arch/tile: Save and restore extra user state for tilegx

During context switch, save and restore a couple of additional bits of
tilegx user state that can be persistently modified by userspace.

Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>

arch/tile/include/arch/chip_tile64.h

@@ -150,6 +150,9 @@
 /** Is the PROC_STATUS SPR supported? */
 #define CHIP_HAS_PROC_STATUS_SPR() 0
 
+/** Is the DSTREAM_PF SPR supported? */
+#define CHIP_HAS_DSTREAM_PF() 0
+
 /** Log of the number of mshims we have. */
 #define CHIP_LOG_NUM_MSHIMS() 2
 

arch/tile/include/arch/chip_tilepro.h

@@ -150,6 +150,9 @@
 /** Is the PROC_STATUS SPR supported? */
 #define CHIP_HAS_PROC_STATUS_SPR() 1
 
+/** Is the DSTREAM_PF SPR supported? */
+#define CHIP_HAS_DSTREAM_PF() 0
+
 /** Log of the number of mshims we have. */
 #define CHIP_LOG_NUM_MSHIMS() 2
 

arch/tile/include/asm/processor.h

@@ -103,6 +103,18 @@ struct thread_struct {
 	/* Any other miscellaneous processor state bits */
 	unsigned long proc_status;
 #endif
+#if !CHIP_HAS_FIXED_INTVEC_BASE()
+	/* Interrupt base for PL0 interrupts */
+	unsigned long interrupt_vector_base;
+#endif
+#if CHIP_HAS_TILE_RTF_HWM()
+	/* Tile cache retry fifo high-water mark */
+	unsigned long tile_rtf_hwm;
+#endif
+#if CHIP_HAS_DSTREAM_PF()
+	/* Data stream prefetch control */
+	unsigned long dstream_pf;
+#endif
 #ifdef CONFIG_HARDWALL
 	/* Is this task tied to an activated hardwall? */
 	struct hardwall_info *hardwall;

arch/tile/kernel/process.c

@@ -408,6 +408,15 @@ static void save_arch_state(struct thread_struct *t)
 #if CHIP_HAS_PROC_STATUS_SPR()
 	t->proc_status = __insn_mfspr(SPR_PROC_STATUS);
 #endif
+#if !CHIP_HAS_FIXED_INTVEC_BASE()
+	t->interrupt_vector_base = __insn_mfspr(SPR_INTERRUPT_VECTOR_BASE_0);
+#endif
+#if CHIP_HAS_TILE_RTF_HWM()
+	t->tile_rtf_hwm = __insn_mfspr(SPR_TILE_RTF_HWM);
+#endif
+#if CHIP_HAS_DSTREAM_PF()
+	t->dstream_pf = __insn_mfspr(SPR_DSTREAM_PF);
+#endif
 }
 
 static void restore_arch_state(const struct thread_struct *t)
@@ -428,14 +437,14 @@ static void restore_arch_state(const struct thread_struct *t)
 #if CHIP_HAS_PROC_STATUS_SPR()
 	__insn_mtspr(SPR_PROC_STATUS, t->proc_status);
 #endif
+#if !CHIP_HAS_FIXED_INTVEC_BASE()
+	__insn_mtspr(SPR_INTERRUPT_VECTOR_BASE_0, t->interrupt_vector_base);
+#endif
 #if CHIP_HAS_TILE_RTF_HWM()
-	/*
-	 * Clear this whenever we switch back to a process in case
-	 * the previous process was monkeying with it.  Even if enabled
-	 * in CBOX_MSR1 via TILE_RTF_HWM_MIN, it's still just a
-	 * performance hint, so isn't worth a full save/restore.
-	 */
-	__insn_mtspr(SPR_TILE_RTF_HWM, 0);
+	__insn_mtspr(SPR_TILE_RTF_HWM, t->tile_rtf_hwm);
+#endif
+#if CHIP_HAS_DSTREAM_PF()
+	__insn_mtspr(SPR_DSTREAM_PF, t->dstream_pf);
 #endif
 }