[MIPS] Enable support for the userlocal hardware register

Which will cut down the cost of RDHWR $29 which is used to obtain the
TLS pointer and so far being emulated in software down to a single cycle
operation.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 8 insertions, 1 deletions

diff --git a/arch/mips/kernel/traps.c b/arch/mips/kernel/traps.c
index c598e890a880..9b19a84d11ef 100644
--- a/arch/mips/kernel/traps.c
+++ b/arch/mips/kernel/traps.c
@@ -1341,7 +1341,14 @@ void __init per_cpu_trap_init(void)
                 set_c0_status(ST0_MX);
 
 #ifdef CONFIG_CPU_MIPSR2
-        write_c0_hwrena (0x0000000f); /* Allow rdhwr to all registers */
+        if (cpu_has_mips_r2) {
+                unsigned int enable = 0x0000000f;
+
+                if (cpu_has_userlocal)
+                        enable |= (1 << 29);
+
+                write_c0_hwrena(enable);
+        }
 #endif
 
 #ifdef CONFIG_MIPS_MT_SMTC