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  1. 03 Mar, 2020 4 commits
    • Quentin Perret's avatar
      kbuild: allow symbol whitelisting with TRIM_UNUSED_KSYMS · 1518c633
      Quentin Perret authored 
      CONFIG_TRIM_UNUSED_KSYMS currently removes all unused exported symbols
from ksymtab. This works really well when using in-tree drivers, but
cannot be used in its current form if some of them are out-of-tree.

Indeed, even if the list of symbols required by out-of-tree drivers is
known at compile time, the only solution today to guarantee these don't
get trimmed is to set CONFIG_TRIM_UNUSED_KSYMS=n. This not only wastes
space, but also makes it difficult to control the ABI usable by vendor
modules in distribution kernels such as Android. Being able to control
the kernel ABI surface is particularly useful to ship a unique Generic
Kernel Image (GKI) for all vendors, which is a first step in the
direction of getting all vendors to contribute their code upstream.

As such, attempt to improve the situation by enabling users to specify a
symbol 'whitelist' at compile time. Any symbol specified in this
whitelist will be kept exported when CONFIG_TRIM_UNUSED_KSYMS is set,
even if it has no in-tree user. The whitelist is defined as a simple
text file, listing symbols, one per line.
Acked-by: default avatarJessica Yu <jeyu@kernel.org>
Acked-by: default avatarNicolas Pitre <nico@fluxnic.net>
Tested-by: default avatarMatthias Maennich <maennich@google.com>
Reviewed-by: default avatarMatthias Maennich <maennich@google.com>
Signed-off-by: default avatarQuentin Perret <qperret@google.com>
Signed-off-by: default avatarMasahiro Yamada <masahiroy@kernel.org>
      1518c633
    • Masahiro Yamada's avatar
      kbuild: use KBUILD_DEFCONFIG as the fallback for DEFCONFIG_LIST · 2a86f661
      Masahiro Yamada authored 
      Most of the Kconfig commands (except defconfig and all*config) read
the .config file as a base set of CONFIG options.

When it does not exist, the files in DEFCONFIG_LIST are searched in
this order and loaded if found.

I do not see much sense in the last two lines in DEFCONFIG_LIST.

[1] ARCH_DEFCONFIG

The entry for DEFCONFIG_LIST is guarded by 'depends on !UML'. So, the
ARCH_DEFCONFIG definition in arch/x86/um/Kconfig is meaningless.

arch/{sh,sparc,x86}/Kconfig define ARCH_DEFCONFIG depending on 32 or
64 bit variant symbols. This is a little bit strange; ARCH_DEFCONFIG
should be a fixed string because the base config file is loaded before
the symbol evaluation stage.

Using KBUILD_DEFCONFIG makes more sense because it is fixed before
Kconfig is invoked. Fortunately, arch/{sh,sparc,x86}/Makefile define it
in the same way, and it works as expected. Hence, replace ARCH_DEFCONFIG
with "arch/$(SRCARCH)/configs/$(KBUILD_DEFCONFIG)".

[2] arch/$(ARCH)/defconfig

This file path is no longer valid. The defconfig files are always located
in the arch configs/ directories.

  $ find arch -name defconfig | sort
  arch/alpha/configs/defconfig
  arch/arm64/configs/defconfig
  arch/csky/configs/defconfig
  arch/nds32/configs/defconfig
  arch/riscv/configs/defconfig
  arch/s390/configs/defconfig
  arch/unicore32/configs/defconfig

The path arch/*/configs/defconfig is already covered by
"arch/$(SRCARCH)/configs/$(KBUILD_DEFCONFIG)". So, this file path is
not necessary.

I moved the default KBUILD_DEFCONFIG to the top Makefile. Otherwise,
the 7 architectures listed above would end up with endless loop of
syncconfig.
Signed-off-by: default avatarMasahiro Yamada <masahiroy@kernel.org>
      2a86f661
    • Nick Desaulniers's avatar
      Documentation/llvm: add documentation on building w/ Clang/LLVM · fcf1b6a3
      Nick Desaulniers authored 
      Added to kbuild documentation. Provides more official info on building
kernels with Clang and LLVM than our wiki.
Suggested-by: default avatarKees Cook <keescook@chromium.org>
Reviewed-by: default avatarKees Cook <keescook@chromium.org>
Reviewed-by: default avatarNathan Chancellor <natechancellor@gmail.com>
Reviewed-by: default avatarSedat Dilek <sedat.dilek@gmail.com>
Signed-off-by: default avatarNick Desaulniers <ndesaulniers@google.com>
Signed-off-by: default avatarMasahiro Yamada <masahiroy@kernel.org>
      fcf1b6a3
    • Masahiro Yamada's avatar
      kbuild: remove trailing slash from devicetree/binding/ for descending · a1af8d71
      Masahiro Yamada authored 
      obj-* needs a trailing slash for a directory, but subdir-* does not
because it already implies a directory.

Also, change subdir-y to subdir- to ensure this is effective only
for cleaning targets.

This makes the cleaning log consistent. (no trailing slash)

Before:

  $ make clean
  CLEAN   Documentation/devicetree/bindings/

After:

  $ make clean
  CLEAN   Documentation/devicetree/bindings
Signed-off-by: default avatarMasahiro Yamada <masahiroy@kernel.org>
      a1af8d71
  3. 02 Mar, 2020 4 commits
    • Masahiro Yamada's avatar
      fixdep: remove redundant null character check · 3f9070a6
      Masahiro Yamada authored 
      If *q is '\0', the condition (isalnum(*q) || *q == '_') is false anyway.

It is redundant to ensure non-zero *q.
Signed-off-by: default avatarMasahiro Yamada <masahiroy@kernel.org>
      3f9070a6
    • Masahiro Yamada's avatar
      fixdep: remove unneeded code and comments about *.ver files · 87d660f0
      Masahiro Yamada authored 
      This is probably stale code. In old days (~ Linux 2.5.59), Kbuild made
genksyms generate include/linux/modules/*.ver files.

The currenct Kbuild does not generate *.ver files at all.
Signed-off-by: default avatarMasahiro Yamada <masahiroy@kernel.org>
      87d660f0
    • Masahiro Yamada's avatar
      kbuild: remove cc-option switch from -Wframe-larger-than= · a83e4ca2
      Masahiro Yamada authored 
      This CONFIG option was added by commit 35bb5b1e ("Add option to
enable -Wframe-larger-than= on gcc 4.4"). At that time, the cc-option
check was needed.

According to Documentation/process/changes.rst, the current minimal
supported version of GCC is 4.6, so you can assume GCC supports it.
Clang supports it as well.

Remove the cc-option switch and redundant comments.
Signed-off-by: default avatarMasahiro Yamada <masahiroy@kernel.org>
Reviewed-by: default avatarNathan Chancellor <natechancellor@gmail.com>
Reviewed-by: default avatarNick Desaulniers <ndesaulniers@google.com>
      a83e4ca2
    • Masahiro Yamada's avatar
      kbuild: remove the owner check in mkcompile_h · f84fdf8d
      Masahiro Yamada authored 
      This reverts a very old commit, which dates back to the pre-git era:

|commit 5d1cfb5b
|Author: Kai Germaschewski <kai@tp1.ruhr-uni-bochum.de>
|Date:   Sat Jul 27 02:53:19 2002 -0500
|
|    kbuild: Fix compiling/installing as different users
|
|    "make bzImage && sudo make install" had the problem that during
|    the "sudo make install" the build system would notice that the information
|    in include/linux/compile.h is not accurate (it says "compiled by <user>",
|    but we are root), thus causing compile.h to be updated and leading to
|    some recompiles.
|
|    We now only update "compile.h" if the current user is the owner of
|    include/linux/autoconf.h, i.e. the user who did the "make *config". So the
|    above sequence will correctly state "compiled by <user>".
|
|diff --git a/scripts/mkcompile_h b/scripts/mkcompile_h
|index 6313db96172..cd956380978 100755
|--- a/scripts/mkcompile_h
|+++ b/scripts/mkcompile_h
|@@ -3,6 +3,17 @@ ARCH=$2
| SMP=$3
| CC=$4
|
|+# If compile.h exists already and we don't own autoconf.h
|+# (i.e. we're not the same user who did make *config), don't
|+# modify compile.h
|+# So "sudo make install" won't change the "compiled by <user>"
|+# do "compiled by root"
|+
|+if [ -r $TARGET -a ! -O ../include/linux/autoconf.h ]; then
|+  echo ' (not modified)'
|+  exit 0
|+fi
|+
| if [ -r ../.version ]; then
|   VERSION=`cat ../.version`
| else

The 'make bzImage && sudo make install' problem no longer happens
because commit 1648e4f8 ("x86, kbuild: make "make install" not
depend on vmlinux") fixed the root cause.

Commit 19514fc6 ("arm, kbuild: make "make install" not depend on
vmlinux") fixed the similar issue on ARM, with detailed explanation.

So, the rule is that the installation targets should never trigger
the builds of any build artifact. By following it, this check is
unneeded.
Signed-off-by: default avatarMasahiro Yamada <masahiroy@kernel.org>
      f84fdf8d
  5. 01 Mar, 2020 5 commits
  7. 29 Feb, 2020 4 commits
    • Dan Carpenter's avatar
      ext4: potential crash on allocation error in ext4_alloc_flex_bg_array() · 37b0b6b8
      Dan Carpenter authored 
      If sbi->s_flex_groups_allocated is zero and the first allocation fails
then this code will crash.  The problem is that "i--" will set "i" to
-1 but when we compare "i >= sbi->s_flex_groups_allocated" then the -1
is type promoted to unsigned and becomes UINT_MAX.  Since UINT_MAX
is more than zero, the condition is true so we call kvfree(new_groups[-1]).
The loop will carry on freeing invalid memory until it crashes.

Fixes: 7c990728 ("ext4: fix potential race between s_flex_groups online resizing and access")
Reviewed-by: default avatarSuraj Jitindar Singh <surajjs@amazon.com>
Signed-off-by: default avatarDan Carpenter <dan.carpenter@oracle.com>
Cc: stable@kernel.org
Link: https://lore.kernel.org/r/20200228092142.7irbc44yaz3by7nb@kili.mountainSigned-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
      37b0b6b8
    • Wolfram Sang's avatar
      macintosh: therm_windtunnel: fix regression when instantiating devices · 38b17afb
      Wolfram Sang authored 
      Removing attach_adapter from this driver caused a regression for at
least some machines. Those machines had the sensors described in their
DT, too, so they didn't need manual creation of the sensor devices. The
old code worked, though, because manual creation came first. Creation of
DT devices then failed later and caused error logs, but the sensors
worked nonetheless because of the manually created devices.

When removing attach_adaper, manual creation now comes later and loses
the race. The sensor devices were already registered via DT, yet with
another binding, so the driver could not be bound to it.

This fix refactors the code to remove the race and only manually creates
devices if there are no DT nodes present. Also, the DT binding is updated
to match both, the DT and manually created devices. Because we don't
know which device creation will be used at runtime, the code to start
the kthread is moved to do_probe() which will be called by both methods.

Fixes: 3e7bed52 ("macintosh: therm_windtunnel: drop using attach_adapter")
Link: https://bugzilla.kernel.org/show_bug.cgi?id=201723Reported-by: default avatarErhard Furtner <erhard_f@mailbox.org>
Tested-by: default avatarErhard Furtner <erhard_f@mailbox.org>
Acked-by: Michael Ellerman <mpe@ellerman.id.au> (powerpc)
Signed-off-by: default avatarWolfram Sang <wsa@the-dreams.de>
Cc: stable@kernel.org # v4.19+
      38b17afb
    • Qian Cai's avatar
      jbd2: fix data races at struct journal_head · 6c5d9112
      Qian Cai authored 
      journal_head::b_transaction and journal_head::b_next_transaction could
be accessed concurrently as noticed by KCSAN,

 LTP: starting fsync04
 /dev/zero: Can't open blockdev
 EXT4-fs (loop0): mounting ext3 file system using the ext4 subsystem
 EXT4-fs (loop0): mounted filesystem with ordered data mode. Opts: (null)
 ==================================================================
 BUG: KCSAN: data-race in __jbd2_journal_refile_buffer [jbd2] / jbd2_write_access_granted [jbd2]

 write to 0xffff99f9b1bd0e30 of 8 bytes by task 25721 on cpu 70:
  __jbd2_journal_refile_buffer+0xdd/0x210 [jbd2]
  __jbd2_journal_refile_buffer at fs/jbd2/transaction.c:2569
  jbd2_journal_commit_transaction+0x2d15/0x3f20 [jbd2]
  (inlined by) jbd2_journal_commit_transaction at fs/jbd2/commit.c:1034
  kjournald2+0x13b/0x450 [jbd2]
  kthread+0x1cd/0x1f0
  ret_from_fork+0x27/0x50

 read to 0xffff99f9b1bd0e30 of 8 bytes by task 25724 on cpu 68:
  jbd2_write_access_granted+0x1b2/0x250 [jbd2]
  jbd2_write_access_granted at fs/jbd2/transaction.c:1155
  jbd2_journal_get_write_access+0x2c/0x60 [jbd2]
  __ext4_journal_get_write_access+0x50/0x90 [ext4]
  ext4_mb_mark_diskspace_used+0x158/0x620 [ext4]
  ext4_mb_new_blocks+0x54f/0xca0 [ext4]
  ext4_ind_map_blocks+0xc79/0x1b40 [ext4]
  ext4_map_blocks+0x3b4/0x950 [ext4]
  _ext4_get_block+0xfc/0x270 [ext4]
  ext4_get_block+0x3b/0x50 [ext4]
  __block_write_begin_int+0x22e/0xae0
  __block_write_begin+0x39/0x50
  ext4_write_begin+0x388/0xb50 [ext4]
  generic_perform_write+0x15d/0x290
  ext4_buffered_write_iter+0x11f/0x210 [ext4]
  ext4_file_write_iter+0xce/0x9e0 [ext4]
  new_sync_write+0x29c/0x3b0
  __vfs_write+0x92/0xa0
  vfs_write+0x103/0x260
  ksys_write+0x9d/0x130
  __x64_sys_write+0x4c/0x60
  do_syscall_64+0x91/0xb05
  entry_SYSCALL_64_after_hwframe+0x49/0xbe

 5 locks held by fsync04/25724:
  #0: ffff99f9911093f8 (sb_writers#13){.+.+}, at: vfs_write+0x21c/0x260
  #1: ffff99f9db4c0348 (&sb->s_type->i_mutex_key#15){+.+.}, at: ext4_buffered_write_iter+0x65/0x210 [ext4]
  #2: ffff99f5e7dfcf58 (jbd2_handle){++++}, at: start_this_handle+0x1c1/0x9d0 [jbd2]
  #3: ffff99f9db4c0168 (&ei->i_data_sem){++++}, at: ext4_map_blocks+0x176/0x950 [ext4]
  #4: ffffffff99086b40 (rcu_read_lock){....}, at: jbd2_write_access_granted+0x4e/0x250 [jbd2]
 irq event stamp: 1407125
 hardirqs last  enabled at (1407125): [<ffffffff980da9b7>] __find_get_block+0x107/0x790
 hardirqs last disabled at (1407124): [<ffffffff980da8f9>] __find_get_block+0x49/0x790
 softirqs last  enabled at (1405528): [<ffffffff98a0034c>] __do_softirq+0x34c/0x57c
 softirqs last disabled at (1405521): [<ffffffff97cc67a2>] irq_exit+0xa2/0xc0

 Reported by Kernel Concurrency Sanitizer on:
 CPU: 68 PID: 25724 Comm: fsync04 Tainted: G L 5.6.0-rc2-next-20200221+ #7
 Hardware name: HPE ProLiant DL385 Gen10/ProLiant DL385 Gen10, BIOS A40 07/10/2019

The plain reads are outside of jh->b_state_lock critical section which result
in data races. Fix them by adding pairs of READ|WRITE_ONCE().
Reviewed-by: default avatarJan Kara <jack@suse.cz>
Signed-off-by: default avatarQian Cai <cai@lca.pw>
Link: https://lore.kernel.org/r/20200222043111.2227-1-cai@lca.pwSigned-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
      6c5d9112
    • Linus Torvalds's avatar
      Merge tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi · 7557c1b3
      Linus Torvalds authored 
      Pull SCSI fixes from James Bottomley:
 "Four small fixes.

  Three are in drivers for fairly obvious bugs. The fourth is a set of
  regressions introduced by the compat_ioctl changes because some of the
  compat updates wrongly replaced .ioctl instead of .compat_ioctl"

* tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi:
  scsi: compat_ioctl: cdrom: Replace .ioctl with .compat_ioctl in four appropriate places
  scsi: zfcp: fix wrong data and display format of SFP+ temperature
  scsi: sd_sbc: Fix sd_zbc_report_zones()
  scsi: libfc: free response frame from GPN_ID
      7557c1b3
  9. 28 Feb, 2020 21 commits
  11. 27 Feb, 2020 2 commits
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