x86: merge 64 and 32 SMP percpu handling
Now that pda is allocated as part of percpu, percpu doesn't need to be
accessed through pda. Unify x86_64 SMP percpu access with x86_32 SMP
one. Other than the segment register, operand size and the base of
percpu symbols, they behave identical now.
This patch replaces now unnecessary pda->data_offset with a dummy
field which is necessary to keep stack_canary at its place. This
patch also moves per_cpu_offset initialization out of init_gdt() into
setup_per_cpu_areas(). Note that this change also necessitates
explicit per_cpu_offset initializations in voyager_smp.c.
With this change, x86_OP_percpu()'s are as efficient on x86_64 as on
x86_32 and also x86_64 can use assembly PER_CPU macros.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/arch/x86/include/asm/percpu.h b/arch/x86/include/asm/percpu.h
index 0ed77cf..556f84b 100644
--- a/arch/x86/include/asm/percpu.h
+++ b/arch/x86/include/asm/percpu.h
@@ -1,62 +1,13 @@
#ifndef _ASM_X86_PERCPU_H
#define _ASM_X86_PERCPU_H
-#ifndef __ASSEMBLY__
#ifdef CONFIG_X86_64
-extern void load_pda_offset(int cpu);
+#define __percpu_seg gs
+#define __percpu_mov_op movq
#else
-static inline void load_pda_offset(int cpu) { }
+#define __percpu_seg fs
+#define __percpu_mov_op movl
#endif
-#endif
-
-#ifdef CONFIG_X86_64
-#include <linux/compiler.h>
-
-/* Same as asm-generic/percpu.h, except that we store the per cpu offset
- in the PDA. Longer term the PDA and every per cpu variable
- should be just put into a single section and referenced directly
- from %gs */
-
-#ifdef CONFIG_SMP
-#include <asm/pda.h>
-
-#define __per_cpu_offset(cpu) (cpu_pda(cpu)->data_offset)
-#define __my_cpu_offset read_pda(data_offset)
-
-#define per_cpu_offset(x) (__per_cpu_offset(x))
-
-#endif
-#include <asm-generic/percpu.h>
-
-DECLARE_PER_CPU(struct x8664_pda, pda);
-
-/*
- * These are supposed to be implemented as a single instruction which
- * operates on the per-cpu data base segment. x86-64 doesn't have
- * that yet, so this is a fairly inefficient workaround for the
- * meantime. The single instruction is atomic with respect to
- * preemption and interrupts, so we need to explicitly disable
- * interrupts here to achieve the same effect. However, because it
- * can be used from within interrupt-disable/enable, we can't actually
- * disable interrupts; disabling preemption is enough.
- */
-#define x86_read_percpu(var) \
- ({ \
- typeof(per_cpu_var(var)) __tmp; \
- preempt_disable(); \
- __tmp = __get_cpu_var(var); \
- preempt_enable(); \
- __tmp; \
- })
-
-#define x86_write_percpu(var, val) \
- do { \
- preempt_disable(); \
- __get_cpu_var(var) = (val); \
- preempt_enable(); \
- } while(0)
-
-#else /* CONFIG_X86_64 */
#ifdef __ASSEMBLY__
@@ -73,42 +24,26 @@
* PER_CPU(cpu_gdt_descr, %ebx)
*/
#ifdef CONFIG_SMP
-#define PER_CPU(var, reg) \
- movl %fs:per_cpu__##this_cpu_off, reg; \
+#define PER_CPU(var, reg) \
+ __percpu_mov_op %__percpu_seg:per_cpu__this_cpu_off, reg; \
lea per_cpu__##var(reg), reg
-#define PER_CPU_VAR(var) %fs:per_cpu__##var
+#define PER_CPU_VAR(var) %__percpu_seg:per_cpu__##var
#else /* ! SMP */
-#define PER_CPU(var, reg) \
- movl $per_cpu__##var, reg
+#define PER_CPU(var, reg) \
+ __percpu_mov_op $per_cpu__##var, reg
#define PER_CPU_VAR(var) per_cpu__##var
#endif /* SMP */
#else /* ...!ASSEMBLY */
-/*
- * PER_CPU finds an address of a per-cpu variable.
- *
- * Args:
- * var - variable name
- * cpu - 32bit register containing the current CPU number
- *
- * The resulting address is stored in the "cpu" argument.
- *
- * Example:
- * PER_CPU(cpu_gdt_descr, %ebx)
- */
+#include <linux/stringify.h>
+
#ifdef CONFIG_SMP
-
-#define __my_cpu_offset x86_read_percpu(this_cpu_off)
-
-/* fs segment starts at (positive) offset == __per_cpu_offset[cpu] */
-#define __percpu_seg "%%fs:"
-
-#else /* !SMP */
-
-#define __percpu_seg ""
-
-#endif /* SMP */
+#define __percpu_seg_str "%%"__stringify(__percpu_seg)":"
+#define __my_cpu_offset x86_read_percpu(this_cpu_off)
+#else
+#define __percpu_seg_str
+#endif
#include <asm-generic/percpu.h>
@@ -128,20 +63,25 @@
} \
switch (sizeof(var)) { \
case 1: \
- asm(op "b %1,"__percpu_seg"%0" \
+ asm(op "b %1,"__percpu_seg_str"%0" \
: "+m" (var) \
: "ri" ((T__)val)); \
break; \
case 2: \
- asm(op "w %1,"__percpu_seg"%0" \
+ asm(op "w %1,"__percpu_seg_str"%0" \
: "+m" (var) \
: "ri" ((T__)val)); \
break; \
case 4: \
- asm(op "l %1,"__percpu_seg"%0" \
+ asm(op "l %1,"__percpu_seg_str"%0" \
: "+m" (var) \
: "ri" ((T__)val)); \
break; \
+ case 8: \
+ asm(op "q %1,"__percpu_seg_str"%0" \
+ : "+m" (var) \
+ : "r" ((T__)val)); \
+ break; \
default: __bad_percpu_size(); \
} \
} while (0)
@@ -151,17 +91,22 @@
typeof(var) ret__; \
switch (sizeof(var)) { \
case 1: \
- asm(op "b "__percpu_seg"%1,%0" \
+ asm(op "b "__percpu_seg_str"%1,%0" \
: "=r" (ret__) \
: "m" (var)); \
break; \
case 2: \
- asm(op "w "__percpu_seg"%1,%0" \
+ asm(op "w "__percpu_seg_str"%1,%0" \
: "=r" (ret__) \
: "m" (var)); \
break; \
case 4: \
- asm(op "l "__percpu_seg"%1,%0" \
+ asm(op "l "__percpu_seg_str"%1,%0" \
+ : "=r" (ret__) \
+ : "m" (var)); \
+ break; \
+ case 8: \
+ asm(op "q "__percpu_seg_str"%1,%0" \
: "=r" (ret__) \
: "m" (var)); \
break; \
@@ -175,8 +120,14 @@
#define x86_add_percpu(var, val) percpu_to_op("add", per_cpu__##var, val)
#define x86_sub_percpu(var, val) percpu_to_op("sub", per_cpu__##var, val)
#define x86_or_percpu(var, val) percpu_to_op("or", per_cpu__##var, val)
+
+#ifdef CONFIG_X86_64
+extern void load_pda_offset(int cpu);
+#else
+static inline void load_pda_offset(int cpu) { }
+#endif
+
#endif /* !__ASSEMBLY__ */
-#endif /* !CONFIG_X86_64 */
#ifdef CONFIG_SMP