lmb: prohibit allocations above ram_top even from same bank

There are platforms which set the value of ram_top based on certain
restrictions that the platform might have in accessing memory above
ram_top, even when the memory region is in the same DRAM bank. So,
even though the LMB allocator works as expected, when trying to
allocate memory above ram_top, prohibit this by marking all memory
above ram_top as reserved, even if the said memory region is from the
same bank.

Signed-off-by: Sughosh Ganu <sughosh.ganu@linaro.org>
Tested-by: Andreas Schwab <schwab@suse.de>
(cherry picked from commit 1a48b0be93)

lib/lmb.c

@@ -603,6 +603,7 @@ static __maybe_unused void lmb_reserve_common_spl(void)
 void lmb_add_memory(void)
 {
 	int i;
+	phys_addr_t bank_end;
 	phys_size_t size;
 	u64 ram_top = gd->ram_top;
 	struct bd_info *bd = gd->bd;
@@ -616,6 +617,8 @@ void lmb_add_memory(void)
 
 	for (i = 0; i < CONFIG_NR_DRAM_BANKS; i++) {
 		size = bd->bi_dram[i].size;
+		bank_end = bd->bi_dram[i].start + size;
+
 		if (size) {
 			lmb_add(bd->bi_dram[i].start, size);
 
@@ -627,6 +630,9 @@ void lmb_add_memory(void)
 			if (bd->bi_dram[i].start >= ram_top)
 				lmb_reserve_flags(bd->bi_dram[i].start, size,
 						  LMB_NOOVERWRITE);
+			else if (bank_end > ram_top)
+				lmb_reserve_flags(ram_top, bank_end - ram_top,
+						  LMB_NOOVERWRITE);
 		}
 	}
 }