ARC: [plat-eznps] handle extra aux regs #2: kernel/entry exit

Preserve eflags and gpa1 aux during entry/exit into kernel as these
could be modified by kernel mode

These registers used by compare exchange instructions.
  - GPA1 is used for compare value,
  - EFLAGS got bit reflects atomic operation response.

EFLAGS is zeroed for each new user task so it won't get its
parent value.

Signed-off-by: Liav Rehana <liavr@mellanox.com>
Signed-off-by: Noam Camus <noamc@ezchip.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>

3 files changed, 33 insertions, 0 deletions

diff --git a/arch/arc/include/asm/entry-compact.h b/arch/arc/include/asm/entry-compact.h
index 14c310f2e0b1..ec36d5b6d435 100644
--- a/arch/arc/include/asm/entry-compact.h
+++ b/arch/arc/include/asm/entry-compact.h
@@ -192,6 +192,12 @@
         PUSHAX  lp_start
         PUSHAX  erbta
 
+#ifdef CONFIG_ARC_PLAT_EZNPS
+        .word CTOP_INST_SCHD_RW
+        PUSHAX  CTOP_AUX_GPA1
+        PUSHAX  CTOP_AUX_EFLAGS
+#endif
+
         lr      r9, [ecr]
         st      r9, [sp, PT_event]    /* EV_Trap expects r9 to have ECR */
 .endm
@@ -208,6 +214,12 @@
  * by hardware and that is not good.
  *-------------------------------------------------------------*/
 .macro EXCEPTION_EPILOGUE
+#ifdef CONFIG_ARC_PLAT_EZNPS
+        .word CTOP_INST_SCHD_RW
+        POPAX   CTOP_AUX_EFLAGS
+        POPAX   CTOP_AUX_GPA1
+#endif
+
         POPAX   erbta
         POPAX   lp_start
         POPAX   lp_end
@@ -265,6 +277,12 @@
         PUSHAX  lp_end
         PUSHAX  lp_start
         PUSHAX  bta_l\LVL\()
+
+#ifdef CONFIG_ARC_PLAT_EZNPS
+        .word CTOP_INST_SCHD_RW
+        PUSHAX  CTOP_AUX_GPA1
+        PUSHAX  CTOP_AUX_EFLAGS
+#endif
 .endm
 
 /*--------------------------------------------------------------
@@ -277,6 +295,12 @@
  * by hardware and that is not good.
  *-------------------------------------------------------------*/
 .macro INTERRUPT_EPILOGUE  LVL
+#ifdef CONFIG_ARC_PLAT_EZNPS
+        .word CTOP_INST_SCHD_RW
+        POPAX   CTOP_AUX_EFLAGS
+        POPAX   CTOP_AUX_GPA1
+#endif
+
         POPAX   bta_l\LVL\()
         POPAX   lp_start
         POPAX   lp_end
diff --git a/arch/arc/include/asm/ptrace.h b/arch/arc/include/asm/ptrace.h
index 5297faa8a378..5a8cb22724a1 100644
--- a/arch/arc/include/asm/ptrace.h
+++ b/arch/arc/include/asm/ptrace.h
@@ -19,6 +19,11 @@
 #ifdef CONFIG_ISA_ARCOMPACT
 struct pt_regs {
 
+#ifdef CONFIG_ARC_PLAT_EZNPS
+        unsigned long eflags;   /* Extended FLAGS */
+        unsigned long gpa1;     /* General Purpose Aux */
+#endif
+
         /* Real registers */
         unsigned long bta;      /* bta_l1, bta_l2, erbta */
 
diff --git a/arch/arc/kernel/process.c b/arch/arc/kernel/process.c
index 5c631a111240..5ac3b547453f 100644
--- a/arch/arc/kernel/process.c
+++ b/arch/arc/kernel/process.c
@@ -234,6 +234,10 @@ void start_thread(struct pt_regs * regs, unsigned long pc, unsigned long usp)
          */
         regs->status32 = STATUS_U_MASK | STATUS_L_MASK | ISA_INIT_STATUS_BITS;
 
+#ifdef CONFIG_EZNPS_MTM_EXT
+        regs->eflags = 0;
+#endif
+
         /* bogus seed values for debugging */
         regs->lp_start = 0x10;
         regs->lp_end = 0x80;