MIPS: Consider value of c0_ebase when computing value of exception base.

It just so happens to be zero on all currently supported systems so this
hasn't bitten yet ...

[Ralf: Original patch from Cavium; handling of set_uncached_handler() and
de-ifdef'ed trap_init() implementation by me.]
Signed-off-by: NTomaso Paoletti <tpaoletti@caviumnetworks.com>
Signed-off-by: NDavid Daney <ddaney@caviumnetworks.com>
Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

arch/mips/kernel/traps.c

@@ -1555,6 +1555,8 @@ void __cpuinit set_uncached_handler(unsigned long offset, void *addr,
 #ifdef CONFIG_64BIT
 	unsigned long uncached_ebase = TO_UNCAC(ebase);
 #endif
+	if (cpu_has_mips_r2)
+		ebase += (read_c0_ebase() & 0x3ffff000);
 
 	if (!addr)
 		panic(panic_null_cerr);
@@ -1588,8 +1590,11 @@ void __init trap_init(void)
 
 	if (cpu_has_veic || cpu_has_vint)
 		ebase = (unsigned long) alloc_bootmem_low_pages(0x200 + VECTORSPACING*64);
-	else
+	else {
 		ebase = CAC_BASE;
+		if (cpu_has_mips_r2)
+			ebase += (read_c0_ebase() & 0x3ffff000);
+	}
 
 	per_cpu_trap_init();
 
@@ -1697,11 +1702,11 @@ void __init trap_init(void)
 
 	if (cpu_has_vce)
 		/* Special exception: R4[04]00 uses also the divec space. */
-		memcpy((void *)(CAC_BASE + 0x180), &except_vec3_r4000, 0x100);
+		memcpy((void *)(ebase + 0x180), &except_vec3_r4000, 0x100);
 	else if (cpu_has_4kex)
-		memcpy((void *)(CAC_BASE + 0x180), &except_vec3_generic, 0x80);
+		memcpy((void *)(ebase + 0x180), &except_vec3_generic, 0x80);
 	else
-		memcpy((void *)(CAC_BASE + 0x080), &except_vec3_generic, 0x80);
+		memcpy((void *)(ebase + 0x080), &except_vec3_generic, 0x80);
 
 	signal_init();
 #ifdef CONFIG_MIPS32_COMPAT