mirror of
https://github.com/openwrt/openwrt.git
synced 2024-12-30 18:47:06 +00:00
76 lines
3.1 KiB
Diff
76 lines
3.1 KiB
Diff
|
From 2f86b9b71a11f86e3d850214ab781ebb17d7260e Mon Sep 17 00:00:00 2001
|
||
|
|
From: Christian Marangi <ansuelsmth@gmail.com>
|
||
|
|
Date: Fri, 19 Jan 2024 19:48:30 +0100
|
||
|
|
Subject: [PATCH v2 1/2] ARM: decompressor: support memory start validation for
|
||
|
|
appended DTB
|
||
|
|
|
||
|
|
There is currently a problem with a very specific sets of kernel config
|
||
|
|
and AUTO_ZRELADDR.
|
||
|
|
|
||
|
|
For the most common case AUTO_ZRELADDR check the PC register and
|
||
|
|
calculate the start of the physical memory. Then fdt_check_mem_start is
|
||
|
|
called to make sure the detected value makes sense by comparing it with
|
||
|
|
what is present in DTB in the memory nodes and if additional fixup are
|
||
|
|
required with the use of linux,usable-memory-range in the chosen node to
|
||
|
|
hardcode usable memory range in case some reserved space needs to be
|
||
|
|
addressed. With the help of this function the right address is
|
||
|
|
calculated and the kernel correctly decompress and loads.
|
||
|
|
|
||
|
|
Things starts to become problematic when in the mix,
|
||
|
|
CONFIG_ARM_APPENDED_DTB is used. This is a particular kernel config is
|
||
|
|
used when legacy systems doesn't support passing a DTB directly and a
|
||
|
|
DTB is appended at the end of the image.
|
||
|
|
|
||
|
|
In such case, fdt_check_mem_start is skipped in AUTO_ZRELADDR iteration
|
||
|
|
as the appended DTB can be augumented later with ATAGS passed from the
|
||
|
|
bootloader (if CONFIG_ARM_ATAG_DTB_COMPAT is enabled).
|
||
|
|
|
||
|
|
The main problem and what this patch address is the fact that
|
||
|
|
fdt_check_mem_start is never called later when the appended DTB is
|
||
|
|
augumented, hence any fixup and validation is not done making AUTO_ZRELADDR
|
||
|
|
detection inconsistent and most of the time wrong.
|
||
|
|
|
||
|
|
Add support in head.S for this by checking if AUTO_ZRELADDR is enabled
|
||
|
|
and calling fdt_check_mem_start with the appended DTB and the augumented
|
||
|
|
values permitting legacy device to provide info in DTB instead of
|
||
|
|
disabling AUTO_ZRELADDR and hardcoding the physical address offsets.
|
||
|
|
|
||
|
|
Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
|
||
|
|
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
|
||
|
|
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
|
||
|
|
---
|
||
|
|
arch/arm/boot/compressed/head.S | 22 ++++++++++++++++++++++
|
||
|
|
1 file changed, 22 insertions(+)
|
||
|
|
|
||
|
|
--- a/arch/arm/boot/compressed/head.S
|
||
|
|
+++ b/arch/arm/boot/compressed/head.S
|
||
|
|
@@ -443,6 +443,28 @@ restart: adr r0, LC1
|
||
|
|
add r6, r6, r5
|
||
|
|
add r10, r10, r5
|
||
|
|
add sp, sp, r5
|
||
|
|
+
|
||
|
|
+#ifdef CONFIG_AUTO_ZRELADDR
|
||
|
|
+ /*
|
||
|
|
+ * Validate calculated start of physical memory with appended DTB.
|
||
|
|
+ * In the first iteration for physical memory start calculation,
|
||
|
|
+ * we skipped validating it as it could have been augumented by
|
||
|
|
+ * ATAGS stored at an offset from the same start of physical memory.
|
||
|
|
+ *
|
||
|
|
+ * We now have parsed them and augumented the appended DTB if asked
|
||
|
|
+ * so we can finally validate the start of physical memory.
|
||
|
|
+ *
|
||
|
|
+ * This is needed to apply additional fixup with
|
||
|
|
+ * linux,usable-memory-range or to make sure AUTO_ZRELADDR detected
|
||
|
|
+ * the correct value.
|
||
|
|
+ */
|
||
|
|
+ sub r0, r4, #TEXT_OFFSET @ revert to base address
|
||
|
|
+ mov r1, r8 @ use appended DTB
|
||
|
|
+ bl fdt_check_mem_start
|
||
|
|
+
|
||
|
|
+ /* Determine final kernel image address. */
|
||
|
|
+ add r4, r0, #TEXT_OFFSET
|
||
|
|
+#endif
|
||
|
|
dtb_check_done:
|
||
|
|
#endif
|
||
|
|
|