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authorLinus Torvalds <torvalds@linux-foundation.org>2014-03-31 14:13:25 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2014-03-31 14:13:25 -0700
commit176ab02d4916f09d5d8cb63372d142df4378cdea (patch)
tree7039b1282e7b34341789a5416fbd7ca5da0e557a /include
parente06df6a7eae1ab1ef4deb076aeeaed90e948e5c0 (diff)
parentef178f9238b142cc1020265e176b20d27fd02ba9 (diff)
downloadlinux-176ab02d4916f09d5d8cb63372d142df4378cdea.tar.bz2
Merge branch 'x86-asmlinkage-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 LTO changes from Peter Anvin: "More infrastructure work in preparation for link-time optimization (LTO). Most of these changes is to make sure symbols accessed from assembly code are properly marked as visible so the linker doesn't remove them. My understanding is that the changes to support LTO are still not upstream in binutils, but are on the way there. This patchset should conclude the x86-specific changes, and remaining patches to actually enable LTO will be fed through the Kbuild tree (other than keeping up with changes to the x86 code base, of course), although not necessarily in this merge window" * 'x86-asmlinkage-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (25 commits) Kbuild, lto: Handle basic LTO in modpost Kbuild, lto: Disable LTO for asm-offsets.c Kbuild, lto: Add a gcc-ld script to let run gcc as ld Kbuild, lto: add ld-version and ld-ifversion macros Kbuild, lto: Drop .number postfixes in modpost Kbuild, lto, workaround: Don't warn for initcall_reference in modpost lto: Disable LTO for sys_ni lto: Handle LTO common symbols in module loader lto, workaround: Add workaround for initcall reordering lto: Make asmlinkage __visible x86, lto: Disable LTO for the x86 VDSO initconst, x86: Fix initconst mistake in ts5500 code initconst: Fix initconst mistake in dcdbas asmlinkage: Make trace_hardirqs_on/off_caller visible asmlinkage, x86: Fix 32bit memcpy for LTO asmlinkage Make __stack_chk_failed and memcmp visible asmlinkage: Mark rwsem functions that can be called from assembler asmlinkage asmlinkage: Make main_extable_sort_needed visible asmlinkage, mutex: Mark __visible asmlinkage: Make trace_hardirq visible ...
Diffstat (limited to 'include')
-rw-r--r--include/linux/init.h20
-rw-r--r--include/linux/io.h2
-rw-r--r--include/linux/linkage.h4
-rw-r--r--include/linux/lockdep.h2
4 files changed, 23 insertions, 5 deletions
diff --git a/include/linux/init.h b/include/linux/init.h
index e1688802964f..a3ba27076342 100644
--- a/include/linux/init.h
+++ b/include/linux/init.h
@@ -163,6 +163,23 @@ extern bool initcall_debug;
#ifndef __ASSEMBLY__
+#ifdef CONFIG_LTO
+/* Work around a LTO gcc problem: when there is no reference to a variable
+ * in a module it will be moved to the end of the program. This causes
+ * reordering of initcalls which the kernel does not like.
+ * Add a dummy reference function to avoid this. The function is
+ * deleted by the linker.
+ */
+#define LTO_REFERENCE_INITCALL(x) \
+ ; /* yes this is needed */ \
+ static __used __exit void *reference_##x(void) \
+ { \
+ return &x; \
+ }
+#else
+#define LTO_REFERENCE_INITCALL(x)
+#endif
+
/* initcalls are now grouped by functionality into separate
* subsections. Ordering inside the subsections is determined
* by link order.
@@ -175,7 +192,8 @@ extern bool initcall_debug;
#define __define_initcall(fn, id) \
static initcall_t __initcall_##fn##id __used \
- __attribute__((__section__(".initcall" #id ".init"))) = fn
+ __attribute__((__section__(".initcall" #id ".init"))) = fn; \
+ LTO_REFERENCE_INITCALL(__initcall_##fn##id)
/*
* Early initcalls run before initializing SMP.
diff --git a/include/linux/io.h b/include/linux/io.h
index f4f42faec686..8a18e75600cc 100644
--- a/include/linux/io.h
+++ b/include/linux/io.h
@@ -24,7 +24,7 @@
struct device;
-void __iowrite32_copy(void __iomem *to, const void *from, size_t count);
+__visible void __iowrite32_copy(void __iomem *to, const void *from, size_t count);
void __iowrite64_copy(void __iomem *to, const void *from, size_t count);
#ifdef CONFIG_MMU
diff --git a/include/linux/linkage.h b/include/linux/linkage.h
index a6a42dd02466..34a513a2727b 100644
--- a/include/linux/linkage.h
+++ b/include/linux/linkage.h
@@ -12,9 +12,9 @@
#endif
#ifdef __cplusplus
-#define CPP_ASMLINKAGE extern "C"
+#define CPP_ASMLINKAGE extern "C" __visible
#else
-#define CPP_ASMLINKAGE
+#define CPP_ASMLINKAGE __visible
#endif
#ifndef asmlinkage
diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h
index 060e5137fd80..008388f920d7 100644
--- a/include/linux/lockdep.h
+++ b/include/linux/lockdep.h
@@ -265,7 +265,7 @@ extern void lockdep_info(void);
extern void lockdep_reset(void);
extern void lockdep_reset_lock(struct lockdep_map *lock);
extern void lockdep_free_key_range(void *start, unsigned long size);
-extern void lockdep_sys_exit(void);
+extern asmlinkage void lockdep_sys_exit(void);
extern void lockdep_off(void);
extern void lockdep_on(void);