Граф коммитов

11 Коммитов

Автор SHA1 Сообщение Дата
Daniel Borkmann b86a50c3b5 compiler-intel: fix wrong compiler barrier() macro
Cleanup commit 73679e5082 ("compiler-intel.h: Remove duplicate
definition") removed the double definition of __memory_barrier()
intrinsics.

However, in doing so, it also removed the preceding #undef barrier by
accident, meaning, the actual barrier() macro from compiler-gcc.h with
inline asm is still in place as __GNUC__ is provided.

Subsequently, barrier() can never be defined as __memory_barrier() from
compiler.h since it already has a definition in place and if we trust
the comment in compiler-intel.h, ecc doesn't support gcc specific asm
statements.

I don't have an ecc at hand (unsure if that's still used in the field?)
and only found this by accident during code review, a revert of that
cleanup would be simplest option.

Fixes: 73679e5082 ("compiler-intel.h: Remove duplicate definition")
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Pranith Kumar <bobby.prani@gmail.com>
Cc: Pranith Kumar <bobby.prani@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: mancha security <mancha1@zoho.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-06-25 17:00:38 -07:00
Daniel Borkmann 7829fb09a2 lib: make memzero_explicit more robust against dead store elimination
In commit 0b053c9518 ("lib: memzero_explicit: use barrier instead
of OPTIMIZER_HIDE_VAR"), we made memzero_explicit() more robust in
case LTO would decide to inline memzero_explicit() and eventually
find out it could be elimiated as dead store.

While using barrier() works well for the case of gcc, recent efforts
from LLVMLinux people suggest to use llvm as an alternative to gcc,
and there, Stephan found in a simple stand-alone user space example
that llvm could nevertheless optimize and thus elimitate the memset().
A similar issue has been observed in the referenced llvm bug report,
which is regarded as not-a-bug.

Based on some experiments, icc is a bit special on its own, while it
doesn't seem to eliminate the memset(), it could do so with an own
implementation, and then result in similar findings as with llvm.

The fix in this patch now works for all three compilers (also tested
with more aggressive optimization levels). Arguably, in the current
kernel tree it's more of a theoretical issue, but imho, it's better
to be pedantic about it.

It's clearly visible with gcc/llvm though, with the below code: if we
would have used barrier() only here, llvm would have omitted clearing,
not so with barrier_data() variant:

  static inline void memzero_explicit(void *s, size_t count)
  {
    memset(s, 0, count);
    barrier_data(s);
  }

  int main(void)
  {
    char buff[20];
    memzero_explicit(buff, sizeof(buff));
    return 0;
  }

  $ gcc -O2 test.c
  $ gdb a.out
  (gdb) disassemble main
  Dump of assembler code for function main:
   0x0000000000400400  <+0>: lea   -0x28(%rsp),%rax
   0x0000000000400405  <+5>: movq  $0x0,-0x28(%rsp)
   0x000000000040040e <+14>: movq  $0x0,-0x20(%rsp)
   0x0000000000400417 <+23>: movl  $0x0,-0x18(%rsp)
   0x000000000040041f <+31>: xor   %eax,%eax
   0x0000000000400421 <+33>: retq
  End of assembler dump.

  $ clang -O2 test.c
  $ gdb a.out
  (gdb) disassemble main
  Dump of assembler code for function main:
   0x00000000004004f0  <+0>: xorps  %xmm0,%xmm0
   0x00000000004004f3  <+3>: movaps %xmm0,-0x18(%rsp)
   0x00000000004004f8  <+8>: movl   $0x0,-0x8(%rsp)
   0x0000000000400500 <+16>: lea    -0x18(%rsp),%rax
   0x0000000000400505 <+21>: xor    %eax,%eax
   0x0000000000400507 <+23>: retq
  End of assembler dump.

As gcc, clang, but also icc defines __GNUC__, it's sufficient to define
this in compiler-gcc.h only to be picked up. For a fallback or otherwise
unsupported compiler, we define it as a barrier. Similarly, for ecc which
does not support gcc inline asm.

Reference: https://llvm.org/bugs/show_bug.cgi?id=15495
Reported-by: Stephan Mueller <smueller@chronox.de>
Tested-by: Stephan Mueller <smueller@chronox.de>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Stephan Mueller <smueller@chronox.de>
Cc: Hannes Frederic Sowa <hannes@stressinduktion.org>
Cc: mancha security <mancha1@zoho.com>
Cc: Mark Charlebois <charlebm@gmail.com>
Cc: Behan Webster <behanw@converseincode.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2015-05-04 17:49:51 +08:00
Pranith Kumar 73679e5082 compiler-intel.h: Remove duplicate definition
barrier is already defined as __memory_barrier in compiler.h
Remove this unnecessary redefinition.

Signed-off-by: Pranith Kumar <bobby.prani@gmail.com>
Link: http://lkml.kernel.org/r/CAJhHMCAnYPy0%2BqD-1KBnJPLt3XgAjdR12j%2BySSnPgmZcpbE7HQ@mail.gmail.com
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
2014-04-15 09:15:39 -07:00
Linus Torvalds 13c789a6b2 Merge git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6
Pull crypto update from Herbert Xu:
 "Here is the crypto update for 3.14:

   - Improved crypto_memneq helper
   - Use cyprto_memneq in arch-specific crypto code
   - Replaced orphaned DCP driver with Freescale MXS DCP driver
   - Added AVX/AVX2 version of AESNI-GCM encode and decode
   - Added AMD Cryptographic Coprocessor (CCP) driver
   - Misc fixes"

* git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6: (41 commits)
  crypto: aesni - fix build on x86 (32bit)
  crypto: mxs - Fix sparse non static symbol warning
  crypto: ccp - CCP device enabled/disabled changes
  crypto: ccp - Cleanup hash invocation calls
  crypto: ccp - Change data length declarations to u64
  crypto: ccp - Check for caller result area before using it
  crypto: ccp - Cleanup scatterlist usage
  crypto: ccp - Apply appropriate gfp_t type to memory allocations
  crypto: drivers - Sort drivers/crypto/Makefile
  ARM: mxs: dts: Enable DCP for MXS
  crypto: mxs - Add Freescale MXS DCP driver
  crypto: mxs - Remove the old DCP driver
  crypto: ahash - Fully restore ahash request before completing
  crypto: aesni - fix build on x86 (32bit)
  crypto: talitos - Remove redundant dev_set_drvdata
  crypto: ccp - Remove redundant dev_set_drvdata
  crypto: crypto4xx - Remove redundant dev_set_drvdata
  crypto: caam - simplify and harden key parsing
  crypto: omap-sham - Fix Polling mode for larger blocks
  crypto: tcrypt - Added speed tests for AEAD crypto alogrithms in tcrypt test suite
  ...
2014-01-23 18:11:00 -08:00
H. Peter Anvin 503cf95c06 x86, build, icc: Remove uninitialized_var() from compiler-intel.h
When compiling with icc, <linux/compiler-gcc.h> ends up included
because the icc environment defines __GNUC__.  Thus, we neither need
nor want to have this macro defined in both compiler-gcc.h and
compiler-intel.h, and the fact that they are inconsistent just makes
the compiler spew warnings.

Reported-by: Sunil K. Pandey <sunil.k.pandey@intel.com>
Cc: Kevin B. Smith <kevin.b.smith@intel.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Link: http://lkml.kernel.org/n/tip-0mbwou1zt7pafij09b897lg3@git.kernel.org
Cc: <stable@vger.kernel.org>
2013-12-10 15:01:01 -08:00
Cesar Eduardo Barros fe8c8a1268 crypto: more robust crypto_memneq
Disabling compiler optimizations can be fragile, since a new
optimization could be added to -O0 or -Os that breaks the assumptions
the code is making.

Instead of disabling compiler optimizations, use a dummy inline assembly
(based on RELOC_HIDE) to block the problematic kinds of optimization,
while still allowing other optimizations to be applied to the code.

The dummy inline assembly is added after every OR, and has the
accumulator variable as its input and output. The compiler is forced to
assume that the dummy inline assembly could both depend on the
accumulator variable and change the accumulator variable, so it is
forced to compute the value correctly before the inline assembly, and
cannot assume anything about its value after the inline assembly.

This change should be enough to make crypto_memneq work correctly (with
data-independent timing) even if it is inlined at its call sites. That
can be done later in a followup patch.

Compile-tested on x86_64.

Signed-off-by: Cesar Eduardo Barros <cesarb@cesarb.eti.br>
Acked-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2013-12-05 21:28:41 +08:00
David Woodhouse cf66bb93e0 byteorder: allow arch to opt to use GCC intrinsics for byteswapping
Since GCC 4.4, there have been __builtin_bswap32() and __builtin_bswap16()
intrinsics. A __builtin_bswap16() came a little later (4.6 for PowerPC,
48 for other platforms).

By using these instead of the inline assembler that most architectures
have in their __arch_swabXX() macros, we let the compiler see what's
actually happening. The resulting code should be at least as good, and
much *better* in the cases where it can be combined with a nearby load
or store, using a load-and-byteswap or store-and-byteswap instruction
(e.g. lwbrx/stwbrx on PowerPC, movbe on Atom).

When GCC is sufficiently recent *and* the architecture opts in to using
the intrinsics by setting CONFIG_ARCH_USE_BUILTIN_BSWAP, they will be
used in preference to the __arch_swabXX() macros. An architecture which
does not set ARCH_USE_BUILTIN_BSWAP will continue to use its own
hand-crafted macros.

Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
Acked-by: H. Peter Anvin <hpa@linux.intel.com>
2012-12-06 01:22:31 +00:00
Robert P. J. Day 94f582f82a Force erroneous inclusions of compiler-*.h files to be errors
Replace worthless comments with actual preprocessor errors when including
the wrong versions of the compiler.h files.

[akpm@linux-foundation.org: make it work]
Signed-off-by: Robert P. J. Day <rpjday@mindspring.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-17 08:42:47 -07:00
Rusty Russell c5e631cf65 ARRAY_SIZE: check for type
We can use a gcc extension to ensure that ARRAY_SIZE() is handed an array,
not a pointer.  This is especially important when code is changed from a
fixed array to a pointer.  I assume the Intel compiler doesn't support
__builtin_types_compatible_p.

[jdike@addtoit.com: uml: update UML definition of ARRAY_SIZE]
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Jeff Dike <jdike@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-07 12:13:00 -07:00
Borislav Petkov 9490991482 Add unitialized_var() macro for suppressing gcc warnings
Introduce a macro for suppressing gcc from generating a warning about a
probable uninitialized state of a variable.

Example:

-	spinlock_t *ptl;
+	spinlock_t *uninitialized_var(ptl);

Not a happy solution, but those warnings are obnoxious.

- Using the usual pointlessly-set-it-to-zero approach wastes several
  bytes of text.

- Using a macro means we can (hopefully) do something else if gcc changes
  cause the `x = x' hack to stop working

- Using a macro means that people who are worried about hiding true bugs
  can easily turn it off.

Signed-off-by: Borislav Petkov <bbpetkov@yahoo.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-07 12:12:52 -07:00
Linus Torvalds 1da177e4c3 Linux-2.6.12-rc2
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!
2005-04-16 15:20:36 -07:00