/* * Copyright (c) 2013-2024, Arm Limited and Contributors. All rights reserved. * * SPDX-License-Identifier: BSD-3-Clause */ #include #include #include #include #include .globl smc .globl zero_normalmem .globl zeromem .globl memcpy16 .globl disable_mmu_el1 .globl disable_mmu_el3 .globl disable_mmu_icache_el1 .globl disable_mmu_icache_el3 .globl fixup_gdt_reloc #if SUPPORT_VFP .globl enable_vfp #endif func smc smc #0 endfunc smc /* ----------------------------------------------------------------------- * void zero_normalmem(void *mem, unsigned int length); * * Initialise a region in normal memory to 0. This functions complies with the * AAPCS and can be called from C code. * * NOTE: MMU must be enabled when using this function as it can only operate on * normal memory. It is intended to be mainly used from C code when MMU * is usually enabled. * ----------------------------------------------------------------------- */ .equ zero_normalmem, zeromem_dczva /* ----------------------------------------------------------------------- * void zeromem(void *mem, unsigned int length); * * Initialise a region of device memory to 0. This functions complies with the * AAPCS and can be called from C code. * * NOTE: When data caches and MMU are enabled, zero_normalmem can usually be * used instead for faster zeroing. * * ----------------------------------------------------------------------- */ func zeromem /* x2 is the address past the last zeroed address */ add x2, x0, x1 /* * Uses the fallback path that does not use DC ZVA instruction and * therefore does not need enabled MMU */ b .Lzeromem_dczva_fallback_entry endfunc zeromem /* ----------------------------------------------------------------------- * void zeromem_dczva(void *mem, unsigned int length); * * Fill a region of normal memory of size "length" in bytes with null bytes. * MMU must be enabled and the memory be of * normal type. This is because this function internally uses the DC ZVA * instruction, which generates an Alignment fault if used on any type of * Device memory (see section D3.4.9 of the ARMv8 ARM, issue k). When the MMU * is disabled, all memory behaves like Device-nGnRnE memory (see section * D4.2.8), hence the requirement on the MMU being enabled. * NOTE: The code assumes that the block size as defined in DCZID_EL0 * register is at least 16 bytes. * * ----------------------------------------------------------------------- */ func zeromem_dczva /* * The function consists of a series of loops that zero memory one byte * at a time, 16 bytes at a time or using the DC ZVA instruction to * zero aligned block of bytes, which is assumed to be more than 16. * In the case where the DC ZVA instruction cannot be used or if the * first 16 bytes loop would overflow, there is fallback path that does * not use DC ZVA. * Note: The fallback path is also used by the zeromem function that * branches to it directly. * * +---------+ zeromem_dczva * | entry | * +----+----+ * | * v * +---------+ * | checks |>o-------+ (If any check fails, fallback) * +----+----+ | * | |---------------+ * v | Fallback path | * +------+------+ |---------------+ * | 1 byte loop | | * +------+------+ .Lzeromem_dczva_initial_1byte_aligned_end * | | * v | * +-------+-------+ | * | 16 bytes loop | | * +-------+-------+ | * | | * v | * +------+------+ .Lzeromem_dczva_blocksize_aligned * | DC ZVA loop | | * +------+------+ | * +--------+ | | * | | | | * | v v | * | +-------+-------+ .Lzeromem_dczva_final_16bytes_aligned * | | 16 bytes loop | | * | +-------+-------+ | * | | | * | v | * | +------+------+ .Lzeromem_dczva_final_1byte_aligned * | | 1 byte loop | | * | +-------------+ | * | | | * | v | * | +---+--+ | * | | exit | | * | +------+ | * | | * | +--------------+ +------------------+ zeromem * | | +----------------| zeromem function | * | | | +------------------+ * | v v * | +-------------+ .Lzeromem_dczva_fallback_entry * | | 1 byte loop | * | +------+------+ * | | * +-----------+ */ /* * Readable names for registers * * Registers x0, x1 and x2 are also set by zeromem which * branches into the fallback path directly, so cursor, length and * stop_address should not be retargeted to other registers. */ cursor .req x0 /* Start address and then current address */ length .req x1 /* Length in bytes of the region to zero out */ /* Reusing x1 as length is never used after block_mask is set */ block_mask .req x1 /* Bitmask of the block size read in DCZID_EL0 */ stop_address .req x2 /* Address past the last zeroed byte */ block_size .req x3 /* Size of a block in bytes as read in DCZID_EL0 */ tmp1 .req x4 tmp2 .req x5 #if ENABLE_ASSERTIONS /* * Check for M bit (MMU enabled) of the current SCTLR_EL(1|3) * register value and panic if the MMU is disabled. */ #if defined(IMAGE_BL1) || defined(IMAGE_BL31) || (defined(IMAGE_BL2) && \ BL2_RUNS_AT_EL3) mrs tmp1, sctlr_el3 #else mrs tmp1, sctlr_el1 #endif tst tmp1, #SCTLR_M_BIT ASM_ASSERT(ne) #endif /* ENABLE_ASSERTIONS */ /* stop_address is the address past the last to zero */ add stop_address, cursor, length /* * Get block_size = (log2() >> 2) (see encoding of * dczid_el0 reg) */ mrs block_size, dczid_el0 /* * Select the 4 lowest bits and convert the extracted log2() to */ ubfx block_size, block_size, #0, #4 mov tmp2, #(1 << 2) lsl block_size, tmp2, block_size #if ENABLE_ASSERTIONS /* * Assumes block size is at least 16 bytes to avoid manual realignment * of the cursor at the end of the DCZVA loop. */ cmp block_size, #16 ASM_ASSERT(hs) #endif /* * Not worth doing all the setup for a region less than a block and * protects against zeroing a whole block when the area to zero is * smaller than that. Also, as it is assumed that the block size is at * least 16 bytes, this also protects the initial aligning loops from * trying to zero 16 bytes when length is less than 16. */ cmp length, block_size b.lo .Lzeromem_dczva_fallback_entry /* * Calculate the bitmask of the block alignment. It will never * underflow as the block size is between 4 bytes and 2kB. * block_mask = block_size - 1 */ sub block_mask, block_size, #1 /* * length alias should not be used after this point unless it is * defined as a register other than block_mask's. */ .unreq length /* * If the start address is already aligned to zero block size, go * straight to the cache zeroing loop. This is safe because at this * point, the length cannot be smaller than a block size. */ tst cursor, block_mask b.eq .Lzeromem_dczva_blocksize_aligned /* * Calculate the first block-size-aligned address. It is assumed that * the zero block size is at least 16 bytes. This address is the last * address of this initial loop. */ orr tmp1, cursor, block_mask add tmp1, tmp1, #1 /* * If the addition overflows, skip the cache zeroing loops. This is * quite unlikely however. */ cbz tmp1, .Lzeromem_dczva_fallback_entry /* * If the first block-size-aligned address is past the last address, * fallback to the simpler code. */ cmp tmp1, stop_address b.hi .Lzeromem_dczva_fallback_entry /* * If the start address is already aligned to 16 bytes, skip this loop. * It is safe to do this because tmp1 (the stop address of the initial * 16 bytes loop) will never be greater than the final stop address. */ tst cursor, #0xf b.eq .Lzeromem_dczva_initial_1byte_aligned_end /* Calculate the next address aligned to 16 bytes */ orr tmp2, cursor, #0xf add tmp2, tmp2, #1 /* If it overflows, fallback to the simple path (unlikely) */ cbz tmp2, .Lzeromem_dczva_fallback_entry /* * Next aligned address cannot be after the stop address because the * length cannot be smaller than 16 at this point. */ /* First loop: zero byte per byte */ 1: strb wzr, [cursor], #1 cmp cursor, tmp2 b.ne 1b .Lzeromem_dczva_initial_1byte_aligned_end: /* * Second loop: we need to zero 16 bytes at a time from cursor to tmp1 * before being able to use the code that deals with block-size-aligned * addresses. */ cmp cursor, tmp1 b.hs 2f 1: stp xzr, xzr, [cursor], #16 cmp cursor, tmp1 b.lo 1b 2: /* * Third loop: zero a block at a time using DC ZVA cache block zeroing * instruction. */ .Lzeromem_dczva_blocksize_aligned: /* * Calculate the last block-size-aligned address. If the result equals * to the start address, the loop will exit immediately. */ bic tmp1, stop_address, block_mask cmp cursor, tmp1 b.hs 2f 1: /* Zero the block containing the cursor */ dc zva, cursor /* Increment the cursor by the size of a block */ add cursor, cursor, block_size cmp cursor, tmp1 b.lo 1b 2: /* * Fourth loop: zero 16 bytes at a time and then byte per byte the * remaining area */ .Lzeromem_dczva_final_16bytes_aligned: /* * Calculate the last 16 bytes aligned address. It is assumed that the * block size will never be smaller than 16 bytes so that the current * cursor is aligned to at least 16 bytes boundary. */ bic tmp1, stop_address, #15 cmp cursor, tmp1 b.hs 2f 1: stp xzr, xzr, [cursor], #16 cmp cursor, tmp1 b.lo 1b 2: /* Fifth and final loop: zero byte per byte */ .Lzeromem_dczva_final_1byte_aligned: cmp cursor, stop_address b.eq 2f 1: strb wzr, [cursor], #1 cmp cursor, stop_address b.ne 1b 2: ret /* Fallback for unaligned start addresses */ .Lzeromem_dczva_fallback_entry: /* * If the start address is already aligned to 16 bytes, skip this loop. */ tst cursor, #0xf b.eq .Lzeromem_dczva_final_16bytes_aligned /* Calculate the next address aligned to 16 bytes */ orr tmp1, cursor, #15 add tmp1, tmp1, #1 /* If it overflows, fallback to byte per byte zeroing */ cbz tmp1, .Lzeromem_dczva_final_1byte_aligned /* If the next aligned address is after the stop address, fall back */ cmp tmp1, stop_address b.hs .Lzeromem_dczva_final_1byte_aligned /* Fallback entry loop: zero byte per byte */ 1: strb wzr, [cursor], #1 cmp cursor, tmp1 b.ne 1b b .Lzeromem_dczva_final_16bytes_aligned .unreq cursor /* * length is already unreq'ed to reuse the register for another * variable. */ .unreq stop_address .unreq block_size .unreq block_mask .unreq tmp1 .unreq tmp2 endfunc zeromem_dczva /* -------------------------------------------------------------------------- * void memcpy16(void *dest, const void *src, unsigned int length) * * Copy length bytes from memory area src to memory area dest. * The memory areas should not overlap. * Destination and source addresses must be 16-byte aligned. * -------------------------------------------------------------------------- */ func memcpy16 #if ENABLE_ASSERTIONS orr x3, x0, x1 tst x3, #0xf ASM_ASSERT(eq) #endif /* copy 16 bytes at a time */ m_loop16: cmp x2, #16 b.lo m_loop1 ldp x3, x4, [x1], #16 stp x3, x4, [x0], #16 sub x2, x2, #16 b m_loop16 /* copy byte per byte */ m_loop1: cbz x2, m_end ldrb w3, [x1], #1 strb w3, [x0], #1 subs x2, x2, #1 b.ne m_loop1 m_end: ret endfunc memcpy16 /* --------------------------------------------------------------------------- * Disable the MMU at EL3 * --------------------------------------------------------------------------- */ func disable_mmu_el3 mov x1, #(SCTLR_M_BIT | SCTLR_C_BIT) do_disable_mmu_el3: mrs x0, sctlr_el3 bic x0, x0, x1 msr sctlr_el3, x0 isb /* ensure MMU is off */ dsb sy ret endfunc disable_mmu_el3 func disable_mmu_icache_el3 mov x1, #(SCTLR_M_BIT | SCTLR_C_BIT | SCTLR_I_BIT) b do_disable_mmu_el3 endfunc disable_mmu_icache_el3 /* --------------------------------------------------------------------------- * Disable the MMU at EL1 * --------------------------------------------------------------------------- */ func disable_mmu_el1 mov x1, #(SCTLR_M_BIT | SCTLR_C_BIT) do_disable_mmu_el1: mrs x0, sctlr_el1 bic x0, x0, x1 msr sctlr_el1, x0 isb /* ensure MMU is off */ dsb sy ret endfunc disable_mmu_el1 func disable_mmu_icache_el1 mov x1, #(SCTLR_M_BIT | SCTLR_C_BIT | SCTLR_I_BIT) b do_disable_mmu_el1 endfunc disable_mmu_icache_el1 /* --------------------------------------------------------------------------- * Enable the use of VFP at EL3 * --------------------------------------------------------------------------- */ #if SUPPORT_VFP func enable_vfp mrs x0, cpacr_el1 orr x0, x0, #CPACR_VFP_BITS msr cpacr_el1, x0 mrs x0, cptr_el3 mov x1, #AARCH64_CPTR_TFP bic x0, x0, x1 msr cptr_el3, x0 isb ret endfunc enable_vfp #endif /* --------------------------------------------------------------------------- * Helper to fixup Global Descriptor table (GDT) and dynamic relocations * (.rela.dyn) at runtime. * * This function is meant to be used when the firmware is compiled with -fpie * and linked with -pie options. We rely on the linker script exporting * appropriate markers for start and end of the section. For GOT, we * expect __GOT_START__ and __GOT_END__. Similarly for .rela.dyn, we expect * __RELA_START__ and __RELA_END__. * * The function takes the limits of the memory to apply fixups to as * arguments (which is usually the limits of the relocable BL image). * x0 - the start of the fixup region * x1 - the limit of the fixup region * These addresses have to be 4KB page aligned. * --------------------------------------------------------------------------- */ /* Relocation codes */ #define R_AARCH64_NONE 0 #define R_AARCH64_RELATIVE 1027 func fixup_gdt_reloc mov x6, x0 mov x7, x1 #if ENABLE_ASSERTIONS /* Test if the limits are 4KB aligned */ orr x0, x0, x1 tst x0, #(PAGE_SIZE_MASK) ASM_ASSERT(eq) #endif /* * Calculate the offset based on return address in x30. * Assume that this function is called within a page at the start of * fixup region. */ and x2, x30, #~(PAGE_SIZE_MASK) subs x0, x2, x6 /* Diff(S) = Current Address - Compiled Address */ b.eq 3f /* Diff(S) = 0. No relocation needed */ adrp x1, __GOT_START__ add x1, x1, :lo12:__GOT_START__ adrp x2, __GOT_END__ add x2, x2, :lo12:__GOT_END__ /* * GOT is an array of 64_bit addresses which must be fixed up as * new_addr = old_addr + Diff(S). * The new_addr is the address currently the binary is executing from * and old_addr is the address at compile time. */ 1: ldr x3, [x1] /* Skip adding offset if address is < lower limit */ cmp x3, x6 b.lo 2f /* Skip adding offset if address is > upper limit */ cmp x3, x7 b.hi 2f add x3, x3, x0 str x3, [x1] 2: add x1, x1, #8 cmp x1, x2 b.lo 1b /* Starting dynamic relocations. Use adrp/adr to get RELA_START and END */ 3: adrp x1, __RELA_START__ add x1, x1, :lo12:__RELA_START__ adrp x2, __RELA_END__ add x2, x2, :lo12:__RELA_END__ /* * According to ELF-64 specification, the RELA data structure is as * follows: * typedef struct { * Elf64_Addr r_offset; * Elf64_Xword r_info; * Elf64_Sxword r_addend; * } Elf64_Rela; * * r_offset is address of reference * r_info is symbol index and type of relocation (in this case * code 1027 which corresponds to R_AARCH64_RELATIVE). * r_addend is constant part of expression. * * Size of Elf64_Rela structure is 24 bytes. */ /* Skip R_AARCH64_NONE entry with code 0 */ 1: ldr x3, [x1, #8] cbz x3, 2f #if ENABLE_ASSERTIONS /* Assert that the relocation type is R_AARCH64_RELATIVE */ cmp x3, #R_AARCH64_RELATIVE ASM_ASSERT(eq) #endif ldr x3, [x1] /* r_offset */ add x3, x0, x3 ldr x4, [x1, #16] /* r_addend */ /* Skip adding offset if r_addend is < lower limit */ cmp x4, x6 b.lo 2f /* Skip adding offset if r_addend entry is > upper limit */ cmp x4, x7 b.hi 2f add x4, x0, x4 /* Diff(S) + r_addend */ str x4, [x3] 2: add x1, x1, #24 cmp x1, x2 b.lo 1b ret endfunc fixup_gdt_reloc