@@ -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
@@ -265,20 +265,7 @@ early_param("mem", early_mem);
void __init arm64_memblock_init(void)
{
- s64 linear_region_size;
-
-#if VA_BITS > 48
- if (cpuid_feature_extract_unsigned_field(
- read_sysreg_s(SYS_ID_AA64MMFR2_EL1),
- ID_AA64MMFR2_LVA_SHIFT))
- vabits_actual = VA_BITS;
-
- /* make the variable visible to secondaries with the MMU off */
- dcache_clean_inval_poc((u64)&vabits_actual,
- (u64)&vabits_actual + sizeof(vabits_actual));
-#endif
-
- linear_region_size = PAGE_END - _PAGE_OFFSET(vabits_actual);
+ s64 linear_region_size = PAGE_END - _PAGE_OFFSET(vabits_actual);
/*
* Corner case: 52-bit VA capable systems running KVM in nVHE mode may
@@ -398,6 +398,8 @@ SYM_FUNC_END(idmap_kpti_install_ng_mappings)
*
* Initialise the processor for turning the MMU on.
*
+ * Input:
+ * x0 - actual number of VA bits (ignored unless VA_BITS > 48)
* Output:
* Return in x0 the value of the SCTLR_EL1 register.
*/
@@ -467,8 +469,7 @@ SYM_FUNC_START(__cpu_setup)
tcr_clear_errata_bits tcr, x9, x5
#ifdef CONFIG_ARM64_VA_BITS_52
- ldr_l x9, vabits_actual
- sub x9, xzr, x9
+ sub x9, xzr, x0
add x9, x9, #64
tcr_set_t1sz tcr, x9
#else
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> --- v3: fix KASAN too arch/arm64/kernel/head.S | 18 ++++++++++++++++++ arch/arm64/mm/init.c | 15 +-------------- arch/arm64/mm/proc.S | 5 +++-- 3 files changed, 22 insertions(+), 16 deletions(-)