MIPS: microMIPS: Add support for exception handling.

All exceptions must be taken in microMIPS mode, never in classic
MIPS mode or the kernel falls apart. A few NOP instructions are
used to maintain the correct alignment of microMIPS versions of
the exception vectors.

Signed-off-by: Steven J. Hill <Steven.Hill@imgtec.com>

1 files changed, 21 insertions, 0 deletions

diff --git a/arch/mips/mm/tlbex.c b/arch/mips/mm/tlbex.c
index fb4ca9984ed1..0a68f2a4e690 100644
--- a/arch/mips/mm/tlbex.c
+++ b/arch/mips/mm/tlbex.c
@@ -2103,6 +2103,13 @@ static void __cpuinit build_r4000_tlb_load_handler(void)
 
         uasm_l_nopage_tlbl(&l, p);
         build_restore_work_registers(&p);
+#ifdef CONFIG_CPU_MICROMIPS
+        if ((unsigned long)tlb_do_page_fault_0 & 1) {
+                uasm_i_lui(&p, K0, uasm_rel_hi((long)tlb_do_page_fault_0));
+                uasm_i_addiu(&p, K0, K0, uasm_rel_lo((long)tlb_do_page_fault_0));
+                uasm_i_jr(&p, K0);
+        } else
+#endif
         uasm_i_j(&p, (unsigned long)tlb_do_page_fault_0 & 0x0fffffff);
         uasm_i_nop(&p);
 
@@ -2150,6 +2157,13 @@ static void __cpuinit build_r4000_tlb_store_handler(void)
 
         uasm_l_nopage_tlbs(&l, p);
         build_restore_work_registers(&p);
+#ifdef CONFIG_CPU_MICROMIPS
+        if ((unsigned long)tlb_do_page_fault_1 & 1) {
+                uasm_i_lui(&p, K0, uasm_rel_hi((long)tlb_do_page_fault_1));
+                uasm_i_addiu(&p, K0, K0, uasm_rel_lo((long)tlb_do_page_fault_1));
+                uasm_i_jr(&p, K0);
+        } else
+#endif
         uasm_i_j(&p, (unsigned long)tlb_do_page_fault_1 & 0x0fffffff);
         uasm_i_nop(&p);
 
@@ -2198,6 +2212,13 @@ static void __cpuinit build_r4000_tlb_modify_handler(void)
 
         uasm_l_nopage_tlbm(&l, p);
         build_restore_work_registers(&p);
+#ifdef CONFIG_CPU_MICROMIPS
+        if ((unsigned long)tlb_do_page_fault_1 & 1) {
+                uasm_i_lui(&p, K0, uasm_rel_hi((long)tlb_do_page_fault_1));
+                uasm_i_addiu(&p, K0, K0, uasm_rel_lo((long)tlb_do_page_fault_1));
+                uasm_i_jr(&p, K0);
+        } else
+#endif
         uasm_i_j(&p, (unsigned long)tlb_do_page_fault_1 & 0x0fffffff);
         uasm_i_nop(&p);