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-rw-r--r--include/asm-generic/vmlinux.lds.h8
-rw-r--r--include/linux/percpu-defs.h66
-rw-r--r--include/linux/percpu.h12
3 files changed, 74 insertions, 12 deletions
diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index dccdbed0584..c5c18ac878a 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -629,6 +629,14 @@
#define INIT_RAM_FS
#endif
+#define DISCARDS \
+ /DISCARD/ : { \
+ EXIT_TEXT \
+ EXIT_DATA \
+ *(.exitcall.exit) \
+ *(.discard) \
+ }
+
/**
* PERCPU_VADDR - define output section for percpu area
* @vaddr: explicit base address (optional)
diff --git a/include/linux/percpu-defs.h b/include/linux/percpu-defs.h
index 68438e18fff..aefc2f12b48 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
diff --git a/include/linux/percpu.h b/include/linux/percpu.h
index 26fd9d12f05..e5000343dd6 100644
--- a/include/linux/percpu.h
+++ b/include/linux/percpu.h
@@ -34,7 +34,7 @@
#ifdef CONFIG_SMP
-#ifdef CONFIG_HAVE_DYNAMIC_PER_CPU_AREA
+#ifndef CONFIG_HAVE_LEGACY_PER_CPU_AREA
/* minimum unit size, also is the maximum supported allocation size */
#define PCPU_MIN_UNIT_SIZE PFN_ALIGN(64 << 10)
@@ -80,7 +80,7 @@ extern ssize_t __init pcpu_embed_first_chunk(
extern void *__alloc_reserved_percpu(size_t size, size_t align);
-#else /* CONFIG_HAVE_DYNAMIC_PER_CPU_AREA */
+#else /* CONFIG_HAVE_LEGACY_PER_CPU_AREA */
struct percpu_data {
void *ptrs[1];
@@ -99,11 +99,15 @@ struct percpu_data {
(__typeof__(ptr))__p->ptrs[(cpu)]; \
})
-#endif /* CONFIG_HAVE_DYNAMIC_PER_CPU_AREA */
+#endif /* CONFIG_HAVE_LEGACY_PER_CPU_AREA */
extern void *__alloc_percpu(size_t size, size_t align);
extern void free_percpu(void *__pdata);
+#ifndef CONFIG_HAVE_SETUP_PER_CPU_AREA
+extern void __init setup_per_cpu_areas(void);
+#endif
+
#else /* CONFIG_SMP */
#define per_cpu_ptr(ptr, cpu) ({ (void)(cpu); (ptr); })
@@ -124,6 +128,8 @@ static inline void free_percpu(void *p)
kfree(p);
}
+static inline void __init setup_per_cpu_areas(void) { }
+
#endif /* CONFIG_SMP */
#define alloc_percpu(type) (type *)__alloc_percpu(sizeof(type), \