From 7c3576d261ce046789a7db14f43303f8120910c7 Mon Sep 17 00:00:00 2001 From: Jeremy Fitzhardinge Date: Wed, 2 May 2007 19:27:16 +0200 Subject: [PATCH] i386: Convert PDA into the percpu section Currently x86 (similar to x84-64) has a special per-cpu structure called "i386_pda" which can be easily and efficiently referenced via the %fs register. An ELF section is more flexible than a structure, allowing any piece of code to use this area. Indeed, such a section already exists: the per-cpu area. So this patch: (1) Removes the PDA and uses per-cpu variables for each current member. (2) Replaces the __KERNEL_PDA segment with __KERNEL_PERCPU. (3) Creates a per-cpu mirror of __per_cpu_offset called this_cpu_off, which can be used to calculate addresses for this CPU's variables. (4) Simplifies startup, because %fs doesn't need to be loaded with a special segment at early boot; it can be deferred until the first percpu area is allocated (or never for UP). The result is less code and one less x86-specific concept. Signed-off-by: Rusty Russell Signed-off-by: Jeremy Fitzhardinge Signed-off-by: Andi Kleen Cc: Andi Kleen --- include/asm-i386/current.h | 5 +- include/asm-i386/irq_regs.h | 12 ++-- include/asm-i386/pda.h | 99 -------------------------------- include/asm-i386/percpu.h | 132 ++++++++++++++++++++++++++++++++++++++++--- include/asm-i386/processor.h | 2 +- include/asm-i386/segment.h | 6 +- include/asm-i386/smp.h | 4 +- 7 files changed, 139 insertions(+), 121 deletions(-) delete mode 100644 include/asm-i386/pda.h (limited to 'include/asm-i386') diff --git a/include/asm-i386/current.h b/include/asm-i386/current.h index 5252ee0f6d7..d3524853991 100644 --- a/include/asm-i386/current.h +++ b/include/asm-i386/current.h @@ -1,14 +1,15 @@ #ifndef _I386_CURRENT_H #define _I386_CURRENT_H -#include #include +#include struct task_struct; +DECLARE_PER_CPU(struct task_struct *, current_task); static __always_inline struct task_struct *get_current(void) { - return read_pda(pcurrent); + return x86_read_percpu(current_task); } #define current get_current() diff --git a/include/asm-i386/irq_regs.h b/include/asm-i386/irq_regs.h index a1b3f7f594a..3368b20c0b4 100644 --- a/include/asm-i386/irq_regs.h +++ b/include/asm-i386/irq_regs.h @@ -1,25 +1,27 @@ /* * Per-cpu current frame pointer - the location of the last exception frame on - * the stack, stored in the PDA. + * the stack, stored in the per-cpu area. * * Jeremy Fitzhardinge */ #ifndef _ASM_I386_IRQ_REGS_H #define _ASM_I386_IRQ_REGS_H -#include +#include + +DECLARE_PER_CPU(struct pt_regs *, irq_regs); static inline struct pt_regs *get_irq_regs(void) { - return read_pda(irq_regs); + return x86_read_percpu(irq_regs); } static inline struct pt_regs *set_irq_regs(struct pt_regs *new_regs) { struct pt_regs *old_regs; - old_regs = read_pda(irq_regs); - write_pda(irq_regs, new_regs); + old_regs = get_irq_regs(); + x86_write_percpu(irq_regs, new_regs); return old_regs; } diff --git a/include/asm-i386/pda.h b/include/asm-i386/pda.h deleted file mode 100644 index aef7f732f77..00000000000 --- a/include/asm-i386/pda.h +++ /dev/null @@ -1,99 +0,0 @@ -/* - Per-processor Data Areas - Jeremy Fitzhardinge 2006 - Based on asm-x86_64/pda.h by Andi Kleen. - */ -#ifndef _I386_PDA_H -#define _I386_PDA_H - -#include -#include -#include - -struct i386_pda -{ - struct i386_pda *_pda; /* pointer to self */ - - int cpu_number; - struct task_struct *pcurrent; /* current process */ - struct pt_regs *irq_regs; -}; - -DECLARE_PER_CPU(struct i386_pda, _cpu_pda); -#define cpu_pda(i) (&per_cpu(_cpu_pda, (i))) -#define pda_offset(field) offsetof(struct i386_pda, field) - -extern void __bad_pda_field(void); - -/* This variable is never instantiated. It is only used as a stand-in - for the real per-cpu PDA memory, so that gcc can understand what - memory operations the inline asms() below are performing. This - eliminates the need to make the asms volatile or have memory - clobbers, so gcc can readily analyse them. */ -extern struct i386_pda _proxy_pda; - -#define pda_to_op(op,field,val) \ - do { \ - typedef typeof(_proxy_pda.field) T__; \ - if (0) { T__ tmp__; tmp__ = (val); } \ - switch (sizeof(_proxy_pda.field)) { \ - case 1: \ - asm(op "b %1,%%fs:%c2" \ - : "+m" (_proxy_pda.field) \ - :"ri" ((T__)val), \ - "i"(pda_offset(field))); \ - break; \ - case 2: \ - asm(op "w %1,%%fs:%c2" \ - : "+m" (_proxy_pda.field) \ - :"ri" ((T__)val), \ - "i"(pda_offset(field))); \ - break; \ - case 4: \ - asm(op "l %1,%%fs:%c2" \ - : "+m" (_proxy_pda.field) \ - :"ri" ((T__)val), \ - "i"(pda_offset(field))); \ - break; \ - default: __bad_pda_field(); \ - } \ - } while (0) - -#define pda_from_op(op,field) \ - ({ \ - typeof(_proxy_pda.field) ret__; \ - switch (sizeof(_proxy_pda.field)) { \ - case 1: \ - asm(op "b %%fs:%c1,%0" \ - : "=r" (ret__) \ - : "i" (pda_offset(field)), \ - "m" (_proxy_pda.field)); \ - break; \ - case 2: \ - asm(op "w %%fs:%c1,%0" \ - : "=r" (ret__) \ - : "i" (pda_offset(field)), \ - "m" (_proxy_pda.field)); \ - break; \ - case 4: \ - asm(op "l %%fs:%c1,%0" \ - : "=r" (ret__) \ - : "i" (pda_offset(field)), \ - "m" (_proxy_pda.field)); \ - break; \ - default: __bad_pda_field(); \ - } \ - ret__; }) - -/* Return a pointer to a pda field */ -#define pda_addr(field) \ - ((typeof(_proxy_pda.field) *)((unsigned char *)read_pda(_pda) + \ - pda_offset(field))) - -#define read_pda(field) pda_from_op("mov",field) -#define write_pda(field,val) pda_to_op("mov",field,val) -#define add_pda(field,val) pda_to_op("add",field,val) -#define sub_pda(field,val) pda_to_op("sub",field,val) -#define or_pda(field,val) pda_to_op("or",field,val) - -#endif /* _I386_PDA_H */ diff --git a/include/asm-i386/percpu.h b/include/asm-i386/percpu.h index a10e7c68ae9..c5f12f0d9c2 100644 --- a/include/asm-i386/percpu.h +++ b/include/asm-i386/percpu.h @@ -1,9 +1,30 @@ #ifndef __ARCH_I386_PERCPU__ #define __ARCH_I386_PERCPU__ -#ifndef __ASSEMBLY__ -#include -#else +#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; \ + addl $per_cpu__##var, reg +#else /* ! SMP */ +#define PER_CPU(var, reg) \ + movl $per_cpu__##var, reg; +#endif /* SMP */ + +#else /* ...!ASSEMBLY */ /* * PER_CPU finds an address of a per-cpu variable. @@ -18,14 +39,107 @@ * PER_CPU(cpu_gdt_descr, %ebx) */ #ifdef CONFIG_SMP -#define PER_CPU(var, cpu) \ - movl __per_cpu_offset(,cpu,4), cpu; \ - addl $per_cpu__##var, cpu; -#else /* ! SMP */ -#define PER_CPU(var, cpu) \ - movl $per_cpu__##var, cpu; +/* Same as generic implementation except for optimized local access. */ +#define __GENERIC_PER_CPU + +/* This is used for other cpus to find our section. */ +extern unsigned long __per_cpu_offset[]; + +/* Separate out the type, so (int[3], foo) works. */ +#define DECLARE_PER_CPU(type, name) extern __typeof__(type) per_cpu__##name +#define DEFINE_PER_CPU(type, name) \ + __attribute__((__section__(".data.percpu"))) __typeof__(type) per_cpu__##name + +/* We can use this directly for local CPU (faster). */ +DECLARE_PER_CPU(unsigned long, this_cpu_off); + +/* var is in discarded region: offset to particular copy we want */ +#define per_cpu(var, cpu) (*({ \ + extern int simple_indentifier_##var(void); \ + RELOC_HIDE(&per_cpu__##var, __per_cpu_offset[cpu]); })) + +#define __raw_get_cpu_var(var) (*({ \ + extern int simple_indentifier_##var(void); \ + RELOC_HIDE(&per_cpu__##var, x86_read_percpu(this_cpu_off)); \ +})) + +#define __get_cpu_var(var) __raw_get_cpu_var(var) + +/* A macro to avoid #include hell... */ +#define percpu_modcopy(pcpudst, src, size) \ +do { \ + unsigned int __i; \ + for_each_possible_cpu(__i) \ + memcpy((pcpudst)+__per_cpu_offset[__i], \ + (src), (size)); \ +} while (0) + +#define EXPORT_PER_CPU_SYMBOL(var) EXPORT_SYMBOL(per_cpu__##var) +#define EXPORT_PER_CPU_SYMBOL_GPL(var) EXPORT_SYMBOL_GPL(per_cpu__##var) + +/* fs segment starts at (positive) offset == __per_cpu_offset[cpu] */ +#define __percpu_seg "%%fs:" +#else /* !SMP */ +#include +#define __percpu_seg "" #endif /* SMP */ +/* 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 /* __ARCH_I386_PERCPU__ */ diff --git a/include/asm-i386/processor.h b/include/asm-i386/processor.h index 92226047464..ced2da8a0d6 100644 --- a/include/asm-i386/processor.h +++ b/include/asm-i386/processor.h @@ -377,7 +377,7 @@ struct thread_struct { .vm86_info = NULL, \ .sysenter_cs = __KERNEL_CS, \ .io_bitmap_ptr = NULL, \ - .fs = __KERNEL_PDA, \ + .fs = __KERNEL_PERCPU, \ } /* diff --git a/include/asm-i386/segment.h b/include/asm-i386/segment.h index 065f10bfa48..07e70624d87 100644 --- a/include/asm-i386/segment.h +++ b/include/asm-i386/segment.h @@ -39,7 +39,7 @@ * 25 - APM BIOS support * * 26 - ESPFIX small SS - * 27 - PDA [ per-cpu private data area ] + * 27 - per-cpu [ offset to per-cpu data area ] * 28 - unused * 29 - unused * 30 - unused @@ -74,8 +74,8 @@ #define GDT_ENTRY_ESPFIX_SS (GDT_ENTRY_KERNEL_BASE + 14) #define __ESPFIX_SS (GDT_ENTRY_ESPFIX_SS * 8) -#define GDT_ENTRY_PDA (GDT_ENTRY_KERNEL_BASE + 15) -#define __KERNEL_PDA (GDT_ENTRY_PDA * 8) +#define GDT_ENTRY_PERCPU (GDT_ENTRY_KERNEL_BASE + 15) +#define __KERNEL_PERCPU (GDT_ENTRY_PERCPU * 8) #define GDT_ENTRY_DOUBLEFAULT_TSS 31 diff --git a/include/asm-i386/smp.h b/include/asm-i386/smp.h index 2d083cb4ca9..090abc1da32 100644 --- a/include/asm-i386/smp.h +++ b/include/asm-i386/smp.h @@ -8,7 +8,6 @@ #include #include #include -#include #endif #if defined(CONFIG_X86_LOCAL_APIC) && !defined(__ASSEMBLY__) @@ -112,7 +111,8 @@ do { } while (0) * from the initial startup. We map APIC_BASE very early in page_setup(), * so this is correct in the x86 case. */ -#define raw_smp_processor_id() (read_pda(cpu_number)) +DECLARE_PER_CPU(int, cpu_number); +#define raw_smp_processor_id() (x86_read_percpu(cpu_number)) extern cpumask_t cpu_callout_map; extern cpumask_t cpu_callin_map; -- cgit v1.2.3