752 899 147 74 120%
madvise_ 4 1313 1513 200 50 115%
madvise_ 8 2271 2627 356 44 116%
madvise_ 16 4312 4883 571 36 113%
madvise_ 32 8376 9319 943 29 111%
Based on the result, for 6.8 kernel, sealing check adds
20-40 nano seconds, or around 50-100 CPU cycles, per VMA.
In addition, I applied the sealing to 5.10 kernel:
The first test (measuring time)
syscall__ vmas t tmseal delta_ns per_vma %
munmap__ 1 357 390 33 33 109%
munmap__ 2 442 463 21 11 105%
munmap__ 4 614 634 20 5 103%
munmap__ 8 1017 1137 120 15 112%
munmap__ 16 1889 2153 263 16 114%
munmap__ 32 4109 4088 -21 -1 99%
mprotect 1 235 227 -7 -7 97%
mprotect 2 495 464 -30 -15 94%
mprotect 4 741 764 24 6 103%
mprotect 8 1434 1437 2 0 100%
mprotect 16 2958 2991 33 2 101%
mprotect 32 6431 6608 177 6 103%
madvise_ 1 191 208 16 16 109%
madvise_ 2 300 324 24 12 108%
madvise_ 4 450 473 23 6 105%
madvise_ 8 753 806 53 7 107%
madvise_ 16 1467 1592 125 8 108%
madvise_ 32 2795 3405 610 19 122%
The second test (measuring cpu cycle)
syscall__ nbr_vma cpu cmseal delta_cpu per_vma %
munmap__ 1 684 715 31 31 105%
munmap__ 2 861 898 38 19 104%
munmap__ 4 1183 1235 51 13 104%
munmap__ 8 1999 2045 46 6 102%
munmap__ 16 3839 3816 -23 -1 99%
munmap__ 32 7672 7887 216 7 103%
mprotect 1 397 443 46 46 112%
mprotect 2 738 788 50 25 107%
mprotect 4 1221 1256 35 9 103%
mprotect 8 2356 2429 72 9 103%
mprotect 16 4961 4935 -26 -2 99%
mprotect 32 9882 10172 291 9 103%
madvise_ 1 351 380 29 29 108%
madvise_ 2 565 615 49 25 109%
madvise_ 4 872 933 61 15 107%
madvise_ 8 1508 1640 132 16 109%
madvise_ 16 3078 3323 245 15 108%
madvise_ 32 5893 6704 811 25 114%
For 5.10 kernel, sealing check adds 0-15 ns in time, or 10-30
CPU cycles, there is even decrease in some cases.
It might be interesting to compare 5.10 and 6.8 kernel
The first test (measuring time)
syscall__ vmas t_5_10 t_6_8 delta_ns per_vma %
munmap__ 1 357 909 552 552 254%
munmap__ 2 442 1398 956 478 316%
munmap__ 4 614 2444 1830 458 398%
munmap__ 8 1017 4029 3012 377 396%
munmap__ 16 1889 6647 4758 297 352%
munmap__ 32 4109 11811 7702 241 287%
mprotect 1 235 439 204 204 187%
mprotect 2 495 1659 1164 582 335%
mprotect 4 741 3747 3006 752 506%
mprotect 8 1434 6755 5320 665 471%
mprotect 16 2958 13748 10790 674 465%
mprotect 32 6431 27827 21397 669 433%
madvise_ 1 191 240 49 49 125%
madvise_ 2 300 366 67 33 122%
madvise_ 4 450 623 173 43 138%
madvise_ 8 753 1110 357 45 147%
madvise_ 16 1467 2127 660 41 145%
madvise_ 32 2795 4109 1314 41 147%
The second test (measuring cpu cycle)
syscall__ vmas cpu_5_10 c_6_8 delta_cpu per_vma %
munmap__ 1 684 1790 1106 1106 262%
munmap__ 2 861 2819 1958 979 327%
munmap__ 4 1183 4959 3776 944 419%
munmap__ 8 1999 8262 6263 783 413%
munmap__ 16 3839 13099 9260 579 341%
munmap__ 32 7672 23221 15549 486 303%
mprotect 1 397 906 509 509 228%
mprotect 2 738 3019 2281 1140 409%
mprotect 4 1221 6149 4929 1232 504%
mprotect 8 2356 9978 7622 953 423%
mprotect 16 4961 20448 15487 968 412%
mprotect 32 9882 40972 31091 972 415%
madvise_ 1 351 434 82 82 123%
madvise_ 2 565 752 186 93 133%
madvise_ 4 872 1313 442 110 151%
madvise_ 8 1508 2271 763 95 151%
madvise_ 16 3078 4312 1234 77 140%
madvise_ 32 5893 8376 2483 78 142%
From 5.10 to 6.8
munmap: added 250-550 ns in time, or 500-1100 in cpu cycle, per vma.
mprotect: added 200-750 ns in time, or 500-1200 in cpu cycle, per vma.
madvise: added 33-50 ns in time, or 70-110 in cpu cycle, per vma.
In comparison to mseal, which adds 20-40 ns or 50-100 CPU cycles, the
increase from 5.10 to 6.8 is significantly larger, approximately ten times
greater for munmap and mprotect.
When I discuss the mm performance with Brian Makin, an engineer who worked
on performance, it was brought to my attention that such performance
benchmarks, which measuring millions of mm syscall in a tight loop, may
not accurately reflect real-world scenarios, such as that of a database
service. Also this is tested using a single HW and ChromeOS, the data
from another HW or distribution might be different. It might be best to
take this data with a grain of salt.
This patch (of 5):
Wire up mseal syscall for all architectures.
Link: https://lkml.kernel.org/r/20240415163527.626541-1-jeffxu@chromium.org
Link: https://lkml.kernel.org/r/20240415163527.626541-2-jeffxu@chromium.org
Signed-off-by: Jeff Xu <jeffxu@chromium.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Guenter Roeck <groeck@chromium.org>
Cc: Jann Horn <jannh@google.com> [Bug #2]
Cc: Jeff Xu <jeffxu@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Jorge Lucangeli Obes <jorgelo@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Muhammad Usama Anjum <usama.anjum@collabora.com>
Cc: Pedro Falcato <pedro.falcato@gmail.com>
Cc: Stephen Röttger <sroettger@google.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Amer Al Shanawany <amer.shanawany@gmail.com>
Cc: Javier Carrasco <javier.carrasco.cruz@gmail.com>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Kbuild conventionally uses $(obj)/ for generated files, and $(src)/ for
checked-in source files. It is merely a convention without any functional
difference. In fact, $(obj) and $(src) are exactly the same, as defined
in scripts/Makefile.build:
src := $(obj)
When the kernel is built in a separate output directory, $(src) does
not accurately reflect the source directory location. While Kbuild
resolves this discrepancy by specifying VPATH=$(srctree) to search for
source files, it does not cover all cases. For example, when adding a
header search path for local headers, -I$(srctree)/$(src) is typically
passed to the compiler.
This introduces inconsistency between upstream and downstream Makefiles
because $(src) is used instead of $(srctree)/$(src) for the latter.
To address this inconsistency, this commit changes the semantics of
$(src) so that it always points to the directory in the source tree.
Going forward, the variables used in Makefiles will have the following
meanings:
$(obj) - directory in the object tree
$(src) - directory in the source tree (changed by this commit)
$(objtree) - the top of the kernel object tree
$(srctree) - the top of the kernel source tree
Consequently, $(srctree)/$(src) in upstream Makefiles need to be replaced
with $(src).
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>
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git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/lsm
Pull security module updates from Paul Moore:
- Add three new syscalls: lsm_list_modules(), lsm_get_self_attr(), and
lsm_set_self_attr().
The first syscall simply lists the LSMs enabled, while the second and
third get and set the current process' LSM attributes. Yes, these
syscalls may provide similar functionality to what can be found under
/proc or /sys, but they were designed to support multiple,
simultaneaous (stacked) LSMs from the start as opposed to the current
/proc based solutions which were created at a time when only one LSM
was allowed to be active at a given time.
We have spent considerable time discussing ways to extend the
existing /proc interfaces to support multiple, simultaneaous LSMs and
even our best ideas have been far too ugly to support as a kernel
API; after +20 years in the kernel, I felt the LSM layer had
established itself enough to justify a handful of syscalls.
Support amongst the individual LSM developers has been nearly
unanimous, with a single objection coming from Tetsuo (TOMOYO) as he
is worried that the LSM_ID_XXX token concept will make it more
difficult for out-of-tree LSMs to survive. Several members of the LSM
community have demonstrated the ability for out-of-tree LSMs to
continue to exist by picking high/unused LSM_ID values as well as
pointing out that many kernel APIs rely on integer identifiers, e.g.
syscalls (!), but unfortunately Tetsuo's objections remain.
My personal opinion is that while I have no interest in penalizing
out-of-tree LSMs, I'm not going to penalize in-tree development to
support out-of-tree development, and I view this as a necessary step
forward to support the push for expanded LSM stacking and reduce our
reliance on /proc and /sys which has occassionally been problematic
for some container users. Finally, we have included the linux-api
folks on (all?) recent revisions of the patchset and addressed all of
their concerns.
- Add a new security_file_ioctl_compat() LSM hook to handle the 32-bit
ioctls on 64-bit systems problem.
This patch includes support for all of the existing LSMs which
provide ioctl hooks, although it turns out only SELinux actually
cares about the individual ioctls. It is worth noting that while
Casey (Smack) and Tetsuo (TOMOYO) did not give explicit ACKs to this
patch, they did both indicate they are okay with the changes.
- Fix a potential memory leak in the CALIPSO code when IPv6 is disabled
at boot.
While it's good that we are fixing this, I doubt this is something
users are seeing in the wild as you need to both disable IPv6 and
then attempt to configure IPv6 labeled networking via
NetLabel/CALIPSO; that just doesn't make much sense.
Normally this would go through netdev, but Jakub asked me to take
this patch and of all the trees I maintain, the LSM tree seemed like
the best fit.
- Update the LSM MAINTAINERS entry with additional information about
our process docs, patchwork, bug reporting, etc.
I also noticed that the Lockdown LSM is missing a dedicated
MAINTAINERS entry so I've added that to the pull request. I've been
working with one of the major Lockdown authors/contributors to see if
they are willing to step up and assume a Lockdown maintainer role;
hopefully that will happen soon, but in the meantime I'll continue to
look after it.
- Add a handful of mailmap entries for Serge Hallyn and myself.
* tag 'lsm-pr-20240105' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/lsm: (27 commits)
lsm: new security_file_ioctl_compat() hook
lsm: Add a __counted_by() annotation to lsm_ctx.ctx
calipso: fix memory leak in netlbl_calipso_add_pass()
selftests: remove the LSM_ID_IMA check in lsm/lsm_list_modules_test
MAINTAINERS: add an entry for the lockdown LSM
MAINTAINERS: update the LSM entry
mailmap: add entries for Serge Hallyn's dead accounts
mailmap: update/replace my old email addresses
lsm: mark the lsm_id variables are marked as static
lsm: convert security_setselfattr() to use memdup_user()
lsm: align based on pointer length in lsm_fill_user_ctx()
lsm: consolidate buffer size handling into lsm_fill_user_ctx()
lsm: correct error codes in security_getselfattr()
lsm: cleanup the size counters in security_getselfattr()
lsm: don't yet account for IMA in LSM_CONFIG_COUNT calculation
lsm: drop LSM_ID_IMA
LSM: selftests for Linux Security Module syscalls
SELinux: Add selfattr hooks
AppArmor: Add selfattr hooks
Smack: implement setselfattr and getselfattr hooks
...
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Wire up all archs.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Link: https://lore.kernel.org/r/20231025140205.3586473-7-mszeredi@redhat.com
Reviewed-by: Ian Kent <raven@themaw.net>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Wireup lsm_get_self_attr, lsm_set_self_attr and lsm_list_modules
system calls.
Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Cc: linux-api@vger.kernel.org
Reviewed-by: Mickaël Salaün <mic@digikod.net>
[PM: forward ported beyond v6.6 due merge window changes]
Signed-off-by: Paul Moore <paul@paul-moore.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-generic
Pull ia64 removal and asm-generic updates from Arnd Bergmann:
- The ia64 architecture gets its well-earned retirement as planned,
now that there is one last (mostly) working release that will be
maintained as an LTS kernel.
- The architecture specific system call tables are updated for the
added map_shadow_stack() syscall and to remove references to the
long-gone sys_lookup_dcookie() syscall.
* tag 'asm-generic-6.7' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-generic:
hexagon: Remove unusable symbols from the ptrace.h uapi
asm-generic: Fix spelling of architecture
arch: Reserve map_shadow_stack() syscall number for all architectures
syscalls: Cleanup references to sys_lookup_dcookie()
Documentation: Drop or replace remaining mentions of IA64
lib/raid6: Drop IA64 support
Documentation: Drop IA64 from feature descriptions
kernel: Drop IA64 support from sig_fault handlers
arch: Remove Itanium (IA-64) architecture
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commit c35559f94ebc ("x86/shstk: Introduce map_shadow_stack syscall")
recently added support for map_shadow_stack() but it is limited to x86
only for now. There is a possibility that other architectures (namely,
arm64 and RISC-V), that are implementing equivalent support for shadow
stacks, might need to add support for it.
Independent of that, reserving arch-specific syscall numbers in the
syscall tables of all architectures is good practice and would help
avoid future conflicts. map_shadow_stack() is marked as a conditional
syscall in sys_ni.c. Adding it to the syscall tables of other
architectures is harmless and would return ENOSYS when exercised.
Note, map_shadow_stack() was assigned #453 during the merge process
since #452 was taken by fchmodat2().
For Powerpc, map it to sys_ni_syscall() as is the norm for Powerpc
syscall tables.
For Alpha, map_shadow_stack() takes up #563 as Alpha still diverges from
the common syscall numbering system in the other architectures.
Link: https://lore.kernel.org/lkml/20230515212255.GA562920@debug.ba.rivosinc.com/
Link: https://lore.kernel.org/lkml/b402b80b-a7c6-4ef0-b977-c0f5f582b78a@sirena.org.uk/
Signed-off-by: Sohil Mehta <sohil.mehta@intel.com>
Reviewed-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
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commit 'be65de6b03aa ("fs: Remove dcookies support")' removed the
syscall definition for lookup_dcookie. However, syscall tables still
point to the old sys_lookup_dcookie() definition. Update syscall tables
of all architectures to directly point to sys_ni_syscall() instead.
Signed-off-by: Sohil Mehta <sohil.mehta@intel.com>
Reviewed-by: Randy Dunlap <rdunlap@infradead.org>
Acked-by: Namhyung Kim <namhyung@kernel.org> # for perf
Acked-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
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Finish off the 'simple' futex2 syscall group by adding
sys_futex_requeue(). Unlike sys_futex_{wait,wake}() its arguments are
too numerous to fit into a regular syscall. As such, use struct
futex_waitv to pass the 'source' and 'destination' futexes to the
syscall.
This syscall implements what was previously known as FUTEX_CMP_REQUEUE
and uses {val, uaddr, flags} for source and {uaddr, flags} for
destination.
This design explicitly allows requeueing between different types of
futex by having a different flags word per uaddr.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Link: https://lore.kernel.org/r/20230921105248.511860556@noisy.programming.kicks-ass.net
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To complement sys_futex_waitv()/wake(), add sys_futex_wait(). This
syscall implements what was previously known as FUTEX_WAIT_BITSET
except it uses 'unsigned long' for the value and bitmask arguments,
takes timespec and clockid_t arguments for the absolute timeout and
uses FUTEX2 flags.
The 'unsigned long' allows FUTEX2_SIZE_U64 on 64bit platforms.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Link: https://lore.kernel.org/r/20230921105248.164324363@noisy.programming.kicks-ass.net
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To complement sys_futex_waitv() add sys_futex_wake(). This syscall
implements what was previously known as FUTEX_WAKE_BITSET except it
uses 'unsigned long' for the bitmask and takes FUTEX2 flags.
The 'unsigned long' allows FUTEX2_SIZE_U64 on 64bit platforms.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Link: https://lore.kernel.org/r/20230921105247.936205525@noisy.programming.kicks-ass.net
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This registers the new fchmodat2 syscall in most places as nuber 452,
with alpha being the exception where it's 562. I found all these sites
by grepping for fspick, which I assume has found me everything.
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
Signed-off-by: Alexey Gladkov <legion@kernel.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Message-Id: <a677d521f048e4ca439e7080a5328f21eb8e960e.1689092120.git.legion@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull mm updates from Andrew Morton:
- Yosry Ahmed brought back some cgroup v1 stats in OOM logs
- Yosry has also eliminated cgroup's atomic rstat flushing
- Nhat Pham adds the new cachestat() syscall. It provides userspace
with the ability to query pagecache status - a similar concept to
mincore() but more powerful and with improved usability
- Mel Gorman provides more optimizations for compaction, reducing the
prevalence of page rescanning
- Lorenzo Stoakes has done some maintanance work on the
get_user_pages() interface
- Liam Howlett continues with cleanups and maintenance work to the
maple tree code. Peng Zhang also does some work on maple tree
- Johannes Weiner has done some cleanup work on the compaction code
- David Hildenbrand has contributed additional selftests for
get_user_pages()
- Thomas Gleixner has contributed some maintenance and optimization
work for the vmalloc code
- Baolin Wang has provided some compaction cleanups,
- SeongJae Park continues maintenance work on the DAMON code
- Huang Ying has done some maintenance on the swap code's usage of
device refcounting
- Christoph Hellwig has some cleanups for the filemap/directio code
- Ryan Roberts provides two patch series which yield some
rationalization of the kernel's access to pte entries - use the
provided APIs rather than open-coding accesses
- Lorenzo Stoakes has some fixes to the interaction between pagecache
and directio access to file mappings
- John Hubbard has a series of fixes to the MM selftesting code
- ZhangPeng continues the folio conversion campaign
- Hugh Dickins has been working on the pagetable handling code, mainly
with a view to reducing the load on the mmap_lock
- Catalin Marinas has reduced the arm64 kmalloc() minimum alignment
from 128 to 8
- Domenico Cerasuolo has improved the zswap reclaim mechanism by
reorganizing the LRU management
- Matthew Wilcox provides some fixups to make gfs2 work better with the
buffer_head code
- Vishal Moola also has done some folio conversion work
- Matthew Wilcox has removed the remnants of the pagevec code - their
functionality is migrated over to struct folio_batch
* tag 'mm-stable-2023-06-24-19-15' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (380 commits)
mm/hugetlb: remove hugetlb_set_page_subpool()
mm: nommu: correct the range of mmap_sem_read_lock in task_mem()
hugetlb: revert use of page_cache_next_miss()
Revert "page cache: fix page_cache_next/prev_miss off by one"
mm/vmscan: fix root proactive reclaim unthrottling unbalanced node
mm: memcg: rename and document global_reclaim()
mm: kill [add|del]_page_to_lru_list()
mm: compaction: convert to use a folio in isolate_migratepages_block()
mm: zswap: fix double invalidate with exclusive loads
mm: remove unnecessary pagevec includes
mm: remove references to pagevec
mm: rename invalidate_mapping_pagevec to mapping_try_invalidate
mm: remove struct pagevec
net: convert sunrpc from pagevec to folio_batch
i915: convert i915_gpu_error to use a folio_batch
pagevec: rename fbatch_count()
mm: remove check_move_unevictable_pages()
drm: convert drm_gem_put_pages() to use a folio_batch
i915: convert shmem_sg_free_table() to use a folio_batch
scatterlist: add sg_set_folio()
...
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The Arm documentation has moved to Documentation/arch/arm; update
references within arch/arm to match.
Cc: Russell King <linux@armlinux.org.uk>
Cc: Alim Akhtar <alim.akhtar@samsung.com>
Cc: Patrice Chotard <patrice.chotard@foss.st.com>
Cc: linux-doc@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-arch@vger.kernel.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
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cachestat is previously only wired in for x86 (and architectures using
the generic unistd.h table):
https://lore.kernel.org/lkml/20230503013608.2431726-1-nphamcs@gmail.com/
This patch wires cachestat in for all the other architectures.
[nphamcs@gmail.com: wire up cachestat for arm64]
Link: https://lkml.kernel.org/r/20230511092843.3896327-1-nphamcs@gmail.com
Link: https://lkml.kernel.org/r/20230510195806.2902878-1-nphamcs@gmail.com
Signed-off-by: Nhat Pham <nphamcs@gmail.com>
Tested-by: Michael Ellerman <mpe@ellerman.id.au> [powerpc]
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org> [m68k]
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Heiko Carstens <hca@linux.ibm.com> [s390]
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Chris Zankel <chris@zankel.net>
Cc: David S. Miller <davem@davemloft.net>
Cc: Helge Deller <deller@gmx.de>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Michal Simek <monstr@monstr.eu>
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: Vasily Gorbik <gor@linux.ibm.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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$(shell ...) expands to empty. There is no need to assign it to _dummy.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
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Link: https://lkml.kernel.org/r/20211202123810.267175-4-aneesh.kumar@linux.ibm.com
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: Ben Widawsky <ben.widawsky@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Feng Tang <feng.tang@intel.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Huang Ying <ying.huang@intel.com>
Cc: <linux-api@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Wire up syscall entry point for ARM architectures, for both 32 and 64-bit.
Signed-off-by: André Almeida <andrealmeid@collabora.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20210923171111.300673-19-andrealmeid@collabora.com
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Pull ARM development updates from Russell King:
- Rename "mod_init" and "mod_exit" so that initcall debug output is
actually useful (Randy Dunlap)
- Update maintainers entries for linux-arm-kernel to indicate it is
moderated for non-subscribers (Randy Dunlap)
- Move install rules to arch/arm/Makefile (Masahiro Yamada)
- Drop unnecessary ARCH_NR_GPIOS definition (Linus Walleij)
- Don't warn about atags_to_fdt() stack size (David Heidelberg)
- Speed up unaligned copy_{from,to}_kernel_nofault (Arnd Bergmann)
- Get rid of set_fs() usage (Arnd Bergmann)
- Remove checks for GCC prior to v4.6 (Geert Uytterhoeven)
* tag 'for-linus' of git://git.armlinux.org.uk/~rmk/linux-arm:
ARM: 9118/1: div64: Remove always-true __div64_const32_is_OK() duplicate
ARM: 9117/1: asm-generic: div64: Remove always-true __div64_const32_is_OK()
ARM: 9116/1: unified: Remove check for gcc < 4
ARM: 9110/1: oabi-compat: fix oabi epoll sparse warning
ARM: 9113/1: uaccess: remove set_fs() implementation
ARM: 9112/1: uaccess: add __{get,put}_kernel_nofault
ARM: 9111/1: oabi-compat: rework fcntl64() emulation
ARM: 9114/1: oabi-compat: rework sys_semtimedop emulation
ARM: 9108/1: oabi-compat: rework epoll_wait/epoll_pwait emulation
ARM: 9107/1: syscall: always store thread_info->abi_syscall
ARM: 9109/1: oabi-compat: add epoll_pwait handler
ARM: 9106/1: traps: use get_kernel_nofault instead of set_fs()
ARM: 9115/1: mm/maccess: fix unaligned copy_{from,to}_kernel_nofault
ARM: 9105/1: atags_to_fdt: don't warn about stack size
ARM: 9103/1: Drop ARCH_NR_GPIOS definition
ARM: 9102/1: move theinstall rules to arch/arm/Makefile
ARM: 9100/1: MAINTAINERS: mark all linux-arm-kernel@infradead list as moderated
ARM: 9099/1: crypto: rename 'mod_init' & 'mod_exit' functions to be module-specific
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Merge misc updates from Andrew Morton:
"173 patches.
Subsystems affected by this series: ia64, ocfs2, block, and mm (debug,
pagecache, gup, swap, shmem, memcg, selftests, pagemap, mremap,
bootmem, sparsemem, vmalloc, kasan, pagealloc, memory-failure,
hugetlb, userfaultfd, vmscan, compaction, mempolicy, memblock,
oom-kill, migration, ksm, percpu, vmstat, and madvise)"
* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (173 commits)
mm/madvise: add MADV_WILLNEED to process_madvise()
mm/vmstat: remove unneeded return value
mm/vmstat: simplify the array size calculation
mm/vmstat: correct some wrong comments
mm/percpu,c: remove obsolete comments of pcpu_chunk_populated()
selftests: vm: add COW time test for KSM pages
selftests: vm: add KSM merging time test
mm: KSM: fix data type
selftests: vm: add KSM merging across nodes test
selftests: vm: add KSM zero page merging test
selftests: vm: add KSM unmerge test
selftests: vm: add KSM merge test
mm/migrate: correct kernel-doc notation
mm: wire up syscall process_mrelease
mm: introduce process_mrelease system call
memblock: make memblock_find_in_range method private
mm/mempolicy.c: use in_task() in mempolicy_slab_node()
mm/mempolicy: unify the create() func for bind/interleave/prefer-many policies
mm/mempolicy: advertise new MPOL_PREFERRED_MANY
mm/hugetlb: add support for mempolicy MPOL_PREFERRED_MANY
...
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Split off from prev patch in the series that implements the syscall.
Link: https://lkml.kernel.org/r/20210809185259.405936-2-surenb@google.com
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Christian Brauner <christian.brauner@ubuntu.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Florian Weimer <fweimer@redhat.com>
Cc: Jan Engelhardt <jengelh@inai.de>
Cc: Jann Horn <jannh@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Tim Murray <timmurray@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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The epoll_wait() system call wrapper is one of the remaining users of
the set_fs() infrasturcture for Arm. Changing it to not require set_fs()
is rather complex unfortunately.
The approach I'm taking here is to allow architectures to override
the code that copies the output to user space, and let the oabi-compat
implementation check whether it is getting called from an EABI or OABI
system call based on the thread_info->syscall value.
The in_oabi_syscall() check here mirrors the in_compat_syscall() and
in_x32_syscall() helpers for 32-bit compat implementations on other
architectures.
Overall, the amount of code goes down, at least with the newly added
sys_oabi_epoll_pwait() helper getting removed again. The downside
is added complexity in the source code for the native implementation.
There should be no difference in runtime performance except for Arm
kernels with CONFIG_OABI_COMPAT enabled that now have to go through
an external function call to check which of the two variants to use.
Acked-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
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The epoll_wait() syscall has a special version for OABI compat
mode to convert the arguments to the EABI structure layout
of the kernel. However, the later epoll_pwait() syscall was
added in arch/arm in linux-2.6.32 without this conversion.
Use the same kind of handler for both.
Fixes: 369842658a36 ("ARM: 5677/1: ARM support for TIF_RESTORE_SIGMASK/pselect6/ppoll/epoll_pwait")
Cc: stable@vger.kernel.org
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
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The bdflush system call has been deprecated for a very long time.
Recently Michael Schmitz tested[1] and found that the last known
caller of of the bdflush system call is unaffected by it's removal.
Since the code is not needed delete it.
[1] https://lkml.kernel.org/r/36123b5d-daa0-6c2b-f2d4-a942f069fd54@gmail.com
Link: https://lkml.kernel.org/r/87sg10quue.fsf_-_@disp2133
Tested-by: Michael Schmitz <schmitzmic@gmail.com>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Cyril Hrubis <chrubis@suse.cz>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
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Pull ARM development updates from Russell King:
- Make it clear __swp_entry_to_pte() uses PTE_TYPE_FAULT
- Updates for setting vmalloc size via command line to resolve an issue
with the 8MiB hole not properly being accounted for, and clean up the
code.
- ftrace support for module PLTs
- Spelling fixes
- kbuild updates for removing generated files and pattern rules for
generating files
- Clang/llvm updates
- Change the way the kernel is mapped, placing it in vmalloc space
instead.
- Remove arm_pm_restart from arm and aarch64.
* tag 'for-linus' of git://git.armlinux.org.uk/~rmk/linux-arm: (29 commits)
ARM: 9098/1: ftrace: MODULE_PLT: Fix build problem without DYNAMIC_FTRACE
ARM: 9097/1: mmu: Declare section start/end correctly
ARM: 9096/1: Remove arm_pm_restart()
ARM: 9095/1: ARM64: Remove arm_pm_restart()
ARM: 9094/1: Register with kernel restart handler
ARM: 9093/1: drivers: firmwapsci: Register with kernel restart handler
ARM: 9092/1: xen: Register with kernel restart handler
ARM: 9091/1: Revert "mm: qsd8x50: Fix incorrect permission faults"
ARM: 9090/1: Map the lowmem and kernel separately
ARM: 9089/1: Define kernel physical section start and end
ARM: 9088/1: Split KERNEL_OFFSET from PAGE_OFFSET
ARM: 9087/1: kprobes: test-thumb: fix for LLVM_IAS=1
ARM: 9086/1: syscalls: use pattern rules to generate syscall headers
ARM: 9085/1: remove unneeded abi parameter to syscallnr.sh
ARM: 9084/1: simplify the build rule of mach-types.h
ARM: 9083/1: uncompress: atags_to_fdt: Spelling s/REturn/Return/
ARM: 9082/1: [v2] mark prepare_page_table as __init
ARM: 9079/1: ftrace: Add MODULE_PLTS support
ARM: 9078/1: Add warn suppress parameter to arm_gen_branch_link()
ARM: 9077/1: PLT: Move struct plt_entries definition to header
...
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Use pattern rules to unify similar build rules between OABI and EABI.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
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You do not need to pass the abi parameter to syscallnr.sh because it
parses all the lines of syscall.tbl except comments anyway.
Simplify the code. Also, remove unneeded single-quoting.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
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The directory of mach-types.h is created a couple of lines above:
_dummy := $(shell [ -d '$(kapi)' ] || mkdir -p '$(kapi)') \
The 'mkdir -p' command is redundant.
scripts/Kbuild.include defines real-prereqs as a shortha |
