+++ /dev/null
-From b2a15cebf1822ff1ce0e390d45202f2231047ee2 Mon Sep 17 00:00:00 2001
-From: Sasha Levin <sashal@kernel.org>
-Date: Fri, 13 Nov 2020 22:51:59 -0800
-Subject: compiler.h: fix barrier_data() on clang
-
-From: Arvind Sankar <nivedita@alum.mit.edu>
-
-[ Upstream commit 3347acc6fcd4ee71ad18a9ff9d9dac176b517329 ]
-
-Commit 815f0ddb346c ("include/linux/compiler*.h: make compiler-*.h
-mutually exclusive") neglected to copy barrier_data() from
-compiler-gcc.h into compiler-clang.h.
-
-The definition in compiler-gcc.h was really to work around clang's more
-aggressive optimization, so this broke barrier_data() on clang, and
-consequently memzero_explicit() as well.
-
-For example, this results in at least the memzero_explicit() call in
-lib/crypto/sha256.c:sha256_transform() being optimized away by clang.
-
-Fix this by moving the definition of barrier_data() into compiler.h.
-
-Also move the gcc/clang definition of barrier() into compiler.h,
-__memory_barrier() is icc-specific (and barrier() is already defined
-using it in compiler-intel.h) and doesn't belong in compiler.h.
-
-[rdunlap@infradead.org: fix ALPHA builds when SMP is not enabled]
-
-Link: https://lkml.kernel.org/r/20201101231835.4589-1-rdunlap@infradead.org
-Fixes: 815f0ddb346c ("include/linux/compiler*.h: make compiler-*.h mutually exclusive")
-Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
-Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
-Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
-Tested-by: Nick Desaulniers <ndesaulniers@google.com>
-Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
-Reviewed-by: Kees Cook <keescook@chromium.org>
-Cc: <stable@vger.kernel.org>
-Link: https://lkml.kernel.org/r/20201014212631.207844-1-nivedita@alum.mit.edu
-Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-Signed-off-by: Sasha Levin <sashal@kernel.org>
----
- include/linux/compiler-clang.h | 5 -----
- include/linux/compiler-gcc.h | 19 -------------------
- include/linux/compiler.h | 18 ++++++++++++++++--
- 3 files changed, 16 insertions(+), 26 deletions(-)
-
-diff --git a/include/linux/compiler-clang.h b/include/linux/compiler-clang.h
-index 333a6695a918c..9b89141604ed0 100644
---- a/include/linux/compiler-clang.h
-+++ b/include/linux/compiler-clang.h
-@@ -37,8 +37,3 @@
- #define COMPILER_HAS_GENERIC_BUILTIN_OVERFLOW 1
- #endif
-
--/* The following are for compatibility with GCC, from compiler-gcc.h,
-- * and may be redefined here because they should not be shared with other
-- * compilers, like ICC.
-- */
--#define barrier() __asm__ __volatile__("" : : : "memory")
-diff --git a/include/linux/compiler-gcc.h b/include/linux/compiler-gcc.h
-index e8579412ad214..d8fab3ecf5120 100644
---- a/include/linux/compiler-gcc.h
-+++ b/include/linux/compiler-gcc.h
-@@ -14,25 +14,6 @@
- # error Sorry, your compiler is too old - please upgrade it.
- #endif
-
--/* Optimization barrier */
--
--/* The "volatile" is due to gcc bugs */
--#define barrier() __asm__ __volatile__("": : :"memory")
--/*
-- * This version is i.e. to prevent dead stores elimination on @ptr
-- * where gcc and llvm may behave differently when otherwise using
-- * normal barrier(): while gcc behavior gets along with a normal
-- * barrier(), llvm needs an explicit input variable to be assumed
-- * clobbered. The issue is as follows: while the inline asm might
-- * access any memory it wants, the compiler could have fit all of
-- * @ptr into memory registers instead, and since @ptr never escaped
-- * from that, it proved that the inline asm wasn't touching any of
-- * it. This version works well with both compilers, i.e. we're telling
-- * the compiler that the inline asm absolutely may see the contents
-- * of @ptr. See also: https://llvm.org/bugs/show_bug.cgi?id=15495
-- */
--#define barrier_data(ptr) __asm__ __volatile__("": :"r"(ptr) :"memory")
--
- /*
- * This macro obfuscates arithmetic on a variable address so that gcc
- * shouldn't recognize the original var, and make assumptions about it.
-diff --git a/include/linux/compiler.h b/include/linux/compiler.h
-index 448c91bf543b7..f164a9b12813f 100644
---- a/include/linux/compiler.h
-+++ b/include/linux/compiler.h
-@@ -80,11 +80,25 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val,
-
- /* Optimization barrier */
- #ifndef barrier
--# define barrier() __memory_barrier()
-+/* The "volatile" is due to gcc bugs */
-+# define barrier() __asm__ __volatile__("": : :"memory")
- #endif
-
- #ifndef barrier_data
--# define barrier_data(ptr) barrier()
-+/*
-+ * This version is i.e. to prevent dead stores elimination on @ptr
-+ * where gcc and llvm may behave differently when otherwise using
-+ * normal barrier(): while gcc behavior gets along with a normal
-+ * barrier(), llvm needs an explicit input variable to be assumed
-+ * clobbered. The issue is as follows: while the inline asm might
-+ * access any memory it wants, the compiler could have fit all of
-+ * @ptr into memory registers instead, and since @ptr never escaped
-+ * from that, it proved that the inline asm wasn't touching any of
-+ * it. This version works well with both compilers, i.e. we're telling
-+ * the compiler that the inline asm absolutely may see the contents
-+ * of @ptr. See also: https://llvm.org/bugs/show_bug.cgi?id=15495
-+ */
-+# define barrier_data(ptr) __asm__ __volatile__("": :"r"(ptr) :"memory")
- #endif
-
- /* workaround for GCC PR82365 if needed */
---
-2.27.0
-
projects / thirdparty / kernel / stable-queue.git / commitdiff
