Commit Graph

2028 Commits

Author SHA1 Message Date
Masahiro Yamada
52cc02b910 kbuild: check CONFIG_AS_IS_LLVM instead of LLVM_IAS
LLVM_IAS is the user interface to set the -(no-)integrated-as flag,
and it should be used only for that purpose.

LLVM_IAS is checked in some places to determine the assembler type,
but it is not precise.

For example,

 $ make CC=gcc LLVM_IAS=1

... will use the GNU assembler (i.e. binutils) since LLVM_IAS=1 is
effective only when $(CC) is clang.

Of course, 'CC=gcc LLVM_IAS=1' is an odd combination, but the build
system can be more robust against such insane input.

Commit ba64beb174 ("kbuild: check the minimum assembler version in
Kconfig") introduced CONFIG_AS_IS_GNU/LLVM, which is more precise
because Kconfig checks the version string from the assembler in use.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
2021-08-10 09:13:25 +09:00
Nick Desaulniers
6f5b41a2f5 Makefile: move initial clang flag handling into scripts/Makefile.clang
With some of the changes we'd like to make to CROSS_COMPILE, the initial
block of clang flag handling which controls things like the target triple,
whether or not to use the integrated assembler and how to find GAS,
and erroring on unknown warnings is becoming unwieldy. Move it into its
own file under scripts/.

Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2021-08-10 09:13:25 +09:00
Masahiro Yamada
6072b2c49d kbuild: warn if a different compiler is used for external module builds
It is always safe to use the same compiler for the kernel and external
modules, but in reality, some distributions such as Fedora release a
different version of GCC from the one used for building the kernel.

There was a long discussion about mixing different compilers [1].

I do not repeat it here, but at least, showing a heads up in that
case is better than nothing.

Linus suggested [2]:
  And a warning might be more palatable even if different compiler
  version work fine together. Just a heads up on "it looks like you
  might be mixing compiler versions" is a valid note, and isn't
  necessarily wrong. Even when they work well together, maybe you want
  to have people at least _aware_ of it.

This commit shows a warning unless the compiler is exactly the same.

  warning: the compiler differs from the one used to build the kernel
    The kernel was built by: gcc (GCC) 11.1.1 20210531 (Red Hat 11.1.1-3)
    You are using:           gcc (GCC) 11.2.1 20210728 (Red Hat 11.2.1-1)

Check the difference, and if it is OK with you, please proceed at your
risk.

To avoid the locale issue as in commit bcbcf50f52 ("kbuild: fix
ld-version.sh to not be affected by locale"), pass LC_ALL=C to
"$(CC) --version".

[1] https://lore.kernel.org/linux-hardening/efe6b039a544da8215d5e54aa7c4b6d1986fc2b0.1611607264.git.jpoimboe@redhat.com/
[2] https://lore.kernel.org/lkml/CAHk-=wgjwhDy-y4mQh34L+2aF=n6BjzHdqAW2=8wri5x7O04pA@mail.gmail.com/

Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2021-08-10 09:13:25 +09:00
Masahiro Yamada
d828563955 kbuild: do not require sub-make for separate output tree builds
As explained in commit 3204a7fb98 ("kbuild: prefix $(srctree)/ to some
included Makefiles"), I want to stop using --include-dir some day.

I already fixed up the top Makefile, but some arch Makefiles (mips, um,
x86) still include check-in Makefiles without $(srctree)/.

Fix them up so 'need-sub-make := 1' can go away for this case.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2021-08-10 08:23:39 +09:00
Linus Torvalds
36a21d5172 Linux 5.14-rc5 2021-08-08 13:49:31 -07:00
Linus Torvalds
4972bb90c3 Kbuild fixes for v5.14 (2nd)
- Correct the Extended Regular Expressions in tools
 
  - Adjust scripts/checkversion.pl for the current Kbuild
 
  - Unset sub_make_done for 'make install' to make DKMS working again
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Merge tag 'kbuild-fixes-v5.14-2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild

Pull Kbuild fixes from Masahiro Yamada:

 - Correct the Extended Regular Expressions in tools

 - Adjust scripts/checkversion.pl for the current Kbuild

 - Unset sub_make_done for 'make install' to make DKMS work again

* tag 'kbuild-fixes-v5.14-2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild:
  kbuild: cancel sub_make_done for the install target to fix DKMS
  scripts: checkversion: modernize linux/version.h search strings
  mips: Fix non-POSIX regexp
  x86/tools/relocs: Fix non-POSIX regexp
2021-08-07 10:03:02 -07:00
Linus Torvalds
3c3e902707 Various tracing fixes:
- Fix NULL pointer dereference caused by an error path
 
 - Give histogram calculation fields a size, otherwise it breaks synthetic
   creation based on them.
 
 - Reject strings being used for number calculations.
 
 - Fix recordmcount.pl warning on llvm building RISC-V allmodconfig
 
 - Fix the draw_functrace.py script to handle the new trace output
 
 - Fix warning of smp_processor_id() in preemptible code
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Merge tag 'trace-v5.14-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace

Pull tracing fixes from Steven Rostedt:
 "Various tracing fixes:

   - Fix NULL pointer dereference caused by an error path

   - Give histogram calculation fields a size, otherwise it breaks
     synthetic creation based on them.

   - Reject strings being used for number calculations.

   - Fix recordmcount.pl warning on llvm building RISC-V allmodconfig

   - Fix the draw_functrace.py script to handle the new trace output

   - Fix warning of smp_processor_id() in preemptible code"

* tag 'trace-v5.14-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
  tracing: Quiet smp_processor_id() use in preemptable warning in hwlat
  scripts/tracing: fix the bug that can't parse raw_trace_func
  scripts/recordmcount.pl: Remove check_objcopy() and $can_use_local
  tracing: Reject string operand in the histogram expression
  tracing / histogram: Give calculation hist_fields a size
  tracing: Fix NULL pointer dereference in start_creating
2021-08-05 11:53:34 -07:00
Masahiro Yamada
14ccc638b0 kbuild: cancel sub_make_done for the install target to fix DKMS
Since commit bcf637f54f ("kbuild: parse C= and M= before changing the
working directory"), external module builds invoked by DKMS fail because
M= option is not parsed.

I wanted to add 'unset sub_make_done' in install.sh but similar scripts,
arch/*/boot/install.sh, are duplicated, so I set sub_make_done empty in
the top Makefile.

Fixes: bcf637f54f ("kbuild: parse C= and M= before changing the working directory")
Reported-by: John S Gruber <johnsgruber@gmail.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Tested-by: John S Gruber <johnsgruber@gmail.com>
2021-08-05 20:56:35 +09:00
Nathan Chancellor
b18b851ba8 scripts/recordmcount.pl: Remove check_objcopy() and $can_use_local
When building ARCH=riscv allmodconfig with llvm-objcopy, the objcopy
version warning from this script appears:

WARNING: could not find objcopy version or version is less than 2.17.
        Local function references are disabled.

The check_objcopy() function in scripts/recordmcount.pl is set up to
parse GNU objcopy's version string, not llvm-objcopy's, which triggers
the warning.

Commit 799c434154 ("kbuild: thin archives make default for all archs")
made binutils 2.20 mandatory and commit ba64beb174 ("kbuild: check the
minimum assembler version in Kconfig") enforces this at configuration
time so just remove check_objcopy() and $can_use_local instead, assuming
--globalize-symbol is always available.

llvm-objcopy has supported --globalize-symbol since LLVM 7.0.0 in 2018
and the minimum version for building the kernel with LLVM is 10.0.1 so
there is no issue introduced:

Link: ee5be798da
Link: https://lkml.kernel.org/r/20210802210307.3202472-1-nathan@kernel.org

Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
2021-08-04 17:49:26 -04:00
Linus Torvalds
c500bee1c5 Linux 5.14-rc4 2021-08-01 17:04:17 -07:00
Linus Torvalds
ff1176468d Linux 5.14-rc3 2021-07-25 15:35:14 -07:00
Linus Torvalds
2734d6c1b1 Linux 5.14-rc2 2021-07-18 14:13:49 -07:00
Linus Torvalds
6750691a82 Kbuild fixes for v5.14
- Restore the original behavior of scripts/setlocalversion when
    LOCALVERSION is set to empty.
 
  - Show Kconfig prompts even for 'make -s'
 
  - Fix the combination of COFNIG_LTO_CLANG=y and CONFIG_MODVERSIONS=y
    for older GNU Make versions
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Merge tag 'kbuild-fixes-v5.14' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild

Pull Kbuild fixes from Masahiro Yamada:

 - Restore the original behavior of scripts/setlocalversion when
   LOCALVERSION is set to empty.

 - Show Kconfig prompts even for 'make -s'

 - Fix the combination of COFNIG_LTO_CLANG=y and CONFIG_MODVERSIONS=y
   for older GNU Make versions

* tag 'kbuild-fixes-v5.14' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild:
  Documentation: Fix intiramfs script name
  Kbuild: lto: fix module versionings mismatch in GNU make 3.X
  kbuild: do not suppress Kconfig prompts for silent build
  scripts/setlocalversion: fix a bug when LOCALVERSION is empty
2021-07-18 11:10:30 -07:00
Masahiro Yamada
d952cfaf0c kbuild: do not suppress Kconfig prompts for silent build
When a new CONFIG option is available, Kbuild shows a prompt to get
the user input.

  $ make
  [ snip ]
  Core Scheduling for SMT (SCHED_CORE) [N/y/?] (NEW)

This is the only interactive place in the build process.

Commit 174a1dcc96 ("kbuild: sink stdout from cmd for silent build")
suppressed Kconfig prompts as well because syncconfig is invoked by
the 'cmd' macro. You cannot notice the fact that Kconfig is waiting
for the user input.

Use 'kecho' to show the equivalent short log without suppressing stdout
from sub-make.

Fixes: 174a1dcc96 ("kbuild: sink stdout from cmd for silent build")
Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Tested-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
2021-07-18 23:48:14 +09:00
Linus Torvalds
d936eb2387 Revert "Makefile: Enable -Wimplicit-fallthrough for Clang"
This reverts commit b7eb335e26.

It turns out that the problem with the clang -Wimplicit-fallthrough
warning is not about the kernel source code, but about clang itself, and
that the warning is unusable until clang fixes its broken ways.

In particular, when you enable this warning for clang, you not only get
warnings about implicit fallthroughs.  You also get this:

   warning: fallthrough annotation in unreachable code [-Wimplicit-fallthrough]

which is completely broken becasue it

 (a) doesn't even tell you where the problem is (seriously: no line
     numbers, no filename, no nothing).

 (b) is fundamentally broken anyway, because there are perfectly valid
     reasons to have a fallthrough statement even if it turns out that
     it can perhaps not be reached.

In the kernel, an example of that second case is code in the scheduler:

                switch (state) {
                case cpuset:
                        if (IS_ENABLED(CONFIG_CPUSETS)) {
                                cpuset_cpus_allowed_fallback(p);
                                state = possible;
                                break;
                        }
                        fallthrough;
                case possible:

where if CONFIG_CPUSETS is enabled you actually never hit the
fallthrough case at all.  But that in no way makes the fallthrough
wrong.

So the warning is completely broken, and enabling it for clang is a very
bad idea.

In the meantime, we can keep the gcc option enabled, and make the gcc
build use

    -Wimplicit-fallthrough=5

which means that we will at least continue to require a proper
fallthrough statement, and that gcc won't silently accept the magic
comment versions. Because gcc does this all correctly, and while the odd
"=5" part is kind of obscure, it's documented in [1]:

  "-Wimplicit-fallthrough=5 doesn’t recognize any comments as
   fallthrough comments, only attributes disable the warning"

so if clang ever fixes its bad behavior we can try enabling it there again.

Link: https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html [1]
Cc: Kees Cook <keescook@chromium.org>
Cc: Gustavo A. R. Silva <gustavoars@kernel.org>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-07-15 18:05:31 -07:00
Gustavo A. R. Silva
b7eb335e26 Makefile: Enable -Wimplicit-fallthrough for Clang
With the recent fixes for fallthrough warnings, it is now possible to
enable -Wimplicit-fallthrough for Clang.

It's important to mention that since we have adopted the use of the
pseudo-keyword macro fallthrough; we also want to avoid having more
/* fall through */ comments being introduced. Notice that contrary
to GCC, Clang doesn't recognize any comments as implicit fall-through
markings when the -Wimplicit-fallthrough option is enabled. So, in
order to avoid having more comments being introduced, we have to use
the option -Wimplicit-fallthrough=5 for GCC, which similar to Clang,
will cause a warning in case a code comment is intended to be used
as a fall-through marking.

Co-developed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
2021-07-14 11:12:21 -05:00
Linus Torvalds
e73f0f0ee7 Linux 5.14-rc1 2021-07-11 15:07:40 -07:00
Linus Torvalds
81361b837a Kbuild updates for v5.14
- Increase the -falign-functions alignment for the debug option.
 
  - Remove ugly libelf checks from the top Makefile.
 
  - Make the silent build (-s) more silent.
 
  - Re-compile the kernel if KBUILD_BUILD_TIMESTAMP is specified.
 
  - Various script cleanups
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Merge tag 'kbuild-v5.14' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild

Pull Kbuild updates from Masahiro Yamada:

 - Increase the -falign-functions alignment for the debug option.

 - Remove ugly libelf checks from the top Makefile.

 - Make the silent build (-s) more silent.

 - Re-compile the kernel if KBUILD_BUILD_TIMESTAMP is specified.

 - Various script cleanups

* tag 'kbuild-v5.14' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (27 commits)
  scripts: add generic syscallnr.sh
  scripts: check duplicated syscall number in syscall table
  sparc: syscalls: use pattern rules to generate syscall headers
  parisc: syscalls: use pattern rules to generate syscall headers
  nds32: add arch/nds32/boot/.gitignore
  kbuild: mkcompile_h: consider timestamp if KBUILD_BUILD_TIMESTAMP is set
  kbuild: modpost: Explicitly warn about unprototyped symbols
  kbuild: remove trailing slashes from $(KBUILD_EXTMOD)
  kconfig.h: explain IS_MODULE(), IS_ENABLED()
  kconfig: constify long_opts
  scripts/setlocalversion: simplify the short version part
  scripts/setlocalversion: factor out 12-chars hash construction
  scripts/setlocalversion: add more comments to -dirty flag detection
  scripts/setlocalversion: remove workaround for old make-kpkg
  scripts/setlocalversion: remove mercurial, svn and git-svn supports
  kbuild: clean up ${quiet} checks in shell scripts
  kbuild: sink stdout from cmd for silent build
  init: use $(call cmd,) for generating include/generated/compile.h
  kbuild: merge scripts/mkmakefile to top Makefile
  sh: move core-y in arch/sh/Makefile to arch/sh/Kbuild
  ...
2021-07-10 11:01:38 -07:00
Linus Torvalds
9840cfcb97 arm64 updates for 5.14
- Optimise SVE switching for CPUs with 128-bit implementations.
 
  - Fix output format from SVE selftest.
 
  - Add support for versions v1.2 and 1.3 of the SMC calling convention.
 
  - Allow Pointer Authentication to be configured independently for
    kernel and userspace.
 
  - PMU driver cleanups for managing IRQ affinity and exposing event
    attributes via sysfs.
 
  - KASAN optimisations for both hardware tagging (MTE) and out-of-line
    software tagging implementations.
 
  - Relax frame record alignment requirements to facilitate 8-byte
    alignment with KASAN and Clang.
 
  - Cleanup of page-table definitions and removal of unused memory types.
 
  - Reduction of ARCH_DMA_MINALIGN back to 64 bytes.
 
  - Refactoring of our instruction decoding routines and addition of some
    missing encodings.
 
  - Move entry code moved into C and hardened against harmful compiler
    instrumentation.
 
  - Update booting requirements for the FEAT_HCX feature, added to v8.7
    of the architecture.
 
  - Fix resume from idle when pNMI is being used.
 
  - Additional CPU sanity checks for MTE and preparatory changes for
    systems where not all of the CPUs support 32-bit EL0.
 
  - Update our kernel string routines to the latest Cortex Strings
    implementation.
 
  - Big cleanup of our cache maintenance routines, which were confusingly
    named and inconsistent in their implementations.
 
  - Tweak linker flags so that GDB can understand vmlinux when using RELR
    relocations.
 
  - Boot path cleanups to enable early initialisation of per-cpu
    operations needed by KCSAN.
 
  - Non-critical fixes and miscellaneous cleanup.
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Merge tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux

Pull arm64 updates from Will Deacon:
 "There's a reasonable amount here and the juicy details are all below.

  It's worth noting that the MTE/KASAN changes strayed outside of our
  usual directories due to core mm changes and some associated changes
  to some other architectures; Andrew asked for us to carry these [1]
  rather that take them via the -mm tree.

  Summary:

   - Optimise SVE switching for CPUs with 128-bit implementations.

   - Fix output format from SVE selftest.

   - Add support for versions v1.2 and 1.3 of the SMC calling
     convention.

   - Allow Pointer Authentication to be configured independently for
     kernel and userspace.

   - PMU driver cleanups for managing IRQ affinity and exposing event
     attributes via sysfs.

   - KASAN optimisations for both hardware tagging (MTE) and out-of-line
     software tagging implementations.

   - Relax frame record alignment requirements to facilitate 8-byte
     alignment with KASAN and Clang.

   - Cleanup of page-table definitions and removal of unused memory
     types.

   - Reduction of ARCH_DMA_MINALIGN back to 64 bytes.

   - Refactoring of our instruction decoding routines and addition of
     some missing encodings.

   - Move entry code moved into C and hardened against harmful compiler
     instrumentation.

   - Update booting requirements for the FEAT_HCX feature, added to v8.7
     of the architecture.

   - Fix resume from idle when pNMI is being used.

   - Additional CPU sanity checks for MTE and preparatory changes for
     systems where not all of the CPUs support 32-bit EL0.

   - Update our kernel string routines to the latest Cortex Strings
     implementation.

   - Big cleanup of our cache maintenance routines, which were
     confusingly named and inconsistent in their implementations.

   - Tweak linker flags so that GDB can understand vmlinux when using
     RELR relocations.

   - Boot path cleanups to enable early initialisation of per-cpu
     operations needed by KCSAN.

   - Non-critical fixes and miscellaneous cleanup"

* tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux: (150 commits)
  arm64: tlb: fix the TTL value of tlb_get_level
  arm64: Restrict undef hook for cpufeature registers
  arm64/mm: Rename ARM64_SWAPPER_USES_SECTION_MAPS
  arm64: insn: avoid circular include dependency
  arm64: smp: Bump debugging information print down to KERN_DEBUG
  drivers/perf: fix the missed ida_simple_remove() in ddr_perf_probe()
  perf/arm-cmn: Fix invalid pointer when access dtc object sharing the same IRQ number
  arm64: suspend: Use cpuidle context helpers in cpu_suspend()
  PSCI: Use cpuidle context helpers in psci_cpu_suspend_enter()
  arm64: Convert cpu_do_idle() to using cpuidle context helpers
  arm64: Add cpuidle context save/restore helpers
  arm64: head: fix code comments in set_cpu_boot_mode_flag
  arm64: mm: drop unused __pa(__idmap_text_start)
  arm64: mm: fix the count comments in compute_indices
  arm64/mm: Fix ttbr0 values stored in struct thread_info for software-pan
  arm64: mm: Pass original fault address to handle_mm_fault()
  arm64/mm: Drop SECTION_[SHIFT|SIZE|MASK]
  arm64/mm: Use CONT_PMD_SHIFT for ARM64_MEMSTART_SHIFT
  arm64/mm: Drop SWAPPER_INIT_MAP_SIZE
  arm64: Conditionally configure PTR_AUTH key of the kernel.
  ...
2021-06-28 14:04:24 -07:00
Linus Torvalds
62fb9874f5 Linux 5.13 2021-06-27 15:21:11 -07:00
Linus Torvalds
13311e7425 Linux 5.13-rc7 2021-06-20 15:03:15 -07:00
Masahiro Yamada
74ee585b7e kbuild: remove trailing slashes from $(KBUILD_EXTMOD)
M= (or KBUILD_EXTMOD) generally expects a directory path without any
trailing slashes, like M=a/b/c.

If you add a trailing slash, like M=a/b/c/, you will get ugly build
logs (two slashes in a series), but it still works fine as long as it
is consistent between 'make modules' and 'make modules_install'.

The following commands correctly build and install the modules.

  $ make M=a/b/c/ modules
  $ sudo make M=a/b/c/ modules_install

Since commit ccae4cfa7b ("kbuild: refactor scripts/Makefile.modinst"),
a problem happens if you add a trailing slash only for modules_install.

  $ make M=a/b/c modules
  $ sudo make M=a/b/c/ modules_install

No module is installed in this case, Johannes Berg reported. [1]

Trim any trailing slashes from $(KBUILD_EXTMOD).

I used the 'dirname' command to remove all the trailing slashes in
case someone adds more slashes like M=a/b/c/////. The Make's built-in
function, $(dir ...) cannot take care of such a case.

[1]: https://lore.kernel.org/lkml/10cc8522b27a051e6a9c3e158a4c4b6414fd04a0.camel@sipsolutions.net/

Fixes: ccae4cfa7b ("kbuild: refactor scripts/Makefile.modinst")
Reported-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2021-06-17 09:50:59 +09:00
Linus Torvalds
cc9aaa2b07 Clang feature fix for v5.13-rc7
- The "-warn-stack-size" option under LTO has moved in Clang 13 (Tor Vic)
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Merge tag 'clang-features-v5.13-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

Pull clang LTO fix from Kees Cook:
 "It seems Clang has been scrubbing through the missing LTO IR flags for
  Clang 13, and the last of these 'only with LTO' flags is fixed now.

  I've asked that they please consider making these changes in a less
  'break all the Clang kernel builds' kind of way in the future. :P

  Summary:

   - The '-warn-stack-size' option under LTO has moved in Clang 13 (Tor
     Vic)"

* tag 'clang-features-v5.13-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
  Makefile: lto: Pass -warn-stack-size only on LLD < 13.0.0
2021-06-16 08:57:44 -07:00
Tor Vic
0236526d76 Makefile: lto: Pass -warn-stack-size only on LLD < 13.0.0
Since LLVM commit fc018eb, the '-warn-stack-size' flag has been dropped
[1], leading to the following error message when building with Clang-13
and LLD-13:

    ld.lld: error: -plugin-opt=-: ld.lld: Unknown command line argument
    '-warn-stack-size=2048'.  Try: 'ld.lld --help'
    ld.lld: Did you mean '--asan-stack=2048'?

In the same way as with commit 2398ce8015 ("x86, lto: Pass
-stack-alignment only on LLD < 13.0.0") , make '-warn-stack-size'
conditional on LLD < 13.0.0.

[1] https://reviews.llvm.org/D103928

Fixes: 24845dcb17 ("Makefile: LTO: have linker check -Wframe-larger-than")
Cc: stable@vger.kernel.org
Link: https://github.com/ClangBuiltLinux/linux/issues/1377
Signed-off-by: Tor Vic <torvic9@mailbox.org>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/7631bab7-a8ab-f884-ab54-f4198976125c@mailbox.org
2021-06-14 14:52:38 -07:00
Linus Torvalds
009c9aa5be Linux 5.13-rc6 2021-06-13 14:43:10 -07:00
Nick Desaulniers
27f2a4db76 Makefile: fix GDB warning with CONFIG_RELR
GDB produces the following warning when debugging kernels built with
CONFIG_RELR:

BFD: /android0/linux-next/vmlinux: unknown type [0x13] section `.relr.dyn'

when loading a kernel built with CONFIG_RELR into GDB. It can also
prevent debugging symbols using such relocations.

Peter sugguests:
  [That flag] means that lld will use dynamic tags and section type
  numbers in the OS-specific range rather than the generic range. The
  kernel itself doesn't care about these numbers; it determines the
  location of the RELR section using symbols defined by a linker script.

Link: https://github.com/ClangBuiltLinux/linux/issues/1057
Suggested-by: Peter Collingbourne <pcc@google.com>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Link: https://lore.kernel.org/r/20210522012626.2811297-1-ndesaulniers@google.com
Signed-off-by: Will Deacon <will@kernel.org>
2021-06-08 13:09:34 +01:00
Linus Torvalds
614124bea7 Linux 5.13-rc5 2021-06-06 15:47:27 -07:00
Linus Torvalds
8124c8a6b3 Linux 5.13-rc4 2021-05-30 11:58:25 -10:00
Linus Torvalds
8508b97ae2 Clang feature fixes for v5.13-rc4
- Correctly pass stack frame size checking under LTO (Nick Desaulniers)
 
 - Avoid CFI mismatches by checking initcall_t types (Marco Elver)
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Merge tag 'clang-features-v5.13-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

Pull clang feature fixes from Kees Cook:

 - Correctly pass stack frame size checking under LTO (Nick Desaulniers)

 - Avoid CFI mismatches by checking initcall_t types (Marco Elver)

* tag 'clang-features-v5.13-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
  Makefile: LTO: have linker check -Wframe-larger-than
  init: verify that function is initcall_t at compile-time
2021-05-28 08:31:48 -10:00
Masahiro Yamada
2728fcfa4f kbuild: merge scripts/mkmakefile to top Makefile
scripts/mkmakefile is simple enough to be merged in the Makefile.

Use $(call cmd,...) to show the log instead of doing it in the
shell script.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2021-05-27 03:59:29 +09:00
Masahiro Yamada
d92cc4d516 kbuild: require all architectures to have arch/$(SRCARCH)/Kbuild
arch/$(SRCARCH)/Kbuild is useful for Makefile cleanups because you can
use the obj-y syntax.

Add an empty file if it is missing in arch/$(SRCARCH)/.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2021-05-26 23:10:37 +09:00
Nick Desaulniers
24845dcb17 Makefile: LTO: have linker check -Wframe-larger-than
-Wframe-larger-than= requires stack frame information, which the
frontend cannot provide. This diagnostic is emitted late during
compilation once stack frame size is available.

When building with LTO, the frontend simply lowers C to LLVM IR and does
not have stack frame information, so it cannot emit this diagnostic.
When the linker drives LTO, it restarts optimizations and lowers LLVM IR
to object code. At that point, it has stack frame information but
doesn't know to check for a specific max stack frame size.

I consider this a bug in LLVM that we need to fix. There are some
details we're working out related to LTO such as which value to use when
there are multiple different values specified per TU, or how to
propagate these to compiler synthesized routines properly, if at all.

Until it's fixed, ensure we don't miss these. At that point we can wrap
this in a compiler version guard or revert this based on the minimum
support version of Clang.

The error message is not generated during link:
  LTO     vmlinux.o
ld.lld: warning: stack size limit exceeded (8224) in foobarbaz

Cc: Sami Tolvanen <samitolvanen@google.com>
Reported-by: Candle Sun <candlesea@gmail.com>
Suggested-by: Fangrui Song <maskray@google.com>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20210312010942.1546679-1-ndesaulniers@google.com
2021-05-24 15:24:34 -07:00
Masahiro Yamada
0d989ac2c9 kbuild: remove libelf checks from top Makefile
I do not see a good reason why only the libelf development package must
be so carefully checked.

Kbuild generally does not check host tools or libraries.

For example, x86_64 defconfig fails to build with no libssl development
package installed.

scripts/extract-cert.c:21:10: fatal error: openssl/bio.h: No such file or directory
   21 | #include <openssl/bio.h>
      |          ^~~~~~~~~~~~~~~

To solve the build error, you need to install libssl-dev or openssl-devel
package, depending on your distribution.

'apt-file search', 'dnf provides', etc. is your frined to find a proper
package to install.

This commit removes all the libelf checks from the top Makefile.

If libelf is missing, objtool will fail to build in a similar pattern:

.../linux/tools/objtool/include/objtool/elf.h:10:10: fatal error: gelf.h: No such file or directory
   10 | #include <gelf.h>

You need to install libelf-dev, libelf-devel, or elfutils-libelf-devel
to proceed.

Another remarkable change is, CONFIG_STACK_VALIDATION (without
CONFIG_UNWINDER_ORC) previously continued to build with a warning,
but now it will treat missing libelf as an error.

This is just a one-time installation, so it should not hurt to break
a build and make a user install the package.

BTW, the traditional way to handle such checks is autotool, but according
to [1], I do not expect the kernel build would have similar scripting
like './configure' does.

[1]: https://lore.kernel.org/lkml/CA+55aFzr2HTZVOuzpHYDwmtRJLsVzE-yqg2DHpHi_9ePsYp5ug@mail.gmail.com/

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
2021-05-24 12:06:51 +09:00
Masahiro Yamada
1bb0b18a06 kbuild: hide tools/ build targets from external module builds
The tools/ directory only exists in the kernel source tree, not in
external modules.

Do not expose the meaningless targets to external modules.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2021-05-24 12:06:51 +09:00
Feng Tang
cf536e1858 Makefile: extend 32B aligned debug option to 64B aligned
Commit 09c60546f0 ("./Makefile: add debug option to enable
function aligned on 32 bytes") was introduced to help debugging
strange kernel performance changes caused by code alignment
change.

Recently we found 2 similar cases [1][2] caused by code-alignment
changes, which can only be identified by forcing 64 bytes aligned
for all functions.

Originally, 32 bytes was used mainly for not wasting too much
text space, but this option is only for debug anyway where text
space is not a big concern. So extend the alignment to 64 bytes
to cover more similar cases.

[1].https://lore.kernel.org/lkml/20210427090013.GG32408@xsang-OptiPlex-9020/
[2].https://lore.kernel.org/lkml/20210420030837.GB31773@xsang-OptiPlex-9020/
Signed-off-by: Feng Tang <feng.tang@intel.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2021-05-24 12:06:50 +09:00
Linus Torvalds
c4681547bc Linux 5.13-rc3 2021-05-23 11:42:48 -10:00
Linus Torvalds
d07f6ca923 Linux 5.13-rc2 2021-05-16 15:27:44 -07:00
Linus Torvalds
6efb943b86 Linux 5.13-rc1 2021-05-09 14:17:44 -07:00
Linus Torvalds
0f979d815c Kbuild updates for v5.13 (2nd)
- Convert sh and sparc to use generic shell scripts to generate the
    syscall headers
 
  - refactor .gitignore files
 
  - Update kernel/config_data.gz only when the content of the .config is
    really changed, which avoids the unneeded re-link of vmlinux
 
  - move "remove stale files" workarounds to scripts/remove-stale-files
 
  - suppress unused-but-set-variable warnings by default for Clang as well
 
  - fix locale setting LANG=C to LC_ALL=C
 
  - improve 'make distclean'
 
  - always keep intermediate objects from scripts/link-vmlinux.sh
 
  - move IF_ENABLED out of <linux/kconfig.h> to make it self-contained
 
  - misc cleanups
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Merge tag 'kbuild-v5.13-2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild

Pull more Kbuild updates from Masahiro Yamada:

 - Convert sh and sparc to use generic shell scripts to generate the
   syscall headers

 - refactor .gitignore files

 - Update kernel/config_data.gz only when the content of the .config
   is really changed, which avoids the unneeded re-link of vmlinux

 - move "remove stale files" workarounds to scripts/remove-stale-files

 - suppress unused-but-set-variable warnings by default for Clang
   as well

 - fix locale setting LANG=C to LC_ALL=C

 - improve 'make distclean'

 - always keep intermediate objects from scripts/link-vmlinux.sh

 - move IF_ENABLED out of <linux/kconfig.h> to make it self-contained

 - misc cleanups

* tag 'kbuild-v5.13-2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (25 commits)
  linux/kconfig.h: replace IF_ENABLED() with PTR_IF() in <linux/kernel.h>
  kbuild: Don't remove link-vmlinux temporary files on exit/signal
  kbuild: remove the unneeded comments for external module builds
  kbuild: make distclean remove tag files in sub-directories
  kbuild: make distclean work against $(objtree) instead of $(srctree)
  kbuild: refactor modname-multi by using suffix-search
  kbuild: refactor fdtoverlay rule
  kbuild: parameterize the .o part of suffix-search
  arch: use cross_compiling to check whether it is a cross build or not
  kbuild: remove ARCH=sh64 support from top Makefile
  .gitignore: prefix local generated files with a slash
  kbuild: replace LANG=C with LC_ALL=C
  Makefile: Move -Wno-unused-but-set-variable out of GCC only block
  kbuild: add a script to remove stale generated files
  kbuild: update config_data.gz only when the content of .config is changed
  .gitignore: ignore only top-level modules.builtin
  .gitignore: move tags and TAGS close to other tag files
  kernel/.gitgnore: remove stale timeconst.h and hz.bc
  usr/include: refactor .gitignore
  genksyms: fix stale comment
  ...
2021-05-08 10:00:11 -07:00
Masahiro Yamada
11122b860b kbuild: remove the unneeded comments for external module builds
The supported targets for external modules are listed in the help target
a few lines below. Let's not have duplicated information in two places.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2021-05-06 02:16:25 +09:00
Masahiro Yamada
7a02cec523 kbuild: make distclean remove tag files in sub-directories
'make tags' and friends create tag files in the top directory, but
people may manually create tag files in sub-directories.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2021-05-06 02:16:08 +09:00
Masahiro Yamada
19c8d91283 kbuild: make distclean work against $(objtree) instead of $(srctree)
This reverts the old commit [1], which seems questionable to me.

It claimed 'make distclean' could not remove editor backup files,
but I believe KBUILD_OUTPUT or O= was set.

When O= is given, Kbuild should always work against $(objtree).
If O= is not given, $(objtree) and $(srctree) are the same, therefore
$(srctree) is cleaned up.

[1]: https://git.kernel.org/pub/scm/linux/kernel/git/history/history.git/commit/?id=dd47df980c02eb33833b2690b033c34fba2fa80d

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2021-05-06 02:15:46 +09:00
Masahiro Yamada
45799491a9 kbuild: remove ARCH=sh64 support from top Makefile
Commit 37744feebc ("sh: remove sh5 support") removed the SUPERH64
support entirely.

Remove the left-over code from the top Makefile.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
2021-05-03 18:20:24 +09:00
Linus Torvalds
e6f0bf09f0 integrity-v5.13
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Merge tag 'integrity-v5.13' of git://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity

Pull IMA updates from Mimi Zohar:
 "In addition to loading the kernel module signing key onto the builtin
  keyring, load it onto the IMA keyring as well.

  Also six trivial changes and bug fixes"

* tag 'integrity-v5.13' of git://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity:
  ima: ensure IMA_APPRAISE_MODSIG has necessary dependencies
  ima: Fix fall-through warnings for Clang
  integrity: Add declarations to init_once void arguments.
  ima: Fix function name error in comment.
  ima: enable loading of build time generated key on .ima keyring
  ima: enable signing of modules with build time generated key
  keys: cleanup build time module signing keys
  ima: Fix the error code for restoring the PCR value
  ima: without an IMA policy loaded, return quickly
2021-05-01 15:32:18 -07:00
Nathan Chancellor
885480b084 Makefile: Move -Wno-unused-but-set-variable out of GCC only block
Currently, -Wunused-but-set-variable is only supported by GCC so it is
disabled unconditionally in a GCC only block (it is enabled with W=1).
clang currently has its implementation for this warning in review so
preemptively move this statement out of the GCC only block and wrap it
with cc-disable-warning so that both compilers function the same.

Cc: stable@vger.kernel.org
Link: https://reviews.llvm.org/D100581
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2021-05-02 00:43:35 +09:00
Masahiro Yamada
1476fee5c5 kbuild: add a script to remove stale generated files
We maintain .gitignore and Makefiles so build artifacts are properly
ignored by Git, and cleaned up by 'make clean'. However, the code is
always changing; generated files are often moved to another directory,
or removed when they become unnecessary. Such garbage files tend to be
left over in the source tree because people usually git-pull without
cleaning the tree.

This is not only the noise for 'git status', but also a build issue
in some cases.

One solution is to remove a stale file like commit 223c24a7db ("kbuild:
Automatically remove stale <linux/version.h> file") did. Such workaround
should be removed after a while, but we forget about that if we scatter
the workaround code in random places.

So, this commit adds a new script to collect cleanings of stale files.

As a start point, move the code in arch/arm/boot/compressed/Makefile
into this script.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2021-05-02 00:43:35 +09:00
Linus Torvalds
8ca5297e7e Kconfig updates for v5.13
- Change 'option defconfig' to the environment variable
    KCONFIG_DEFCONFIG_LIST
 
  - Refactor tinyconfig without using allnoconfig_y
 
  - Remove 'option allnoconfig_y' syntax
 
  - Change 'option modules' to 'modules'
 
  - Do not use /boot/config-* etc. as base config for cross-compilation
 
  - Fix a search bug in nconf
 
  - Various code cleanups
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Merge tag 'kconfig-v5.13' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild

Pull Kconfig updates from Masahiro Yamada:

 - Change 'option defconfig' to the environment variable
   KCONFIG_DEFCONFIG_LIST

 - Refactor tinyconfig without using allnoconfig_y

 - Remove 'option allnoconfig_y' syntax

 - Change 'option modules' to 'modules'

 - Do not use /boot/config-* etc. as base config for cross-compilation

 - Fix a search bug in nconf

 - Various code cleanups

* tag 'kconfig-v5.13' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (34 commits)
  kconfig: refactor .gitignore
  kconfig: highlight xconfig 'comment' lines with '***'
  kconfig: highlight gconfig 'comment' lines with '***'
  kconfig: gconf: remove unused code
  kconfig: remove unused PACKAGE definition
  kconfig: nconf: stop endless search loops
  kconfig: split menu.c out of parser.y
  kconfig: nconf: refactor in print_in_middle()
  kconfig: nconf: remove meaningless wattrset() call from show_menu()
  kconfig: nconf: change set_config_filename() to void function
  kconfig: nconf: refactor attributes setup code
  kconfig: nconf: remove unneeded default for menu prompt
  kconfig: nconf: get rid of (void) casts from wattrset() calls
  kconfig: nconf: fix NORMAL attributes
  kconfig: mconf,nconf: remove unneeded '\0' termination after snprintf()
  kconfig: use /boot/config-* etc. as DEFCONFIG_LIST only for native build
  kconfig: change sym_change_count to a boolean flag
  kconfig: nconf: fix core dump when searching in empty menu
  kconfig: lxdialog: A spello fix and a punctuation added
  kconfig: streamline_config.pl: Couple of typo fixes
  ...
2021-04-29 14:32:00 -07:00
Linus Torvalds
b0030af53a Kbuild updates for v5.13
- Evaluate $(call cc-option,...) etc. only for build targets
 
  - Add CONFIG_VMLINUX_MAP to generate .map file when linking vmlinux
 
  - Remove unnecessary --gcc-toolchains Clang flag because the --prefix
    flag finds the toolchains
 
  - Do not pass Clang's --prefix flag when using the integrated as
 
  - Check the assembler version in Kconfig time
 
  - Add new CONFIG options, AS_VERSION, AS_IS_GNU, AS_IS_LLVM to clean up
    some dependencies in Kconfig
 
  - Fix invalid Module.symvers creation when building only modules without
    vmlinux
 
  - Fix false-positive modpost warnings when CONFIG_TRIM_UNUSED_KSYMS is
    set, but there is no module to build
 
  - Refactor module installation Makefile
 
  - Support zstd for module compression
 
  - Convert alpha and ia64 to use generic shell scripts to generate the
    syscall headers
 
  - Add a new elfnote to indicate if the kernel was built with LTO, which
    will be used by pahole
 
  - Flatten the directory structure under include/config/ so CONFIG options
    and filenames match
 
  - Change the deb source package name from linux-$(KERNELRELEASE) to
    linux-upstream
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Merge tag 'kbuild-v5.13' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild

Pull Kbuild updates from Masahiro Yamada:

 - Evaluate $(call cc-option,...) etc. only for build targets

 - Add CONFIG_VMLINUX_MAP to generate .map file when linking vmlinux

 - Remove unnecessary --gcc-toolchains Clang flag because the --prefix
   flag finds the toolchains

 - Do not pass Clang's --prefix flag when using the integrated as

 - Check the assembler version in Kconfig time

 - Add new CONFIG options, AS_VERSION, AS_IS_GNU, AS_IS_LLVM to clean up
   some dependencies in Kconfig

 - Fix invalid Module.symvers creation when building only modules
   without vmlinux

 - Fix false-positive modpost warnings when CONFIG_TRIM_UNUSED_KSYMS is
   set, but there is no module to build

 - Refactor module installation Makefile

 - Support zstd for module compression

 - Convert alpha and ia64 to use generic shell scripts to generate the
   syscall headers

 - Add a new elfnote to indicate if the kernel was built with LTO, which
   will be used by pahole

 - Flatten the directory structure under include/config/ so CONFIG
   options and filenames match

 - Change the deb source package name from linux-$(KERNELRELEASE) to
   linux-upstream

* tag 'kbuild-v5.13' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (42 commits)
  kbuild: Add $(KBUILD_HOSTLDFLAGS) to 'has_libelf' test
  kbuild: deb-pkg: change the source package name to linux-upstream
  tools: do not include scripts/Kbuild.include
  kbuild: redo fake deps at include/config/*.h
  kbuild: remove TMPO from try-run
  MAINTAINERS: add pattern for dummy-tools
  kbuild: add an elfnote for whether vmlinux is built with lto
  ia64: syscalls: switch to generic syscallhdr.sh
  ia64: syscalls: switch to generic syscalltbl.sh
  alpha: syscalls: switch to generic syscallhdr.sh
  alpha: syscalls: switch to generic syscalltbl.sh
  sysctl: use min() helper for namecmp()
  kbuild: add support for zstd compressed modules
  kbuild: remove CONFIG_MODULE_COMPRESS
  kbuild: merge scripts/Makefile.modsign to scripts/Makefile.modinst
  kbuild: move module strip/compression code into scripts/Makefile.modinst
  kbuild: refactor scripts/Makefile.modinst
  kbuild: rename extmod-prefix to extmod_prefix
  kbuild: check module name conflict for external modules as well
  kbuild: show the target directory for depmod log
  ...
2021-04-29 14:24:39 -07:00
Linus Torvalds
57fa2369ab CFI on arm64 series for v5.13-rc1
- Clean up list_sort prototypes (Sami Tolvanen)
 
 - Introduce CONFIG_CFI_CLANG for arm64 (Sami Tolvanen)
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Merge tag 'cfi-v5.13-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

Pull CFI on arm64 support from Kees Cook:
 "This builds on last cycle's LTO work, and allows the arm64 kernels to
  be built with Clang's Control Flow Integrity feature. This feature has
  happily lived in Android kernels for almost 3 years[1], so I'm excited
  to have it ready for upstream.

  The wide diffstat is mainly due to the treewide fixing of mismatched
  list_sort prototypes. Other things in core kernel are to address
  various CFI corner cases. The largest code portion is the CFI runtime
  implementation itself (which will be shared by all architectures
  implementing support for CFI). The arm64 pieces are Acked by arm64
  maintainers rather than coming through the arm64 tree since carrying
  this tree over there was going to be awkward.

  CFI support for x86 is still under development, but is pretty close.
  There are a handful of corner cases on x86 that need some improvements
  to Clang and objtool, but otherwise works well.

  Summary:

   - Clean up list_sort prototypes (Sami Tolvanen)

   - Introduce CONFIG_CFI_CLANG for arm64 (Sami Tolvanen)"

* tag 'cfi-v5.13-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
  arm64: allow CONFIG_CFI_CLANG to be selected
  KVM: arm64: Disable CFI for nVHE
  arm64: ftrace: use function_nocfi for ftrace_call
  arm64: add __nocfi to __apply_alternatives
  arm64: add __nocfi to functions that jump to a physical address
  arm64: use function_nocfi with __pa_symbol
  arm64: implement function_nocfi
  psci: use function_nocfi for cpu_resume
  lkdtm: use function_nocfi
  treewide: Change list_sort to use const pointers
  bpf: disable CFI in dispatcher functions
  kallsyms: strip ThinLTO hashes from static functions
  kthread: use WARN_ON_FUNCTION_MISMATCH
  workqueue: use WARN_ON_FUNCTION_MISMATCH
  module: ensure __cfi_check alignment
  mm: add generic function_nocfi macro
  cfi: add __cficanonical
  add support for Clang CFI
2021-04-27 10:16:46 -07:00
Linus Torvalds
eea2647e74 Entry code update:
Provide support for randomized stack offsets per syscall to make
  stack-based attacks harder which rely on the deterministic stack layout.
 
  The feature is based on the original idea of PaX's RANDSTACK feature, but
  uses a significantly different implementation.
 
  The offset does not affect the pt_regs location on the task stack as this
  was agreed on to be of dubious value. The offset is applied before the
  actual syscall is invoked.
 
  The offset is stored per cpu and the randomization happens at the end of
  the syscall which is less predictable than on syscall entry.
 
  The mechanism to apply the offset is via alloca(), i.e. abusing the
  dispised VLAs. This comes with the drawback that stack-clash-protection
  has to be disabled for the affected compilation units and there is also
  a negative interaction with stack-protector.
 
  Those downsides are traded with the advantage that this approach does not
  require any intrusive changes to the low level assembly entry code, does
  not affect the unwinder and the correct stack alignment is handled
  automatically by the compiler.
 
  The feature is guarded with a static branch which avoids the overhead when
  disabled.
 
  Currently this is supported for X86 and ARM64.
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Merge tag 'x86-entry-2021-04-26' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull entry code update from Thomas Gleixner:
 "Provide support for randomized stack offsets per syscall to make
  stack-based attacks harder which rely on the deterministic stack
  layout.

  The feature is based on the original idea of PaX's RANDSTACK feature,
  but uses a significantly different implementation.

  The offset does not affect the pt_regs location on the task stack as
  this was agreed on to be of dubious value. The offset is applied
  before the actual syscall is invoked.

  The offset is stored per cpu and the randomization happens at the end
  of the syscall which is less predictable than on syscall entry.

  The mechanism to apply the offset is via alloca(), i.e. abusing the
  dispised VLAs. This comes with the drawback that
  stack-clash-protection has to be disabled for the affected compilation
  units and there is also a negative interaction with stack-protector.

  Those downsides are traded with the advantage that this approach does
  not require any intrusive changes to the low level assembly entry
  code, does not affect the unwinder and the correct stack alignment is
  handled automatically by the compiler.

  The feature is guarded with a static branch which avoids the overhead
  when disabled.

  Currently this is supported for X86 and ARM64"

* tag 'x86-entry-2021-04-26' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  arm64: entry: Enable random_kstack_offset support
  lkdtm: Add REPORT_STACK for checking stack offsets
  x86/entry: Enable random_kstack_offset support
  stack: Optionally randomize kernel stack offset each syscall
  init_on_alloc: Optimize static branches
  jump_label: Provide CONFIG-driven build state defaults
2021-04-26 10:02:09 -07:00