path: root/mm
diff options
authorNick Desaulniers <ndesaulniers@google.com>2018-08-22 16:37:24 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2018-08-22 17:31:34 -0700
commit815f0ddb346c196018d4d8f8f55c12b83da1de3f (patch)
tree4805bf7e3cb7ec4e727aba8e62f9211e9001a760 /mm
parent899fbc33fd775b9dfa363db28f322272920a2196 (diff)
include/linux/compiler*.h: make compiler-*.h mutually exclusive
Commit cafa0010cd51 ("Raise the minimum required gcc version to 4.6") recently exposed a brittle part of the build for supporting non-gcc compilers. Both Clang and ICC define __GNUC__, __GNUC_MINOR__, and __GNUC_PATCHLEVEL__ for quick compatibility with code bases that haven't added compiler specific checks for __clang__ or __INTEL_COMPILER. This is brittle, as they happened to get compatibility by posing as a certain version of GCC. This broke when upgrading the minimal version of GCC required to build the kernel, to a version above what ICC and Clang claim to be. Rather than always including compiler-gcc.h then undefining or redefining macros in compiler-intel.h or compiler-clang.h, let's separate out the compiler specific macro definitions into mutually exclusive headers, do more proper compiler detection, and keep shared definitions in compiler_types.h. Fixes: cafa0010cd51 ("Raise the minimum required gcc version to 4.6") Reported-by: Masahiro Yamada <yamada.masahiro@socionext.com> Suggested-by: Eli Friedman <efriedma@codeaurora.org> Suggested-by: Joe Perches <joe@perches.com> Signed-off-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
2 files changed, 4 insertions, 3 deletions
diff --git a/mm/ksm.c b/mm/ksm.c
index 1bd514c9e5d0..5b0894b45ee5 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -652,9 +652,9 @@ static void remove_node_from_stable_tree(struct stable_node *stable_node)
* list_head to stay clear from the rb_parent_color union
* (aligned and different than any node) and also different
* from &migrate_nodes. This will verify that future list.h changes
- * don't break STABLE_NODE_DUP_HEAD.
+ * don't break STABLE_NODE_DUP_HEAD. Only recent gcc can handle it.
-#if GCC_VERSION >= 40903 /* only recent gcc can handle it */
+#if defined(GCC_VERSION) && GCC_VERSION >= 40903
BUILD_BUG_ON(STABLE_NODE_DUP_HEAD >= &migrate_nodes + 1);
diff --git a/mm/migrate.c b/mm/migrate.c
index 4a83268e23c2..c27e97b5b69d 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1131,7 +1131,8 @@ out:
* gcc 4.7 and 4.8 on arm get an ICEs when inlining unmap_and_move(). Work
* around it.
-#if (GCC_VERSION >= 40700 && GCC_VERSION < 40900) && defined(CONFIG_ARM)
+#if defined(CONFIG_ARM) && \
+ defined(GCC_VERSION) && GCC_VERSION < 40900 && GCC_VERSION >= 40700
#define ICE_noinline noinline
#define ICE_noinline