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| author | Ard Biesheuvel <ardb@kernel.org> | 2022-07-01 13:10:45 +0200 |
|---|---|---|
| committer | Will Deacon <will@kernel.org> | 2022-07-01 15:19:07 +0100 |
| commit | 0aaa68532e9da5cd6b1383e1535a5526253e359f (patch) | |
| tree | 25ed4fb29514509bdb8e05458c302e05a8c4840f /arch/arm64/kernel/head.S | |
| parent | bdbcd22d491212c266589892f0818c65a2bc4704 (diff) | |
| download | linux-0aaa68532e9da5cd6b1383e1535a5526253e359f.tar.gz linux-0aaa68532e9da5cd6b1383e1535a5526253e359f.tar.bz2 linux-0aaa68532e9da5cd6b1383e1535a5526253e359f.zip | |
arm64: mm: fix booting with 52-bit address space
Joey reports that booting 52-bit VA capable builds on 52-bit VA capable
CPUs is broken since commit 0d9b1ffefabe ("arm64: mm: make vabits_actual
a build time constant if possible"). This is due to the fact that the
primary CPU reads the vabits_actual variable before it has been
assigned.
The reason for deferring the assignment of vabits_actual was that we try
to perform as few stores to memory as we can with the MMU and caches
off, due to the cache coherency issues it creates.
Since __cpu_setup() [which is where the read of vabits_actual occurs] is
also called on the secondary boot path, we cannot just read the CPU ID
registers directly, given that the size of the VA space is decided by
the capabilities of the primary CPU. So let's read vabits_actual only on
the secondary boot path, and read the CPU ID registers directly on the
primary boot path, by making it a function parameter of __cpu_setup().
To ensure that all users of vabits_actual (including kasan_early_init())
observe the correct value, move the assignment of vabits_actual back
into asm code, but still defer it to after the MMU and caches have been
enabled.
Cc: Will Deacon <will@kernel.org>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Fixes: 0d9b1ffefabe ("arm64: mm: make vabits_actual a build time constant if possible")
Reported-by: Joey Gouly <joey.gouly@arm.com>
Co-developed-by: Joey Gouly <joey.gouly@arm.com>
Signed-off-by: Joey Gouly <joey.gouly@arm.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20220701111045.2944309-1-ardb@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
Diffstat (limited to 'arch/arm64/kernel/head.S')
| -rw-r--r-- | arch/arm64/kernel/head.S | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S index c300b43659dc..ae0a9e44ca19 100644 --- a/arch/arm64/kernel/head.S +++ b/arch/arm64/kernel/head.S @@ -82,6 +82,7 @@ * x22 create_idmap() .. start_kernel() ID map VA of the DT blob * x23 primary_entry() .. start_kernel() physical misalignment/KASLR offset * x24 __primary_switch() linear map KASLR seed + * x25 primary_entry() .. start_kernel() supported VA size * x28 create_idmap() callee preserved temp register */ SYM_CODE_START(primary_entry) @@ -96,6 +97,14 @@ SYM_CODE_START(primary_entry) * On return, the CPU will be ready for the MMU to be turned on and * the TCR will have been set. */ +#if VA_BITS > 48 + mrs_s x0, SYS_ID_AA64MMFR2_EL1 + tst x0, #0xf << ID_AA64MMFR2_LVA_SHIFT + mov x0, #VA_BITS + mov x25, #VA_BITS_MIN + csel x25, x25, x0, eq + mov x0, x25 +#endif bl __cpu_setup // initialise processor b __primary_switch SYM_CODE_END(primary_entry) @@ -434,6 +443,12 @@ SYM_FUNC_START_LOCAL(__primary_switched) bl __pi_memset dsb ishst // Make zero page visible to PTW +#if VA_BITS > 48 + adr_l x8, vabits_actual // Set this early so KASAN early init + str x25, [x8] // ... observes the correct value + dc civac, x8 // Make visible to booting secondaries +#endif + #ifdef CONFIG_RANDOMIZE_BASE adrp x5, memstart_offset_seed // Save KASLR linear map seed strh w24, [x5, :lo12:memstart_offset_seed] @@ -579,6 +594,9 @@ SYM_FUNC_START_LOCAL(secondary_startup) mov x20, x0 // preserve boot mode bl switch_to_vhe bl __cpu_secondary_check52bitva +#if VA_BITS > 48 + ldr_l x0, vabits_actual +#endif bl __cpu_setup // initialise processor adrp x1, swapper_pg_dir adrp x2, idmap_pg_dir |