[U-Boot] [PATCH 05/20] x86: Override calculate_relocation_address to use the e820 map

[Simon Glass]

From: Gabe Black <gabeblack at chromium.org>

Because calculate_relocation_address now uses the e820 map, it will be able
to avoid addresses over 32 bits and regions that are at high addresses but
not big enough for U-Boot. It also means we can remove the hack which
limitted U-Boot's idea of the size of memory to less than 4GB.

Also take into account the space needed for the heap and stack, so we avoid
picking a very small region those areas might overlap with something it
shouldn't.

Signed-off-by: Gabe Black <gabeblack at google.com>
Signed-off-by: Gabe Black <gabeblack at google.com>
Signed-off-by: Simon Glass <sjg at chromium.org>
---
 arch/x86/cpu/coreboot/sdram.c |   53 +++++++++++++++++++++++++++++++++++++---
 1 files changed, 49 insertions(+), 4 deletions(-)

diff --git a/arch/x86/cpu/coreboot/sdram.c b/arch/x86/cpu/coreboot/sdram.c
index 5d3da99..611f554 100644
--- a/arch/x86/cpu/coreboot/sdram.c
+++ b/arch/x86/cpu/coreboot/sdram.c
@@ -51,6 +51,55 @@ unsigned install_e820_map(unsigned max_entries, struct e820entry *entries)
 	return num_entries;
 }
 
+/*
+ * This function looks for the highest region of memory lower than 4GB which
+ * has enough space for U-Boot where U-Boot is aligned on a page boundary. It
+ * overrides the default implementation found elsewhere which simply picks the
+ * end of ram, wherever that may be. The location of the stack, the relocation
+ * address, and how far U-Boot is moved by relocation are set in the global
+ * data structure.
+ */
+int calculate_relocation_address(void)
+{
+	const uint64_t uboot_size = &__bss_end - &__text_start;
+	const uint64_t total_size = uboot_size + CONFIG_SYS_MALLOC_LEN +
+		CONFIG_SYS_STACK_SIZE;
+	uintptr_t dest_addr = 0;
+	int i;
+
+	for (i = 0; i < lib_sysinfo.n_memranges; i++) {
+		struct memrange *memrange = &lib_sysinfo.memrange[i];
+		/* Force U-Boot to relocate to a page aligned address. */
+		uint64_t start = roundup(memrange->base, 1 << 12);
+		uint64_t end = memrange->base + memrange->size;
+
+		/* Ignore non-memory regions. */
+		if (memrange->type != CB_MEM_RAM)
+			continue;
+
+		/* Filter memory over 4GB. */
+		if (end > 0xffffffffULL)
+			end = 0x100000000ULL;
+		/* Skip this region if it's too small. */
+		if (end - start < total_size)
+			continue;
+
+		/* Use this address if it's the largest so far. */
+		if (end - uboot_size > dest_addr)
+			dest_addr = (end - uboot_size) & ~((1 << 12) - 1);
+	}
+
+	/* If no suitable area was found, return an error. */
+	if (!dest_addr)
+		return 1;
+
+	gd->start_addr_sp = dest_addr - CONFIG_SYS_MALLOC_LEN;
+	gd->relocaddr = dest_addr;
+	gd->reloc_off = dest_addr - (uintptr_t)&__text_start;
+
+	return 0;
+}
+
 int dram_init_f(void)
 {
 	int i;
@@ -60,10 +109,6 @@ int dram_init_f(void)
 		struct memrange *memrange = &lib_sysinfo.memrange[i];
 		unsigned long long end = memrange->base + memrange->size;
 
-		/* Ignore memory over 4GB, we can't use it. */
-		if (memrange->base > 0xffffffff)
-			continue;
-
 		if (memrange->type == CB_MEM_RAM && end > ram_size)
 			ram_size = end;
 	}
-- 
1.7.7.3