x86, um: ... and asm-x86 move

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

1 files changed, 218 insertions, 0 deletions

diff --git a/arch/x86/include/asm/percpu.h b/arch/x86/include/asm/percpu.h
new file mode 100644
index 00000000000..e10a1d0678c
--- /dev/null
+++ b/arch/x86/include/asm/percpu.h
@@ -0,0 +1,218 @@
+#ifndef ASM_X86__PERCPU_H
+#define ASM_X86__PERCPU_H
+
+#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__
+
+/*
+ * PER_CPU finds an address of a per-cpu variable.
+ *
+ * Args:
+ *    var - variable name
+ *    reg - 32bit register
+ *
+ * The resulting address is stored in the "reg" argument.
+ *
+ * Example:
+ *    PER_CPU(cpu_gdt_descr, %ebx)
+ */
+#ifdef CONFIG_SMP
+#define PER_CPU(var, reg)				\
+	movl %fs:per_cpu__##this_cpu_off, reg;		\
+	lea per_cpu__##var(reg), reg
+#define PER_CPU_VAR(var)	%fs:per_cpu__##var
+#else /* ! SMP */
+#define PER_CPU(var, reg)			\
+	movl $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)
+ */
+#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 */
+
+#include <asm-generic/percpu.h>
+
+/* We can use this directly for local CPU (faster). */
+DECLARE_PER_CPU(unsigned long, this_cpu_off);
+
+/* For arch-specific code, we can use direct single-insn ops (they
+ * don't give an lvalue though). */
+extern void __bad_percpu_size(void);
+
+#define percpu_to_op(op, var, val)			\
+do {							\
+	typedef typeof(var) T__;			\
+	if (0) {					\
+		T__ tmp__;				\
+		tmp__ = (val);				\
+	}						\
+	switch (sizeof(var)) {				\
+	case 1:						\
+		asm(op "b %1,"__percpu_seg"%0"		\
+		    : "+m" (var)			\
+		    : "ri" ((T__)val));			\
+		break;					\
+	case 2:						\
+		asm(op "w %1,"__percpu_seg"%0"		\
+		    : "+m" (var)			\
+		    : "ri" ((T__)val));			\
+		break;					\
+	case 4:						\
+		asm(op "l %1,"__percpu_seg"%0"		\
+		    : "+m" (var)			\
+		    : "ri" ((T__)val));			\
+		break;					\
+	default: __bad_percpu_size();			\
+	}						\
+} while (0)
+
+#define percpu_from_op(op, var)				\
+({							\
+	typeof(var) ret__;				\
+	switch (sizeof(var)) {				\
+	case 1:						\
+		asm(op "b "__percpu_seg"%1,%0"		\
+		    : "=r" (ret__)			\
+		    : "m" (var));			\
+		break;					\
+	case 2:						\
+		asm(op "w "__percpu_seg"%1,%0"		\
+		    : "=r" (ret__)			\
+		    : "m" (var));			\
+		break;					\
+	case 4:						\
+		asm(op "l "__percpu_seg"%1,%0"		\
+		    : "=r" (ret__)			\
+		    : "m" (var));			\
+		break;					\
+	default: __bad_percpu_size();			\
+	}						\
+	ret__;						\
+})
+
+#define x86_read_percpu(var) percpu_from_op("mov", per_cpu__##var)
+#define x86_write_percpu(var, val) percpu_to_op("mov", per_cpu__##var, val)
+#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)
+#endif /* !__ASSEMBLY__ */
+#endif /* !CONFIG_X86_64 */
+
+#ifdef CONFIG_SMP
+
+/*
+ * Define the "EARLY_PER_CPU" macros.  These are used for some per_cpu
+ * variables that are initialized and accessed before there are per_cpu
+ * areas allocated.
+ */
+
+#define	DEFINE_EARLY_PER_CPU(_type, _name, _initvalue)			\
+	DEFINE_PER_CPU(_type, _name) = _initvalue;			\
+	__typeof__(_type) _name##_early_map[NR_CPUS] __initdata =	\
+				{ [0 ... NR_CPUS-1] = _initvalue };	\
+	__typeof__(_type) *_name##_early_ptr __refdata = _name##_early_map
+
+#define EXPORT_EARLY_PER_CPU_SYMBOL(_name)			\
+	EXPORT_PER_CPU_SYMBOL(_name)
+
+#define DECLARE_EARLY_PER_CPU(_type, _name)			\
+	DECLARE_PER_CPU(_type, _name);				\
+	extern __typeof__(_type) *_name##_early_ptr;		\
+	extern __typeof__(_type)  _name##_early_map[]
+
+#define	early_per_cpu_ptr(_name) (_name##_early_ptr)
+#define	early_per_cpu_map(_name, _idx) (_name##_early_map[_idx])
+#define	early_per_cpu(_name, _cpu) 				\
+	(early_per_cpu_ptr(_name) ?				\
+		early_per_cpu_ptr(_name)[_cpu] :		\
+		per_cpu(_name, _cpu))
+
+#else	/* !CONFIG_SMP */
+#define	DEFINE_EARLY_PER_CPU(_type, _name, _initvalue)		\
+	DEFINE_PER_CPU(_type, _name) = _initvalue
+
+#define EXPORT_EARLY_PER_CPU_SYMBOL(_name)			\
+	EXPORT_PER_CPU_SYMBOL(_name)
+
+#define DECLARE_EARLY_PER_CPU(_type, _name)			\
+	DECLARE_PER_CPU(_type, _name)
+
+#define	early_per_cpu(_name, _cpu) per_cpu(_name, _cpu)
+#define	early_per_cpu_ptr(_name) NULL
+/* no early_per_cpu_map() */
+
+#endif	/* !CONFIG_SMP */
+
+#endif /* ASM_X86__PERCPU_H */