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  1. 13 Dec, 2018 1 commit
    • Nick Desaulniers's avatar
      kbuild: fix linker feature test macros when cross compiling with Clang · 51d137ca
      Nick Desaulniers authored 
      (commit 86a9df59 upstream)

I was not seeing my linker flags getting added when using ld-option when
cross compiling with Clang. Upon investigation, this seems to be due to
a difference in how GCC vs Clang handle cross compilation.

GCC is configured at build time to support one backend, that is implicit
when compiling.  Clang is explicit via the use of `-target <triple>` and
ships with all supported backends by default.

GNU Make feature test macros that compile then link will always fail
when cross compiling with Clang unless Clang's triple is passed along to
the compiler. For example:

$ clang -x c /dev/null -c -o temp.o
$ aarch64-linux-android/bin/ld -E temp.o
aarch64-linux-android/bin/ld:
unknown architecture of input file `temp.o' is incompatible with
aarch64 output
aarch64-linux-android/bin/ld:
warning: cannot find entry symbol _start; defaulting to
0000000000400078
$ echo $?
1

$ clang -target aarch64-linux-android- -x c /dev/null -c -o temp.o
$ aarch64-linux-android/bin/ld -E temp.o
aarch64-linux-android/bin/ld:
warning: cannot find entry symbol _start; defaulting to 00000000004002e4
$ echo $?
0

This causes conditional checks that invoke $(CC) without the target
triple, then $(LD) on the result, to always fail.
Suggested-by: Masahiro Yamada's avatarMasahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: default avatarNick Desaulniers <ndesaulniers@google.com>
Reviewed-by: default avatarMatthias Kaehlcke <mka@chromium.org>
Signed-off-by: Masahiro Yamada's avatarMasahiro Yamada <yamada.masahiro@socionext.com>
[ND: readjusted for context]
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      51d137ca
  3. 08 Dec, 2018 2 commits
  5. 23 Nov, 2018 7 commits
  7. 26 Sep, 2018 1 commit
    • Masahiro Yamada's avatar
      kbuild: add .DELETE_ON_ERROR special target · 48a90a9e
      Masahiro Yamada authored 
      [ Upstream commit 9c2af1c7377a8a6ef86e5cabf80978f3dbbb25c0 ]

If Make gets a fatal signal while a shell is executing, it may delete
the target file that the recipe was supposed to update.  This is needed
to make sure that it is remade from scratch when Make is next run; if
Make is interrupted after the recipe has begun to write the target file,
it results in an incomplete file whose time stamp is newer than that
of the prerequisites files.  Make automatically deletes the incomplete
file on interrupt unless the target is marked .PRECIOUS.

The situation is just the same as when the shell fails for some reasons.
Usually when a recipe line fails, if it has changed the target file at
all, the file is corrupted, or at least it is not completely updated.
Yet the file’s time stamp says that it is now up to date, so the next
time Make runs, it will not try to update that file.

However, Make does not cater to delete the incomplete target file in
this case.  We need to add .DELETE_ON_ERROR somewhere in the Makefile
to request it.

scripts/Kbuild.include seems a suitable place to add it because it is
included from almost all sub-makes.

Please note .DELETE_ON_ERROR is not effective for phony targets.

The external module building should never ever touch the kernel tree.
The following recipe fails if include/generated/autoconf.h is missing.
However, include/config/auto.conf is not deleted since it is a phony
target.

 PHONY += include/config/auto.conf

 include/config/auto.conf:
         $(Q)test -e include/generated/autoconf.h -a -e $@ || (          \
         echo >&2;                                                       \
         echo >&2 "  ERROR: Kernel configuration is invalid.";           \
         echo >&2 "         include/generated/autoconf.h or $@ are missing.";\
         echo >&2 "         Run 'make oldconfig && make prepare' on kernel src to fix it."; \
         echo >&2 ;                                                      \
         /bin/false)
Signed-off-by: Masahiro Yamada's avatarMasahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: default avatarSasha Levin <alexander.levin@microsoft.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      48a90a9e
  9. 15 Sep, 2018 2 commits
  11. 17 Aug, 2018 2 commits
  13. 11 Jul, 2018 1 commit
    • Rasmus Villemoes's avatar
      Kbuild: fix # escaping in .cmd files for future Make · b5d7d7d9
      Rasmus Villemoes authored 
      commit 9564a8cf422d7b58f6e857e3546d346fa970191e upstream.

I tried building using a freshly built Make (4.2.1-69-g8a731d1), but
already the objtool build broke with

orc_dump.c: In function ‘orc_dump’:
orc_dump.c:106:2: error: ‘elf_getshnum’ is deprecated [-Werror=deprecated-declarations]
  if (elf_getshdrnum(elf, &nr_sections)) {

Turns out that with that new Make, the backslash was not removed, so cpp
didn't see a #include directive, grep found nothing, and
-DLIBELF_USE_DEPRECATED was wrongly put in CFLAGS.

Now, that new Make behaviour is documented in their NEWS file:

  * WARNING: Backward-incompatibility!
    Number signs (#) appearing inside a macro reference or function invocation
    no longer introduce comments and should not be escaped with backslashes:
    thus a call such as:
      foo := $(shell echo '#')
    is legal.  Previously the number sign needed to be escaped, for example:
      foo := $(shell echo '\#')
    Now this latter will resolve to "\#".  If you want to write makefiles
    portable to both versions, assign the number sign to a variable:
      C := \#
      foo := $(shell echo '$C')
    This was claimed to be fixed in 3.81, but wasn't, for some reason.
    To detect this change search for 'nocomment' in the .FEATURES variable.

This also fixes up the two make-cmd instances to replace # with $(pound)
rather than with \#. There might very well be other places that need
similar fixup in preparation for whatever future Make release contains
the above change, but at least this builds an x86_64 defconfig with the
new make.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=197847
Cc: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: default avatarRasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Masahiro Yamada's avatarMasahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      b5d7d7d9
  15. 13 Jun, 2018 2 commits
    • Josh Poimboeuf's avatar
      objtool: Fix gcov check for older versions of GCC · 23873aed
      Josh Poimboeuf authored 
      commit 867ac9d7 upstream.

Objtool tries to silence 'unreachable instruction' warnings when it
detects gcov is enabled, because gcov produces a lot of unreachable
instructions and they don't really matter.

However, the 0-day bot is still reporting some unreachable instruction
warnings with CONFIG_GCOV_KERNEL=y on GCC 4.6.4.

As it turns out, objtool's gcov detection doesn't work with older
versions of GCC because they don't create a bunch of symbols with the
'gcov.' prefix like newer versions of GCC do.

Move the gcov check out of objtool and instead just create a new
'--no-unreachable' flag which can be passed in by the kernel Makefile
when CONFIG_GCOV_KERNEL is defined.

Also rename the 'nofp' variable to 'no_fp' for consistency with the new
'no_unreachable' variable.
Reported-by: default avatarkbuild test robot <fengguang.wu@intel.com>
Signed-off-by: default avatarJosh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: 9cfffb11 ("objtool: Skip all "unreachable instruction" warnings for gcov kernels")
Link: http://lkml.kernel.org/r/c243dc78eb2ffdabb6e927844dea39b6033cd395.1500939244.git.jpoimboe@redhat.comSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
[just Makefile.build as the other parts of this patch already applied - gregkh]
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      23873aed
    • Nathan Chancellor's avatar
      kconfig: Avoid format overflow warning from GCC 8.1 · 1ec1dfba
      Nathan Chancellor authored 
      commit 2ae89c7a upstream.

In file included from scripts/kconfig/zconf.tab.c:2485:
scripts/kconfig/confdata.c: In function ‘conf_write’:
scripts/kconfig/confdata.c:773:22: warning: ‘%s’ directive writing likely 7 or more bytes into a region of size between 1 and 4097 [-Wformat-overflow=]
  sprintf(newname, "%s%s", dirname, basename);
                      ^~
scripts/kconfig/confdata.c:773:19: note: assuming directive output of 7 bytes
  sprintf(newname, "%s%s", dirname, basename);
                   ^~~~~~
scripts/kconfig/confdata.c:773:2: note: ‘sprintf’ output 1 or more bytes (assuming 4104) into a destination of size 4097
  sprintf(newname, "%s%s", dirname, basename);
  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
scripts/kconfig/confdata.c:776:23: warning: ‘.tmpconfig.’ directive writing 11 bytes into a region of size between 1 and 4097 [-Wformat-overflow=]
   sprintf(tmpname, "%s.tmpconfig.%d", dirname, (int)getpid());
                       ^~~~~~~~~~~
scripts/kconfig/confdata.c:776:3: note: ‘sprintf’ output between 13 and 4119 bytes into a destination of size 4097
   sprintf(tmpname, "%s.tmpconfig.%d", dirname, (int)getpid());
   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Increase the size of tmpname and newname to make GCC happy.
Signed-off-by: default avatarNathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Masahiro Yamada's avatarMasahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      1ec1dfba
  17. 30 May, 2018 5 commits
  19. 13 Apr, 2018 1 commit
  21. 18 Mar, 2018 1 commit
    • James Hogan's avatar
      kbuild: Handle builtin dtb file names containing hyphens · 333cdd17
      James Hogan authored 
      commit 55fe6da9 upstream.

cmd_dt_S_dtb constructs the assembly source to incorporate a devicetree
FDT (that is, the .dtb file) as binary data in the kernel image. This
assembly source contains labels before and after the binary data. The
label names incorporate the file name of the corresponding .dtb file.
Hyphens are not legal characters in labels, so .dtb files built into the
kernel with hyphens in the file name result in errors like the
following:

bcm3368-netgear-cvg834g.dtb.S: Assembler messages:
bcm3368-netgear-cvg834g.dtb.S:5: Error: : no such section
bcm3368-netgear-cvg834g.dtb.S:5: Error: junk at end of line, first unrecognized character is `-'
bcm3368-netgear-cvg834g.dtb.S:6: Error: unrecognized opcode `__dtb_bcm3368-netgear-cvg834g_begin:'
bcm3368-netgear-cvg834g.dtb.S:8: Error: unrecognized opcode `__dtb_bcm3368-netgear-cvg834g_end:'
bcm3368-netgear-cvg834g.dtb.S:9: Error: : no such section
bcm3368-netgear-cvg834g.dtb.S:9: Error: junk at end of line, first unrecognized character is `-'

Fix this by updating cmd_dt_S_dtb to transform all hyphens from the file
name to underscores when constructing the labels.

As of v4.16-rc2, 1139 .dts files across ARM64, ARM, MIPS and PowerPC
contain hyphens in their names, but the issue only currently manifests
on Broadcom MIPS platforms, as that is the only place where such files
are built into the kernel. For example when CONFIG_DT_NETGEAR_CVG834G=y,
or on BMIPS kernels when the dtbs target is used (in the latter case it
admittedly shouldn't really build all the dtb.o files, but thats a
separate issue).

Fixes: 69583551 ("MIPS: BMIPS: rename bcm96358nb4ser to bcm6358-neufbox4-sercom")
Signed-off-by: default avatarJames Hogan <jhogan@kernel.org>
Reviewed-by: default avatarFrank Rowand <frowand.list@gmail.com>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: Michal Marek <michal.lkml@markovi.net>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Florian Fainelli <f.fainelli@gmail.com>
Cc: Kevin Cernekee <cernekee@gmail.com>
Cc: <stable@vger.kernel.org> # 4.9+
Signed-off-by: Masahiro Yamada's avatarMasahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      333cdd17
  23. 25 Feb, 2018 1 commit
    • Will Deacon's avatar
      scripts/kernel-doc: Don't fail with status != 0 if error encountered with -none · e985f5a9
      Will Deacon authored 
      
[ Upstream commit e814bccb ]

My bisect scripts starting running into build failures when trying to
compile 4.15-rc1 with the builds failing with things like:

drivers/net/wireless/broadcom/brcm80211/brcmfmac/sdio.c:2078: error: Cannot parse struct or union!

The line in question is actually just a #define, but after some digging
it turns out that my scripts pass W=1 and since commit 3a025e1d
("Add optional check for bad kernel-doc comments") that results in
kernel-doc running on each source file. The file in question has a
badly formatted comment immediately before the #define:

/**
 * struct brcmf_skbuff_cb reserves first two bytes in sk_buff::cb for
 * bus layer usage.
 */

which causes the regex in dump_struct to fail (lack of braces following
struct declaration) and kernel-doc returns 1, which causes the build
to fail.

Fix the issue by always returning 0 from kernel-doc when invoked with
-none. It successfully generates no documentation, and prints out any
issues.

Cc: Matthew Wilcox <mawilcox@microsoft.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
Signed-off-by: default avatarJonathan Corbet <corbet@lwn.net>
Signed-off-by: default avatarSasha Levin <alexander.levin@microsoft.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      e985f5a9
  25. 13 Feb, 2018 1 commit
  27. 23 Jan, 2018 1 commit
  29. 17 Jan, 2018 1 commit
  31. 14 Dec, 2017 3 commits
  33. 21 Jul, 2017 1 commit
  35. 12 Jan, 2017 1 commit
  37. 09 Jan, 2017 2 commits
  39. 06 Jan, 2017 1 commit
  41. 01 Dec, 2016 1 commit
  43. 11 Nov, 2016 2 commits
    • Arnd Bergmann's avatar
      Kbuild: enable -Wmaybe-uninitialized warnings by default · 4324cb23
      Arnd Bergmann authored 
      Previously the warnings were added back at the W=1 level and above, this
now turns them on again by default, assuming that we have addressed all
warnings and again have a clean build for v4.10.

I found a number of new warnings in linux-next already and submitted
bugfixes for those.  Hopefully they are caught by the 0day builder in
the future as soon as this patch is merged.
Signed-off-by: default avatarArnd Bergmann <arnd@arndb.de>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      4324cb23
    • Arnd Bergmann's avatar
      Kbuild: enable -Wmaybe-uninitialized warning for "make W=1" · a76bcf55
      Arnd Bergmann authored 
      Traditionally, we have always had warnings about uninitialized variables
enabled, as this is part of -Wall, and generally a good idea [1], but it
also always produced false positives, mainly because this is a variation
of the halting problem and provably impossible to get right in all cases
[2].

Various people have identified cases that are particularly bad for false
positives, and in commit e74fc973 ("Turn off -Wmaybe-uninitialized
when building with -Os"), I turned off the warning for any build that
was done with CC_OPTIMIZE_FOR_SIZE.  This drastically reduced the number
of false positive warnings in the default build but unfortunately had
the side effect of turning the warning off completely in 'allmodconfig'
builds, which in turn led to a lot of warnings (both actual bugs, and
remaining false positives) to go in unnoticed.

With commit 877417e6 ("Kbuild: change CC_OPTIMIZE_FOR_SIZE
definition") enabled the warning again for allmodconfig builds in v4.7
and in v4.8-rc1, I had finally managed to address all warnings I get in
an ARM allmodconfig build and most other maybe-uninitialized warnings
for ARM randconfig builds.

However, commit 6e8d666e ("Disable "maybe-uninitialized" warning
globally") was merged at the same time and disabled it completely for
all configurations, because of false-positive warnings on x86 that I had
not addressed until then.  This caused a lot of actual bugs to get
merged into mainline, and I sent several dozen patches for these during
the v4.9 development cycle.  Most of these are actual bugs, some are for
correct code that is safe because it is only called under external
constraints that make it impossible to run into the case that gcc sees,
and in a few cases gcc is just stupid and finds something that can
obviously never happen.

I have now done a few thousand randconfig builds on x86 and collected
all patches that I needed to address every single warning I got (I can
provide the combined patch for the other warnings if anyone is
interested), so I hope we can get the warning back and let people catch
the actual bugs earlier.

This reverts the change to disable the warning completely and for now
brings it back at the "make W=1" level, so we can get it merged into
mainline without introducing false positives.  A follow-up patch enables
it on all levels unless some configuration option turns it off because
of false-positives.

Link: https://rusty.ozlabs.org/?p=232 [1]
Link: https://gcc.gnu.org/wiki/Better_Uninitialized_Warnings [2]
Signed-off-by: default avatarArnd Bergmann <arnd@arndb.de>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      a76bcf55