powerpc/32: enter syscall with MSR_EE inconditionaly set

syscalls are expected to be entered with MSR_EE set. Lets
make it inconditional by forcing MSR_EE on syscalls.

This patch adds EXC_XFER_SYS for that.
Suggested-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
[splited out from benh RFC patch]
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/kernel/head_32.S

@@ -375,7 +375,7 @@ END_FTR_SECTION_IFSET(CPU_FTR_FPU_UNAVAILABLE)
 	DO_KVM  0xc00
 SystemCall:
 	EXCEPTION_PROLOG
-	EXC_XFER_EE_LITE(0xc00, DoSyscall)
+	EXC_XFER_SYS(0xc00, DoSyscall)
 
 /* Single step - not used on 601 */
 	EXCEPTION(0xd00, SingleStep, single_step_exception, EXC_XFER_STD)

arch/powerpc/kernel/head_32.h

@@ -123,6 +123,10 @@
 	EXC_XFER_TEMPLATE(hdlr, n+1, MSR_KERNEL, NOCOPY, transfer_to_handler, \
 			  ret_from_except)
 
+#define EXC_XFER_SYS(n, hdlr)		\
+	EXC_XFER_TEMPLATE(hdlr, n+1, MSR_KERNEL | MSR_EE, NOCOPY, transfer_to_handler, \
+			  ret_from_except)
+
 #define EXC_XFER_EE(n, hdlr)		\
 	EXC_XFER_TEMPLATE(hdlr, n, MSR_KERNEL, COPY_EE, transfer_to_handler_full, \
 			  ret_from_except_full)

arch/powerpc/kernel/head_40x.S

@@ -350,7 +350,7 @@ _ENTRY(saved_ksp_limit)
 /* 0x0C00 - System Call Exception */
 	START_EXCEPTION(0x0C00,	SystemCall)
 	EXCEPTION_PROLOG
-	EXC_XFER_EE_LITE(0xc00, DoSyscall)
+	EXC_XFER_SYS(0xc00, DoSyscall)
 
 	EXCEPTION(0x0D00, Trap_0D, unknown_exception, EXC_XFER_EE)
 	EXCEPTION(0x0E00, Trap_0E, unknown_exception, EXC_XFER_EE)

arch/powerpc/kernel/head_44x.S

@@ -286,7 +286,7 @@ interrupt_base:
 	/* System Call Interrupt */
 	START_EXCEPTION(SystemCall)
 	NORMAL_EXCEPTION_PROLOG(BOOKE_INTERRUPT_SYSCALL)
-	EXC_XFER_EE_LITE(0x0c00, DoSyscall)
+	EXC_XFER_SYS(0x0c00, DoSyscall)
 
 	/* Auxiliary Processor Unavailable Interrupt */
 	EXCEPTION(0x2020, BOOKE_INTERRUPT_AP_UNAVAIL, \

arch/powerpc/kernel/head_8xx.S

@@ -186,7 +186,7 @@ Alignment:
 	. = 0xc00
 SystemCall:
 	EXCEPTION_PROLOG
-	EXC_XFER_EE_LITE(0xc00, DoSyscall)
+	EXC_XFER_SYS(0xc00, DoSyscall)
 
 /* Single step - not used on 601 */
 	EXCEPTION(0xd00, SingleStep, single_step_exception, EXC_XFER_STD)

arch/powerpc/kernel/head_booke.h

@@ -251,6 +251,10 @@ END_BTB_FLUSH_SECTION
 	EXC_XFER_TEMPLATE(hdlr, n+1, MSR_KERNEL, NOCOPY, transfer_to_handler, \
 			  ret_from_except)
 
+#define EXC_XFER_SYS(n, hdlr)						\
+	EXC_XFER_TEMPLATE(hdlr, n+1, MSR_KERNEL | MSR_EE, NOCOPY, transfer_to_handler, \
+			  ret_from_except)
+
 #define EXC_XFER_EE(n, hdlr)		\
 	EXC_XFER_TEMPLATE(hdlr, n, MSR_KERNEL, COPY_EE, transfer_to_handler_full, \
 			  ret_from_except_full)

arch/powerpc/kernel/head_fsl_booke.S

@@ -414,7 +414,7 @@ interrupt_base:
 	/* System Call Interrupt */
 	START_EXCEPTION(SystemCall)
 	NORMAL_EXCEPTION_PROLOG(SYSCALL)
-	EXC_XFER_EE_LITE(0x0c00, DoSyscall)
+	EXC_XFER_SYS(0x0c00, DoSyscall)
 
 	/* Auxiliary Processor Unavailable Interrupt */
 	EXCEPTION(0x2900, AP_UNAVAIL, AuxillaryProcessorUnavailable, \