diff options
| -rw-r--r-- | arch/arm64/include/asm/mmu_context.h | 43 | ||||
| -rw-r--r-- | arch/arm64/include/asm/page.h | 6 | ||||
| -rw-r--r-- | arch/arm64/include/asm/pgtable-hwdef.h | 7 | ||||
| -rw-r--r-- | arch/arm64/kernel/head.S | 37 | ||||
| -rw-r--r-- | arch/arm64/kernel/smp.c | 1 | ||||
| -rw-r--r-- | arch/arm64/mm/mmu.c | 7 | ||||
| -rw-r--r-- | arch/arm64/mm/proc-macros.S | 10 | ||||
| -rw-r--r-- | arch/arm64/mm/proc.S | 3 |
8 files changed, 110 insertions, 4 deletions
diff --git a/arch/arm64/include/asm/mmu_context.h b/arch/arm64/include/asm/mmu_context.h index a9eee33..ecf2d06 100644 --- a/arch/arm64/include/asm/mmu_context.h +++ b/arch/arm64/include/asm/mmu_context.h @@ -64,6 +64,49 @@ static inline void cpu_set_reserved_ttbr0(void) : "r" (ttbr)); } +/* + * TCR.T0SZ value to use when the ID map is active. Usually equals + * TCR_T0SZ(VA_BITS), unless system RAM is positioned very high in + * physical memory, in which case it will be smaller. + */ +extern u64 idmap_t0sz; + +static inline bool __cpu_uses_extended_idmap(void) +{ + return (!IS_ENABLED(CONFIG_ARM64_VA_BITS_48) && + unlikely(idmap_t0sz != TCR_T0SZ(VA_BITS))); +} + +static inline void __cpu_set_tcr_t0sz(u64 t0sz) +{ + unsigned long tcr; + + if (__cpu_uses_extended_idmap()) + asm volatile ( + " mrs %0, tcr_el1 ;" + " bfi %0, %1, %2, %3 ;" + " msr tcr_el1, %0 ;" + " isb" + : "=&r" (tcr) + : "r"(t0sz), "I"(TCR_T0SZ_OFFSET), "I"(TCR_TxSZ_WIDTH)); +} + +/* + * Set TCR.T0SZ to the value appropriate for activating the identity map. + */ +static inline void cpu_set_idmap_tcr_t0sz(void) +{ + __cpu_set_tcr_t0sz(idmap_t0sz); +} + +/* + * Set TCR.T0SZ to its default value (based on VA_BITS) + */ +static inline void cpu_set_default_tcr_t0sz(void) +{ + __cpu_set_tcr_t0sz(TCR_T0SZ(VA_BITS)); +} + static inline void switch_new_context(struct mm_struct *mm) { unsigned long flags; diff --git a/arch/arm64/include/asm/page.h b/arch/arm64/include/asm/page.h index 22b1623..3d02b18 100644 --- a/arch/arm64/include/asm/page.h +++ b/arch/arm64/include/asm/page.h @@ -33,7 +33,9 @@ * image. Both require pgd, pud (4 levels only) and pmd tables to (section) * map the kernel. With the 64K page configuration, swapper and idmap need to * map to pte level. The swapper also maps the FDT (see __create_page_tables - * for more information). + * for more information). Note that the number of ID map translation levels + * could be increased on the fly if system RAM is out of reach for the default + * VA range, so 3 pages are reserved in all cases. */ #ifdef CONFIG_ARM64_64K_PAGES #define SWAPPER_PGTABLE_LEVELS (CONFIG_ARM64_PGTABLE_LEVELS) @@ -42,7 +44,7 @@ #endif #define SWAPPER_DIR_SIZE (SWAPPER_PGTABLE_LEVELS * PAGE_SIZE) -#define IDMAP_DIR_SIZE (SWAPPER_DIR_SIZE) +#define IDMAP_DIR_SIZE (3 * PAGE_SIZE) #ifndef __ASSEMBLY__ diff --git a/arch/arm64/include/asm/pgtable-hwdef.h b/arch/arm64/include/asm/pgtable-hwdef.h index 5f930cc..847e864 100644 --- a/arch/arm64/include/asm/pgtable-hwdef.h +++ b/arch/arm64/include/asm/pgtable-hwdef.h @@ -143,7 +143,12 @@ /* * TCR flags. */ -#define TCR_TxSZ(x) (((UL(64) - (x)) << 16) | ((UL(64) - (x)) << 0)) +#define TCR_T0SZ_OFFSET 0 +#define TCR_T1SZ_OFFSET 16 +#define TCR_T0SZ(x) ((UL(64) - (x)) << TCR_T0SZ_OFFSET) +#define TCR_T1SZ(x) ((UL(64) - (x)) << TCR_T1SZ_OFFSET) +#define TCR_TxSZ(x) (TCR_T0SZ(x) | TCR_T1SZ(x)) +#define TCR_TxSZ_WIDTH 6 #define TCR_IRGN_NC ((UL(0) << 8) | (UL(0) << 24)) #define TCR_IRGN_WBWA ((UL(1) << 8) | (UL(1) << 24)) #define TCR_IRGN_WT ((UL(2) << 8) | (UL(2) << 24)) diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S index 1fdf420..51c9811 100644 --- a/arch/arm64/kernel/head.S +++ b/arch/arm64/kernel/head.S @@ -383,6 +383,43 @@ __create_page_tables: */ mov x0, x25 // idmap_pg_dir adrp x3, KERNEL_START // __pa(KERNEL_START) + +#ifndef CONFIG_ARM64_VA_BITS_48 +#define EXTRA_SHIFT (PGDIR_SHIFT + PAGE_SHIFT - 3) +#define EXTRA_PTRS (1 << (48 - EXTRA_SHIFT)) + + /* + * If VA_BITS < 48, it may be too small to allow for an ID mapping to be + * created that covers system RAM if that is located sufficiently high + * in the physical address space. So for the ID map, use an extended + * virtual range in that case, by configuring an additional translation + * level. + * First, we have to verify our assumption that the current value of + * VA_BITS was chosen such that all translation levels are fully + * utilised, and that lowering T0SZ will always result in an additional + * translation level to be configured. + */ +#if VA_BITS != EXTRA_SHIFT +#error "Mismatch between VA_BITS and page size/number of translation levels" +#endif + + /* + * Calculate the maximum allowed value for TCR_EL1.T0SZ so that the + * entire kernel image can be ID mapped. As T0SZ == (64 - #bits used), + * this number conveniently equals the number of leading zeroes in + * the physical address of KERNEL_END. + */ + adrp x5, KERNEL_END + clz x5, x5 + cmp x5, TCR_T0SZ(VA_BITS) // default T0SZ small enough? + b.ge 1f // .. then skip additional level + + str_l x5, idmap_t0sz, x6 + + create_table_entry x0, x3, EXTRA_SHIFT, EXTRA_PTRS, x5, x6 +1: +#endif + create_pgd_entry x0, x3, x5, x6 mov x5, x3 // __pa(KERNEL_START) adr_l x6, KERNEL_END // __pa(KERNEL_END) diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c index 4257369..ffe8e1b 100644 --- a/arch/arm64/kernel/smp.c +++ b/arch/arm64/kernel/smp.c @@ -151,6 +151,7 @@ asmlinkage void secondary_start_kernel(void) */ cpu_set_reserved_ttbr0(); flush_tlb_all(); + cpu_set_default_tcr_t0sz(); preempt_disable(); trace_hardirqs_off(); diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c index c9267ac..428aaf8 100644 --- a/arch/arm64/mm/mmu.c +++ b/arch/arm64/mm/mmu.c @@ -40,6 +40,8 @@ #include "mm.h" +u64 idmap_t0sz = TCR_T0SZ(VA_BITS); + /* * Empty_zero_page is a special page that is used for zero-initialized data * and COW. @@ -454,6 +456,7 @@ void __init paging_init(void) */ cpu_set_reserved_ttbr0(); flush_tlb_all(); + cpu_set_default_tcr_t0sz(); } /* @@ -461,8 +464,10 @@ void __init paging_init(void) */ void setup_mm_for_reboot(void) { - cpu_switch_mm(idmap_pg_dir, &init_mm); + cpu_set_reserved_ttbr0(); flush_tlb_all(); + cpu_set_idmap_tcr_t0sz(); + cpu_switch_mm(idmap_pg_dir, &init_mm); } /* diff --git a/arch/arm64/mm/proc-macros.S b/arch/arm64/mm/proc-macros.S index 005d29e..4c4d93c 100644 --- a/arch/arm64/mm/proc-macros.S +++ b/arch/arm64/mm/proc-macros.S @@ -52,3 +52,13 @@ mov \reg, #4 // bytes per word lsl \reg, \reg, \tmp // actual cache line size .endm + +/* + * tcr_set_idmap_t0sz - update TCR.T0SZ so that we can load the ID map + */ + .macro tcr_set_idmap_t0sz, valreg, tmpreg +#ifndef CONFIG_ARM64_VA_BITS_48 + ldr_l \tmpreg, idmap_t0sz + bfi \valreg, \tmpreg, #TCR_T0SZ_OFFSET, #TCR_TxSZ_WIDTH +#endif + .endm diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S index 28eebfb..cdd754e 100644 --- a/arch/arm64/mm/proc.S +++ b/arch/arm64/mm/proc.S @@ -156,6 +156,7 @@ ENTRY(cpu_do_resume) msr cpacr_el1, x6 msr ttbr0_el1, x1 msr ttbr1_el1, x7 + tcr_set_idmap_t0sz x8, x7 msr tcr_el1, x8 msr vbar_el1, x9 msr mdscr_el1, x10 @@ -233,6 +234,8 @@ ENTRY(__cpu_setup) */ ldr x10, =TCR_TxSZ(VA_BITS) | TCR_CACHE_FLAGS | TCR_SMP_FLAGS | \ TCR_TG_FLAGS | TCR_ASID16 | TCR_TBI0 + tcr_set_idmap_t0sz x10, x9 + /* * Read the PARange bits from ID_AA64MMFR0_EL1 and set the IPS bits in * TCR_EL1. |