Initialize the per-CPU data area. When a CPU is brought up, a PDA and GDT are allocated for it. The GDT's __KERNEL_PDA entry is pointed to the allocated PDA memory, so that all references using this segment descriptor will refer to the PDA. This patch rearranges CPU initialization a bit, so that the GDT/PDA are set up as early as possible in cpu_init(). Also for secondary CPUs, GDT+PDA are preallocated and initialized so all the secondary CPU needs to do is set up the ldt and load %gs. This will be important once smp_processor_id() and current use the PDA. In all cases, the PDA is set up in head.S, before a CPU starts running C code, so the PDA is always available. Signed-off-by: Jeremy Fitzhardinge Cc: Chuck Ebbert <76306.1226@compuserve.com> Cc: Zachary Amsden Cc: Jan Beulich Cc: Andi Kleen Cc: James Bottomley Cc: Matt Tolentino --- arch/i386/kernel/cpu/common.c | 293 +++++++++++++++++++++++++++-------------- arch/i386/kernel/smpboot.c | 31 +++- include/asm-i386/pda.h | 20 ++ include/asm-i386/processor.h | 3 4 files changed, 239 insertions(+), 108 deletions(-) diff -r 575ec0ce9e80 arch/i386/kernel/cpu/common.c --- a/arch/i386/kernel/cpu/common.c Mon Sep 25 23:29:45 2006 -0700 +++ b/arch/i386/kernel/cpu/common.c Mon Sep 25 23:30:45 2006 -0700 @@ -18,6 +18,7 @@ #include #include #endif +#include #include "cpu.h" @@ -26,6 +27,9 @@ EXPORT_PER_CPU_SYMBOL(cpu_gdt_descr); DEFINE_PER_CPU(unsigned char, cpu_16bit_stack[CPU_16BIT_STACK_SIZE]); EXPORT_PER_CPU_SYMBOL(cpu_16bit_stack); + +struct i386_pda *_cpu_pda[NR_CPUS] __read_mostly; +EXPORT_SYMBOL(_cpu_pda); static int cachesize_override __cpuinitdata = -1; static int disable_x86_fxsr __cpuinitdata; @@ -582,6 +586,184 @@ void __init early_cpu_init(void) disable_pse = 1; #endif } + +__cpuinit int alloc_gdt(int cpu) +{ + struct Xgt_desc_struct *cpu_gdt_descr = &per_cpu(cpu_gdt_descr, cpu); + struct desc_struct *gdt; + struct i386_pda *pda; + + gdt = (struct desc_struct *)cpu_gdt_descr->address; + pda = cpu_pda(cpu); + + /* + * This is a horrible hack to allocate the GDT. The problem + * is that cpu_init() is called really early for the boot CPU + * (and hence needs bootmem) but much later for the secondary + * CPUs, when bootmem will have gone away + */ + if (NODE_DATA(0)->bdata->node_bootmem_map) { + BUG_ON(gdt != NULL || pda != NULL); + + gdt = alloc_bootmem_pages(PAGE_SIZE); + pda = alloc_bootmem(sizeof(*pda)); + /* alloc_bootmem(_pages) panics on failure, so no check */ + + memset(gdt, 0, PAGE_SIZE); + memset(pda, 0, sizeof(*pda)); + } else { + /* GDT and PDA might already have been allocated if + this is a CPU hotplug re-insertion. */ + if (gdt == NULL) + gdt = (struct desc_struct *)get_zeroed_page(GFP_KERNEL); + + if (pda == NULL) + pda = kmalloc_node(sizeof(*pda), GFP_KERNEL, cpu_to_node(cpu)); + + if (unlikely(!gdt || !pda)) { + free_pages((unsigned long)gdt, 0); + kfree(pda); + return 0; + } + } + + cpu_gdt_descr->address = (unsigned long)gdt; + cpu_pda(cpu) = pda; + + return 1; +} + +/* Initial PDA used by boot CPU */ +struct i386_pda boot_pda = { + ._pda = &boot_pda, + .cpu_number = 0, + .pcurrent = &init_task, +}; + +/* Initialize the CPU's GDT and PDA. The boot CPU does this for + itself, but secondaries find this done for them. */ +__cpuinit int init_gdt(int cpu, struct task_struct *idle) +{ + struct Xgt_desc_struct *cpu_gdt_descr = &per_cpu(cpu_gdt_descr, cpu); + __u32 stk16_off = (__u32)&per_cpu(cpu_16bit_stack, cpu); + struct desc_struct *gdt; + struct i386_pda *pda; + + /* For non-boot CPUs, the GDT and PDA should already have been + allocated. */ + if (!alloc_gdt(cpu)) { + printk(KERN_CRIT "CPU%d failed to allocate GDT or PDA\n", cpu); + return 0; + } + + gdt = (struct desc_struct *)cpu_gdt_descr->address; + pda = cpu_pda(cpu); + + BUG_ON(gdt == NULL || pda == NULL); + + /* + * Initialize the per-CPU GDT with the boot GDT, + * and set up the GDT descriptor: + */ + memcpy(gdt, cpu_gdt_table, GDT_SIZE); + cpu_gdt_descr->size = GDT_SIZE - 1; + + /* Set up GDT entry for 16bit stack */ + *(__u64 *)(&gdt[GDT_ENTRY_ESPFIX_SS]) |= + ((((__u64)stk16_off) << 16) & 0x000000ffffff0000ULL) | + ((((__u64)stk16_off) << 32) & 0xff00000000000000ULL) | + (CPU_16BIT_STACK_SIZE - 1); + + pack_descriptor((u32 *)&gdt[GDT_ENTRY_PDA].a, + (u32 *)&gdt[GDT_ENTRY_PDA].b, + (unsigned long)pda, sizeof(*pda) - 1, + 0x80 | DESCTYPE_S | 0x2, 0); /* present read-write data segment */ + + memset(pda, 0, sizeof(*pda)); + pda->_pda = pda; + pda->cpu_number = cpu; + pda->pcurrent = idle; + + return 1; +} + +/* Common CPU init for both boot and secondary CPUs */ +static void __cpuinit _cpu_init(int cpu, struct task_struct *curr) +{ + struct tss_struct * t = &per_cpu(init_tss, cpu); + struct thread_struct *thread = &curr->thread; + struct Xgt_desc_struct *cpu_gdt_descr = &per_cpu(cpu_gdt_descr, cpu); + + /* Reinit these anyway, even if they've already been done (on + the boot CPU, this will transition from the boot gdt+pda to + the real ones). */ + load_gdt(cpu_gdt_descr); + + if (cpu_test_and_set(cpu, cpu_initialized)) { + printk(KERN_WARNING "CPU#%d already initialized!\n", cpu); + for (;;) local_irq_enable(); + } + + printk(KERN_INFO "Initializing CPU#%d\n", cpu); + + if (cpu_has_vme || cpu_has_tsc || cpu_has_de) + clear_in_cr4(X86_CR4_VME|X86_CR4_PVI|X86_CR4_TSD|X86_CR4_DE); + if (tsc_disable && cpu_has_tsc) { + printk(KERN_NOTICE "Disabling TSC...\n"); + /**** FIX-HPA: DOES THIS REALLY BELONG HERE? ****/ + clear_bit(X86_FEATURE_TSC, boot_cpu_data.x86_capability); + set_in_cr4(X86_CR4_TSD); + } + + load_idt(&idt_descr); + + /* + * Set up and load the per-CPU TSS and LDT + */ + atomic_inc(&init_mm.mm_count); + curr->active_mm = &init_mm; + if (curr->mm) + BUG(); + enter_lazy_tlb(&init_mm, curr); + + load_esp0(t, thread); + set_tss_desc(cpu,t); + load_TR_desc(); + load_LDT(&init_mm.context); + +#ifdef CONFIG_DOUBLEFAULT + /* Set up doublefault TSS pointer in the GDT */ + __set_tss_desc(cpu, GDT_ENTRY_DOUBLEFAULT_TSS, &doublefault_tss); +#endif + + /* Clear %fs and %gs. */ + asm volatile ("movl %0, %%fs; movl %0, %%gs" : : "r" (0)); + + /* Clear all 6 debug registers: */ + set_debugreg(0, 0); + set_debugreg(0, 1); + set_debugreg(0, 2); + set_debugreg(0, 3); + set_debugreg(0, 6); + set_debugreg(0, 7); + + /* + * Force FPU initialization: + */ + current_thread_info()->status = 0; + clear_used_math(); + mxcsr_feature_mask_init(); +} + +/* Entrypoint to initialize secondary CPU */ +void __cpuinit secondary_cpu_init(void) +{ + int cpu = smp_processor_id(); + struct task_struct *curr = current; + + _cpu_init(cpu, curr); +} + /* * cpu_init() initializes state that is per-CPU. Some data is already * initialized (naturally) in the bootstrap process, such as the GDT @@ -591,106 +773,17 @@ void __cpuinit cpu_init(void) void __cpuinit cpu_init(void) { int cpu = smp_processor_id(); - struct tss_struct * t = &per_cpu(init_tss, cpu); - struct thread_struct *thread = ¤t->thread; - struct desc_struct *gdt; - __u32 stk16_off = (__u32)&per_cpu(cpu_16bit_stack, cpu); - struct Xgt_desc_struct *cpu_gdt_descr = &per_cpu(cpu_gdt_descr, cpu); - - if (cpu_test_and_set(cpu, cpu_initialized)) { - printk(KERN_WARNING "CPU#%d already initialized!\n", cpu); - for (;;) local_irq_enable(); - } - printk(KERN_INFO "Initializing CPU#%d\n", cpu); - - if (cpu_has_vme || cpu_has_tsc || cpu_has_de) - clear_in_cr4(X86_CR4_VME|X86_CR4_PVI|X86_CR4_TSD|X86_CR4_DE); - if (tsc_disable && cpu_has_tsc) { - printk(KERN_NOTICE "Disabling TSC...\n"); - /**** FIX-HPA: DOES THIS REALLY BELONG HERE? ****/ - clear_bit(X86_FEATURE_TSC, boot_cpu_data.x86_capability); - set_in_cr4(X86_CR4_TSD); - } - - /* The CPU hotplug case */ - if (cpu_gdt_descr->address) { - gdt = (struct desc_struct *)cpu_gdt_descr->address; - memset(gdt, 0, PAGE_SIZE); - goto old_gdt; - } - /* - * This is a horrible hack to allocate the GDT. The problem - * is that cpu_init() is called really early for the boot CPU - * (and hence needs bootmem) but much later for the secondary - * CPUs, when bootmem will have gone away - */ - if (NODE_DATA(0)->bdata->node_bootmem_map) { - gdt = (struct desc_struct *)alloc_bootmem_pages(PAGE_SIZE); - /* alloc_bootmem_pages panics on failure, so no check */ - memset(gdt, 0, PAGE_SIZE); - } else { - gdt = (struct desc_struct *)get_zeroed_page(GFP_KERNEL); - if (unlikely(!gdt)) { - printk(KERN_CRIT "CPU%d failed to allocate GDT\n", cpu); - for (;;) - local_irq_enable(); - } - } -old_gdt: - /* - * Initialize the per-CPU GDT with the boot GDT, - * and set up the GDT descriptor: - */ - memcpy(gdt, cpu_gdt_table, GDT_SIZE); - - /* Set up GDT entry for 16bit stack */ - *(__u64 *)(&gdt[GDT_ENTRY_ESPFIX_SS]) |= - ((((__u64)stk16_off) << 16) & 0x000000ffffff0000ULL) | - ((((__u64)stk16_off) << 32) & 0xff00000000000000ULL) | - (CPU_16BIT_STACK_SIZE - 1); - - cpu_gdt_descr->size = GDT_SIZE - 1; - cpu_gdt_descr->address = (unsigned long)gdt; - - load_gdt(cpu_gdt_descr); - load_idt(&idt_descr); - - /* - * Set up and load the per-CPU TSS and LDT - */ - atomic_inc(&init_mm.mm_count); - current->active_mm = &init_mm; - if (current->mm) - BUG(); - enter_lazy_tlb(&init_mm, current); - - load_esp0(t, thread); - set_tss_desc(cpu,t); - load_TR_desc(); - load_LDT(&init_mm.context); - -#ifdef CONFIG_DOUBLEFAULT - /* Set up doublefault TSS pointer in the GDT */ - __set_tss_desc(cpu, GDT_ENTRY_DOUBLEFAULT_TSS, &doublefault_tss); -#endif - - /* Clear %fs and %gs. */ - asm volatile ("movl %0, %%fs; movl %0, %%gs" : : "r" (0)); - - /* Clear all 6 debug registers: */ - set_debugreg(0, 0); - set_debugreg(0, 1); - set_debugreg(0, 2); - set_debugreg(0, 3); - set_debugreg(0, 6); - set_debugreg(0, 7); - - /* - * Force FPU initialization: - */ - current_thread_info()->status = 0; - clear_used_math(); - mxcsr_feature_mask_init(); + struct task_struct *curr = current; + + /* Set up the real GDT and PDA, so we can transition from the + boot versions. */ + if (!init_gdt(cpu, curr)) { + /* failed to allocate something; not much we can do... */ + for (;;) + local_irq_enable(); + } + + _cpu_init(cpu, curr); } #ifdef CONFIG_HOTPLUG_CPU diff -r 575ec0ce9e80 arch/i386/kernel/smpboot.c --- a/arch/i386/kernel/smpboot.c Mon Sep 25 23:29:45 2006 -0700 +++ b/arch/i386/kernel/smpboot.c Mon Sep 25 23:29:47 2006 -0700 @@ -534,11 +534,11 @@ static void __devinit start_secondary(vo static void __devinit start_secondary(void *unused) { /* - * Dont put anything before smp_callin(), SMP + * Don't put *anything* before secondary_cpu_init(), SMP * booting is too fragile that we want to limit the * things done here to the most necessary things. */ - cpu_init(); + secondary_cpu_init(); preempt_disable(); smp_callin(); while (!cpu_isset(smp_processor_id(), smp_commenced_mask)) @@ -597,13 +597,16 @@ void __devinit initialize_secondary(void "movl %0,%%esp\n\t" "jmp *%1" : - :"r" (current->thread.esp),"r" (current->thread.eip)); -} - + :"m" (current->thread.esp),"m" (current->thread.eip)); +} + +/* Static state in head.S used to set up a CPU */ extern struct { void * esp; unsigned short ss; } stack_start; +extern struct i386_pda *start_pda; +extern struct Xgt_desc_struct cpu_gdt_descr; #ifdef CONFIG_NUMA @@ -929,9 +932,6 @@ static int __devinit do_boot_cpu(int api unsigned long start_eip; unsigned short nmi_high = 0, nmi_low = 0; - ++cpucount; - alternatives_smp_switch(1); - /* * We can't use kernel_thread since we must avoid to * reschedule the child. @@ -939,14 +939,29 @@ static int __devinit do_boot_cpu(int api idle = alloc_idle_task(cpu); if (IS_ERR(idle)) panic("failed fork for CPU %d", cpu); + + /* Pre-allocate and initialize the CPU's GDT and PDA so it + doesn't have to do any memory allocation during the + delicate CPU-bringup phase. */ + if (!init_gdt(cpu, idle)) { + printk(KERN_INFO "Couldn't allocate GDT/PDA for CPU %d\n", cpu); + return -1; /* ? */ + } + idle->thread.eip = (unsigned long) start_secondary; /* start_eip had better be page-aligned! */ start_eip = setup_trampoline(); + + ++cpucount; + alternatives_smp_switch(1); /* So we see what's up */ printk("Booting processor %d/%d eip %lx\n", cpu, apicid, start_eip); /* Stack for startup_32 can be just as for start_secondary onwards */ stack_start.esp = (void *) idle->thread.esp; + + start_pda = cpu_pda(cpu); + cpu_gdt_descr = per_cpu(cpu_gdt_descr, cpu); irq_ctx_init(cpu); diff -r 575ec0ce9e80 include/asm-i386/processor.h --- a/include/asm-i386/processor.h Mon Sep 25 23:29:45 2006 -0700 +++ b/include/asm-i386/processor.h Mon Sep 25 23:29:47 2006 -0700 @@ -731,4 +731,7 @@ extern void enable_sep_cpu(void); extern void enable_sep_cpu(void); extern int sysenter_setup(void); +extern int init_gdt(int cpu, struct task_struct *idle); +extern void secondary_cpu_init(void); + #endif /* __ASM_I386_PROCESSOR_H */