MIPS: Use memblock_phys_alloc() for exception vector

Allocate the exception vector using memblock_phys_alloc() which gives us
a physical address, rather than the previous convoluted setup which
obtained a virtual address using memblock_alloc(), converted it to a
physical address & then back to a virtual address.
Signed-off-by: Paul Burton <paul.burton@mips.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Serge Semin <fancer.lancer@gmail.com>
Tested-by: Serge Semin <fancer.lancer@gmail.com>
Cc: linux-mips@vger.kernel.org

arch/mips/kernel/traps.c

@@ -2292,9 +2292,8 @@ void __init trap_init(void)
 		unsigned long size = 0x200 + VECTORSPACING*64;
 		phys_addr_t ebase_pa;
 
-		ebase = (unsigned long)
-			memblock_alloc(size, 1 << fls(size));
-		if (!ebase)
+		ebase_pa = memblock_phys_alloc(size, 1 << fls(size));
+		if (!ebase_pa)
 			panic("%s: Failed to allocate %lu bytes align=0x%x\n",
 			      __func__, size, 1 << fls(size));
 
@@ -2309,9 +2308,10 @@ void __init trap_init(void)
 		 * EVA is special though as it allows segments to be rearranged
 		 * and to become uncached during cache error handling.
 		 */
-		ebase_pa = __pa(ebase);
 		if (!IS_ENABLED(CONFIG_EVA) && !WARN_ON(ebase_pa >= 0x20000000))
 			ebase = CKSEG0ADDR(ebase_pa);
+		else
+			ebase = (unsigned long)phys_to_virt(ebase_pa);
 	} else {
 		ebase = CAC_BASE;