diff options
| author | Ard Biesheuvel <[email protected]> | 2024-02-14 13:29:12 +0100 |
|---|---|---|
| committer | Catalin Marinas <[email protected]> | 2024-02-16 12:42:36 +0000 |
| commit | 68aec33f8f5a87b0450159e5e141d2d6c9d76850 (patch) | |
| tree | 843df4cd63f61c422fef4013e184d8748c62f9a3 /arch/arm64/include/asm/assembler.h | |
| parent | 9cce9c6c2c3b7d46698d9bb693389d37740fec28 (diff) | |
arm64: mm: Add feature override support for LVA
Add support for overriding the VARange field of the MMFR2 CPU ID
register. This permits the associated LVA feature to be overridden early
enough for the boot code that creates the kernel mapping to take it into
account.
Given that LPA2 implies LVA, disabling the latter should disable the
former as well. So override the ID_AA64MMFR0.TGran field of the current
page size as well if it advertises support for 52-bit addressing.
Signed-off-by: Ard Biesheuvel <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Catalin Marinas <[email protected]>
Diffstat (limited to 'arch/arm64/include/asm/assembler.h')
| -rw-r--r-- | arch/arm64/include/asm/assembler.h | 17 |
1 files changed, 10 insertions, 7 deletions
diff --git a/arch/arm64/include/asm/assembler.h b/arch/arm64/include/asm/assembler.h index 6a467c694039..68a99b116256 100644 --- a/arch/arm64/include/asm/assembler.h +++ b/arch/arm64/include/asm/assembler.h @@ -576,18 +576,21 @@ alternative_endif .endm /* - * Offset ttbr1 to allow for 48-bit kernel VAs set with 52-bit PTRS_PER_PGD. + * If the kernel is built for 52-bit virtual addressing but the hardware only + * supports 48 bits, we cannot program the pgdir address into TTBR1 directly, + * but we have to add an offset so that the TTBR1 address corresponds with the + * pgdir entry that covers the lowest 48-bit addressable VA. + * * orr is used as it can cover the immediate value (and is idempotent). - * In future this may be nop'ed out when dealing with 52-bit kernel VAs. * ttbr: Value of ttbr to set, modified. */ .macro offset_ttbr1, ttbr, tmp #ifdef CONFIG_ARM64_VA_BITS_52 - mrs_s \tmp, SYS_ID_AA64MMFR2_EL1 - and \tmp, \tmp, #(0xf << ID_AA64MMFR2_EL1_VARange_SHIFT) - cbnz \tmp, .Lskipoffs_\@ - orr \ttbr, \ttbr, #TTBR1_BADDR_4852_OFFSET -.Lskipoffs_\@ : + mrs \tmp, tcr_el1 + and \tmp, \tmp, #TCR_T1SZ_MASK + cmp \tmp, #TCR_T1SZ(VA_BITS_MIN) + orr \tmp, \ttbr, #TTBR1_BADDR_4852_OFFSET + csel \ttbr, \tmp, \ttbr, eq #endif .endm |