6 files changed, 24 insertions, 40 deletions
diff --git a/arch/arc/include/asm/entry.h b/arch/arc/include/asm/entry.h
index 2cf6aa08cfca..72a7ed47117a 100644
--- a/arch/arc/include/asm/entry.h
+++ b/arch/arc/include/asm/entry.h
@@ -102,6 +102,10 @@
 	POP	r2
 	POP	r1
 	POP	r0
+
+#ifdef CONFIG_ARC_CURR_IN_REG
+	ld	r25, [sp, 12]
+#endif
 .endm
 
 /*--------------------------------------------------------------
@@ -138,6 +142,7 @@
 	POP	r13
 .endm
 
+#define OFF_USER_R25_FROM_R24	(SZ_CALLEE_REGS + SZ_PT_REGS - 8)/4
 
 /*--------------------------------------------------------------
  * Collect User Mode callee regs as struct callee_regs - needed by
@@ -155,7 +160,7 @@
 
 #ifdef CONFIG_ARC_CURR_IN_REG
 	; Retrieve orig r25 and save it on stack
-	ld      r12, [r25, TASK_THREAD + THREAD_USER_R25]
+	ld.as   r12, [sp, OFF_USER_R25_FROM_R24]
 	st.a    r12, [sp, -4]
 #else
 	PUSH	r25
@@ -204,7 +209,7 @@
 
 #ifdef CONFIG_ARC_CURR_IN_REG
 	ld.ab   r12, [sp, 4]
-	st      r12, [r25, TASK_THREAD + THREAD_USER_R25]
+	st.as   r12, [sp, OFF_USER_R25_FROM_R24]
 #else
 	POP	r25
 #endif
@@ -218,13 +223,6 @@
 	add     sp, sp, SZ_CALLEE_REGS
 .endm
 
-/*--------------------------------------------------------------
- * Restore User mode r25 saved in task_struct->thread.user_r25
- *-------------------------------------------------------------*/
-.macro RESTORE_USER_R25
-	ld  r25, [r25, TASK_THREAD + THREAD_USER_R25]
-.endm
-
 /*-------------------------------------------------------------
  * given a tsk struct, get to the base of it's kernel mode stack
  * tsk->thread_info is really a PAGE, whose bottom hoists stack
@@ -297,22 +295,21 @@
 
 	GET_CURR_TASK_ON_CPU   r9
 
-#ifdef CONFIG_ARC_CURR_IN_REG
-
-	/* If current task pointer cached in r25, time to
-	 *  -safekeep USER r25 in task->thread_struct->user_r25
-	 *  -load r25 with current task ptr
-	 */
-	st.as	r25, [r9, (TASK_THREAD + THREAD_USER_R25)/4]
-	mov	r25, r9
-#endif
-
 	/* With current tsk in r9, get it's kernel mode stack base */
 	GET_TSK_STACK_BASE  r9, r9
 
 66:
+#ifdef CONFIG_ARC_CURR_IN_REG
+	/*
+	 * Treat r25 as scratch reg, save it on stack first
+	 * Load it with current task pointer
+	 */
+	st	r25, [r9, -4]
+	GET_CURR_TASK_ON_CPU   r25
+#endif
+
 	/* Save Pre Intr/Exception User SP on kernel stack */
-	st.a    sp, [r9, -12]	; Make room for orig_r0 and orig_r8
+	st.a    sp, [r9, -16]	; Make room for orig_r0, orig_r8, user_r25
 
 	/* CAUTION:
 	 * SP should be set at the very end when we are done with everything
@@ -466,7 +463,7 @@
 	RESTORE_R12_TO_R0
 
 	ld  sp, [sp] /* restore original sp */
-	/* orig_r0 and orig_r8 skipped automatically */
+	/* orig_r0, orig_r8, user_r25 skipped automatically */
 .endm
 
 
@@ -549,7 +546,7 @@
 	RESTORE_R12_TO_R0
 
 	ld  sp, [sp] /* restore original sp */
-	/* orig_r0 and orig_r8 skipped automatically */
+	/* orig_r0, orig_r8, user_r25 skipped automatically */
 .endm
 
 .macro RESTORE_ALL_INT2
@@ -568,7 +565,7 @@
 	RESTORE_R12_TO_R0
 
 	ld  sp, [sp] /* restore original sp */
-	/* orig_r0 and orig_r8 skipped automatically */
+	/* orig_r0, orig_r8, user_r25 skipped automatically */
 .endm
 
 
diff --git a/arch/arc/include/asm/processor.h b/arch/arc/include/asm/processor.h
index 8c77e623c4e5..b0b5d2d9b3d3 100644
--- a/arch/arc/include/asm/processor.h
+++ b/arch/arc/include/asm/processor.h
@@ -30,9 +30,6 @@ struct thread_struct {
 	unsigned long callee_reg;	/* pointer to callee regs */
 	unsigned long fault_address;	/* dbls as brkpt holder as well */
 	unsigned long cause_code;	/* Exception Cause Code (ECR) */
-#ifdef CONFIG_ARC_CURR_IN_REG
-	unsigned long user_r25;
-#endif
 #ifdef CONFIG_ARC_FPU_SAVE_RESTORE
 	struct arc_fpu fpu;
 #endif
diff --git a/arch/arc/include/asm/ptrace.h b/arch/arc/include/asm/ptrace.h
index 47801ba135b3..7b2de6f7025a 100644
--- a/arch/arc/include/asm/ptrace.h
+++ b/arch/arc/include/asm/ptrace.h
@@ -54,6 +54,8 @@ struct pt_regs {
 #endif
 		long orig_r8_word;
 	};
+
+	long user_r25;
 };
 
 /* Callee saved registers - need to be saved only when you are scheduled out */
diff --git a/arch/arc/kernel/asm-offsets.c b/arch/arc/kernel/asm-offsets.c
index fdcd76532b70..75f05b83d77d 100644
--- a/arch/arc/kernel/asm-offsets.c
+++ b/arch/arc/kernel/asm-offsets.c
@@ -24,9 +24,6 @@ int main(void)
 
 	DEFINE(THREAD_KSP, offsetof(struct thread_struct, ksp));
 	DEFINE(THREAD_CALLEE_REG, offsetof(struct thread_struct, callee_reg));
-#ifdef CONFIG_ARC_CURR_IN_REG
-	DEFINE(THREAD_USER_R25, offsetof(struct thread_struct, user_r25));
-#endif
 	DEFINE(THREAD_FAULT_ADDR,
 	       offsetof(struct thread_struct, fault_address));
 
@@ -61,5 +58,6 @@ int main(void)
 	DEFINE(PT_r7, offsetof(struct pt_regs, r7));
 
 	DEFINE(SZ_CALLEE_REGS, sizeof(struct callee_regs));
+	DEFINE(SZ_PT_REGS, sizeof(struct pt_regs));
 	return 0;
 }
diff --git a/arch/arc/kernel/entry.S b/arch/arc/kernel/entry.S
index 919e2f065d2f..fd5f9160bbd2 100644
--- a/arch/arc/kernel/entry.S
+++ b/arch/arc/kernel/entry.S
@@ -680,17 +680,6 @@ restore_regs :
 	; XXX can this be optimised out
 	IRQ_DISABLE_SAVE    r9, r10	;@r10 has prisitine (pre-disable) copy
 
-#ifdef CONFIG_ARC_CURR_IN_REG
-	; Restore User R25
-	; Earlier this used to be only for returning to user mode
-	; However with 2 levels of IRQ this can also happen even if
-	; in kernel mode
-	ld r9, [sp, PT_sp]
-	brhs r9, VMALLOC_START, 8f
-	RESTORE_USER_R25
-8:
-#endif
-
 	; Restore REG File. In case multiple Events outstanding,
 	; use the same priorty as rtie: EXCPN, L2 IRQ, L1 IRQ, None
 	; Note that we use realtime STATUS32 (not pt_regs->status32) to
diff --git a/arch/arc/kernel/process.c b/arch/arc/kernel/process.c
index c6e22e060578..a3cc6a577039 100644
--- a/arch/arc/kernel/process.c
+++ b/arch/arc/kernel/process.c
@@ -77,6 +77,7 @@ asmlinkage void ret_from_fork(void);
  * |      SP        |
  * |    orig_r0     |
  * |    orig_r8     |
+ * |    user_r25    |
  * ------------------  <===== END of PAGE
  */
 int copy_thread(unsigned long clone_flags,