When boot-time page size is in operation, TRAMP_VALIAS is no longer a compile-time constant, because the VA of a fixmap slot depends upon PAGE_SIZE. Let's handle this by instead exporting the slot index, FIX_ENTRY_TRAMP_BEGIN,to assembly, then do the TRAMP_VALIAS calculation per page size and use alternatives to decide which variant to activate. Note that for the tramp_map_kernel case, we are one instruction short of space in the vector to have NOPs for all 3 page size variants. So we do if/else for 16K/64K and branch around it for the 4K case. This saves 2 instructions. Signed-off-by: Ryan Roberts <ryan.roberts@xxxxxxx> --- ***NOTE*** Any confused maintainers may want to read the cover note here for context: https://lore.kernel.org/all/20241014105514.3206191-1-ryan.roberts@xxxxxxx/ arch/arm64/kernel/asm-offsets.c | 2 +- arch/arm64/kernel/entry.S | 50 ++++++++++++++++++++++++++------- 2 files changed, 41 insertions(+), 11 deletions(-) diff --git a/arch/arm64/kernel/asm-offsets.c b/arch/arm64/kernel/asm-offsets.c index f32b8d7f00b2a..c45fa3e281884 100644 --- a/arch/arm64/kernel/asm-offsets.c +++ b/arch/arm64/kernel/asm-offsets.c @@ -172,7 +172,7 @@ int main(void) DEFINE(ARM64_FTR_SYSVAL, offsetof(struct arm64_ftr_reg, sys_val)); BLANK(); #ifdef CONFIG_UNMAP_KERNEL_AT_EL0 - DEFINE(TRAMP_VALIAS, TRAMP_VALIAS); + DEFINE(FIX_ENTRY_TRAMP_BEGIN, FIX_ENTRY_TRAMP_BEGIN); #endif #ifdef CONFIG_ARM_SDE_INTERFACE DEFINE(SDEI_EVENT_INTREGS, offsetof(struct sdei_registered_event, interrupted_regs)); diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index 7ef0e127b149f..ba47dc8672c04 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -101,11 +101,27 @@ .org .Lventry_start\@ + 128 // Did we overflow the ventry slot? .endm +#define TRAMP_VALIAS(page_shift) (FIXADDR_TOP - (FIX_ENTRY_TRAMP_BEGIN << (page_shift))) + .macro tramp_alias, dst, sym - .set .Lalias\@, TRAMP_VALIAS + \sym - .entry.tramp.text - movz \dst, :abs_g2_s:.Lalias\@ - movk \dst, :abs_g1_nc:.Lalias\@ - movk \dst, :abs_g0_nc:.Lalias\@ +alternative_if ARM64_USE_PAGE_SIZE_4K + .set .Lalias4k\@, TRAMP_VALIAS(ARM64_PAGE_SHIFT_4K) + \sym - .entry.tramp.text + movz \dst, :abs_g2_s:.Lalias4k\@ + movk \dst, :abs_g1_nc:.Lalias4k\@ + movk \dst, :abs_g0_nc:.Lalias4k\@ +alternative_else_nop_endif +alternative_if ARM64_USE_PAGE_SIZE_16K + .set .Lalias16k\@, TRAMP_VALIAS(ARM64_PAGE_SHIFT_16K) + \sym - .entry.tramp.text + movz \dst, :abs_g2_s:.Lalias16k\@ + movk \dst, :abs_g1_nc:.Lalias16k\@ + movk \dst, :abs_g0_nc:.Lalias16k\@ +alternative_else_nop_endif +alternative_if ARM64_USE_PAGE_SIZE_64K + .set .Lalias64k\@, TRAMP_VALIAS(ARM64_PAGE_SHIFT_64K) + \sym - .entry.tramp.text + movz \dst, :abs_g2_s:.Lalias64k\@ + movk \dst, :abs_g1_nc:.Lalias64k\@ + movk \dst, :abs_g0_nc:.Lalias64k\@ +alternative_else_nop_endif .endm /* @@ -627,16 +643,30 @@ SYM_CODE_END(ret_to_user) bic \tmp, \tmp, #USER_ASID_FLAG msr ttbr1_el1, \tmp #ifdef CONFIG_QCOM_FALKOR_ERRATUM_1003 -alternative_if ARM64_WORKAROUND_QCOM_FALKOR_E1003 +alternative_if_not ARM64_WORKAROUND_QCOM_FALKOR_E1003 + b .Lskip_falkor_e1003\@ +alternative_else_nop_endif /* ASID already in \tmp[63:48] */ - movk \tmp, #:abs_g2_nc:(TRAMP_VALIAS >> 12) - movk \tmp, #:abs_g1_nc:(TRAMP_VALIAS >> 12) - /* 2MB boundary containing the vectors, so we nobble the walk cache */ - movk \tmp, #:abs_g0_nc:((TRAMP_VALIAS & ~(SZ_2M - 1)) >> 12) +alternative_if ARM64_USE_PAGE_SIZE_4K + movk \tmp, #:abs_g2_nc:(TRAMP_VALIAS(ARM64_PAGE_SHIFT_4K) >> 12) + movk \tmp, #:abs_g1_nc:(TRAMP_VALIAS(ARM64_PAGE_SHIFT_4K) >> 12) + movk \tmp, #:abs_g0_nc:((TRAMP_VALIAS(ARM64_PAGE_SHIFT_4K) & ~(SZ_2M - 1)) >> 12) + b .Lfinish_falkor_e1003\@ +alternative_else_nop_endif +alternative_if ARM64_USE_PAGE_SIZE_16K + movk \tmp, #:abs_g2_nc:(TRAMP_VALIAS(ARM64_PAGE_SHIFT_16K) >> 12) + movk \tmp, #:abs_g1_nc:(TRAMP_VALIAS(ARM64_PAGE_SHIFT_16K) >> 12) + movk \tmp, #:abs_g0_nc:((TRAMP_VALIAS(ARM64_PAGE_SHIFT_16K) & ~(SZ_2M - 1)) >> 12) +alternative_else /* ARM64_USE_PAGE_SIZE_64K */ + movk \tmp, #:abs_g2_nc:(TRAMP_VALIAS(ARM64_PAGE_SHIFT_64K) >> 12) + movk \tmp, #:abs_g1_nc:(TRAMP_VALIAS(ARM64_PAGE_SHIFT_64K) >> 12) + movk \tmp, #:abs_g0_nc:((TRAMP_VALIAS(ARM64_PAGE_SHIFT_64K) & ~(SZ_2M - 1)) >> 12) +alternative_endif +.Lfinish_falkor_e1003\@: isb tlbi vae1, \tmp dsb nsh -alternative_else_nop_endif +.Lskip_falkor_e1003\@: #endif /* CONFIG_QCOM_FALKOR_ERRATUM_1003 */ .endm -- 2.43.0
