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From: takahiro.akashi@linaro.org (AKASHI Takahiro)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v35 14/14] efi/libstub/arm*: Set default address and size cells values for an empty dtb
Date: Mon,  3 Apr 2017 11:26:33 +0900	[thread overview]
Message-ID: <20170403022633.12655-1-takahiro.akashi@linaro.org> (raw)
In-Reply-To: <20170403022139.12383-1-takahiro.akashi@linaro.org>

From: Sameer Goel <sgoel@codeaurora.org>

In cases where a device tree is not provided (ie ACPI based system), an
empty fdt is generated by efistub.  #address-cells and #size-cells are not
set in the empty fdt, so they default to 1 (4 byte wide).  This can be an
issue on 64-bit systems where values representing addresses, etc may be
8 bytes wide as the default value does not align with the general
requirements for an empty DTB, and is fragile when passed to other agents
as extra care is required to read the entire width of a value.

This issue is observed on Qualcomm Technologies QDF24XX platforms when
kexec-tools inserts 64-bit addresses into the "linux,elfcorehdr" and
"linux,usable-memory-range" properties of the fdt.  When the values are
later consumed, they are truncated to 32-bit.

Setting #address-cells and #size-cells to 2 at creation of the empty fdt
resolves the observed issue, and makes the fdt less fragile.

Signed-off-by: Sameer Goel <sgoel@codeaurora.org>
Signed-off-by: Jeffrey Hugo <jhugo@codeaurora.org>
Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
---
 drivers/firmware/efi/libstub/fdt.c | 28 ++++++++++++++++++++++++++--
 1 file changed, 26 insertions(+), 2 deletions(-)

diff --git a/drivers/firmware/efi/libstub/fdt.c b/drivers/firmware/efi/libstub/fdt.c
index 260c4b4b492e..82973b86efe4 100644
--- a/drivers/firmware/efi/libstub/fdt.c
+++ b/drivers/firmware/efi/libstub/fdt.c
@@ -16,6 +16,22 @@
 
 #include "efistub.h"
 
+#define EFI_DT_ADDR_CELLS_DEFAULT 2
+#define EFI_DT_SIZE_CELLS_DEFAULT 2
+
+static void fdt_update_cell_size(efi_system_table_t *sys_table, void *fdt)
+{
+	int offset;
+
+	offset = fdt_path_offset(fdt, "/");
+	/* Set the #address-cells and #size-cells values for an empty tree */
+
+	fdt_setprop_u32(fdt, offset, "#address-cells",
+			EFI_DT_ADDR_CELLS_DEFAULT);
+
+	fdt_setprop_u32(fdt, offset, "#size-cells", EFI_DT_SIZE_CELLS_DEFAULT);
+}
+
 static efi_status_t update_fdt(efi_system_table_t *sys_table, void *orig_fdt,
 			       unsigned long orig_fdt_size,
 			       void *fdt, int new_fdt_size, char *cmdline_ptr,
@@ -42,10 +58,18 @@ static efi_status_t update_fdt(efi_system_table_t *sys_table, void *orig_fdt,
 		}
 	}
 
-	if (orig_fdt)
+	if (orig_fdt) {
 		status = fdt_open_into(orig_fdt, fdt, new_fdt_size);
-	else
+	} else {
 		status = fdt_create_empty_tree(fdt, new_fdt_size);
+		if (status == 0) {
+			/*
+			 * Any failure from the following function is non
+			 * critical
+			 */
+			fdt_update_cell_size(sys_table, fdt);
+		}
+	}
 
 	if (status != 0)
 		goto fdt_set_fail;
-- 
2.11.1

  parent reply	other threads:[~2017-04-03  2:26 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-04-03  2:21 [PATCH v35 00/14] arm64: add kdump support AKASHI Takahiro
2017-04-03  2:23 ` [PATCH v35 01/14] memblock: add memblock_clear_nomap() AKASHI Takahiro
2017-04-03  2:23 ` [PATCH v35 02/14] memblock: add memblock_cap_memory_range() AKASHI Takahiro
2017-04-05 17:20   ` Catalin Marinas
2017-04-03  2:24 ` [PATCH v35 03/14] arm64: limit memory regions based on DT property, usable-memory-range AKASHI Takahiro
2017-04-03  2:24 ` [PATCH v35 04/14] arm64: kdump: reserve memory for crash dump kernel AKASHI Takahiro
2017-04-03  2:24 ` [PATCH v35 05/14] arm64: mm: add set_memory_valid() AKASHI Takahiro
2017-04-03  2:24 ` [PATCH v35 06/14] arm64: kdump: protect crash dump kernel memory AKASHI Takahiro
2017-04-03  2:24 ` [PATCH v35 07/14] arm64: hibernate: preserve kdump image around hibernation AKASHI Takahiro
2017-04-03  2:24 ` [PATCH v35 08/14] arm64: kdump: implement machine_crash_shutdown() AKASHI Takahiro
2017-04-03  9:21   ` David Woodhouse
2017-04-04  7:29     ` AKASHI Takahiro
2017-04-03  2:24 ` [PATCH v35 09/14] arm64: kdump: add VMCOREINFO's for user-space tools AKASHI Takahiro
2017-04-03  2:24 ` [PATCH v35 10/14] arm64: kdump: provide /proc/vmcore file AKASHI Takahiro
2017-04-03  2:24 ` [PATCH v35 11/14] arm64: kdump: enable kdump in defconfig AKASHI Takahiro
2017-04-03  2:24 ` [PATCH v35 12/14] Documentation: kdump: describe arm64 port AKASHI Takahiro
2017-04-03  2:26 ` [PATCH v35 13/14] Documentation: dt: chosen properties for arm64 kdump AKASHI Takahiro
2017-04-03  2:26 ` AKASHI Takahiro [this message]
2017-05-22  0:25 ` [PATCH v35 00/14] arm64: add kdump support AKASHI Takahiro

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