From bf50467204b435421d8de33ad080fa46c6f3d50b Mon Sep 17 00:00:00 2001 From: Rusty Russell Date: Wed, 2 May 2007 19:27:10 +0200 Subject: [PATCH] i386: Use per-cpu GDT immediately upon boot Now we are no longer dynamically allocating the GDT, we don't need the "cpu_gdt_table" at all: we can switch straight from "boot_gdt_table" to the per-cpu GDT. This means initializing the cpu_gdt array in C. The boot CPU uses the per-cpu var directly, then in smp_prepare_cpus() it switches to the per-cpu copy just allocated. For secondary CPUs, the early_gdt_descr is set to point directly to their per-cpu copy. For UP the code is very simple: it keeps using the "per-cpu" GDT as per SMP, but we never have to move. Signed-off-by: Rusty Russell Signed-off-by: Andi Kleen Cc: Andi Kleen Signed-off-by: Andrew Morton --- arch/i386/kernel/cpu/common.c | 72 ++++++++++++++++--------------------------- 1 file changed, 27 insertions(+), 45 deletions(-) (limited to 'arch/i386/kernel/cpu') diff --git a/arch/i386/kernel/cpu/common.c b/arch/i386/kernel/cpu/common.c index 2335f4464ead..fd6b079f7609 100644 --- a/arch/i386/kernel/cpu/common.c +++ b/arch/i386/kernel/cpu/common.c @@ -25,7 +25,33 @@ DEFINE_PER_CPU(struct Xgt_desc_struct, cpu_gdt_descr); EXPORT_PER_CPU_SYMBOL(cpu_gdt_descr); -DEFINE_PER_CPU(struct desc_struct, cpu_gdt[GDT_ENTRIES]); +DEFINE_PER_CPU(struct desc_struct, cpu_gdt[GDT_ENTRIES]) = { + [GDT_ENTRY_KERNEL_CS] = { 0x0000ffff, 0x00cf9a00 }, + [GDT_ENTRY_KERNEL_DS] = { 0x0000ffff, 0x00cf9200 }, + [GDT_ENTRY_DEFAULT_USER_CS] = { 0x0000ffff, 0x00cffa00 }, + [GDT_ENTRY_DEFAULT_USER_DS] = { 0x0000ffff, 0x00cff200 }, + /* + * Segments used for calling PnP BIOS have byte granularity. + * They code segments and data segments have fixed 64k limits, + * the transfer segment sizes are set at run time. + */ + [GDT_ENTRY_PNPBIOS_CS32] = { 0x0000ffff, 0x00409a00 },/* 32-bit code */ + [GDT_ENTRY_PNPBIOS_CS16] = { 0x0000ffff, 0x00009a00 },/* 16-bit code */ + [GDT_ENTRY_PNPBIOS_DS] = { 0x0000ffff, 0x00009200 }, /* 16-bit data */ + [GDT_ENTRY_PNPBIOS_TS1] = { 0x00000000, 0x00009200 },/* 16-bit data */ + [GDT_ENTRY_PNPBIOS_TS2] = { 0x00000000, 0x00009200 },/* 16-bit data */ + /* + * The APM segments have byte granularity and their bases + * are set at run time. All have 64k limits. + */ + [GDT_ENTRY_APMBIOS_BASE] = { 0x0000ffff, 0x00409a00 },/* 32-bit code */ + /* 16-bit code */ + [GDT_ENTRY_APMBIOS_BASE+1] = { 0x0000ffff, 0x00009a00 }, + [GDT_ENTRY_APMBIOS_BASE+2] = { 0x0000ffff, 0x00409200 }, /* data */ + + [GDT_ENTRY_ESPFIX_SS] = { 0x00000000, 0x00c09200 }, + [GDT_ENTRY_PDA] = { 0x00000000, 0x00c09200 }, /* set in setup_pda */ +}; DEFINE_PER_CPU(struct i386_pda, _cpu_pda); EXPORT_PER_CPU_SYMBOL(_cpu_pda); @@ -618,46 +644,6 @@ struct i386_pda boot_pda = { .pcurrent = &init_task, }; -static inline void set_kernel_fs(void) -{ - /* Set %fs for this CPU's PDA. Memory clobber is to create a - barrier with respect to any PDA operations, so the compiler - doesn't move any before here. */ - asm volatile ("mov %0, %%fs" : : "r" (__KERNEL_PDA) : "memory"); -} - -/* Initialize the CPU's GDT and PDA. This is either the boot CPU doing itself - (still using cpu_gdt_table), or a CPU doing it for a secondary which - will soon come up. */ -__cpuinit void init_gdt(int cpu, struct task_struct *idle) -{ - struct Xgt_desc_struct *cpu_gdt_descr = &per_cpu(cpu_gdt_descr, cpu); - struct desc_struct *gdt = per_cpu(cpu_gdt, cpu); - struct i386_pda *pda = &per_cpu(_cpu_pda, cpu); - - memcpy(gdt, cpu_gdt_table, GDT_SIZE); - cpu_gdt_descr->address = (unsigned long)gdt; - cpu_gdt_descr->size = GDT_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; -} - -void __cpuinit cpu_set_gdt(int cpu) -{ - struct Xgt_desc_struct *cpu_gdt_descr = &per_cpu(cpu_gdt_descr, cpu); - - load_gdt(cpu_gdt_descr); - set_kernel_fs(); -} - /* Common CPU init for both boot and secondary CPUs */ static void __cpuinit _cpu_init(int cpu, struct task_struct *curr) { @@ -740,10 +726,6 @@ void __cpuinit cpu_init(void) int cpu = smp_processor_id(); struct task_struct *curr = current; - /* Set up the real GDT and PDA, so we can transition from the - boot_gdt_table & boot_pda. */ - init_gdt(cpu, curr); - cpu_set_gdt(cpu); _cpu_init(cpu, curr); } -- cgit v1.2.1