From 7b78d6438a2b3a7f58a34934b54a1a83733b8fdd Mon Sep 17 00:00:00 2001 From: Alexander Graf Date: Fri, 30 Nov 2018 21:24:56 +0100 Subject: [PATCH] efi_loader: Reserve unaccessible memory On some systems, not all RAM may be usable within U-Boot. Maybe the memory maps are incomplete, maybe it's used as workaround for broken DMA. But whatever the reason may be, a platform can say that it does not wish to have its RAM accessed above a certain address by defining board_get_usable_ram_top(). In the efi_loader world, we ignored that hint, mostly because very few boards actually have real restrictions around this. So let's honor the board's wish to not access high addresses during boot time. The best way to do so is by indicating the respective pages as "allocated by firmware". That way, Operating Systems will still use the pages after boot, but before boot no allocation will use them. Reported-by: Baruch Siach Signed-off-by: Alexander Graf Reviewed-by: Stephen Warren Reviewed-by: Heinrich Schuchardt Tested-by: Baruch Siach --- include/common.h | 11 +++++++++++ lib/efi_loader/efi_memory.c | 32 +++++++++++++++++++++++++++++--- 2 files changed, 40 insertions(+), 3 deletions(-) diff --git a/include/common.h b/include/common.h index 8b56137032..a8e879e1b9 100644 --- a/include/common.h +++ b/include/common.h @@ -105,6 +105,17 @@ int mdm_init(void); */ void board_show_dram(phys_size_t size); +/** + * Get the uppermost pointer that is valid to access + * + * Some systems may not map all of their address space. This function allows + * boards to indicate what their highest support pointer value is for DRAM + * access. + * + * @param total_size Size of U-Boot (unused?) + */ +ulong board_get_usable_ram_top(ulong total_size); + /** * arch_fixup_fdt() - Write arch-specific information to fdt * diff --git a/lib/efi_loader/efi_memory.c b/lib/efi_loader/efi_memory.c index f225a9028c..73bfbb65c4 100644 --- a/lib/efi_loader/efi_memory.c +++ b/lib/efi_loader/efi_memory.c @@ -551,8 +551,13 @@ efi_status_t efi_get_memory_map(efi_uintn_t *memory_map_size, __weak void efi_add_known_memory(void) { + u64 ram_top = board_get_usable_ram_top(0) & ~EFI_PAGE_MASK; int i; + /* Fix for 32bit targets with ram_top at 4G */ + if (!ram_top) + ram_top = 0x100000000ULL; + /* Add RAM */ for (i = 0; i < CONFIG_NR_DRAM_BANKS; i++) { u64 ram_end, ram_start, pages; @@ -564,11 +569,32 @@ __weak void efi_add_known_memory(void) ram_end &= ~EFI_PAGE_MASK; ram_start = (ram_start + EFI_PAGE_MASK) & ~EFI_PAGE_MASK; - if (ram_end > ram_start) { - pages = (ram_end - ram_start) >> EFI_PAGE_SHIFT; + if (ram_end <= ram_start) { + /* Invalid mapping, keep going. */ + continue; + } + + pages = (ram_end - ram_start) >> EFI_PAGE_SHIFT; + efi_add_memory_map(ram_start, pages, + EFI_CONVENTIONAL_MEMORY, false); + + /* + * Boards may indicate to the U-Boot memory core that they + * can not support memory above ram_top. Let's honor this + * in the efi_loader subsystem too by declaring any memory + * above ram_top as "already occupied by firmware". + */ + if (ram_top < ram_start) { + /* ram_top is before this region, reserve all */ efi_add_memory_map(ram_start, pages, - EFI_CONVENTIONAL_MEMORY, false); + EFI_BOOT_SERVICES_DATA, true); + } else if ((ram_top >= ram_start) && (ram_top < ram_end)) { + /* ram_top is inside this region, reserve parts */ + pages = (ram_end - ram_top) >> EFI_PAGE_SHIFT; + + efi_add_memory_map(ram_top, pages, + EFI_BOOT_SERVICES_DATA, true); } } } -- 2.25.1