[PATCH] ARM: Remove global nwfpe register variable

Recent changes to nwfpe broke the build with some gcc versions:

In file included from arch/arm/nwfpe/softfloat.c:33:
arch/arm/nwfpe/fpa11.h:32: global register variable follows a function definition
make[1]: *** [arch/arm/nwfpe/softfloat.o] Error 1

Since we now ensure that the kernel stack is empty when returning
to user space, we can now access the userspace registers with
reference to the kernel stack using current_thread_info(), rather
than remembering the stack pointer at the time nwfpe was called.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

arch/arm/nwfpe/fpa11.h

@@ -29,9 +29,7 @@
  * stack+task struct.  Use the same method as 'current' uses to
  * reach them.
  */
-register unsigned long *user_registers asm("sl");
-
-#define GET_USERREG() (user_registers)
+#define GET_USERREG() ((struct pt_regs *)(THREAD_START_SP + (unsigned long)current_thread_info()) - 1)
 
 #include <linux/config.h>
 #include <linux/thread_info.h>

arch/arm/nwfpe/fpmodule.c

@@ -132,7 +132,7 @@ void float_raise(signed char flags)
 	printk(KERN_DEBUG
 	       "NWFPE: %s[%d] takes exception %08x at %p from %08lx\n",
 	       current->comm, current->pid, flags,
-	       __builtin_return_address(0), GET_USERREG()[15]);
+	       __builtin_return_address(0), GET_USERREG()->ARM_pc);
 #endif
 
 	/* Keep SoftFloat exception flags up to date.  */

arch/arm/nwfpe/fpmodule.inl

@@ -28,8 +28,8 @@ static inline unsigned long readRegister(const unsigned int nReg)
 	   for this in this routine.  LDF/STF instructions with Rn = PC
 	   depend on the PC being correct, as they use PC+8 in their
 	   address calculations. */
-	unsigned long *userRegisters = GET_USERREG();
-	unsigned int val = userRegisters[nReg];
+	struct pt_regs *regs = GET_USERREG();
+	unsigned int val = regs->uregs[nReg];
 	if (REG_PC == nReg)
 		val -= 4;
 	return val;
@@ -38,8 +38,8 @@ static inline unsigned long readRegister(const unsigned int nReg)
 static inline void
 writeRegister(const unsigned int nReg, const unsigned long val)
 {
-	unsigned long *userRegisters = GET_USERREG();
-	userRegisters[nReg] = val;
+	struct pt_regs *regs = GET_USERREG();
+	regs->uregs[nReg] = val;
 }
 
 static inline unsigned long readCPSR(void)
@@ -63,12 +63,12 @@ static inline unsigned long readConditionCodes(void)
 
 static inline void writeConditionCodes(const unsigned long val)
 {
-	unsigned long *userRegisters = GET_USERREG();
+	struct pt_regs *regs = GET_USERREG();
 	unsigned long rval;
 	/*
 	 * Operate directly on userRegisters since
 	 * the CPSR may be the PC register itself.
 	 */
-	rval = userRegisters[REG_CPSR] & ~CC_MASK;
-	userRegisters[REG_CPSR] = rval | (val & CC_MASK);
+	rval = regs->ARM_cpsr & ~CC_MASK;
+	regs->ARM_cpsr = rval | (val & CC_MASK);
 }