+++ /dev/null
-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
-
projects / openwrt / openwrt.git / blobdiff