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Date: Mon, 9 Jun 2008 11:16:47 -0300
From: Glauber Costa <gcosta@...hat.com>
To: linux-kernel@...r.kernel.org
Cc: akpm@...ux-foundation.org, tglx@...utronix.de, mingo@...e.hu,
hugh@...itas.com
Subject: [PATCH 04/15] x86: move x86_64 gdt closer to i386
i386 and x86_64 used two different schemes for maintaining the gdt.
With this patch, x86_64 initial gdt table is defined in a .c file,
same way as i386 is now. Also, we call it "gdt_page", and the descriptor,
"early_gdt_descr". This way we achieve common naming, which can allow for
more code integration.
Signed-off-by: Glauber Costa <gcosta@...hat.com>
---
arch/x86/kernel/head_64.S | 48 ++++----------------------------------
arch/x86/kernel/setup64.c | 5 +---
arch/x86/kernel/setup_64.c | 27 +++++++++++++++++++++
arch/x86/kernel/smpboot.c | 10 +------
arch/x86/kernel/x8664_ksyms_64.c | 5 ----
include/asm-x86/desc.h | 24 ++++++++-----------
include/asm-x86/segment.h | 23 +++++++++--------
7 files changed, 57 insertions(+), 85 deletions(-)
diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S
index 4949c32..febeabb 100644
--- a/arch/x86/kernel/head_64.S
+++ b/arch/x86/kernel/head_64.S
@@ -203,7 +203,7 @@ ENTRY(secondary_startup_64)
* addresses where we're currently running on. We have to do that here
* because in 32bit we couldn't load a 64bit linear address.
*/
- lgdt cpu_gdt_descr(%rip)
+ lgdt early_gdt_descr(%rip)
/* set up data segments. actually 0 would do too */
movl $__KERNEL_DS,%eax
@@ -391,54 +391,16 @@ NEXT_PAGE(level2_spare_pgt)
.data
.align 16
- .globl cpu_gdt_descr
-cpu_gdt_descr:
- .word gdt_end-cpu_gdt_table-1
-gdt:
- .quad cpu_gdt_table
-#ifdef CONFIG_SMP
- .rept NR_CPUS-1
- .word 0
- .quad 0
- .endr
-#endif
+ .globl early_gdt_descr
+early_gdt_descr:
+ .word GDT_ENTRIES*8-1
+ .quad per_cpu__gdt_page
ENTRY(phys_base)
/* This must match the first entry in level2_kernel_pgt */
.quad 0x0000000000000000
-/* We need valid kernel segments for data and code in long mode too
- * IRET will check the segment types kkeil 2000/10/28
- * Also sysret mandates a special GDT layout
- */
-
- .section .data.page_aligned, "aw"
- .align PAGE_SIZE
-
-/* The TLS descriptors are currently at a different place compared to i386.
- Hopefully nobody expects them at a fixed place (Wine?) */
-ENTRY(cpu_gdt_table)
- .quad 0x0000000000000000 /* NULL descriptor */
- .quad 0x00cf9b000000ffff /* __KERNEL32_CS */
- .quad 0x00af9b000000ffff /* __KERNEL_CS */
- .quad 0x00cf93000000ffff /* __KERNEL_DS */
- .quad 0x00cffb000000ffff /* __USER32_CS */
- .quad 0x00cff3000000ffff /* __USER_DS, __USER32_DS */
- .quad 0x00affb000000ffff /* __USER_CS */
- .quad 0x0 /* unused */
- .quad 0,0 /* TSS */
- .quad 0,0 /* LDT */
- .quad 0,0,0 /* three TLS descriptors */
- .quad 0x0000f40000000000 /* node/CPU stored in limit */
-gdt_end:
- /* asm/segment.h:GDT_ENTRIES must match this */
- /* This should be a multiple of the cache line size */
- /* GDTs of other CPUs are now dynamically allocated */
-
- /* zero the remaining page */
- .fill PAGE_SIZE / 8 - GDT_ENTRIES,8,0
-
.section .bss, "aw", @nobits
.align L1_CACHE_BYTES
ENTRY(idt_table)
diff --git a/arch/x86/kernel/setup64.c b/arch/x86/kernel/setup64.c
index fc1a56d..70ff071 100644
--- a/arch/x86/kernel/setup64.c
+++ b/arch/x86/kernel/setup64.c
@@ -202,11 +202,8 @@ void __cpuinit cpu_init (void)
* Initialize the per-CPU GDT with the boot GDT,
* and set up the GDT descriptor:
*/
- if (cpu)
- memcpy(get_cpu_gdt_table(cpu), cpu_gdt_table, GDT_SIZE);
- cpu_gdt_descr[cpu].size = GDT_SIZE;
- load_gdt((const struct desc_ptr *)&cpu_gdt_descr[cpu]);
+ switch_to_new_gdt();
load_idt((const struct desc_ptr *)&idt_descr);
memset(me->thread.tls_array, 0, GDT_ENTRY_TLS_ENTRIES * 8);
diff --git a/arch/x86/kernel/setup_64.c b/arch/x86/kernel/setup_64.c
index 2aee441..c57223f 100644
--- a/arch/x86/kernel/setup_64.c
+++ b/arch/x86/kernel/setup_64.c
@@ -83,6 +83,22 @@
#define ARCH_SETUP
#endif
+/* We need valid kernel segments for data and code in long mode too
+ * IRET will check the segment types kkeil 2000/10/28
+ * Also sysret mandates a special GDT layout
+ */
+/* The TLS descriptors are currently at a different place compared to i386.
+ Hopefully nobody expects them at a fixed place (Wine?) */
+DEFINE_PER_CPU_PAGE_ALIGNED(struct gdt_page, gdt_page) = { .gdt = {
+ [GDT_ENTRY_KERNEL32_CS] = { { { 0x0000ffff, 0x00cf9b00 } } },
+ [GDT_ENTRY_KERNEL_CS] = { { { 0x0000ffff, 0x00af9b00 } } },
+ [GDT_ENTRY_KERNEL_DS] = { { { 0x0000ffff, 0x00cf9300 } } },
+ [GDT_ENTRY_DEFAULT_USER32_CS] = { { { 0x0000ffff, 0x00cffb00 } } },
+ [GDT_ENTRY_DEFAULT_USER_DS] = { { { 0x0000ffff, 0x00cff300 } } },
+ [GDT_ENTRY_DEFAULT_USER_CS] = { { { 0x0000ffff, 0x00affb00 } } },
+} };
+EXPORT_PER_CPU_SYMBOL_GPL(gdt_page);
+
/*
* Machine setup..
*/
@@ -273,6 +289,17 @@ void __attribute__((weak)) __init memory_setup(void)
machine_specific_memory_setup();
}
+/* Current gdt points %fs at the "master" per-cpu area: after this,
+ * it's on the real one. */
+void switch_to_new_gdt(void)
+{
+ struct desc_ptr gdt_descr;
+
+ gdt_descr.address = (long)get_cpu_gdt_table(smp_processor_id());
+ gdt_descr.size = GDT_SIZE - 1;
+ load_gdt(&gdt_descr);
+}
+
/*
* setup_arch - architecture-specific boot-time initializations
*
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 181b109..69639fd 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -849,14 +849,8 @@ static int __cpuinit do_boot_cpu(int apicid, int cpu)
.done = COMPLETION_INITIALIZER_ONSTACK(c_idle.done),
};
INIT_WORK(&c_idle.work, do_fork_idle);
-#ifdef CONFIG_X86_64
- /* allocate memory for gdts of secondary cpus. Hotplug is considered */
- if (!cpu_gdt_descr[cpu].address &&
- !(cpu_gdt_descr[cpu].address = get_zeroed_page(GFP_KERNEL))) {
- printk(KERN_ERR "Failed to allocate GDT for CPU %d\n", cpu);
- return -1;
- }
+#ifdef CONFIG_X86_64
/* Allocate node local memory for AP pdas */
if (cpu > 0) {
boot_error = get_local_pda(cpu);
@@ -1253,8 +1247,8 @@ void __init native_smp_prepare_boot_cpu(void)
int me = smp_processor_id();
#ifdef CONFIG_X86_32
init_gdt(me);
- switch_to_new_gdt();
#endif
+ switch_to_new_gdt();
/* already set me in cpu_online_map in boot_cpu_init() */
cpu_set(me, cpu_callout_map);
per_cpu(cpu_state, me) = CPU_ONLINE;
diff --git a/arch/x86/kernel/x8664_ksyms_64.c b/arch/x86/kernel/x8664_ksyms_64.c
index 122885b..16a6751 100644
--- a/arch/x86/kernel/x8664_ksyms_64.c
+++ b/arch/x86/kernel/x8664_ksyms_64.c
@@ -60,8 +60,3 @@ EXPORT_SYMBOL(init_level4_pgt);
EXPORT_SYMBOL(load_gs_index);
EXPORT_SYMBOL(_proxy_pda);
-
-#ifdef CONFIG_PARAVIRT
-/* Virtualized guests may want to use it */
-EXPORT_SYMBOL_GPL(cpu_gdt_descr);
-#endif
diff --git a/include/asm-x86/desc.h b/include/asm-x86/desc.h
index b3875d4..07f9f2b 100644
--- a/include/asm-x86/desc.h
+++ b/include/asm-x86/desc.h
@@ -29,11 +29,17 @@ static inline void fill_ldt(struct desc_struct *desc,
extern struct desc_ptr idt_descr;
extern gate_desc idt_table[];
+struct gdt_page {
+ struct desc_struct gdt[GDT_ENTRIES];
+} __attribute__((aligned(PAGE_SIZE)));
+DECLARE_PER_CPU(struct gdt_page, gdt_page);
+
+static inline struct desc_struct *get_cpu_gdt_table(unsigned int cpu)
+{
+ return per_cpu(gdt_page, cpu).gdt;
+}
+
#ifdef CONFIG_X86_64
-extern struct desc_struct cpu_gdt_table[GDT_ENTRIES];
-extern struct desc_ptr cpu_gdt_descr[];
-/* the cpu gdt accessor */
-#define get_cpu_gdt_table(x) ((struct desc_struct *)cpu_gdt_descr[x].address)
static inline void pack_gate(gate_desc *gate, unsigned type, unsigned long func,
unsigned dpl, unsigned ist, unsigned seg)
@@ -51,16 +57,6 @@ static inline void pack_gate(gate_desc *gate, unsigned type, unsigned long func,
}
#else
-struct gdt_page {
- struct desc_struct gdt[GDT_ENTRIES];
-} __attribute__((aligned(PAGE_SIZE)));
-DECLARE_PER_CPU(struct gdt_page, gdt_page);
-
-static inline struct desc_struct *get_cpu_gdt_table(unsigned int cpu)
-{
- return per_cpu(gdt_page, cpu).gdt;
-}
-
static inline void pack_gate(gate_desc *gate, unsigned char type,
unsigned long base, unsigned dpl, unsigned flags,
unsigned short seg)
diff --git a/include/asm-x86/segment.h b/include/asm-x86/segment.h
index ed5131d..dfc8601 100644
--- a/include/asm-x86/segment.h
+++ b/include/asm-x86/segment.h
@@ -61,18 +61,14 @@
#define GDT_ENTRY_TLS_MAX (GDT_ENTRY_TLS_MIN + GDT_ENTRY_TLS_ENTRIES - 1)
#define GDT_ENTRY_DEFAULT_USER_CS 14
-#define __USER_CS (GDT_ENTRY_DEFAULT_USER_CS * 8 + 3)
#define GDT_ENTRY_DEFAULT_USER_DS 15
-#define __USER_DS (GDT_ENTRY_DEFAULT_USER_DS * 8 + 3)
#define GDT_ENTRY_KERNEL_BASE 12
#define GDT_ENTRY_KERNEL_CS (GDT_ENTRY_KERNEL_BASE + 0)
-#define __KERNEL_CS (GDT_ENTRY_KERNEL_CS * 8)
#define GDT_ENTRY_KERNEL_DS (GDT_ENTRY_KERNEL_BASE + 1)
-#define __KERNEL_DS (GDT_ENTRY_KERNEL_DS * 8)
#define GDT_ENTRY_TSS (GDT_ENTRY_KERNEL_BASE + 4)
#define GDT_ENTRY_LDT (GDT_ENTRY_KERNEL_BASE + 5)
@@ -139,10 +135,11 @@
#else
#include <asm/cache.h>
-#define __KERNEL_CS 0x10
-#define __KERNEL_DS 0x18
+#define GDT_ENTRY_KERNEL32_CS 1
+#define GDT_ENTRY_KERNEL_CS 2
+#define GDT_ENTRY_KERNEL_DS 3
-#define __KERNEL32_CS 0x08
+#define __KERNEL32_CS (GDT_ENTRY_KERNEL32_CS * 8)
/*
* we cannot use the same code segment descriptor for user and kernel
@@ -150,10 +147,10 @@
* The segment offset needs to contain a RPL. Grr. -AK
* GDT layout to get 64bit syscall right (sysret hardcodes gdt offsets)
*/
-
-#define __USER32_CS 0x23 /* 4*8+3 */
-#define __USER_DS 0x2b /* 5*8+3 */
-#define __USER_CS 0x33 /* 6*8+3 */
+#define GDT_ENTRY_DEFAULT_USER32_CS 4
+#define GDT_ENTRY_DEFAULT_USER_DS 5
+#define GDT_ENTRY_DEFAULT_USER_CS 6
+#define __USER32_CS (GDT_ENTRY_DEFAULT_USER32_CS * 8 + 3)
#define __USER32_DS __USER_DS
#define GDT_ENTRY_TSS 8 /* needs two entries */
@@ -175,6 +172,10 @@
#endif
+#define __KERNEL_CS (GDT_ENTRY_KERNEL_CS * 8)
+#define __KERNEL_DS (GDT_ENTRY_KERNEL_DS * 8)
+#define __USER_DS (GDT_ENTRY_DEFAULT_USER_DS* 8 + 3)
+#define __USER_CS (GDT_ENTRY_DEFAULT_USER_CS* 8 + 3)
#ifndef CONFIG_PARAVIRT
#define get_kernel_rpl() 0
#endif
--
1.5.4.5
--
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