diff options
| author | Ard Biesheuvel <ardb@kernel.org> | 2024-02-14 15:29:19 +0300 |
|---|---|---|
| committer | Catalin Marinas <catalin.marinas@arm.com> | 2024-02-16 15:42:40 +0300 |
| commit | 9684ec186f8fadde52d6b6eaf64ca508897d0c71 (patch) | |
| tree | 882ec5014e3d34cb826a7236a847e3591bc7129b /arch/arm64/mm | |
| parent | 2b6c8f96cc47eb1b41f7ebf28dfc2459c39f7fa9 (diff) | |
| download | linux-9684ec186f8fadde52d6b6eaf64ca508897d0c71.tar.xz | |
arm64: Enable LPA2 at boot if supported by the system
Update the early kernel mapping code to take 52-bit virtual addressing
into account based on the LPA2 feature. This is a bit more involved than
LVA (which is supported with 64k pages only), given that some page table
descriptor bits change meaning in this case.
To keep the handling in asm to a minimum, the initial ID map is still
created with 48-bit virtual addressing, which implies that the kernel
image must be loaded into 48-bit addressable physical memory. This is
currently required by the boot protocol, even though we happen to
support placement outside of that for LVA/64k based configurations.
Enabling LPA2 involves more than setting TCR.T1SZ to a lower value,
there is also a DS bit in TCR that needs to be set, and which changes
the meaning of bits [9:8] in all page table descriptors. Since we cannot
enable DS and every live page table descriptor at the same time, let's
pivot through another temporary mapping. This avoids the need to
reintroduce manipulations of the page tables with the MMU and caches
disabled.
To permit the LPA2 feature to be overridden on the kernel command line,
which may be necessary to work around silicon errata, or to deal with
mismatched features on heterogeneous SoC designs, test for CPU feature
overrides first, and only then enable LPA2.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20240214122845.2033971-78-ardb+git@google.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Diffstat (limited to 'arch/arm64/mm')
| -rw-r--r-- | arch/arm64/mm/init.c | 2 | ||||
| -rw-r--r-- | arch/arm64/mm/mmu.c | 6 | ||||
| -rw-r--r-- | arch/arm64/mm/proc.S | 3 |
3 files changed, 9 insertions, 2 deletions
diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c index 74c1db8ce271..0f427b50fdc3 100644 --- a/arch/arm64/mm/init.c +++ b/arch/arm64/mm/init.c @@ -238,7 +238,7 @@ void __init arm64_memblock_init(void) * physical address of PAGE_OFFSET, we have to *subtract* from it. */ if (IS_ENABLED(CONFIG_ARM64_VA_BITS_52) && (vabits_actual != 52)) - memstart_addr -= _PAGE_OFFSET(48) - _PAGE_OFFSET(52); + memstart_addr -= _PAGE_OFFSET(vabits_actual) - _PAGE_OFFSET(52); /* * Apply the memory limit if it was set. Since the kernel may be loaded diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c index d2e9dec38a15..d30ae4d3fdd9 100644 --- a/arch/arm64/mm/mmu.c +++ b/arch/arm64/mm/mmu.c @@ -582,8 +582,12 @@ static void __init map_mem(pgd_t *pgdp) * entries at any level are being shared between the linear region and * the vmalloc region. Check whether this is true for the PGD level, in * which case it is guaranteed to be true for all other levels as well. + * (Unless we are running with support for LPA2, in which case the + * entire reduced VA space is covered by a single pgd_t which will have + * been populated without the PXNTable attribute by the time we get here.) */ - BUILD_BUG_ON(pgd_index(direct_map_end - 1) == pgd_index(direct_map_end)); + BUILD_BUG_ON(pgd_index(direct_map_end - 1) == pgd_index(direct_map_end) && + pgd_index(_PAGE_OFFSET(VA_BITS_MIN)) != PTRS_PER_PGD - 1); early_kfence_pool = arm64_kfence_alloc_pool(); diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S index fa0d7c63f8d2..9d40f3ffd8d2 100644 --- a/arch/arm64/mm/proc.S +++ b/arch/arm64/mm/proc.S @@ -488,6 +488,9 @@ SYM_FUNC_START(__cpu_setup) mov x9, #64 - VA_BITS alternative_if ARM64_HAS_VA52 tcr_set_t1sz tcr, x9 +#ifdef CONFIG_ARM64_LPA2 + orr tcr, tcr, #TCR_DS +#endif alternative_else_nop_endif #endif |