Do this before relocating the compressed kernel + device tree data. Otherwise we would have to split the copying into two parts, or copy the device tree data twice.
As we only have one register available, pass the size of kernel BSS via linker and do the following calculation using r1. Signed-off-by: Tony Lindgren <[email protected]> --- a/arch/arm/boot/compressed/Makefile +++ b/arch/arm/boot/compressed/Makefile @@ -98,6 +98,9 @@ endif ccflags-y := -fpic -fno-builtin asflags-y := -Wa,-march=all +# Supply kernel BSS size to the decompressor via a linker symbol. +KBSS_SZ = $(shell size $(obj)/../../../../vmlinux | awk 'END{print $$3}') +LDFLAGS_vmlinux = --defsym _kbss_sz=$(KBSS_SZ) # Supply ZRELADDR to the decompressor via a linker symbol. ifneq ($(CONFIG_AUTO_ZRELADDR),y) LDFLAGS_vmlinux += --defsym zreladdr=$(ZRELADDR) --- a/arch/arm/boot/compressed/head.S +++ b/arch/arm/boot/compressed/head.S @@ -273,17 +273,35 @@ dtb_check_done: /* * Check to see if we will overwrite ourselves. + * r1 = corrupted * r4 = final kernel address + * r5 = start of this image + * r6 = _edata * r9 = size of decompressed image * r10 = end of this image, including bss/stack/malloc space if non XIP * We basically want: * r4 - 16k page directory >= r10 -> OK * r4 + image length <= current position (pc) -> OK + * For the appended device tree case, check that the device tree data does + * not overlap the kernel BSS area. */ add r10, r10, #16384 cmp r4, r10 bhs wont_overwrite add r10, r4, r9 +#if defined(CONFIG_ARM_APPENDED_DTB) + cmp lr, #0 + beq no_kbss_check + adr r1, kbss + ldr r1, [r1, #0] @ kernel BSS size, _kbss_sz + add r1, r10, r1 @ inflated kernel end + kbss + sub r1, r1, r5 @ minus start of this data + add r1, r1, r6 @ plus end of this data + sub r1, r1, lr @ minus size of DT data + cmp r10, r1 @ DT start < kernel BSS end? + movlt r10, r1 @ yes, move past kernel BSS end +no_kbss_check: +#endif cmp r10, pc bls wont_overwrite @@ -331,6 +349,8 @@ dtb_check_done: add r0, r0, r6 mov pc, r0 +kbss: .word _kbss_sz + wont_overwrite: /* * If delta is zero, we are running at the address we were linked at. _______________________________________________ devicetree-discuss mailing list [email protected] https://lists.ozlabs.org/listinfo/devicetree-discuss
