From 011b9e1c2a1825b4c2d5df7f24672fc4f635a95d Mon Sep 17 00:00:00 2001 From: Ard Biesheuvel Date: Fri, 5 Feb 2021 19:23:00 +0100 Subject: [PATCH] ARM: 9056/1: decompressor: fix BSS size calculation for LLVM ld.lld commit c4e792d1acce31c2eb7b9193ab06ab94de05bf42 upstream. The LLVM ld.lld linker uses a different symbol type for __bss_start, resulting in the calculation of KBSS_SZ to be thrown off. Up until now, this has gone unnoticed as it only affects the appended DTB case, but pending changes for ARM in the way the decompressed kernel is cleaned from the caches has uncovered this problem. On a ld.lld build: $ nm vmlinux |grep bss_ c1c22034 D __bss_start c1c86e98 B __bss_stop resulting in $ readelf -s arch/arm/boot/compressed/vmlinux | grep bss_size 433: c1c86e98 0 NOTYPE GLOBAL DEFAULT ABS _kernel_bss_size which is obviously incorrect, and may cause the cache clean to access unmapped memory, or cause the size calculation to wrap, resulting in no cache clean to be performed at all. Fix this by updating the sed regex to take D type symbols into account. Link: https://lore.kernel.org/linux-arm-kernel/6c65bcef-d4e7-25fa-43cf-2c435bb61bb9@collabora.com/ Link: https://lore.kernel.org/linux-arm-kernel/20210205085220.31232-1-ardb@kernel.org/ Cc: # v4.19+ Reviewed-by: Nick Desaulniers Tested-by: Nick Desaulniers Reported-by: Guillaume Tucker Reported-by: "kernelci.org bot" Signed-off-by: Ard Biesheuvel Signed-off-by: Russell King Signed-off-by: Greg Kroah-Hartman --- arch/arm/boot/compressed/Makefile | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/arm/boot/compressed/Makefile b/arch/arm/boot/compressed/Makefile index e1567418a2b1..0d6ee56f5831 100644 --- a/arch/arm/boot/compressed/Makefile +++ b/arch/arm/boot/compressed/Makefile @@ -114,8 +114,8 @@ asflags-y := -DZIMAGE # Supply kernel BSS size to the decompressor via a linker symbol. KBSS_SZ = $(shell echo $$(($$($(NM) $(obj)/../../../../vmlinux | \ - sed -n -e 's/^\([^ ]*\) [AB] __bss_start$$/-0x\1/p' \ - -e 's/^\([^ ]*\) [AB] __bss_stop$$/+0x\1/p') )) ) + sed -n -e 's/^\([^ ]*\) [ABD] __bss_start$$/-0x\1/p' \ + -e 's/^\([^ ]*\) [ABD] __bss_stop$$/+0x\1/p') )) ) LDFLAGS_vmlinux = --defsym _kernel_bss_size=$(KBSS_SZ) # Supply ZRELADDR to the decompressor via a linker symbol. ifneq ($(CONFIG_AUTO_ZRELADDR),y) -- 2.25.1