From: James Bottomley Date: Fri, 24 Feb 2006 21:04:14 +0000 (-0800) Subject: [PATCH] x86: fix broken SMP boot sequence X-Git-Tag: v2.6.16-rc5~36 X-Git-Url: http://pilppa.com/gitweb/?a=commitdiff_plain;h=2b932f6cf052920fb3a6281499e08209b08f5086;p=linux-2.6-omap-h63xx.git [PATCH] x86: fix broken SMP boot sequence Recent GDT changes broke the SMP boot sequence if the booting CPU is numbered anything other than zero. There's also a subtle source of error in that the boot time CPU now uses cpu_gdt_table (which is actually the GDT for booting CPUs in head.S). This patch fixes both problems by making GDT descriptors themselves allocated from a per_cpu area and switching to them in cpu_init(), which now means that cpu_gdt_table is exclusively used for booting CPUs again. Signed-off-by: James Bottomley Cc: Zachary Amsden Cc: Matt Tolentino Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/arch/i386/kernel/cpu/common.c b/arch/i386/kernel/cpu/common.c index 7eb9213734a..4ecd4b326de 100644 --- a/arch/i386/kernel/cpu/common.c +++ b/arch/i386/kernel/cpu/common.c @@ -4,6 +4,7 @@ #include #include #include +#include #include #include #include @@ -18,6 +19,9 @@ #include "cpu.h" +DEFINE_PER_CPU(struct Xgt_desc_struct, cpu_gdt_descr); +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); @@ -571,8 +575,9 @@ void __devinit 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 = get_cpu_gdt_table(cpu); + 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); @@ -589,6 +594,25 @@ void __devinit cpu_init(void) set_in_cr4(X86_CR4_TSD); } + /* + * 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(); + } + } + /* * Initialize the per-CPU GDT with the boot GDT, * and set up the GDT descriptor: @@ -601,10 +625,10 @@ void __devinit cpu_init(void) ((((__u64)stk16_off) << 32) & 0xff00000000000000ULL) | (CPU_16BIT_STACK_SIZE - 1); - cpu_gdt_descr[cpu].size = GDT_SIZE - 1; - cpu_gdt_descr[cpu].address = (unsigned long)gdt; + cpu_gdt_descr->size = GDT_SIZE - 1; + cpu_gdt_descr->address = (unsigned long)gdt; - load_gdt(&cpu_gdt_descr[cpu]); + load_gdt(cpu_gdt_descr); load_idt(&idt_descr); /* diff --git a/arch/i386/kernel/efi.c b/arch/i386/kernel/efi.c index ecad519fd39..e3e42fd6240 100644 --- a/arch/i386/kernel/efi.c +++ b/arch/i386/kernel/efi.c @@ -103,17 +103,19 @@ static void efi_call_phys_prelog(void) */ local_flush_tlb(); - cpu_gdt_descr[0].address = __pa(cpu_gdt_descr[0].address); - load_gdt((struct Xgt_desc_struct *) __pa(&cpu_gdt_descr[0])); + per_cpu(cpu_gdt_descr, 0).address = + __pa(per_cpu(cpu_gdt_descr, 0).address); + load_gdt((struct Xgt_desc_struct *)__pa(&per_cpu(cpu_gdt_descr, 0))); } static void efi_call_phys_epilog(void) { unsigned long cr4; - cpu_gdt_descr[0].address = - (unsigned long) __va(cpu_gdt_descr[0].address); - load_gdt(&cpu_gdt_descr[0]); + per_cpu(cpu_gdt_descr, 0).address = + (unsigned long)__va(per_cpu(cpu_gdt_descr, 0).address); + load_gdt((struct Xgt_desc_struct *)__va(&per_cpu(cpu_gdt_descr, 0))); + cr4 = read_cr4(); if (cr4 & X86_CR4_PSE) { diff --git a/arch/i386/kernel/head.S b/arch/i386/kernel/head.S index 2bee6499edd..e0b7c632efb 100644 --- a/arch/i386/kernel/head.S +++ b/arch/i386/kernel/head.S @@ -534,5 +534,3 @@ ENTRY(cpu_gdt_table) .quad 0x0000000000000000 /* 0xf0 - unused */ .quad 0x0000000000000000 /* 0xf8 - GDT entry 31: double-fault TSS */ - /* Be sure this is zeroed to avoid false validations in Xen */ - .fill PAGE_SIZE_asm / 8 - GDT_ENTRIES,8,0 diff --git a/arch/i386/kernel/i386_ksyms.c b/arch/i386/kernel/i386_ksyms.c index 3999bec50c3..055325056a7 100644 --- a/arch/i386/kernel/i386_ksyms.c +++ b/arch/i386/kernel/i386_ksyms.c @@ -3,8 +3,6 @@ #include #include -EXPORT_SYMBOL_GPL(cpu_gdt_descr); - EXPORT_SYMBOL(__down_failed); EXPORT_SYMBOL(__down_failed_interruptible); EXPORT_SYMBOL(__down_failed_trylock); diff --git a/arch/i386/kernel/smpboot.c b/arch/i386/kernel/smpboot.c index fb00ab7b761..eba7f53f8b4 100644 --- a/arch/i386/kernel/smpboot.c +++ b/arch/i386/kernel/smpboot.c @@ -898,12 +898,6 @@ static int __devinit do_boot_cpu(int apicid, int cpu) unsigned long start_eip; unsigned short nmi_high = 0, nmi_low = 0; - if (!cpu_gdt_descr[cpu].address && - !(cpu_gdt_descr[cpu].address = get_zeroed_page(GFP_KERNEL))) { - printk("Failed to allocate GDT for CPU %d\n", cpu); - return 1; - } - ++cpucount; /* diff --git a/include/asm-i386/desc.h b/include/asm-i386/desc.h index 494e73bca09..89b8b82c82b 100644 --- a/include/asm-i386/desc.h +++ b/include/asm-i386/desc.h @@ -24,11 +24,13 @@ struct Xgt_desc_struct { unsigned short pad; } __attribute__ ((packed)); -extern struct Xgt_desc_struct idt_descr, cpu_gdt_descr[NR_CPUS]; +extern struct Xgt_desc_struct idt_descr; +DECLARE_PER_CPU(struct Xgt_desc_struct, cpu_gdt_descr); + static inline struct desc_struct *get_cpu_gdt_table(unsigned int cpu) { - return ((struct desc_struct *)cpu_gdt_descr[cpu].address); + return (struct desc_struct *)per_cpu(cpu_gdt_descr, cpu).address; } #define load_TR_desc() __asm__ __volatile__("ltr %w0"::"q" (GDT_ENTRY_TSS*8))