Commit dc0a0839 authored by Ard Biesheuvel's avatar Ard Biesheuvel Committed by Will Deacon
Browse files

arm64: Work around convergence issue with LLD linker 



LLD will occasionally error out with a '__init_end does not converge'
error if INIT_IDMAP_DIR_SIZE is defined in terms of _end, as this
results in a circular dependency.

Counter this by dimensioning the initial IDMAP page tables based on a
new boundary marker 'kimage_limit', and define it such that its value
should not change as a result of the initdata segment being pushed over
a 64k segment boundary due to changes in INIT_IDMAP_DIR_SIZE, provided
that its value doesn't change by more than 2M between linker passes.

Reported-by: default avatarArnd Bergmann <arnd@arndb.de>
Signed-off-by: default avatarArd Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20250531123005.3866382-2-ardb+git@google.com


Signed-off-by: default avatarWill Deacon <will@kernel.org>
parent e21560b7

arch/arm64/include/asm/kernel-pgtable.h

+1 −1
Original line number Diff line number Diff line
@@ -58,7 +58,7 @@ 
#define INIT_DIR_SIZE (PAGE_SIZE * (EARLY_PAGES(SWAPPER_PGTABLE_LEVELS, KIMAGE_VADDR, _end, EXTRA_PAGE) \

				    + EARLY_SEGMENT_EXTRA_PAGES))



#define INIT_IDMAP_DIR_PAGES	(EARLY_PAGES(INIT_IDMAP_PGTABLE_LEVELS, KIMAGE_VADDR, _end, 1))

#define INIT_IDMAP_DIR_PAGES	(EARLY_PAGES(INIT_IDMAP_PGTABLE_LEVELS, KIMAGE_VADDR, kimage_limit, 1))

#define INIT_IDMAP_DIR_SIZE	((INIT_IDMAP_DIR_PAGES + EARLY_IDMAP_EXTRA_PAGES) * PAGE_SIZE)



#define INIT_IDMAP_FDT_PAGES	(EARLY_PAGES(INIT_IDMAP_PGTABLE_LEVELS, 0UL, UL(MAX_FDT_SIZE), 1) - 1)

arch/arm64/kernel/image-vars.h

+11 −0
Original line number Diff line number Diff line
@@ -146,6 +146,17 @@ KVM_NVHE_ALIAS(kvm_protected_mode_initialized); 
_kernel_codesize = ABSOLUTE(__inittext_end - _text);

#endif



/*

 * LLD will occasionally error out with a '__init_end does not converge' error

 * if INIT_IDMAP_DIR_SIZE is defined in terms of _end, as this results in a

 * circular dependency. Counter this by dimensioning the initial IDMAP page

 * tables based on kimage_limit, which is defined such that its value should

 * not change as a result of the initdata segment being pushed over a 64k

 * segment boundary due to changes in INIT_IDMAP_DIR_SIZE, provided that its

 * value doesn't change by more than 2M between linker passes.

 */

kimage_limit = ALIGN(ABSOLUTE(_end + SZ_64K), SZ_2M);



#undef ASSERT



#endif /* __ARM64_KERNEL_IMAGE_VARS_H */