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arm64: head: use relative references to the RELA and RELR tables

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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@kernel.org>
Link: https://lore.kernel.org/r/20220624150651.1358849-14-ardb@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
This commit is contained in:
Ard Biesheuvel 2022-06-24 17:06:43 +02:00 committed by Will Deacon
parent c3cee924bd
commit d7bea55027
2 changed files with 8 additions and 17 deletions
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13
arch/arm64/kernel/head.S
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@ -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

12
arch/arm64/kernel/vmlinux.lds.S
View File

@ -256,21 +256,17 @@ 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 = .;