linux-kernel - [PATCH 1/1] efi/libstub: DRAM base calculation

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Message-Id: <20200904155025.55718-1-xypron.glpk@gmx.de>
Date:   Fri,  4 Sep 2020 17:50:25 +0200
From:   Heinrich Schuchardt <xypron.glpk@....de>
To:     Ard Biesheuvel <ardb@...nel.org>
Cc:     Ingo Molnar <mingo@...nel.org>,
        Arvind Sankar <nivedita@...m.mit.edu>,
        linux-efi@...r.kernel.org, linux-kernel@...r.kernel.org,
        Maxim Uvarov <maxim.uvarov@...aro.org>,
        Jens Wiklander <jens.wiklander@...aro.org>,
        Heinrich Schuchardt <xypron.glpk@....de>
Subject: [PATCH 1/1] efi/libstub: DRAM base calculation

In the memory map the regions with the lowest addresses may be of type
EFI_RESERVED_TYPE. The reserved areas may be discontinuous relative to the
rest of the memory. So for calculating the maximum loading address for the
device tree and the initial ramdisk image these reserved areas should not
be taken into account.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@....de>
---
 drivers/firmware/efi/libstub/efi-stub.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/firmware/efi/libstub/efi-stub.c b/drivers/firmware/efi/libstub/efi-stub.c
index c2484bf75c5d..13058ac75765 100644
--- a/drivers/firmware/efi/libstub/efi-stub.c
+++ b/drivers/firmware/efi/libstub/efi-stub.c
@@ -106,7 +106,8 @@ static unsigned long get_dram_base(void)
 	map.map_end = map.map + map_size;

 	for_each_efi_memory_desc_in_map(&map, md) {
-		if (md->attribute & EFI_MEMORY_WB) {
+		if (md->attribute & EFI_MEMORY_WB &&
+		    md->type != EFI_RESERVED_TYPE) {
 			if (membase > md->phys_addr)
 				membase = md->phys_addr;
 		}
--
2.28.0