[PATCH] i386-pda updates

[Jeremy Fitzhardinge]

Updates to i386-pda:

- fix typo
- add a self-pointer to the PDA, so that finding its
 linear address is easy
- add type checking to PDA write operations
- add byte-sized read/writes to the PDA

Signed-off-by: Jeremy Fitzhardinge <jeremy@xxxxxxxxxxxxx>

---
arch/i386/kernel/cpu/common.c |    4 +++-
include/asm-i386/pda.h        |   19 +++++++++++++++++++
2 files changed, 22 insertions(+), 1 deletion(-)

diff -r 69614542c834 arch/i386/kernel/cpu/common.c
--- a/arch/i386/kernel/cpu/common.c	Fri Sep 08 16:53:26 2006 -0700
+++ b/arch/i386/kernel/cpu/common.c	Sat Sep 09 00:19:48 2006 -0700
@@ -588,7 +588,7 @@ void __init early_cpu_init(void)
#endif
}

-/* Make sure %gs it initialized properly in idle threads */
+/* Make sure %gs is initialized properly in idle threads */
struct pt_regs * __devinit idle_regs(struct pt_regs *regs)
{
	memset(regs, 0, sizeof(struct pt_regs));
@@ -648,6 +648,8 @@ static __cpuinit void pda_init(int cpu, 

	memset(pda, 0, sizeof(*pda));

+	pda->_pda = pda;
+
	pda->cpu_number = cpu;
	pda->pcurrent = curr;

diff -r 69614542c834 include/asm-i386/pda.h
--- a/include/asm-i386/pda.h	Fri Sep 08 16:53:26 2006 -0700
+++ b/include/asm-i386/pda.h	Sat Sep 09 00:19:48 2006 -0700
@@ -3,6 +3,8 @@

struct i386_pda
{
+	struct i386_pda *_pda;		/* pointer to self */
+
	struct task_struct *pcurrent;	/* current process */
	int cpu_number;
};
@@ -20,7 +22,14 @@ 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)			\
@@ -41,6 +50,12 @@ extern struct i386_pda _proxy_pda;
	({								\
		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__)				\
@@ -57,6 +72,10 @@ extern struct i386_pda _proxy_pda;
		}							\
		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)

-
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