MIPS: Malta: Detect and fix bad memsize values

commit f7f8aea4 upstream.

memsize denotes the amount of RAM we can access from kseg{0,1} and
that should be up to 256M. In case the bootloader reports a value
higher than that (perhaps reporting all the available RAM) it's best
if we fix it ourselves and just warn the user about that. This is
usually a problem with the bootloader and/or its environment.

[ralf@linux-mips.org: Remove useless parens as suggested bei Sergei.
Reformat long pr_warn statement to fit into 80 column limit.]
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9362/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

arch/mips/mti-malta/malta-memory.c

@@ -53,6 +53,12 @@ fw_memblock_t * __init fw_getmdesc(int eva)
 		pr_warn("memsize not set in YAMON, set to default (32Mb)\n");
 		physical_memsize = 0x02000000;
 	} else {
+		if (memsize > (256 << 20)) { /* memsize should be capped to 256M */
+			pr_warn("Unsupported memsize value (0x%lx) detected! "
+				"Using 0x10000000 (256M) instead\n",
+				memsize);
+			memsize = 256 << 20;
+		}
 		/* If ememsize is set, then set physical_memsize to that */
 		physical_memsize = ememsize ? : memsize;
 	}