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authorLinus Torvalds <torvalds@linux-foundation.org>2009-09-15 20:39:44 +0400
committerLinus Torvalds <torvalds@linux-foundation.org>2009-09-15 20:39:44 +0400
commitada3fa15057205b7d3f727bba5cd26b5912e350f (patch)
tree60962fc9e4021b92f484d1a58e72cd3906d4f3db /include/linux/percpu-defs.h
parent2f82af08fcc7dc01a7e98a49a5995a77e32a2925 (diff)
parent5579fd7e6aed8860ea0c8e3f11897493153b10ad (diff)
downloadlinux-ada3fa15057205b7d3f727bba5cd26b5912e350f.tar.xz
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu: (46 commits) powerpc64: convert to dynamic percpu allocator sparc64: use embedding percpu first chunk allocator percpu: kill lpage first chunk allocator x86,percpu: use embedding for 64bit NUMA and page for 32bit NUMA percpu: update embedding first chunk allocator to handle sparse units percpu: use group information to allocate vmap areas sparsely vmalloc: implement pcpu_get_vm_areas() vmalloc: separate out insert_vmalloc_vm() percpu: add chunk->base_addr percpu: add pcpu_unit_offsets[] percpu: introduce pcpu_alloc_info and pcpu_group_info percpu: move pcpu_lpage_build_unit_map() and pcpul_lpage_dump_cfg() upward percpu: add @align to pcpu_fc_alloc_fn_t percpu: make @dyn_size mandatory for pcpu_setup_first_chunk() percpu: drop @static_size from first chunk allocators percpu: generalize first chunk allocator selection percpu: build first chunk allocators selectively percpu: rename 4k first chunk allocator to page percpu: improve boot messages percpu: fix pcpu_reclaim() locking ... Fix trivial conflict as by Tejun Heo in kernel/sched.c
Diffstat (limited to 'include/linux/percpu-defs.h')
-rw-r--r--include/linux/percpu-defs.h66
1 files changed, 57 insertions, 9 deletions
diff --git a/include/linux/percpu-defs.h b/include/linux/percpu-defs.h
index 0761491b3eec..9bd03193ecd4 100644
--- a/include/linux/percpu-defs.h
+++ b/include/linux/percpu-defs.h
@@ -10,22 +10,70 @@
/*
* Base implementations of per-CPU variable declarations and definitions, where
* the section in which the variable is to be placed is provided by the
- * 'section' argument. This may be used to affect the parameters governing the
+ * 'sec' argument. This may be used to affect the parameters governing the
* variable's storage.
*
* NOTE! The sections for the DECLARE and for the DEFINE must match, lest
* linkage errors occur due the compiler generating the wrong code to access
* that section.
*/
-#define DECLARE_PER_CPU_SECTION(type, name, section) \
- extern \
- __attribute__((__section__(PER_CPU_BASE_SECTION section))) \
- PER_CPU_ATTRIBUTES __typeof__(type) per_cpu__##name
-
-#define DEFINE_PER_CPU_SECTION(type, name, section) \
- __attribute__((__section__(PER_CPU_BASE_SECTION section))) \
- PER_CPU_ATTRIBUTES PER_CPU_DEF_ATTRIBUTES \
+#define __PCPU_ATTRS(sec) \
+ __attribute__((section(PER_CPU_BASE_SECTION sec))) \
+ PER_CPU_ATTRIBUTES
+
+#define __PCPU_DUMMY_ATTRS \
+ __attribute__((section(".discard"), unused))
+
+/*
+ * s390 and alpha modules require percpu variables to be defined as
+ * weak to force the compiler to generate GOT based external
+ * references for them. This is necessary because percpu sections
+ * will be located outside of the usually addressable area.
+ *
+ * This definition puts the following two extra restrictions when
+ * defining percpu variables.
+ *
+ * 1. The symbol must be globally unique, even the static ones.
+ * 2. Static percpu variables cannot be defined inside a function.
+ *
+ * Archs which need weak percpu definitions should define
+ * ARCH_NEEDS_WEAK_PER_CPU in asm/percpu.h when necessary.
+ *
+ * To ensure that the generic code observes the above two
+ * restrictions, if CONFIG_DEBUG_FORCE_WEAK_PER_CPU is set weak
+ * definition is used for all cases.
+ */
+#if defined(ARCH_NEEDS_WEAK_PER_CPU) || defined(CONFIG_DEBUG_FORCE_WEAK_PER_CPU)
+/*
+ * __pcpu_scope_* dummy variable is used to enforce scope. It
+ * receives the static modifier when it's used in front of
+ * DEFINE_PER_CPU() and will trigger build failure if
+ * DECLARE_PER_CPU() is used for the same variable.
+ *
+ * __pcpu_unique_* dummy variable is used to enforce symbol uniqueness
+ * such that hidden weak symbol collision, which will cause unrelated
+ * variables to share the same address, can be detected during build.
+ */
+#define DECLARE_PER_CPU_SECTION(type, name, sec) \
+ extern __PCPU_DUMMY_ATTRS char __pcpu_scope_##name; \
+ extern __PCPU_ATTRS(sec) __typeof__(type) per_cpu__##name
+
+#define DEFINE_PER_CPU_SECTION(type, name, sec) \
+ __PCPU_DUMMY_ATTRS char __pcpu_scope_##name; \
+ __PCPU_DUMMY_ATTRS char __pcpu_unique_##name; \
+ __PCPU_ATTRS(sec) PER_CPU_DEF_ATTRIBUTES __weak \
+ __typeof__(type) per_cpu__##name
+#else
+/*
+ * Normal declaration and definition macros.
+ */
+#define DECLARE_PER_CPU_SECTION(type, name, sec) \
+ extern __PCPU_ATTRS(sec) __typeof__(type) per_cpu__##name
+
+#define DEFINE_PER_CPU_SECTION(type, name, sec) \
+ __PCPU_ATTRS(sec) PER_CPU_DEF_ATTRIBUTES \
__typeof__(type) per_cpu__##name
+#endif
/*
* Variant on the per-CPU variable declaration/definition theme used for