diff options
Diffstat (limited to 'services/std_svc/spm/common/aarch64')
| -rw-r--r-- | services/std_svc/spm/common/aarch64/spm_helpers.S | 74 |
1 files changed, 74 insertions, 0 deletions
diff --git a/services/std_svc/spm/common/aarch64/spm_helpers.S b/services/std_svc/spm/common/aarch64/spm_helpers.S new file mode 100644 index 0000000..95e69fb --- /dev/null +++ b/services/std_svc/spm/common/aarch64/spm_helpers.S @@ -0,0 +1,74 @@ +/* + * Copyright (c) 2017-2022, ARM Limited and Contributors. All rights reserved. + * + * SPDX-License-Identifier: BSD-3-Clause + */ + +#include <asm_macros.S> +#include "spm_common.h" + + .global spm_secure_partition_enter + .global spm_secure_partition_exit + + /* --------------------------------------------------------------------- + * This function is called with SP_EL0 as stack. Here we stash our EL3 + * callee-saved registers on to the stack as a part of saving the C + * runtime and enter the secure payload. + * 'x0' contains a pointer to the memory where the address of the C + * runtime context is to be saved. + * --------------------------------------------------------------------- + */ +func spm_secure_partition_enter + /* Make space for the registers that we're going to save */ + mov x3, sp + str x3, [x0, #0] + sub sp, sp, #SP_C_RT_CTX_SIZE + + /* Save callee-saved registers on to the stack */ + stp x19, x20, [sp, #SP_C_RT_CTX_X19] + stp x21, x22, [sp, #SP_C_RT_CTX_X21] + stp x23, x24, [sp, #SP_C_RT_CTX_X23] + stp x25, x26, [sp, #SP_C_RT_CTX_X25] + stp x27, x28, [sp, #SP_C_RT_CTX_X27] + stp x29, x30, [sp, #SP_C_RT_CTX_X29] + + /* --------------------------------------------------------------------- + * Everything is setup now. el3_exit() will use the secure context to + * restore to the general purpose and EL3 system registers to ERET + * into the secure payload. + * --------------------------------------------------------------------- + */ + b el3_exit +endfunc spm_secure_partition_enter + + /* --------------------------------------------------------------------- + * This function is called with 'x0' pointing to a C runtime context + * saved in spm_secure_partition_enter(). + * It restores the saved registers and jumps to that runtime with 'x0' + * as the new SP register. This destroys the C runtime context that had + * been built on the stack below the saved context by the caller. Later + * the second parameter 'x1' is passed as a return value to the caller. + * --------------------------------------------------------------------- + */ +func spm_secure_partition_exit + /* Restore the previous stack */ + mov sp, x0 + + /* Restore callee-saved registers on to the stack */ + ldp x19, x20, [x0, #(SP_C_RT_CTX_X19 - SP_C_RT_CTX_SIZE)] + ldp x21, x22, [x0, #(SP_C_RT_CTX_X21 - SP_C_RT_CTX_SIZE)] + ldp x23, x24, [x0, #(SP_C_RT_CTX_X23 - SP_C_RT_CTX_SIZE)] + ldp x25, x26, [x0, #(SP_C_RT_CTX_X25 - SP_C_RT_CTX_SIZE)] + ldp x27, x28, [x0, #(SP_C_RT_CTX_X27 - SP_C_RT_CTX_SIZE)] + ldp x29, x30, [x0, #(SP_C_RT_CTX_X29 - SP_C_RT_CTX_SIZE)] + + /* --------------------------------------------------------------------- + * This should take us back to the instruction after the call to the + * last spm_secure_partition_enter().* Place the second parameter to x0 + * so that the caller will see it as a return value from the original + * entry call. + * --------------------------------------------------------------------- + */ + mov x0, x1 + ret +endfunc spm_secure_partition_exit |