[PATCH] i386: Basic definitions for i386-pda
This patch has the basic definitions of struct i386_pda, and the segment
selector in the GDT.
asm-i386/pda.h is more or less a direct copy of asm-x86_64/pda.h. The most
interesting difference is the use of _proxy_pda, which is used to give gcc a
model for the actual memory operations on the real pda structure. No actual
reference is ever made to _proxy_pda, so it is never defined.
Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Chuck Ebbert <76306.1226@compuserve.com>
Cc: Zachary Amsden <zach@vmware.com>
Cc: Jan Beulich <jbeulich@novell.com>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
diff --git a/arch/i386/kernel/head.S b/arch/i386/kernel/head.S
index b1f1df1..4a83384 100644
--- a/arch/i386/kernel/head.S
+++ b/arch/i386/kernel/head.S
@@ -585,7 +585,7 @@
.quad 0x004092000000ffff /* 0xc8 APM DS data */
.quad 0x00c0920000000000 /* 0xd0 - ESPFIX SS */
- .quad 0x0000000000000000 /* 0xd8 - unused */
+ .quad 0x0000000000000000 /* 0xd8 - PDA */
.quad 0x0000000000000000 /* 0xe0 - unused */
.quad 0x0000000000000000 /* 0xe8 - unused */
.quad 0x0000000000000000 /* 0xf0 - unused */
diff --git a/include/asm-i386/pda.h b/include/asm-i386/pda.h
new file mode 100644
index 0000000..4c39ccb
--- /dev/null
+++ b/include/asm-i386/pda.h
@@ -0,0 +1,95 @@
+/*
+ Per-processor Data Areas
+ Jeremy Fitzhardinge <jeremy@goop.org> 2006
+ Based on asm-x86_64/pda.h by Andi Kleen.
+ */
+#ifndef _I386_PDA_H
+#define _I386_PDA_H
+
+#include <linux/stddef.h>
+
+struct i386_pda
+{
+ struct i386_pda *_pda; /* pointer to self */
+};
+
+extern struct i386_pda *_cpu_pda[];
+
+#define cpu_pda(i) (_cpu_pda[i])
+
+#define pda_offset(field) offsetof(struct i386_pda, field)
+
+extern void __bad_pda_field(void);
+
+/* This variable is never instantiated. It is only used as a stand-in
+ for the real per-cpu PDA memory, so that gcc can understand what
+ memory operations the inline asms() below are performing. This
+ eliminates the need to make the asms volatile or have memory
+ clobbers, so gcc can readily analyse them. */
+extern struct i386_pda _proxy_pda;
+
+#define pda_to_op(op,field,val) \
+ do { \
+ typedef typeof(_proxy_pda.field) T__; \
+ if (0) { T__ tmp__; tmp__ = (val); } \
+ switch (sizeof(_proxy_pda.field)) { \
+ case 1: \
+ asm(op "b %1,%%gs:%c2" \
+ : "+m" (_proxy_pda.field) \
+ :"ri" ((T__)val), \
+ "i"(pda_offset(field))); \
+ break; \
+ case 2: \
+ asm(op "w %1,%%gs:%c2" \
+ : "+m" (_proxy_pda.field) \
+ :"ri" ((T__)val), \
+ "i"(pda_offset(field))); \
+ break; \
+ case 4: \
+ asm(op "l %1,%%gs:%c2" \
+ : "+m" (_proxy_pda.field) \
+ :"ri" ((T__)val), \
+ "i"(pda_offset(field))); \
+ break; \
+ default: __bad_pda_field(); \
+ } \
+ } while (0)
+
+#define pda_from_op(op,field) \
+ ({ \
+ typeof(_proxy_pda.field) ret__; \
+ switch (sizeof(_proxy_pda.field)) { \
+ case 1: \
+ asm(op "b %%gs:%c1,%0" \
+ : "=r" (ret__) \
+ : "i" (pda_offset(field)), \
+ "m" (_proxy_pda.field)); \
+ break; \
+ case 2: \
+ asm(op "w %%gs:%c1,%0" \
+ : "=r" (ret__) \
+ : "i" (pda_offset(field)), \
+ "m" (_proxy_pda.field)); \
+ break; \
+ case 4: \
+ asm(op "l %%gs:%c1,%0" \
+ : "=r" (ret__) \
+ : "i" (pda_offset(field)), \
+ "m" (_proxy_pda.field)); \
+ break; \
+ default: __bad_pda_field(); \
+ } \
+ ret__; })
+
+/* Return a pointer to a pda field */
+#define pda_addr(field) \
+ ((typeof(_proxy_pda.field) *)((unsigned char *)read_pda(_pda) + \
+ pda_offset(field)))
+
+#define read_pda(field) pda_from_op("mov",field)
+#define write_pda(field,val) pda_to_op("mov",field,val)
+#define add_pda(field,val) pda_to_op("add",field,val)
+#define sub_pda(field,val) pda_to_op("sub",field,val)
+#define or_pda(field,val) pda_to_op("or",field,val)
+
+#endif /* _I386_PDA_H */
diff --git a/include/asm-i386/segment.h b/include/asm-i386/segment.h
index b7ab596..5bdda79 100644
--- a/include/asm-i386/segment.h
+++ b/include/asm-i386/segment.h
@@ -39,7 +39,7 @@
* 25 - APM BIOS support
*
* 26 - ESPFIX small SS
- * 27 - unused
+ * 27 - PDA [ per-cpu private data area ]
* 28 - unused
* 29 - unused
* 30 - unused
@@ -74,6 +74,9 @@
#define GDT_ENTRY_ESPFIX_SS (GDT_ENTRY_KERNEL_BASE + 14)
#define __ESPFIX_SS (GDT_ENTRY_ESPFIX_SS * 8)
+#define GDT_ENTRY_PDA (GDT_ENTRY_KERNEL_BASE + 15)
+#define __KERNEL_PDA (GDT_ENTRY_PDA * 8)
+
#define GDT_ENTRY_DOUBLEFAULT_TSS 31
/*