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From: Zachary Amsden &lt;zach@vmware.com&gt;

Add an accessor function for getting the per-CPU gdt.  Callee must already
have the CPU.

Signed-off-by: Zachary Amsden &lt;zach@vmware.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@osdl.org&gt;
---

 arch/i386/kernel/apm.c                    |   40 ++++++++++++++++--------------
 arch/i386/kernel/cpu/common.c             |    9 +++---
 arch/i386/mm/fault.c                      |    2 -
 include/asm-i386/desc.h                   |    2 +
 include/asm-i386/mach-default/mach_desc.h |    6 ++--
 5 files changed, 32 insertions(+), 27 deletions(-)

diff -puN arch/i386/kernel/apm.c~i386--add-a-per-cpu-gdt-accessor arch/i386/kernel/apm.c
--- 25/arch/i386/kernel/apm.c~i386--add-a-per-cpu-gdt-accessor	Wed Aug 17 13:33:52 2005
+++ 25-akpm/arch/i386/kernel/apm.c	Wed Aug 17 13:33:52 2005
@@ -597,12 +597,14 @@ static u8 apm_bios_call(u32 func, u32 eb
 	cpumask_t		cpus;
 	int			cpu;
 	struct desc_struct	save_desc_40;
+	struct desc_struct	*gdt;
 
 	cpus = apm_save_cpus();
 	
 	cpu = get_cpu();
-	save_desc_40 = per_cpu(cpu_gdt_table, cpu)[0x40 / 8];
-	per_cpu(cpu_gdt_table, cpu)[0x40 / 8] = bad_bios_desc;
+	gdt = get_cpu_gdt_table(cpu);
+	save_desc_40 = gdt[segment_index(0x40)];
+	gdt[segment_index(0x40)] = bad_bios_desc;
 
 	local_save_flags(flags);
 	APM_DO_CLI;
@@ -610,7 +612,7 @@ static u8 apm_bios_call(u32 func, u32 eb
 	apm_bios_call_asm(func, ebx_in, ecx_in, eax, ebx, ecx, edx, esi);
 	APM_DO_RESTORE_SEGS;
 	local_irq_restore(flags);
-	per_cpu(cpu_gdt_table, cpu)[0x40 / 8] = save_desc_40;
+	gdt[segment_index(0x40)] = save_desc_40;
 	put_cpu();
 	apm_restore_cpus(cpus);
 	
@@ -639,13 +641,14 @@ static u8 apm_bios_call_simple(u32 func,
 	cpumask_t		cpus;
 	int			cpu;
 	struct desc_struct	save_desc_40;
-
+	struct desc_struct	*gdt;
 
 	cpus = apm_save_cpus();
 	
 	cpu = get_cpu();
-	save_desc_40 = per_cpu(cpu_gdt_table, cpu)[0x40 / 8];
-	per_cpu(cpu_gdt_table, cpu)[0x40 / 8] = bad_bios_desc;
+	gdt = get_cpu_gdt_table(cpu);
+	save_desc_40 = gdt[segment_index(0x40)];
+	gdt[segment_index(0x40)] = bad_bios_desc;
 
 	local_save_flags(flags);
 	APM_DO_CLI;
@@ -653,7 +656,7 @@ static u8 apm_bios_call_simple(u32 func,
 	error = apm_bios_call_simple_asm(func, ebx_in, ecx_in, eax);
 	APM_DO_RESTORE_SEGS;
 	local_irq_restore(flags);
-	__get_cpu_var(cpu_gdt_table)[0x40 / 8] = save_desc_40;
+	gdt[segment_index(0x40)] = save_desc_40;
 	put_cpu();
 	apm_restore_cpus(cpus);
 	return error;
@@ -2295,35 +2298,36 @@ static int __init apm_init(void)
 	apm_bios_entry.segment = APM_CS;
 
 	for (i = 0; i &lt; NR_CPUS; i++) {
-		set_base(per_cpu(cpu_gdt_table, i)[APM_CS &gt;&gt; 3],
+		struct desc_struct *gdt = get_cpu_gdt_table(i);
+		set_base(gdt[segment_index(APM_CS)],
 			 __va((unsigned long)apm_info.bios.cseg &lt;&lt; 4));
-		set_base(per_cpu(cpu_gdt_table, i)[APM_CS_16 &gt;&gt; 3],
+		set_base(gdt[segment_index(APM_CS_16)],
 			 __va((unsigned long)apm_info.bios.cseg_16 &lt;&lt; 4));
-		set_base(per_cpu(cpu_gdt_table, i)[APM_DS &gt;&gt; 3],
+		set_base(gdt[segment_index(APM_DS)],
 			 __va((unsigned long)apm_info.bios.dseg &lt;&lt; 4));
 #ifndef APM_RELAX_SEGMENTS
 		if (apm_info.bios.version == 0x100) {
 #endif
 			/* For ASUS motherboard, Award BIOS rev 110 (and others?) */
-			_set_limit((char *)&amp;per_cpu(cpu_gdt_table, i)[APM_CS &gt;&gt; 3], 64 * 1024 - 1);
+			_set_limit((char *)&amp;gdt[segment_index(APM_CS)], 64 * 1024 - 1);
 			/* For some unknown machine. */
-			_set_limit((char *)&amp;per_cpu(cpu_gdt_table, i)[APM_CS_16 &gt;&gt; 3], 64 * 1024 - 1);
+			_set_limit((char *)&amp;gdt[segment_index(APM_CS_16)], 64 * 1024 - 1);
 			/* For the DEC Hinote Ultra CT475 (and others?) */
-			_set_limit((char *)&amp;per_cpu(cpu_gdt_table, i)[APM_DS &gt;&gt; 3], 64 * 1024 - 1);
+			_set_limit((char *)&amp;gdt[segment_index(APM_DS)], 64 * 1024 - 1);
 #ifndef APM_RELAX_SEGMENTS
 		} else {
-			_set_limit((char *)&amp;per_cpu(cpu_gdt_table, i)[APM_CS &gt;&gt; 3],
+			_set_limit((char *)&amp;gdt[segment_index(APM_CS)],
 				(apm_info.bios.cseg_len - 1) &amp; 0xffff);
-			_set_limit((char *)&amp;per_cpu(cpu_gdt_table, i)[APM_CS_16 &gt;&gt; 3],
+			_set_limit((char *)&amp;gdt[segment_index(APM_CS_16)],
 				(apm_info.bios.cseg_16_len - 1) &amp; 0xffff);
-			_set_limit((char *)&amp;per_cpu(cpu_gdt_table, i)[APM_DS &gt;&gt; 3],
+			_set_limit((char *)&amp;gdt[segment_index(APM_DS)],
 				(apm_info.bios.dseg_len - 1) &amp; 0xffff);
 		      /* workaround for broken BIOSes */
 	                if (apm_info.bios.cseg_len &lt;= apm_info.bios.offset)
-        	                _set_limit((char *)&amp;per_cpu(cpu_gdt_table, i)[APM_CS &gt;&gt; 3], 64 * 1024 -1);
+        	                _set_limit((char *)&amp;gdt[segment_index(APM_CS)], 64 * 1024 -1);
                        if (apm_info.bios.dseg_len &lt;= 0x40) { /* 0x40 * 4kB == 64kB */
                         	/* for the BIOS that assumes granularity = 1 */
-                        	per_cpu(cpu_gdt_table, i)[APM_DS &gt;&gt; 3].b |= 0x800000;
+                        	gdt[segment_index(APM_DS)].b |= 0x800000;
                         	printk(KERN_NOTICE "apm: we set the granularity of dseg.\n");
         	        }
 		}
diff -puN arch/i386/kernel/cpu/common.c~i386--add-a-per-cpu-gdt-accessor arch/i386/kernel/cpu/common.c
--- 25/arch/i386/kernel/cpu/common.c~i386--add-a-per-cpu-gdt-accessor	Wed Aug 17 13:33:52 2005
+++ 25-akpm/arch/i386/kernel/cpu/common.c	Wed Aug 17 13:33:52 2005
@@ -573,6 +573,7 @@ void __devinit cpu_init(void)
 	int cpu = smp_processor_id();
 	struct tss_struct * t = &amp;per_cpu(init_tss, cpu);
 	struct thread_struct *thread = &amp;current-&gt;thread;
+	struct desc_struct *gdt = get_cpu_gdt_table(cpu);
 	__u32 stk16_off = (__u32)&amp;per_cpu(cpu_16bit_stack, cpu);
 
 	if (cpu_test_and_set(cpu, cpu_initialized)) {
@@ -594,18 +595,16 @@ void __devinit cpu_init(void)
 	 * Initialize the per-CPU GDT with the boot GDT,
 	 * and set up the GDT descriptor:
 	 */
-	memcpy(&amp;per_cpu(cpu_gdt_table, cpu), cpu_gdt_table,
-	       GDT_SIZE);
+ 	memcpy(gdt, cpu_gdt_table, GDT_SIZE);
 
 	/* Set up GDT entry for 16bit stack */
-	*(__u64 *)&amp;(per_cpu(cpu_gdt_table, cpu)[GDT_ENTRY_ESPFIX_SS]) |=
+ 	*(__u64 *)(&amp;gdt[GDT_ENTRY_ESPFIX_SS]) |=
 		((((__u64)stk16_off) &lt;&lt; 16) &amp; 0x000000ffffff0000ULL) |
 		((((__u64)stk16_off) &lt;&lt; 32) &amp; 0xff00000000000000ULL) |
 		(CPU_16BIT_STACK_SIZE - 1);
 
 	cpu_gdt_descr[cpu].size = GDT_SIZE - 1;
-	cpu_gdt_descr[cpu].address =
-	    (unsigned long)&amp;per_cpu(cpu_gdt_table, cpu);
+ 	cpu_gdt_descr[cpu].address = (unsigned long)gdt;
 
 	load_gdt(&amp;cpu_gdt_descr[cpu]);
 	load_idt(&amp;idt_descr);
diff -puN arch/i386/mm/fault.c~i386--add-a-per-cpu-gdt-accessor arch/i386/mm/fault.c
--- 25/arch/i386/mm/fault.c~i386--add-a-per-cpu-gdt-accessor	Wed Aug 17 13:33:52 2005
+++ 25-akpm/arch/i386/mm/fault.c	Wed Aug 17 13:33:52 2005
@@ -108,7 +108,7 @@ static inline unsigned long get_segment_
 		desc = (void *)desc + (seg &amp; ~7);
 	} else {
 		/* Must disable preemption while reading the GDT. */
-		desc = per_cpu(cpu_gdt_table, get_cpu());
+		desc = get_cpu_gdt_table(get_cpu());
 		desc = (void *)desc + (seg &amp; ~7);
 	}
 
diff -puN include/asm-i386/desc.h~i386--add-a-per-cpu-gdt-accessor include/asm-i386/desc.h
--- 25/include/asm-i386/desc.h~i386--add-a-per-cpu-gdt-accessor	Wed Aug 17 13:33:52 2005
+++ 25-akpm/include/asm-i386/desc.h	Wed Aug 17 13:33:52 2005
@@ -39,6 +39,8 @@ static inline unsigned long get_desc_lim
 extern struct desc_struct cpu_gdt_table[GDT_ENTRIES];
 DECLARE_PER_CPU(struct desc_struct, cpu_gdt_table[GDT_ENTRIES]);
 
+#define get_cpu_gdt_table(_cpu) (per_cpu(cpu_gdt_table, _cpu))
+
 DECLARE_PER_CPU(unsigned char, cpu_16bit_stack[CPU_16BIT_STACK_SIZE]);
 
 struct Xgt_desc_struct {
diff -puN include/asm-i386/mach-default/mach_desc.h~i386--add-a-per-cpu-gdt-accessor include/asm-i386/mach-default/mach_desc.h
--- 25/include/asm-i386/mach-default/mach_desc.h~i386--add-a-per-cpu-gdt-accessor	Wed Aug 17 13:33:52 2005
+++ 25-akpm/include/asm-i386/mach-default/mach_desc.h	Wed Aug 17 13:33:52 2005
@@ -53,13 +53,13 @@ static inline unsigned int get_LDT_desc(
 
 static inline void __set_tss_desc(unsigned int cpu, unsigned int entry, void *addr)
 {
-	_set_tssldt_desc(&amp;per_cpu(cpu_gdt_table, cpu)[entry], (int)addr,
+	_set_tssldt_desc(&amp;get_cpu_gdt_table(cpu)[entry], (int)addr,
 		offsetof(struct tss_struct, __cacheline_filler) - 1, 0x89);
 }
 
 static inline void set_ldt_desc(unsigned int cpu, void *addr, unsigned int size)
 {
-	_set_tssldt_desc(&amp;per_cpu(cpu_gdt_table, cpu)[GDT_ENTRY_LDT], (int)addr, ((size &lt;&lt; 3)-1), 0x82);
+	_set_tssldt_desc(&amp;get_cpu_gdt_table(cpu)[GDT_ENTRY_LDT], (int)addr, ((size &lt;&lt; 3)-1), 0x82);
 }
 
 static inline int write_ldt_entry(void *ldt, int entry, __u32 entry_a, __u32 entry_b)
@@ -72,7 +72,7 @@ static inline int write_ldt_entry(void *
 
 static inline void load_TLS(struct thread_struct *t, unsigned int cpu)
 {
-	memcpy(&amp;per_cpu(cpu_gdt_table, cpu)[GDT_ENTRY_TLS_MIN], t-&gt;tls_array, TLS_SIZE);
+	memcpy(&amp;get_cpu_gdt_table(cpu)[GDT_ENTRY_TLS_MIN], t-&gt;tls_array, TLS_SIZE);
 }
 
 #endif
_
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