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Date: Mon, 13 Jun 2022 16:45:37 +0200 From: Ard Biesheuvel <ardb@...nel.org> To: linux-arm-kernel@...ts.infradead.org Cc: linux-hardening@...r.kernel.org, Ard Biesheuvel <ardb@...nel.org>, Marc Zyngier <maz@...nel.org>, Will Deacon <will@...nel.org>, Mark Rutland <mark.rutland@....com>, Kees Cook <keescook@...omium.org>, Catalin Marinas <catalin.marinas@....com>, Mark Brown <broonie@...nel.org>, Anshuman Khandual <anshuman.khandual@....com> Subject: [PATCH v4 13/26] arm64: head: use relative references to the RELA and RELR tables Formerly, we had to access the RELA and RELR tables via the kernel mapping that was being relocated, and so deriving the start and end addresses using ADRP/ADD references was not possible, as the relocation code runs from the ID map. Now that we map the entire kernel image via the ID map, we can simplify this, and just load the entries via the ID map as well. Signed-off-by: Ard Biesheuvel <ardb@...nel.org> --- arch/arm64/kernel/head.S | 13 ++++--------- arch/arm64/kernel/vmlinux.lds.S | 12 ++++-------- 2 files changed, 8 insertions(+), 17 deletions(-) diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S index 93734c91a29a..f1497f7b4da0 100644 --- a/arch/arm64/kernel/head.S +++ b/arch/arm64/kernel/head.S @@ -757,13 +757,10 @@ SYM_FUNC_START_LOCAL(__relocate_kernel) * Iterate over each entry in the relocation table, and apply the * relocations in place. */ - ldr w9, =__rela_offset // offset to reloc table - ldr w10, =__rela_size // size of reloc table - + adr_l x9, __rela_start + adr_l x10, __rela_end mov_q x11, KIMAGE_VADDR // default virtual offset add x11, x11, x23 // actual virtual offset - add x9, x9, x11 // __va(.rela) - add x10, x9, x10 // __va(.rela) + sizeof(.rela) 0: cmp x9, x10 b.hs 1f @@ -813,10 +810,8 @@ SYM_FUNC_START_LOCAL(__relocate_kernel) * __relocate_kernel is called twice with non-zero displacements (i.e. * if there is both a physical misalignment and a KASLR displacement). */ - ldr w9, =__relr_offset // offset to reloc table - ldr w10, =__relr_size // size of reloc table - add x9, x9, x11 // __va(.relr) - add x10, x9, x10 // __va(.relr) + sizeof(.relr) + adr_l x9, __relr_start + adr_l x10, __relr_end sub x15, x23, x24 // delta from previous offset cbz x15, 7f // nothing to do if unchanged diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S index 0ce3a7c9f8c4..45131e354e27 100644 --- a/arch/arm64/kernel/vmlinux.lds.S +++ b/arch/arm64/kernel/vmlinux.lds.S @@ -257,21 +257,17 @@ SECTIONS HYPERVISOR_RELOC_SECTION .rela.dyn : ALIGN(8) { + __rela_start = .; *(.rela .rela*) + __rela_end = .; } - __rela_offset = ABSOLUTE(ADDR(.rela.dyn) - KIMAGE_VADDR); - __rela_size = SIZEOF(.rela.dyn); - -#ifdef CONFIG_RELR .relr.dyn : ALIGN(8) { + __relr_start = .; *(.relr.dyn) + __relr_end = .; } - __relr_offset = ABSOLUTE(ADDR(.relr.dyn) - KIMAGE_VADDR); - __relr_size = SIZEOF(.relr.dyn); -#endif - . = ALIGN(SEGMENT_ALIGN); __initdata_end = .; __init_end = .; -- 2.30.2
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