MIPS n64 support - support kstack in XKSEG.

- enable KX on entry from user-space, we need KX set to save to XKSEG
  addresses.
- add MIPS_XKSEG_START to genassym.c
- Add n64 case for swth.S

3 files changed, 19 insertions, 4 deletions

diff --git a/sys/mips/mips/exception.S b/sys/mips/mips/exception.S
index 7cc4059..3be0d4b 100644
--- a/sys/mips/mips/exception.S
+++ b/sys/mips/mips/exception.S
@@ -426,6 +426,12 @@ NNON_LEAF(MipsUserGenException, CALLFRAME_SIZ, ra)
 /*
  * Save all of the registers except for the kernel temporaries in u.u_pcb.
  */
+	mfc0	k0, MIPS_COP_0_STATUS
+	HAZARD_DELAY
+#ifdef __mips_n64
+	ori	k1, k0, MIPS_SR_KX
+	mtc0	k1, MIPS_COP_0_STATUS
+#endif
 	GET_CPU_PCPU(k1)
 	PTR_L	k1, PC_CURPCB(k1)
 	SAVE_U_PCB_REG(AT, AST, k1)
@@ -443,7 +449,7 @@ NNON_LEAF(MipsUserGenException, CALLFRAME_SIZ, ra)
 	SAVE_U_PCB_REG(t2, T2, k1)
 	SAVE_U_PCB_REG(t3, T3, k1)
 	SAVE_U_PCB_REG(ta0, TA0, k1)
-	mfc0	a0, MIPS_COP_0_STATUS		# First arg is the status reg.
+	move	a0, k0				# First arg is the status reg.
 	SAVE_U_PCB_REG(ta1, TA1, k1)
 	SAVE_U_PCB_REG(ta2, TA2, k1)
 	SAVE_U_PCB_REG(ta3, TA3, k1)
@@ -642,6 +648,12 @@ NNON_LEAF(MipsUserIntr, CALLFRAME_SIZ, ra)
  * Save the relevant user registers into the u.u_pcb struct.
  * We don't need to save s0 - s8 because the compiler does it for us.
  */
+	mfc0	k0, MIPS_COP_0_STATUS
+	HAZARD_DELAY
+#ifdef __mips_n64
+	ori	k1, k0, MIPS_SR_KX
+	mtc0	k1, MIPS_COP_0_STATUS
+#endif
 	GET_CPU_PCPU(k1)
 	PTR_L	k1, PC_CURPCB(k1)
 	SAVE_U_PCB_REG(AT, AST, k1)
@@ -680,7 +692,7 @@ NNON_LEAF(MipsUserIntr, CALLFRAME_SIZ, ra)
 
 	mflo	v0			# get lo/hi late to avoid stall
 	mfhi	v1
-	mfc0	a0, MIPS_COP_0_STATUS
+	move	a0, k0
 	mfc0	a1, MIPS_COP_0_CAUSE
 	MFC0	a3, MIPS_COP_0_EXC_PC
 	SAVE_U_PCB_REG(v0, MULLO, k1)
diff --git a/sys/mips/mips/genassym.c b/sys/mips/mips/genassym.c
index 53f962b..8a5cbf3 100644
--- a/sys/mips/mips/genassym.c
+++ b/sys/mips/mips/genassym.c
@@ -103,3 +103,4 @@ ASSYM(MAXCOMLEN, MAXCOMLEN);
 ASSYM(MIPS_KSEG0_START, MIPS_KSEG0_START);
 ASSYM(MIPS_KSEG1_START, MIPS_KSEG1_START);
 ASSYM(MIPS_KSEG2_START, MIPS_KSEG2_START);
+ASSYM(MIPS_XKSEG_START, MIPS_XKSEG_START);
diff --git a/sys/mips/mips/swtch.S b/sys/mips/mips/swtch.S
index b6412db..9e1f39d 100644
--- a/sys/mips/mips/swtch.S
+++ b/sys/mips/mips/swtch.S
@@ -278,10 +278,12 @@ blocked_loop:
 	PTR_L	a2, TD_PCB(a1)
 	PTR_S	a2, PC_CURPCB(a3)
 	PTR_L	v0, TD_KSTACK(a1)
-#if !defined(__mips_n64)
+#if defined(__mips_n64)
+	PTR_LI	s0, MIPS_XKSEG_START
+#else
 	PTR_LI	s0, MIPS_KSEG2_START		# If Uarea addr is below kseg2,
-	bltu	v0, s0, sw2			# no need to insert in TLB.
 #endif
+	bltu	v0, s0, sw2			# no need to insert in TLB.
 	lw	a1, TD_UPTE + 0(s7)		# a1 = u. pte #0
 	lw	a2, TD_UPTE + 4(s7)		# a2 = u. pte #1
 /*