From: Peter Hoyes Peter.Hoyes@arm.com
Armv8r64 is the first Armv8 platform that only has a PMSA at the current exception level. The architecture supplement for Armv8r64 describes new fields in ID_AA64MMFR0_EL1 which can be used to detect whether a VMSA or PMSA is present. These fields are RES0 on Armv8a.
Add logic to read these fields and, for the protection of the memory used by U-Boot, initialize the MPU instead of the MMU during init, then clear the MPU regions before transition to the next stage.
Provide a default (blank) MPU memory map, which can be overridden by board configurations.
Signed-off-by: Peter Hoyes Peter.Hoyes@arm.com --- arch/arm/cpu/armv8/cache_v8.c | 96 +++++++++++++++++++++++++++++++- arch/arm/include/asm/armv8/mpu.h | 61 ++++++++++++++++++++ 2 files changed, 154 insertions(+), 3 deletions(-) create mode 100644 arch/arm/include/asm/armv8/mpu.h
diff --git a/arch/arm/cpu/armv8/cache_v8.c b/arch/arm/cpu/armv8/cache_v8.c index 3de18c7675..46625675bd 100644 --- a/arch/arm/cpu/armv8/cache_v8.c +++ b/arch/arm/cpu/armv8/cache_v8.c @@ -15,6 +15,7 @@ #include <asm/global_data.h> #include <asm/system.h> #include <asm/armv8/mmu.h> +#include <asm/armv8/mpu.h>
DECLARE_GLOBAL_DATA_PTR;
@@ -365,6 +366,86 @@ __weak u64 get_page_table_size(void) return size; }
+static void mpu_clear_regions(void) +{ + int i; + + for (i = 0; mpu_mem_map[i].end || mpu_mem_map[i].attrs; i++) { + setup_el2_mpu_region(i, 0, 0); + } +} + +static struct mpu_region default_mpu_mem_map[] = {{0,}}; +__weak struct mpu_region *mpu_mem_map = default_mpu_mem_map; + +static void mpu_setup(void) +{ + int i; + + if (current_el() != 2) { + panic("MPU configuration is only supported at EL2"); + } + + set_sctlr(get_sctlr() & ~(CR_M | CR_WXN)); + + asm volatile("msr MAIR_EL2, %0" : : "r" MEMORY_ATTRIBUTES); + + for (i = 0; mpu_mem_map[i].end || mpu_mem_map[i].attrs; i++) { + setup_el2_mpu_region(i, + PRBAR_ADDRESS(mpu_mem_map[i].start) + | PRBAR_OUTER_SH | PRBAR_AP_RW_ANY, + PRLAR_ADDRESS(mpu_mem_map[i].end) + | mpu_mem_map[i].attrs | PRLAR_EN_BIT + ); + } + + set_sctlr(get_sctlr() | CR_M); +} + +static bool el_has_mmu(void) +{ + uint64_t id_aa64mmfr0; + asm volatile("mrs %0, id_aa64mmfr0_el1" + : "=r" (id_aa64mmfr0) : : "cc"); + uint64_t msa = id_aa64mmfr0 & ID_AA64MMFR0_EL1_MSA_MASK; + uint64_t msa_frac = id_aa64mmfr0 & ID_AA64MMFR0_EL1_MSA_FRAC_MASK; + + switch (msa) { + case ID_AA64MMFR0_EL1_MSA_VMSA: + /* + * VMSA supported in all translation regimes. + * No support for PMSA. + */ + return true; + case ID_AA64MMFR0_EL1_MSA_USE_FRAC: + /* See MSA_frac for the supported MSAs. */ + switch (msa_frac) { + case ID_AA64MMFR0_EL1_MSA_FRAC_NO_PMSA: + /* + * PMSA not supported in any translation + * regime. + */ + return true; + case ID_AA64MMFR0_EL1_MSA_FRAC_VMSA: + /* + * PMSA supported in all translation + * regimes. No support for VMSA. + */ + case ID_AA64MMFR0_EL1_MSA_FRAC_PMSA: + /* + * PMSA supported in all translation + * regimes. + */ + return false; + default: + panic("Unsupported id_aa64mmfr0_el1 " \ + "MSA_frac value"); + } + default: + panic("Unsupported id_aa64mmfr0_el1 MSA value"); + } +} + void setup_pgtables(void) { int i; @@ -479,8 +560,13 @@ void dcache_enable(void) /* The data cache is not active unless the mmu is enabled */ if (!(get_sctlr() & CR_M)) { invalidate_dcache_all(); - __asm_invalidate_tlb_all(); - mmu_setup(); + + if (el_has_mmu()) { + __asm_invalidate_tlb_all(); + mmu_setup(); + } else { + mpu_setup(); + } }
set_sctlr(get_sctlr() | CR_C); @@ -499,7 +585,11 @@ void dcache_disable(void) set_sctlr(sctlr & ~(CR_C|CR_M));
flush_dcache_all(); - __asm_invalidate_tlb_all(); + + if (el_has_mmu()) + __asm_invalidate_tlb_all(); + else + mpu_clear_regions(); }
int dcache_status(void) diff --git a/arch/arm/include/asm/armv8/mpu.h b/arch/arm/include/asm/armv8/mpu.h new file mode 100644 index 0000000000..c6c8828325 --- /dev/null +++ b/arch/arm/include/asm/armv8/mpu.h @@ -0,0 +1,61 @@ +/* + * SPDX-License-Identifier: GPL-2.0+ + * + * (C) Copyright 2021 Arm Limited + */ + +#ifndef _ASM_ARMV8_MPU_H_ +#define _ASM_ARMV8_MPU_H_ + +#include <asm/armv8/mmu.h> +#include <asm/barriers.h> +#include <linux/stringify.h> + +#define PRSELR_EL2 S3_4_c6_c2_1 +#define PRBAR_EL2 S3_4_c6_c8_0 +#define PRLAR_EL2 S3_4_c6_c8_1 +#define MPUIR_EL2 S3_4_c0_c0_4 + +#define PRBAR_ADDRESS(addr) ((addr) & ~(0x3fULL)) + +/* Access permissions */ +#define PRBAR_AP(val) (((val) & 0x3) << 2) +#define PRBAR_AP_RW_HYP PRBAR_AP(0x0) +#define PRBAR_AP_RW_ANY PRBAR_AP(0x1) +#define PRBAR_AP_RO_HYP PRBAR_AP(0x2) +#define PRBAR_AP_RO_ANY PRBAR_AP(0x3) + +/* Shareability */ +#define PRBAR_SH(val) (((val) & 0x3) << 4) +#define PRBAR_NON_SH PRBAR_SH(0x0) +#define PRBAR_OUTER_SH PRBAR_SH(0x2) +#define PRBAR_INNER_SH PRBAR_SH(0x3) + +/* Memory attribute (MAIR idx) */ +#define PRLAR_ATTRIDX(val) (((val) & 0x7) << 1) +#define PRLAR_EN_BIT (0x1) +#define PRLAR_ADDRESS(addr) ((addr) & ~(0x3fULL)) + +#ifndef __ASSEMBLY__ + +static inline void setup_el2_mpu_region(uint8_t region, uint64_t base, uint64_t limit) +{ + asm volatile("msr " __stringify(PRSELR_EL2) ", %0" : : "r" (region)); + isb(); + asm volatile("msr " __stringify(PRBAR_EL2) ", %0" : : "r" (base)); + asm volatile("msr " __stringify(PRLAR_EL2) ", %0" : : "r" (limit)); + dsb(); + isb(); +} + +#endif + +struct mpu_region { + u64 start; + u64 end; + u64 attrs; +}; + +extern struct mpu_region *mpu_mem_map; + +#endif /* _ASM_ARMV8_MPU_H_ */