patches for 3.18

Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/queue-3.18/lib-string.c-implement-a-basic-bcmp.patch b/queue-3.18/lib-string.c-implement-a-basic-bcmp.patch
new file mode 100644 (file)
index 0000000..b684121
--- /dev/null
+++ b/queue-3.18/lib-string.c-implement-a-basic-bcmp.patch
@@ -0,0 +1,111 @@
+From 4974ffe3e72f4a065a9b8f01661a378156b94bd8 Mon Sep 17 00:00:00 2001
+From: Nick Desaulniers <ndesaulniers@google.com>
+Date: Fri, 5 Apr 2019 18:38:45 -0700
+Subject: lib/string.c: implement a basic bcmp
+
+[ Upstream commit 5f074f3e192f10c9fade898b9b3b8812e3d83342 ]
+
+A recent optimization in Clang (r355672) lowers comparisons of the
+return value of memcmp against zero to comparisons of the return value
+of bcmp against zero.  This helps some platforms that implement bcmp
+more efficiently than memcmp.  glibc simply aliases bcmp to memcmp, but
+an optimized implementation is in the works.
+
+This results in linkage failures for all targets with Clang due to the
+undefined symbol.  For now, just implement bcmp as a tailcail to memcmp
+to unbreak the build.  This routine can be further optimized in the
+future.
+
+Other ideas discussed:
+
+ * A weak alias was discussed, but breaks for architectures that define
+   their own implementations of memcmp since aliases to declarations are
+   not permitted (only definitions). Arch-specific memcmp
+   implementations typically declare memcmp in C headers, but implement
+   them in assembly.
+
+ * -ffreestanding also is used sporadically throughout the kernel.
+
+ * -fno-builtin-bcmp doesn't work when doing LTO.
+
+Link: https://bugs.llvm.org/show_bug.cgi?id=41035
+Link: https://code.woboq.org/userspace/glibc/string/memcmp.c.html#bcmp
+Link: https://github.com/llvm/llvm-project/commit/8e16d73346f8091461319a7dfc4ddd18eedcff13
+Link: https://github.com/ClangBuiltLinux/linux/issues/416
+Link: http://lkml.kernel.org/r/20190313211335.165605-1-ndesaulniers@google.com
+Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
+Reported-by: Nathan Chancellor <natechancellor@gmail.com>
+Reported-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
+Suggested-by: Arnd Bergmann <arnd@arndb.de>
+Suggested-by: James Y Knight <jyknight@google.com>
+Suggested-by: Masahiro Yamada <yamada.masahiro@socionext.com>
+Suggested-by: Nathan Chancellor <natechancellor@gmail.com>
+Suggested-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
+Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
+Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
+Tested-by: Nathan Chancellor <natechancellor@gmail.com>
+Reviewed-by: Masahiro Yamada <yamada.masahiro@socionext.com>
+Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
+Cc: David Laight <David.Laight@ACULAB.COM>
+Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
+Cc: Namhyung Kim <namhyung@kernel.org>
+Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
+Cc: Dan Williams <dan.j.williams@intel.com>
+Cc: <stable@vger.kernel.org>
+Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
+Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
+Signed-off-by: Sasha Levin <sashal@kernel.org>
+---
+ include/linux/string.h |  3 +++
+ lib/string.c           | 20 ++++++++++++++++++++
+ 2 files changed, 23 insertions(+)
+
+diff --git a/include/linux/string.h b/include/linux/string.h
+index b29098d154c3..4cf10407ba84 100644
+--- a/include/linux/string.h
++++ b/include/linux/string.h
+@@ -113,6 +113,9 @@ extern void * memscan(void *,int,__kernel_size_t);
+ #ifndef __HAVE_ARCH_MEMCMP
+ extern int memcmp(const void *,const void *,__kernel_size_t);
+ #endif
++#ifndef __HAVE_ARCH_BCMP
++extern int bcmp(const void *,const void *,__kernel_size_t);
++#endif
+ #ifndef __HAVE_ARCH_MEMCHR
+ extern void * memchr(const void *,int,__kernel_size_t);
+ #endif
+diff --git a/lib/string.c b/lib/string.c
+index de4bf3778958..63be6c2d4551 100644
+--- a/lib/string.c
++++ b/lib/string.c
+@@ -778,6 +778,26 @@ __visible int memcmp(const void *cs, const void *ct, size_t count)
+ EXPORT_SYMBOL(memcmp);
+ #endif
+ 
++#ifndef __HAVE_ARCH_BCMP
++/**
++ * bcmp - returns 0 if and only if the buffers have identical contents.
++ * @a: pointer to first buffer.
++ * @b: pointer to second buffer.
++ * @len: size of buffers.
++ *
++ * The sign or magnitude of a non-zero return value has no particular
++ * meaning, and architectures may implement their own more efficient bcmp(). So
++ * while this particular implementation is a simple (tail) call to memcmp, do
++ * not rely on anything but whether the return value is zero or non-zero.
++ */
++#undef bcmp
++int bcmp(const void *a, const void *b, size_t len)
++{
++      return memcmp(a, b, len);
++}
++EXPORT_SYMBOL(bcmp);
++#endif
++
+ #ifndef __HAVE_ARCH_MEMSCAN
+ /**
+  * memscan - Find a character in an area of memory.
+-- 
+2.19.1
+

diff --git a/queue-3.18/series b/queue-3.18/series
index 83cb0fd0bb93fa1f6273906e8b0d0c078dd7f26e..7b077c72888de45365cdecabbdd55e0d97b85419 100644 (file)
--- a/queue-3.18/series
+++ b/queue-3.18/series
@@ -40,3 +40,4 @@ x86-build-mark-per-cpu-symbols-as-absolute-explicitl.patch
 dmaengine-tegra-avoid-overflow-of-byte-tracking.patch
 drm-dp-mst-configure-no_stop_bit-correctly-for-remot.patch
 binfmt_elf-switch-to-new-creds-when-switching-to-new-mm.patch
+lib-string.c-implement-a-basic-bcmp.patch