In Linux build system convention, pre-generated files are version-
controlled with a "_shipped" suffix.  During the kernel building,
they are simply shipped (copied) removing the suffix.

This approach can reduce external tool dependency for the kernel build,
but it is tedious to manually regenerate such artifacts from developers'
point of view.  (We need to do "make REGENERATE_PARSERS=1" every time
we touch real source files such as *.l, *.y)

Some months ago, I sent out RFC patches to run flex, bison, and gperf
during the build.

In the review and test, Linus noticed gperf-3.1 had changed the lookup
function prototype.  Then, the use of gperf in kernel was entirely
removed by commit bb3290d9 ("Remove gperf usage from toolchain").

This time, I tested several versions of flex and bison, and I was not
hit by any compatibility issue except a flaw in flex-2.6.3; if you
generate lexer for dtc and genksyms with flex-2.6.3, you will see
"yywrap redefined" warning.  This was not intentional, but a bug,
fixed by flex-2.6.4.  Otherwise, both flex and bison look fairly
stable for a long time.

This commit prepares some build rules to remove the _shipped files.
Also, document minimal requirement for flex and bison.

Rationale for the minimal version:
The -Wmissing-prototypes option of GCC warns "no previous prototype"
for lexers generated by flex-2.5.34 or older, so I chose 2.5.35 as the
required version for flex.  Flex-2.5.35 was released in 2008.  Bison
looks more stable.  I did not see any problem with bison-2.0, released
in 2004.  I did not test bison-1.x, but bison-2.0 should be old enough.

Tested flex versions:
  2.5.35
  2.5.36
  2.5.37
  2.5.39
  2.6.0
  2.6.1
  2.6.2
  2.6.3   (*)
  2.6.4

 (*) flex-2.6.3 causes "yywrap redefined" warning

Tested bison versions:
  2.0
  2.1
  2.2
  2.3
  2.4
  2.4.1
  2.5.1
  2.6
  2.6.1
  2.6.2
  2.6.3
  2.6.4
  2.6.5
  2.7
  2.7.1
  3.0
  3.0.1
  3.0.2
  3.0.3
  3.0.4
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

Allow users to use their favorite lexer / parser generators.
This is useful for me to test various flex and bison versions.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

Commit 1c199f28 ("kbuild: document recursive dependency limitation
/ resolution") probably intended to show a hint along with "recursive
dependency detected!" error, but it missed to add {...} guard, and the
hint is displayed in every loop of the dep_stack traverse, annoyingly.

This error was detected by GCC's -Wmisleading-indentation when switching
to build-time generation of lexer/parser.

scripts/kconfig/symbol.c: In function ‘sym_check_print_recursive’:
scripts/kconfig/symbol.c:1150:3: warning: this ‘if’ clause does not guard... [-Wmisleading-indentation]
   if (stack->sym == last_sym)
   ^~
scripts/kconfig/symbol.c:1153:4: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the ‘if’
    fprintf(stderr, "For a resolution refer to Documentation/kbuild/kconfig-language.txt\n");
    ^~~~~~~

I could simply add {...} to surround the three fprintf(), but I rather
chose to move the hint after the loop to make the whole message readable.

Fixes: 1c199f28 ("kbuild: document recursive dependency limitation / resolution"
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Acked-by: Luis R. Rodriguez <mcgrof@kernel.org>

Kconfig currently doesn't handle 'm' appearing in a Kconfig file before
the modules symbol is defined (the symbol with 'option modules'). The
problem is the following code, which runs during parsing:

	/* change 'm' into 'm' && MODULES */
	if (e->left.sym == &symbol_mod)
		return expr_alloc_and(e, expr_alloc_symbol(modules_sym));

If the modules symbol has not yet been defined, modules_sym is NULL,
giving an invalid expression.

Here is a test file where both BEFORE_1 and BEFORE_2 trigger a segfault.
If the modules symbol is removed, all symbols trigger segfaults.

	config BEFORE_1
		def_tristate y if m

	if m
	config BEFORE_2
		def_tristate y
	endif

	config MODULES
		def_bool y
		option modules

	config AFTER_1
		def_tristate y if m

	if m
	config AFTER_2
		def_tristate y
	endif

Fix the issue by rewriting 'm' in menu_finalize() instead. This function
runs after parsing and is the proper place to do it. The following
existing code in conf_parse() in zconf.y ensures that the modules symbol
exists at that point:

	if (!modules_sym)
		modules_sym = sym_find( "n" );

	...

	menu_finalize(&rootmenu);

The following tests were done to ensure no functional changes for
configurations that don't reference 'm' before the modules symbol:

	- zconfdump(stdout) was run with ARCH=x86 and ARCH=arm before
	  and after the change and verified to produce identical output.
	  This function prints all symbols, choices, and menus together
	  with their properties and their dependency expressions. A
	  rewritten 'm' appears as 'm && MODULES'.

	  A small annoyance is that the assert(len != 0) in xfwrite()
	  needs to be disabled in order to use zconfdump(), because it
	  chokes on e.g. 'default ""'.

	- The Kconfiglib test suite was run to indirectly verify that
	  alldefconfig, allyesconfig, allnoconfig, and all defconfigs in
	  the kernel still generate the same final .config.

	- Valgrind was used to check for memory errors and (new) memory
	  leaks.
Signed-off-by: Ulf Magnusson <ulfalizer@gmail.com>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

menu_finalize() is one of the more opaque parts of Kconfig, and I need
to make some changes to it to fix an issue related to modules. Add some
comments related to expression rewriting and dependency propagation as a
review aid. They will also help other people trying to understand the
code.
Signed-off-by: Ulf Magnusson <ulfalizer@gmail.com>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

More directly describes the only thing it does.
Signed-off-by: Ulf Magnusson <ulfalizer@gmail.com>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

Looks like a change to a comment in zconf.y was never committed, because
the updated version only appears it zconf.tab.c_shipped. Update the
comment in zconf.y to match.
Signed-off-by: Ulf Magnusson <ulfalizer@gmail.com>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

Visibility and choices in particular might be a bit tricky to figure
out.

Also fix existing comment to point out that P_MENU is also used for
menus.
Signed-off-by: Ulf Magnusson <ulfalizer@gmail.com>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

Understanding what it represents helps a lot when reading the code, and
it's not obvious, so document it.

The ROOT_MENU flag is only set and tested by the gconf and qconf front
ends, so leave it undocumented here. The obvious guess for what it means
is correct.
Signed-off-by: Ulf Magnusson <ulfalizer@gmail.com>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

This will catch mistakes like in the following real-world example, where
a "CONFIG_" prefix snuck in, making an undefined symbol the default:

	choice
		prompt "Compiler optimization level"
		default CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE

	config CC_OPTIMIZE_FOR_PERFORMANCE
		...

	config CC_OPTIMIZE_FOR_SIZE
		...

	endchoice

This now prints the following warning:

	init/Kconfig:1036:warning: choice default symbol 'CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE' is not contained in the choice

Cases where the default symbol belongs to the wrong choice are also
detected.

(The mistake is harmless here: Since the default symbol is not visible,
the choice falls back on using the first visible symbol as the default,
which is CC_OPTIMIZE_FOR_PERFORMANCE, as intended.)

Discovered while playing around with Kconfiglib
(https://github.com/ulfalizer/Kconfiglib).
Signed-off-by: Ulf Magnusson <ulfalizer@gmail.com>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

Pull ARM fix from Russell King:
 "Just one fix this time around, for the late commit in the merge window
  that triggered a problem with qemu. Qemu is apparently also going to
  receive a fix for the discovered issue"

* 'fixes' of git://git.armlinux.org.uk/~rmk/linux-arm:
  ARM: avoid faulting on qemu

Pull i2c fixes from Wolfram Sang:
 "Here are two bugfixes for I2C, fixing a memleak in the core and irq
  allocation for i801.

  Also three bugfixes for the at24 eeprom driver which Bartosz collected
  while taking over maintainership for this driver"

* 'i2c/for-current' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux:
  eeprom: at24: check at24_read/write arguments
  eeprom: at24: fix reading from 24MAC402/24MAC602
  eeprom: at24: correctly set the size for at24mac402
  i2c: i2c-boardinfo: fix memory leaks on devinfo
  i2c: i801: Fix Failed to allocate irq -2147483648 error

Merge tag 'hwmon-for-linus-v4.15-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/groeck/linux-staging

Pull hwmon fixes from Guenter Roeck:
 "Fixes:

   - Drop reference to obsolete maintainer tree

   - Fix overflow bug in pmbus driver

   - Fix SMBUS timeout problem in jc42 driver

  For the SMBUS timeout handling, we had a brief discussion if this
  should be considered a bug fix or a feature. Peter says "it fixes real
  problems where the application misbehave due to faulty content when
  reading from an eeprom", and he needs the patch in his company's v4.14
  images. This is good enough for me and warrants backport to stable
  kernels"

* tag 'hwmon-for-linus-v4.15-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/groeck/linux-staging:
  hwmon: (jc42) optionally try to disable the SMBUS timeout
  hwmon: (pmbus) Use 64bit math for DIRECT format values
  hwmon: Drop reference to Jean's tree

Merge tag 'at24-4.15-fixes-for-wolfram' of git://git.kernel.org/pub/scm/linux/kernel/git/brgl/linux into i2c/for-current

Please consider pulling the following fixes for v4.15. While it doesn't
fix any regression introduced in the v4.15 merge window, we have a
feature in at24 since linux v4.8 - reading the mac address block from
at24mac series - which turned out to be not working.

This pull request contains changes that fix it together with a patch
that hardens the read and write argument sanitization with
out-of-bounds checks that were missing.

Pull NFS client fixes from Anna Schumaker:
 "These patches fix a problem with compiling using an old version of
  gcc, and also fix up error handling in the SUNRPC layer.

   - NFSv4: Ensure gcc 4.4.4 can compile initialiser for
     "invalid_stateid"

   - SUNRPC: Allow connect to return EHOSTUNREACH

   - SUNRPC: Handle ENETDOWN errors"

* tag 'nfs-for-4.15-2' of git://git.linux-nfs.org/projects/anna/linux-nfs:
  SUNRPC: Handle ENETDOWN errors
  SUNRPC: Allow connect to return EHOSTUNREACH
  NFSv4: Ensure gcc 4.4.4 can compile initialiser for "invalid_stateid"

Pull xfs fixes from Darrick Wong:
 "Here are some bug fixes for 4.15-rc2.

   - fix memory leaks that appeared after removing ifork inline data
     buffer

   - recover deferred rmap update log items in correct order

   - fix memory leaks when buffer construction fails

   - fix memory leaks when bmbt is corrupt

   - fix some uninitialized variables and math problems in the quota
     scrubber

   - add some omitted attribution tags on the log replay commit

   - fix some UBSAN complaints about integer overflows with large sparse
     files

   - implement an effective inode mode check in online fsck

   - fix log's inability to retry quota item writeout due to transient
     errors"

* tag 'xfs-4.15-fixes-4' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux:
  xfs: Properly retry failed dquot items in case of error during buffer writeback
  xfs: scrub inode mode properly
  xfs: remove unused parameter from xfs_writepage_map
  xfs: ubsan fixes
  xfs: calculate correct offset in xfs_scrub_quota_item
  xfs: fix uninitialized variable in xfs_scrub_quota
  xfs: fix leaks on corruption errors in xfs_bmap.c
  xfs: fortify xfs_alloc_buftarg error handling
  xfs: log recovery should replay deferred ops in order
  xfs: always free inline data before resetting inode fork during ifree

Merge tag 'riscv-for-linus-4.15-rc2_cleanups' of git://git.kernel.org/pub/scm/linux/kernel/git/palmer/linux

Pull RISC-V cleanups and ABI fixes from Palmer Dabbelt:
 "This contains a handful of small cleanups that are a result of
  feedback that didn't make it into our original patch set, either
  because the feedback hadn't been given yet, I missed the original
  emails, or we weren't ready to submit the changes yet.

  I've been maintaining the various cleanup patch sets I have as their
  own branches, which I then merged together and signed. Each merge
  commit has a short summary of the changes, and each branch is based on
  your latest tag (4.15-rc1, in this case). If this isn't the right way
  to do this then feel free to suggest something else, but it seems sane
  to me.

  Here's a short summary of the changes, roughly in order of how
  interesting they are.

   - libgcc.h has been moved from include/lib, where it's the only
     member, to include/linux. This is meant to avoid tab completion
     conflicts.

   - VDSO entries for clock_get/gettimeofday/getcpu have been added.
     These are simple syscalls now, but we want to let glibc use them
     from the start so we can make them faster later.

   - A VDSO entry for instruction cache flushing has been added so
     userspace can flush the instruction cache.

   - The VDSO symbol versions for __vdso_cmpxchg{32,64} have been
     removed, as those VDSO entries don't actually exist.

   - __io_writes has been corrected to respect the given type.

   - A new READ_ONCE in arch_spin_is_locked().

   - __test_and_op_bit_ord() is now actually ordered.

   - Various small fixes throughout the tree to enable allmodconfig to
     build cleanly.

   - Removal of some dead code in our atomic support headers.

   - Improvements to various comments in our atomic support headers"

* tag 'riscv-for-linus-4.15-rc2_cleanups' of git://git.kernel.org/pub/scm/linux/kernel/git/palmer/linux: (23 commits)
  RISC-V: __io_writes should respect the length argument
  move libgcc.h to include/linux
  RISC-V: Clean up an unused include
  RISC-V: Allow userspace to flush the instruction cache
  RISC-V: Flush I$ when making a dirty page executable
  RISC-V: Add missing include
  RISC-V: Use define for get_cycles like other architectures
  RISC-V: Provide stub of setup_profiling_timer()
  RISC-V: Export some expected symbols for modules
  RISC-V: move empty_zero_page definition to C and export it
  RISC-V: io.h: type fixes for warnings
  RISC-V: use RISCV_{INT,SHORT} instead of {INT,SHORT} for asm macros
  RISC-V: use generic serial.h
  RISC-V: remove spin_unlock_wait()
  RISC-V: `sfence.vma` orderes the instruction cache
  RISC-V: Add READ_ONCE in arch_spin_is_locked()
  RISC-V: __test_and_op_bit_ord should be strongly ordered
  RISC-V: Remove smb_mb__{before,after}_spinlock()
  RISC-V: Remove __smp_bp__{before,after}_atomic
  RISC-V: Comment on why {,cmp}xchg is ordered how it is
  ...

Pull arm64 fixes from Will Deacon:
 "The critical one here is a fix for fpsimd register corruption across
  signals which was introduced by the SVE support code (the register
  files overlap), but the others are worth having as well.

  Summary:

   - Fix FP register corruption when SVE is not available or in use

   - Fix out-of-tree module build failure when CONFIG_ARM64_MODULE_PLTS=y

   - Missing 'const' generating errors with LTO builds

   - Remove unsupported events from Cortex-A73 PMU description

   - Removal of stale and incorrect comments"

* tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux:
  arm64: context: Fix comments and remove pointless smp_wmb()
  arm64: cpu_ops: Add missing 'const' qualifiers
  arm64: perf: remove unsupported events for Cortex-A73
  arm64: fpsimd: Fix failure to restore FPSIMD state after signals
  arm64: pgd: Mark pgd_cache as __ro_after_init
  arm64: ftrace: emit ftrace-mod.o contents through code
  arm64: module-plts: factor out PLT generation code for ftrace
  arm64: mm: cleanup stale AIVIVT references

Olaf said: Here's a short series of patches that produces a working
allmodconfig. Would be nice to see them go in so we can add build
coverage.

I've dropped patches 8 and 10 from the original set:

* [PATCH 08/10] (RISC-V: Set __ARCH_WANT_RENAMEAT to pick up generic
  version) has a better fix that I've sent out for review, we don't want
  renameat.
* [PATCH 10/10] (input: joystick: riscv has get_cycles) has already been
  taken into Dmitry Torokhov's tree.

This merge contains the user-visible, ABI-breaking changes that we want
to make sure we have in Linux before our first release.   Highlights
include:

* VDSO entries for clock_get/gettimeofday/getcpu have been added.  These
  are simple syscalls now, but we want to let glibc use them from the
  start so we can make them faster later.
* A VDSO entry for instruction cache flushing has been added so
  userspace can flush the instruction cache.
* The VDSO symbol versions for __vdso_cmpxchg{32,64} have been removed,
  as those VDSO entries don't actually exist.

Conflicts:
        arch/riscv/include/asm/tlbflush.h

This patch set is the result of some feedback that filtered through
after our original patch set was reviewed, some of which was the result
of me missing some email.  It contains:

* A new READ_ONCE in arch_spin_is_locked()
* __test_and_op_bit_ord() is now actually ordered
* Improvements to various comments
* Removal of some dead code

Whoops -- I must have just been being an idiot again.  Thanks to Segher
for finding the bug :).

CC: Segher Boessenkool <segher@kernel.crashing.org>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>

Introducing a new include/lib directory just for this file totally
messes up tab completion for include/linux, which is highly annoying.

Move it to include/linux where we have headers for all kinds of other
lib/ code as well.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>

Pull powerpc fixes from Michael Ellerman:
 "Two fixes for nasty kexec/kdump crashes in certain configurations.

  A couple of minor fixes for the new TIDR code.

  A fix for an oops in a CXL error handling path.

  Thanks to: Andrew Donnellan, Christophe Lombard, David Gibson, Mahesh
  Salgaonkar, Vaibhav Jain"

* tag 'powerpc-4.15-3' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
  powerpc: Do not assign thread.tidr if already assigned
  powerpc: Avoid signed to unsigned conversion in set_thread_tidr()
  powerpc/kexec: Fix kexec/kdump in P9 guest kernels
  powerpc/powernv: Fix kexec crashes caused by tlbie tracing
  cxl: Check if vphb exists before iterating over AFU devices

Pull AFS fixes from David Howells:
 "Two fix patches for the AFS filesystem:

   - Fix the refcounting on permit caching.

   - AFS inode (afs_vnode) fields need resetting after allocation
     because they're only initialised when slab pages are obtained from
     the page allocator"

* tag 'afs-fixes-20171201' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs:
  afs: Properly reset afs_vnode (inode) fields
  afs: Fix permit refcounting

Pull MMC fixes from Ulf Hansson:
 "MMC core:
   - Ensure that debugfs files are removed properly
   - Fix missing blk_put_request()
   - Deal with errors from blk_get_request()
   - Rewind mmc bus suspend operations at failures
   - Prepend '0x' to ocr and pre_eol_info in sysfs to identify as hex

  MMC host:
   - sdhci-msm: Make it optional to wait for signal level changes
   - sdhci: Avoid swiotlb buffer being full"

* tag 'mmc-v4.15-2' of git://git.kernel.org/pub/scm/linux/kernel/git/ulfh/mmc:
  mmc: core: prepend 0x to OCR entry in sysfs
  mmc: core: prepend 0x to pre_eol_info entry in sysfs
  mmc: sdhci: Avoid swiotlb buffer being full
  mmc: sdhci-msm: Optionally wait for signal level changes
  mmc: block: Ensure that debugfs files are removed
  mmc: core: Do not leave the block driver in a suspended state
  mmc: block: Check return value of blk_get_request()
  mmc: block: Fix missing blk_put_request()

Pull drm fixes and cleanups from Dave Airlie:
 "The main thing are a bunch of fixes for the new amd display code, a
  bunch of smatch fixes.

  core:
   - Atomic helper regression fix.
   - Deferred fbdev fallout regression fix.

  amdgpu:
   - New display code (dc) dpms, suspend/resume and smatch fixes, along
     with some others
   - Some regression fixes for amdkfd/radeon.
   - Fix a ttm regression for swiotlb disabled

  bridge:
   - A bunch of fixes for the tc358767 bridge

  mali-dp + hdlcd:
   - some fixes and internal API catchups.

  imx-drm:
   -regression fix in atomic code.

  omapdrm:
   - platform detection regression fixes"

* tag 'drm-fixes-for-v4.15-rc2' of git://people.freedesktop.org/~airlied/linux: (76 commits)
  drm/imx: always call wait_for_flip_done in commit_tail
  omapdrm: hdmi4_cec: signedness bug in hdmi4_cec_init()
  drm: omapdrm: Fix DPI on platforms using the DSI VDDS
  omapdrm: hdmi4: Correct the SoC revision matching
  drm/omap: displays: panel-dpi: add backlight dependency
  drm/omap: Fix error handling path in 'omap_dmm_probe()'
  drm/i915: Disable THP until we have a GPU read BW W/A
  drm/bridge: tc358767: fix 1-lane behavior
  drm/bridge: tc358767: fix AUXDATAn registers access
  drm/bridge: tc358767: fix timing calculations
  drm/bridge: tc358767: fix DP0_MISC register set
  drm/bridge: tc358767: filter out too high modes
  drm/bridge: tc358767: do no fail on hi-res displays
  drm/bridge: Fix lvds-encoder since the panel_bridge rework.
  drm/bridge: synopsys/dw-hdmi: Enable cec clock
  drm/bridge: adv7511/33: Fix adv7511_cec_init() failure handling
  drm/radeon: remove init of CIK VMIDs 8-16 for amdkfd
  drm/ttm: fix populate_and_map() functions once more
  drm/fb_helper: Disable all crtc's when initial setup fails.
  drm/atomic: make drm_atomic_helper_wait_for_vblanks more agressive
  ...

Pull block fixes from Jens Axboe:
 "A selection of fixes/changes that should make it into this series.
  This contains:

   - NVMe, two merges, containing:
        - pci-e, rdma, and fc fixes
        - Device quirks

   - Fix for a badblocks leak in null_blk

   - bcache fix from Rui Hua for a race condition regression where
     -EINTR was returned to upper layers that didn't expect it.

   - Regression fix for blktrace for a bug introduced in this series.

   - blktrace cleanup for cgroup id.

   - bdi registration error handling.

   - Small series with cleanups for blk-wbt.

   - Various little fixes for typos and the like.

  Nothing earth shattering, most important are the NVMe and bcache fixes"

* 'for-linus' of git://git.kernel.dk/linux-block: (34 commits)
  nvme-pci: fix NULL pointer dereference in nvme_free_host_mem()
  nvme-rdma: fix memory leak during queue allocation
  blktrace: fix trace mutex deadlock
  nvme-rdma: Use mr pool
  nvme-rdma: Check remotely invalidated rkey matches our expected rkey
  nvme-rdma: wait for local invalidation before completing a request
  nvme-rdma: don't complete requests before a send work request has completed
  nvme-rdma: don't suppress send completions
  bcache: check return value of register_shrinker
  bcache: recover data from backing when data is clean
  bcache: Fix building error on MIPS
  bcache: add a comment in journal bucket reading
  nvme-fc: don't use bit masks for set/test_bit() numbers
  blk-wbt: fix comments typo
  blk-wbt: move wbt_clear_stat to common place in wbt_done
  blk-sysfs: remove NULL pointer checking in queue_wb_lat_store
  blk-wbt: remove duplicated setting in wbt_init
  nvme-pci: add quirk for delay before CHK RDY for WDC SN200
  block: remove useless assignment in bio_split
  null_blk: fix dev->badblocks leak
  ...

The comments in the ASID allocator incorrectly hint at an MP-style idiom
using the asid_generation and the active_asids array. In fact, the
synchronisation is achieved using a combination of an xchg operation
and a spinlock, so update the comments and remove the pointless smp_wmb().

Cc: James Morse <james.morse@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

Building the kernel with an LTO-enabled GCC spits out the following "const"
warning for the cpu_ops code:

  mm/percpu.c:2168:20: error: pcpu_fc_names causes a section type conflict
  with dt_supported_cpu_ops
  const char * const pcpu_fc_names[PCPU_FC_NR] __initconst = {
          ^
  arch/arm64/kernel/cpu_ops.c:34:37: note: ‘dt_supported_cpu_ops’ was declared here
  static const struct cpu_operations *dt_supported_cpu_ops[] __initconst = {

Fix it by adding missed const qualifiers.
Signed-off-by: Yury Norov <ynorov@caviumnetworks.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

bus access read/write events are not supported in A73, based on the
Cortex-A73 TRM r0p2, section 11.9 Events (pages 11-457 to 11-460).

Fixes: 5561b6c5 "arm64: perf: add support for Cortex-A73"
Acked-by: Julien Thierry <julien.thierry@arm.com>
Signed-off-by: Xu YiPing <xuyiping@hisilicon.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

The fpsimd_update_current_state() function is responsible for
loading the FPSIMD state from the user signal frame into the
current task during sigreturn.  When implementing support for SVE,
conditional code was added to this function in order to handle the
case where SVE state need to be loaded for the task and merged with
the FPSIMD data from the signal frame; however, the FPSIMD-only
case was unintentionally dropped.

As a result of this, sigreturn does not currently restore the
FPSIMD state of the task, except in the case where the system
supports SVE and the signal frame contains SVE state in addition to
FPSIMD state.

This patch fixes this bug by making the copy-in of the FPSIMD data
from the signal frame to thread_struct unconditional.

This remains a performance regression from v4.14, since the FPSIMD
state is now copied into thread_struct and then loaded back,
instead of _only_ being loaded into the CPU FPSIMD registers.
However, it is essential to call task_fpsimd_load() here anyway in
order to ensure that the SVE enable bit in CPACR_EL1 is set
correctly before returning to userspace.  This could use some
refactoring, but since sigreturn is not a fast path I have kept
this patch as a pure fix and left the refactoring for later.

Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Fixes: 8cd969d2 ("arm64/sve: Signal handling support")
Reported-by: Alex Bennée <alex.bennee@linaro.org>
Tested-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

pgd_cache is setup once while init stage and never changed after
that, so it is good candidate for __ro_after_init
Signed-off-by: Jinbum Park <jinb.park7@gmail.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

When building the arm64 kernel with both CONFIG_ARM64_MODULE_PLTS and
CONFIG_DYNAMIC_FTRACE enabled, the ftrace-mod.o object file is built
with the kernel and contains a trampoline that is linked into each
module, so that modules can be loaded far away from the kernel and
still reach the ftrace entry point in the core kernel with an ordinary
relative branch, as is emitted by the compiler instrumentation code
dynamic ftrace relies on.

In order to be able to build out of tree modules, this object file
needs to be included into the linux-headers or linux-devel packages,
which is undesirable, as it makes arm64 a special case (although a
precedent does exist for 32-bit PPC).

Given that the trampoline essentially consists of a PLT entry, let's
not bother with a source or object file for it, and simply patch it
in whenever the trampoline is being populated, using the existing
PLT support routines.

Cc: <stable@vger.kernel.org>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>

To allow the ftrace trampoline code to reuse the PLT entry routines,
factor it out and move it into asm/module.h.

Cc: <stable@vger.kernel.org>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>

When an AFS inode is allocated by afs_alloc_inode(), the allocated
afs_vnode struct isn't necessarily reset from the last time it was used as
an inode because the slab constructor is only invoked once when the memory
is obtained from the page allocator.

This means that information can leak from one inode to the next because
we're not calling kmem_cache_zalloc().  Some of the information isn't
reset, in particular the permit cache pointer.

Bring the clearances up to date.
Signed-off-by: David Howells <dhowells@redhat.com>
Tested-by: Marc Dionne <marc.dionne@auristor.com>

Fix four refcount bugs in afs_cache_permit():

 (1) When checking the result of the kzalloc(), we can't just return, but
     must put 'permits'.

 (2) We shouldn't put permits immediately after hashing a new permit as we
     need to keep the pointer stable so that we can check to see if
     vnode->permit_cache has changed before we decide whether to assign to
     it.

 (3) 'permits' is being put twice.

 (4) We need to put either the replacement or the thing replaced after the
     assignment to vnode->permit_cache.

Without this, lots of the following are seen:

  Kernel BUG at ffffffffa039857b [verbose debug info unavailable]
  ------------[ cut here ]------------
  Kernel BUG at ffffffffa039858a [verbose debug info unavailable]
  ------------[ cut here ]------------

The addresses are in the .text..refcount section of the kafs.ko module.
Following the relocation records for the __ex_table section shows one to be
due to the decrement in afs_put_permits() and the other to be key_get() in
afs_cache_permit().

Occasionally, the following is seen:

  refcount_t overflow at afs_cache_permit+0x57d/0x5c0 [kafs] in cc1[562], uid/euid: 0/0
  WARNING: CPU: 0 PID: 562 at kernel/panic.c:657 refcount_error_report+0x9c/0xac
  ...
Reported-by: Marc Dionne <marc.dionne@auristor.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Tested-by: Marc Dionne <marc.dionne@auristor.com>