[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/head.S b/arch/i386/kernel/head.S
index cb185f4..633fd2f 100644
--- a/arch/i386/kernel/head.S
+++ b/arch/i386/kernel/head.S
@@ -599,7 +599,7 @@
.word 0 # 32 bit align gdt_desc.address
ENTRY(early_gdt_descr)
.word GDT_ENTRIES*8-1
- .long cpu_gdt_table
+ .long per_cpu__cpu_gdt /* Overwritten for secondary CPUs */
/*
* The boot_gdt_table must mirror the equivalent in setup.S and is
@@ -610,56 +610,3 @@
.fill GDT_ENTRY_BOOT_CS,8,0
.quad 0x00cf9a000000ffff /* kernel 4GB code at 0x00000000 */
.quad 0x00cf92000000ffff /* kernel 4GB data at 0x00000000 */
-
-/*
- * The Global Descriptor Table contains 32 quadwords, per-CPU.
- */
- .align L1_CACHE_BYTES
-ENTRY(cpu_gdt_table)
- .quad 0x0000000000000000 /* NULL descriptor */
- .quad 0x0000000000000000 /* 0x0b reserved */
- .quad 0x0000000000000000 /* 0x13 reserved */
- .quad 0x0000000000000000 /* 0x1b reserved */
- .quad 0x0000000000000000 /* 0x20 unused */
- .quad 0x0000000000000000 /* 0x28 unused */
- .quad 0x0000000000000000 /* 0x33 TLS entry 1 */
- .quad 0x0000000000000000 /* 0x3b TLS entry 2 */
- .quad 0x0000000000000000 /* 0x43 TLS entry 3 */
- .quad 0x0000000000000000 /* 0x4b reserved */
- .quad 0x0000000000000000 /* 0x53 reserved */
- .quad 0x0000000000000000 /* 0x5b reserved */
-
- .quad 0x00cf9a000000ffff /* 0x60 kernel 4GB code at 0x00000000 */
- .quad 0x00cf92000000ffff /* 0x68 kernel 4GB data at 0x00000000 */
- .quad 0x00cffa000000ffff /* 0x73 user 4GB code at 0x00000000 */
- .quad 0x00cff2000000ffff /* 0x7b user 4GB data at 0x00000000 */
-
- .quad 0x0000000000000000 /* 0x80 TSS descriptor */
- .quad 0x0000000000000000 /* 0x88 LDT descriptor */
-
- /*
- * Segments used for calling PnP BIOS have byte granularity.
- * The code segments and data segments have fixed 64k limits,
- * the transfer segment sizes are set at run time.
- */
- .quad 0x00409a000000ffff /* 0x90 32-bit code */
- .quad 0x00009a000000ffff /* 0x98 16-bit code */
- .quad 0x000092000000ffff /* 0xa0 16-bit data */
- .quad 0x0000920000000000 /* 0xa8 16-bit data */
- .quad 0x0000920000000000 /* 0xb0 16-bit data */
-
- /*
- * The APM segments have byte granularity and their bases
- * are set at run time. All have 64k limits.
- */
- .quad 0x00409a000000ffff /* 0xb8 APM CS code */
- .quad 0x00009a000000ffff /* 0xc0 APM CS 16 code (16 bit) */
- .quad 0x004092000000ffff /* 0xc8 APM DS data */
-
- .quad 0x00c0920000000000 /* 0xd0 - ESPFIX SS */
- .quad 0x00cf92000000ffff /* 0xd8 - PDA */
- .quad 0x0000000000000000 /* 0xe0 - unused */
- .quad 0x0000000000000000 /* 0xe8 - unused */
- .quad 0x0000000000000000 /* 0xf0 - unused */
- .quad 0x0000000000000000 /* 0xf8 - GDT entry 31: double-fault TSS */
-