From 9939ddaff52787b2a7c1adf1b2afc95421aa0884 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Tue, 13 Jan 2009 20:41:35 +0900 Subject: [PATCH] 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 Signed-off-by: Ingo Molnar --- arch/x86/include/asm/pda.h | 3 +- arch/x86/include/asm/percpu.h | 127 +++++++++++------------------------- arch/x86/kernel/asm-offsets_64.c | 1 - arch/x86/kernel/entry_64.S | 7 +- arch/x86/kernel/head64.c | 2 - arch/x86/kernel/setup_percpu.c | 15 +++-- arch/x86/kernel/smpcommon.c | 3 +- arch/x86/mach-voyager/voyager_smp.c | 2 + 8 files changed, 55 insertions(+), 105 deletions(-) diff --git a/arch/x86/include/asm/pda.h b/arch/x86/include/asm/pda.h index 2d5b49c..e91558e 100644 --- a/arch/x86/include/asm/pda.h +++ b/arch/x86/include/asm/pda.h @@ -11,8 +11,7 @@ /* Per processor datastructure. %gs points to it while the kernel runs */ struct x8664_pda { struct task_struct *pcurrent; /* 0 Current process */ - unsigned long data_offset; /* 8 Per cpu data offset from linker - address */ + unsigned long dummy; unsigned long kernelstack; /* 16 top of kernel stack for current */ unsigned long oldrsp; /* 24 user rsp for system call */ int irqcount; /* 32 Irq nesting counter. Starts -1 */ 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) { } -#endif -#endif - -#ifdef CONFIG_X86_64 -#include - -/* 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 - -#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)) - +#define __percpu_seg fs +#define __percpu_mov_op movl #endif -#include - -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 @@ DECLARE_PER_CPU(struct x8664_pda, pda); * 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) - */ -#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:" +#include -#else /* !SMP */ - -#define __percpu_seg "" - -#endif /* SMP */ +#ifdef CONFIG_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 @@ -128,20 +63,25 @@ do { \ } \ 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 @@ do { \ 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 @@ do { \ #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 diff --git a/arch/x86/kernel/asm-offsets_64.c b/arch/x86/kernel/asm-offsets_64.c index f8d1b04..f4cc81b 100644 --- a/arch/x86/kernel/asm-offsets_64.c +++ b/arch/x86/kernel/asm-offsets_64.c @@ -55,7 +55,6 @@ int main(void) ENTRY(irqcount); ENTRY(cpunumber); ENTRY(irqstackptr); - ENTRY(data_offset); DEFINE(pda_size, sizeof(struct x8664_pda)); BLANK(); #undef ENTRY diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S index e28c7a9..4833f3a 100644 --- a/arch/x86/kernel/entry_64.S +++ b/arch/x86/kernel/entry_64.S @@ -52,6 +52,7 @@ #include #include #include +#include /* Avoid __ASSEMBLER__'ifying just for this. */ #include @@ -1072,10 +1073,10 @@ ENTRY(\sym) TRACE_IRQS_OFF movq %rsp,%rdi /* pt_regs pointer */ xorl %esi,%esi /* no error code */ - movq %gs:pda_data_offset, %rbp - subq $EXCEPTION_STKSZ, per_cpu__init_tss + TSS_ist + (\ist - 1) * 8(%rbp) + PER_CPU(init_tss, %rbp) + subq $EXCEPTION_STKSZ, TSS_ist + (\ist - 1) * 8(%rbp) call \do_sym - addq $EXCEPTION_STKSZ, per_cpu__init_tss + TSS_ist + (\ist - 1) * 8(%rbp) + addq $EXCEPTION_STKSZ, TSS_ist + (\ist - 1) * 8(%rbp) jmp paranoid_exit /* %ebx: no swapgs flag */ CFI_ENDPROC END(\sym) diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c index 1a31129..e99b661 100644 --- a/arch/x86/kernel/head64.c +++ b/arch/x86/kernel/head64.c @@ -38,8 +38,6 @@ void __init x86_64_init_pda(void) #else cpu_pda(0) = &_boot_cpu_pda; #endif - cpu_pda(0)->data_offset = - (unsigned long)(__per_cpu_load - __per_cpu_start); pda_init(0); } diff --git a/arch/x86/kernel/setup_percpu.c b/arch/x86/kernel/setup_percpu.c index 63d4628..be1ff34 100644 --- a/arch/x86/kernel/setup_percpu.c +++ b/arch/x86/kernel/setup_percpu.c @@ -125,14 +125,14 @@ static void __init setup_per_cpu_maps(void) #endif } -#ifdef CONFIG_X86_32 -/* - * Great future not-so-futuristic plan: make i386 and x86_64 do it - * the same way - */ +#ifdef CONFIG_X86_64 +unsigned long __per_cpu_offset[NR_CPUS] __read_mostly = { + [0] = (unsigned long)__per_cpu_load, +}; +#else unsigned long __per_cpu_offset[NR_CPUS] __read_mostly; -EXPORT_SYMBOL(__per_cpu_offset); #endif +EXPORT_SYMBOL(__per_cpu_offset); /* * Great future plan: @@ -178,6 +178,7 @@ void __init setup_per_cpu_areas(void) #endif memcpy(ptr, __per_cpu_load, __per_cpu_end - __per_cpu_start); + per_cpu_offset(cpu) = ptr - __per_cpu_start; #ifdef CONFIG_X86_64 cpu_pda(cpu) = (void *)ptr; @@ -190,7 +191,7 @@ void __init setup_per_cpu_areas(void) else memset(cpu_pda(cpu), 0, sizeof(*cpu_pda(cpu))); #endif - per_cpu_offset(cpu) = ptr - __per_cpu_start; + per_cpu(this_cpu_off, cpu) = per_cpu_offset(cpu); DBG("PERCPU: cpu %4d %p\n", cpu, ptr); } diff --git a/arch/x86/kernel/smpcommon.c b/arch/x86/kernel/smpcommon.c index 397e309..84395fa 100644 --- a/arch/x86/kernel/smpcommon.c +++ b/arch/x86/kernel/smpcommon.c @@ -4,10 +4,10 @@ #include #include -#ifdef CONFIG_X86_32 DEFINE_PER_CPU(unsigned long, this_cpu_off); EXPORT_PER_CPU_SYMBOL(this_cpu_off); +#ifdef CONFIG_X86_32 /* * Initialize the CPU's GDT. This is either the boot CPU doing itself * (still using the master per-cpu area), or a CPU doing it for a @@ -24,7 +24,6 @@ __cpuinit void init_gdt(int cpu) write_gdt_entry(get_cpu_gdt_table(cpu), GDT_ENTRY_PERCPU, &gdt, DESCTYPE_S); - per_cpu(this_cpu_off, cpu) = __per_cpu_offset[cpu]; per_cpu(cpu_number, cpu) = cpu; } #endif diff --git a/arch/x86/mach-voyager/voyager_smp.c b/arch/x86/mach-voyager/voyager_smp.c index 9840b7e..1a48368 100644 --- a/arch/x86/mach-voyager/voyager_smp.c +++ b/arch/x86/mach-voyager/voyager_smp.c @@ -531,6 +531,7 @@ static void __init do_boot_cpu(__u8 cpu) stack_start.sp = (void *)idle->thread.sp; init_gdt(cpu); + per_cpu(this_cpu_off, cpu) = __per_cpu_offset[cpu]; per_cpu(current_task, cpu) = idle; early_gdt_descr.address = (unsigned long)get_cpu_gdt_table(cpu); irq_ctx_init(cpu); @@ -1748,6 +1749,7 @@ static void __init voyager_smp_prepare_cpus(unsigned int max_cpus) static void __cpuinit voyager_smp_prepare_boot_cpu(void) { init_gdt(smp_processor_id()); + per_cpu(this_cpu_off, cpu) = __per_cpu_offset[cpu]; switch_to_new_gdt(); cpu_set(smp_processor_id(), cpu_online_map); -- 2.7.4