WARNING - OLD ARCHIVES

This is an archived copy of the Xen.org mailing list, which we have preserved to ensure that existing links to archives are not broken. The live archive, which contains the latest emails, can be found at http://lists.xen.org/
   
 
 
Xen 
 
Home Products Support Community News
 
   
 

xen-devel

[Xen-devel] [patch 1/5] i386-gdt-pda Page-align the GDT

To: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>, Andi Kleen <ak@xxxxxxx>
Subject: [Xen-devel] [patch 1/5] i386-gdt-pda Page-align the GDT
From: Jeremy Fitzhardinge <jeremy@xxxxxxxx>
Date: Mon, 26 Mar 2007 17:21:30 -0700
Cc: virtualization@xxxxxxxxxxxxxx, Rusty Russell <rusty@xxxxxxxxxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxx, Linux Kernel <linux-kernel@xxxxxxxxxxxxxxx>
Delivery-date: Mon, 26 Mar 2007 17:32:36 -0700
Envelope-to: www-data@xxxxxxxxxxxxxxxxxx
List-help: <mailto:xen-devel-request@lists.xensource.com?subject=help>
List-id: Xen developer discussion <xen-devel.lists.xensource.com>
List-post: <mailto:xen-devel@lists.xensource.com>
List-subscribe: <http://lists.xensource.com/cgi-bin/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=subscribe>
List-unsubscribe: <http://lists.xensource.com/cgi-bin/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=unsubscribe>
References: <20070327002129.240126099@xxxxxxxx>
Sender: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
User-agent: quilt/0.46-1
Xen wants a dedicated page for the GDT.  I believe VMI likes it too.
lguest, KVM and native don't care.

Simple transformation to page-aligned "struct gdt_page".

Signed-off-by: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
Acked-by: Jeremy Fitzhardinge <jeremy@xxxxxxxxxxxxx>

---
 arch/i386/kernel/cpu/common.c |    6 +++---
 arch/i386/kernel/entry.S      |    2 +-
 arch/i386/kernel/head.S       |    2 +-
 arch/i386/kernel/traps.c      |    2 +-
 include/asm-i386/desc.h       |    9 +++++++--
 5 files changed, 13 insertions(+), 8 deletions(-)

===================================================================
--- a/arch/i386/kernel/cpu/common.c
+++ b/arch/i386/kernel/cpu/common.c
@@ -22,7 +22,7 @@
 
 #include "cpu.h"
 
-DEFINE_PER_CPU(struct desc_struct, cpu_gdt[GDT_ENTRIES]) = {
+DEFINE_PER_CPU(struct gdt_page, gdt_page) = { .gdt = {
        [GDT_ENTRY_KERNEL_CS] = { 0x0000ffff, 0x00cf9a00 },
        [GDT_ENTRY_KERNEL_DS] = { 0x0000ffff, 0x00cf9200 },
        [GDT_ENTRY_DEFAULT_USER_CS] = { 0x0000ffff, 0x00cffa00 },
@@ -48,8 +48,8 @@ DEFINE_PER_CPU(struct desc_struct, cpu_g
 
        [GDT_ENTRY_ESPFIX_SS] = { 0x00000000, 0x00c09200 },
        [GDT_ENTRY_PDA] = { 0x00000000, 0x00c09200 }, /* set in setup_pda */
-};
-EXPORT_PER_CPU_SYMBOL_GPL(cpu_gdt);
+} };
+EXPORT_PER_CPU_SYMBOL_GPL(gdt_page);
 
 DEFINE_PER_CPU(struct i386_pda, _cpu_pda) = {
        ._pda = &per_cpu___cpu_pda,
===================================================================
--- a/arch/i386/kernel/entry.S
+++ b/arch/i386/kernel/entry.S
@@ -558,7 +558,7 @@ END(syscall_badsys)
 #define FIXUP_ESPFIX_STACK \
        /* since we are on a wrong stack, we cant make it a C code :( */ \
        movl %fs:PDA_cpu, %ebx; \
-       PER_CPU(cpu_gdt, %ebx); \
+       PER_CPU(gdt_page, %ebx); \
        GET_DESC_BASE(GDT_ENTRY_ESPFIX_SS, %ebx, %eax, %ax, %al, %ah); \
        addl %esp, %eax; \
        pushl $__KERNEL_DS; \
===================================================================
--- a/arch/i386/kernel/head.S
+++ b/arch/i386/kernel/head.S
@@ -599,7 +599,7 @@ idt_descr:
        .word 0                         # 32 bit align gdt_desc.address
 ENTRY(early_gdt_descr)
        .word GDT_ENTRIES*8-1
-       .long per_cpu__cpu_gdt          /* Overwritten for secondary CPUs */
+       .long per_cpu__gdt_page         /* Overwritten for secondary CPUs */
 
 /*
  * The boot_gdt_table must mirror the equivalent in setup.S and is
===================================================================
--- a/arch/i386/kernel/traps.c
+++ b/arch/i386/kernel/traps.c
@@ -1037,7 +1037,7 @@ fastcall unsigned long patch_espfix_desc
 fastcall unsigned long patch_espfix_desc(unsigned long uesp,
                                          unsigned long kesp)
 {
-       struct desc_struct *gdt = __get_cpu_var(cpu_gdt);
+       struct desc_struct *gdt = __get_cpu_var(gdt_page).gdt;
        unsigned long base = (kesp - uesp) & -THREAD_SIZE;
        unsigned long new_kesp = kesp - base;
        unsigned long lim_pages = (new_kesp | (THREAD_SIZE - 1)) >> PAGE_SHIFT;
===================================================================
--- a/include/asm-i386/desc.h
+++ b/include/asm-i386/desc.h
@@ -18,10 +18,15 @@ struct Xgt_desc_struct {
        unsigned short pad;
 } __attribute__ ((packed));
 
-DECLARE_PER_CPU(struct desc_struct, cpu_gdt[GDT_ENTRIES]);
+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(cpu_gdt, cpu);
+       return per_cpu(gdt_page, cpu).gdt;
 }
 
 extern struct Xgt_desc_struct idt_descr;

-- 


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel