[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 <rusty@rustcorp.com.au>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
diff --git a/arch/i386/kernel/cpu/common.c b/arch/i386/kernel/cpu/common.c
index 2335f44..fd6b079 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 @@
.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 @@
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);
}