From 9b7dcd3f96b7de11d09fb2efb12dca48cc486733 Mon Sep 17 00:00:00 2001 From: Ard Biesheuvel Date: Sat, 27 Aug 2022 09:09:04 +0200 Subject: [PATCH] arm64: head: Ignore bogus KASLR displacement on non-relocatable kernels Even non-KASLR kernels can be built as relocatable, to work around broken bootloaders that violate the rules regarding physical placement of the kernel image - in this case, the physical offset modulo 2 MiB is used as the KASLR offset, and all absolute symbol references are fixed up in the usual way. This workaround is enabled by default. CONFIG_RELOCATABLE can also be disabled entirely, in which case the relocation code and the code that captures the offset are omitted from the build. However, since commit f1233e1f9c35 ("arm64: head: avoid relocating the kernel twice for KASLR"), this code got out of sync, and we still add the offset to the kernel virtual address before populating the page tables even though we never capture it. This means we add a bogus value instead, breaking the boot entirely. Fixes: f1233e1f9c35 ("arm64: head: avoid relocating the kernel twice for KASLR") Signed-off-by: Ard Biesheuvel Tested-by: Mikulas Patocka Link: https://lore.kernel.org/r/20220827070904.2216989-1-ardb@kernel.org Signed-off-by: Will Deacon --- arch/arm64/kernel/head.S | 2 ++ 1 file changed, 2 insertions(+) diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S index cefe6a73ee546..814b6587ccb78 100644 --- a/arch/arm64/kernel/head.S +++ b/arch/arm64/kernel/head.S @@ -371,7 +371,9 @@ SYM_FUNC_END(create_idmap) SYM_FUNC_START_LOCAL(create_kernel_mapping) adrp x0, init_pg_dir mov_q x5, KIMAGE_VADDR // compile time __va(_text) +#ifdef CONFIG_RELOCATABLE add x5, x5, x23 // add KASLR displacement +#endif adrp x6, _end // runtime __pa(_end) adrp x3, _text // runtime __pa(_text) sub x6, x6, x3 // _end - _text -- 2.39.5