[U-Boot] [PATCH 1/1] x86: efi_loader: Fix invalid address return from efi_alloc()

[Park, Aiden]

This issue can be seen on 32bit operation when one of E820_RAM type
entries is greater than 4GB memory space.

The efi_alloc() finds a free memory in the conventional memory which
is greater than 4GB. But, it does type cast to 32bit address space
and eventually returns invalid address.

Signed-off-by: Aiden Park <aiden.park at intel.com>
---
 arch/x86/lib/e820.c | 22 +++++++++++++++++++++-
 1 file changed, 21 insertions(+), 1 deletion(-)

diff --git a/arch/x86/lib/e820.c b/arch/x86/lib/e820.c
index d6ae2c4e9d..3e93931231 100644
--- a/arch/x86/lib/e820.c
+++ b/arch/x86/lib/e820.c
@@ -41,11 +41,15 @@ void efi_add_known_memory(void)
 {
 	struct e820_entry e820[E820MAX];
 	unsigned int i, num;
-	u64 start, pages;
+	u64 start, pages, ram_top;
 	int type;
 
 	num = install_e820_map(ARRAY_SIZE(e820), e820);
 
+	ram_top = (u64)gd->ram_top & ~EFI_PAGE_MASK;
+	if (!ram_top)
+		ram_top = 0x100000000ULL;
+
 	for (i = 0; i < num; ++i) {
 		start = e820[i].addr;
 		pages = ALIGN(e820[i].size, EFI_PAGE_SIZE) >> EFI_PAGE_SHIFT;
@@ -70,6 +74,22 @@ void efi_add_known_memory(void)
 		}
 
 		efi_add_memory_map(start, pages, type, false);
+
+		if (type == EFI_CONVENTIONAL_MEMORY) {
+			u64 end = start + (pages << EFI_PAGE_SHIFT);
+
+			/* reserve the memory region greater than ram_top */
+			if (ram_top < start) {
+				efi_add_memory_map(start, pages,
+						   EFI_BOOT_SERVICES_DATA,
+						   true);
+			} else if (start < ram_top && ram_top < end) {
+				pages = (end - ram_top) >> EFI_PAGE_SHIFT;
+				efi_add_memory_map(ram_top, pages,
+						   EFI_BOOT_SERVICES_DATA,
+						   true);
+			}
+		}
 	}
 }
 #endif /* CONFIG_IS_ENABLED(EFI_LOADER) */
-- 
2.20.1