linux-toradex.git/include/linux/compiler-clang.h, branch v5.10-rc2

compiler-clang: add build check for clang 10.0.1

2020-10-14T01:38:26+00:00

Patch series "set clang minimum version to 10.0.1", v3.

Adds a compile time #error to compiler-clang.h setting the effective
minimum supported version to clang 10.0.1.  A separate patch has already
been picked up into the Documentation/ tree also confirming the version.

Next are a series of reverts. One for 32b arm is a partial revert.

Then Marco suggested fixes to KASAN docs.

Finally, improve the warning for GCC too as per Kees.

This patch (of 7):

During Plumbers 2020, we voted to just support the latest release of Clang
for now.  Add a compile time check for this.

We plan to remove workarounds for older versions now, which will break in
subtle and not so subtle ways.

Suggested-by: Sedat Dilek 
Suggested-by: Nathan Chancellor 
Suggested-by: Kees Cook 
Signed-off-by: Nick Desaulniers 
Signed-off-by: Andrew Morton 
Tested-by: Sedat Dilek 
Reviewed-by: Kees Cook 
Reviewed-by: Miguel Ojeda 
Reviewed-by: Sedat Dilek 
Acked-by: Marco Elver 
Acked-by: Nathan Chancellor 
Acked-by: Sedat Dilek 
Cc: Andrey Konovalov 
Cc: Fangrui Song 
Cc: Masahiro Yamada 
Cc: Daniel Borkmann 
Cc: Alexei Starovoitov 
Cc: Will Deacon 
Cc: Vincenzo Frascino 
Link: https://lkml.kernel.org/r/20200902225911.209899-1-ndesaulniers@google.com
Link: https://lkml.kernel.org/r/20200902225911.209899-2-ndesaulniers@google.com
Link: https://github.com/ClangBuiltLinux/linux/issues/9
Link: https://github.com/ClangBuiltLinux/linux/issues/941
Signed-off-by: Linus Torvalds

include/linux/compiler-clang.h: drop duplicated word in a comment

2020-08-12T17:57:59+00:00

Drop the doubled word "the" in a comment.

Signed-off-by: Randy Dunlap 
Signed-off-by: Andrew Morton 
Reviewed-by: Nathan Chancellor 
Link: http://lkml.kernel.org/r/6a18c301-3505-742f-4dd7-0f38d0e537b9@infradead.org
Signed-off-by: Linus Torvalds

compiler: Remove uninitialized_var() macro

2020-07-16T19:35:31+00:00

Using uninitialized_var() is dangerous as it papers over real bugs[1]
(or can in the future), and suppresses unrelated compiler warnings
(e.g. "unused variable"). If the compiler thinks it is uninitialized,
either simply initialize the variable or make compiler changes.

As recommended[2] by[3] Linus[4], remove the macro. With the recent
change to disable -Wmaybe-uninitialized in v5.7 in commit 78a5255ffb6a
("Stop the ad-hoc games with -Wno-maybe-initialized"), this is likely
the best time to make this treewide change.

[1] https://lore.kernel.org/lkml/20200603174714.192027-1-glider@google.com/
[2] https://lore.kernel.org/lkml/CA+55aFw+Vbj0i=1TGqCR5vQkCzWJ0QxK6CernOU6eedsudAixw@mail.gmail.com/
[3] https://lore.kernel.org/lkml/CA+55aFwgbgqhbp1fkxvRKEpzyR5J8n1vKT1VZdz9knmPuXhOeg@mail.gmail.com/
[4] https://lore.kernel.org/lkml/CA+55aFz2500WfbKXAx8s67wrm9=yVJu65TpLgN_ybYNv0VEOKA@mail.gmail.com/

Suggested-by: Linus Torvalds 
Reviewed-by: Bart van Assche 
Reviewed-by: Miguel Ojeda 
Tested-by: Nathan Chancellor 
Tested-by: Sedat Dilek 
Signed-off-by: Kees Cook

compiler_types.h: Add __no_sanitize_{address,undefined} to noinstr

2020-06-15T12:10:09+00:00

Adds the portable definitions for __no_sanitize_address, and
__no_sanitize_undefined, and subsequently changes noinstr to use the
attributes to disable instrumentation via KASAN or UBSAN.

Reported-by: syzbot+dc1fa714cb070b184db5@syzkaller.appspotmail.com
Signed-off-by: Marco Elver 
Signed-off-by: Peter Zijlstra (Intel) 
Acked-by: Miguel Ojeda 
Link: https://lore.kernel.org/lkml/000000000000d2474c05a6c938fe@google.com/

Rebase locking/kcsan to locking/urgent

2020-06-11T18:02:46+00:00

Merge the state of the locking kcsan branch before the read/write_once()
and the atomics modifications got merged.

Squash the fallout of the rebase on top of the read/write once and atomic
fallback work into the merge. The history of the original branch is
preserved in tag locking-kcsan-2020-06-02.

Signed-off-by: Thomas Gleixner

scs: Add support for Clang's Shadow Call Stack (SCS)

2020-05-15T15:35:45+00:00

This change adds generic support for Clang's Shadow Call Stack,
which uses a shadow stack to protect return addresses from being
overwritten by an attacker. Details are available here:

  https://clang.llvm.org/docs/ShadowCallStack.html

Note that security guarantees in the kernel differ from the ones
documented for user space. The kernel must store addresses of
shadow stacks in memory, which means an attacker capable reading
and writing arbitrary memory may be able to locate them and hijack
control flow by modifying the stacks.

Signed-off-by: Sami Tolvanen 
Reviewed-by: Kees Cook 
Reviewed-by: Miguel Ojeda 
[will: Numerous cosmetic changes]
Signed-off-by: Will Deacon

kcsan: Improve various small stylistic details

2019-11-20T09:47:23+00:00

Tidy up a few bits:

  - Fix typos and grammar, improve wording.

  - Remove spurious newlines that are col80 warning artifacts where the
    resulting line-break is worse than the disease it's curing.

  - Use core kernel coding style to improve readability and reduce
    spurious code pattern variations.

  - Use better vertical alignment for structure definitions and initialization
    sequences.

  - Misc other small details.

No change in functionality intended.

Cc: linux-kernel@vger.kernel.org
Cc: Marco Elver 
Cc: Paul E. McKenney 
Cc: Peter Zijlstra 
Cc: Linus Torvalds 
Cc: Andrew Morton 
Cc: Thomas Gleixner 
Cc: Paul E. McKenney 
Cc: Will Deacon 
Signed-off-by: Ingo Molnar

kcsan: Add Kernel Concurrency Sanitizer infrastructure

2019-11-16T15:23:13+00:00

Kernel Concurrency Sanitizer (KCSAN) is a dynamic data-race detector for
kernel space. KCSAN is a sampling watchpoint-based data-race detector.
See the included Documentation/dev-tools/kcsan.rst for more details.

This patch adds basic infrastructure, but does not yet enable KCSAN for
any architecture.

Signed-off-by: Marco Elver 
Acked-by: Paul E. McKenney 
Signed-off-by: Paul E. McKenney

include/linux/compiler*.h: fix OPTIMIZER_HIDE_VAR

2019-01-09T10:36:41+00:00

Since commit 815f0ddb346c ("include/linux/compiler*.h: make compiler-*.h
mutually exclusive") clang no longer reuses the OPTIMIZER_HIDE_VAR macro
from compiler-gcc - instead it gets the version in
include/linux/compiler.h.  Unfortunately that version doesn't actually
prevent compiler from optimizing out the variable.

Fix up by moving the macro out from compiler-gcc.h to compiler.h.
Compilers without incline asm support will keep working
since it's protected by an ifdef.

Also fix up comments to match reality since we are no longer overriding
any macros.

Build-tested with gcc and clang.

Fixes: 815f0ddb346c ("include/linux/compiler*.h: make compiler-*.h mutually exclusive")
Cc: Eli Friedman 
Cc: Joe Perches 
Cc: Linus Torvalds 
Reviewed-by: Nick Desaulniers 
Signed-off-by: Michael S. Tsirkin 
Signed-off-by: Miguel Ojeda

kasan: add CONFIG_KASAN_GENERIC and CONFIG_KASAN_SW_TAGS

2018-12-28T20:11:43+00:00

This commit splits the current CONFIG_KASAN config option into two:
1. CONFIG_KASAN_GENERIC, that enables the generic KASAN mode (the one
   that exists now);
2. CONFIG_KASAN_SW_TAGS, that enables the software tag-based KASAN mode.

The name CONFIG_KASAN_SW_TAGS is chosen as in the future we will have
another hardware tag-based KASAN mode, that will rely on hardware memory
tagging support in arm64.

With CONFIG_KASAN_SW_TAGS enabled, compiler options are changed to
instrument kernel files with -fsantize=kernel-hwaddress (except the ones
for which KASAN_SANITIZE := n is set).

Both CONFIG_KASAN_GENERIC and CONFIG_KASAN_SW_TAGS support both
CONFIG_KASAN_INLINE and CONFIG_KASAN_OUTLINE instrumentation modes.

This commit also adds empty placeholder (for now) implementation of
tag-based KASAN specific hooks inserted by the compiler and adjusts
common hooks implementation.

While this commit adds the CONFIG_KASAN_SW_TAGS config option, this option
is not selectable, as it depends on HAVE_ARCH_KASAN_SW_TAGS, which we will
enable once all the infrastracture code has been added.

Link: http://lkml.kernel.org/r/b2550106eb8a68b10fefbabce820910b115aa853.1544099024.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov 
Reviewed-by: Andrey Ryabinin 
Reviewed-by: Dmitry Vyukov 
Cc: Christoph Lameter 
Cc: Mark Rutland 
Cc: Will Deacon 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds