| /* |
| * Copyright (c) 2021-2022, ProvenRun S.A.S. All rights reserved. |
| * |
| * SPDX-License-Identifier: BSD-3-Clause |
| */ |
| |
| #include <asm_macros.S> |
| #include "pncd_private.h" |
| |
| .global pncd_enter_sp |
| /* --------------------------------------------- |
| * 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 pncd_enter_sp |
| /* Make space for the registers that we're going to save */ |
| mov x3, sp |
| str x3, [x0, #0] |
| sub sp, sp, #PNCD_C_RT_CTX_SIZE |
| |
| /* Save callee-saved registers on to the stack */ |
| stp x19, x20, [sp, #PNCD_C_RT_CTX_X19] |
| stp x21, x22, [sp, #PNCD_C_RT_CTX_X21] |
| stp x23, x24, [sp, #PNCD_C_RT_CTX_X23] |
| stp x25, x26, [sp, #PNCD_C_RT_CTX_X25] |
| stp x27, x28, [sp, #PNCD_C_RT_CTX_X27] |
| stp x29, x30, [sp, #PNCD_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 pncd_enter_sp |
| |
| /* --------------------------------------------- |
| * This function is called 'x0' pointing to a C |
| * runtime context saved in pncd_enter_sp(). It |
| * restores the saved registers and jumps to |
| * that runtime with 'x0' as the new sp. 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 return value to the caller |
| * --------------------------------------------- |
| */ |
| .global pncd_exit_sp |
| func pncd_exit_sp |
| /* Restore the previous stack */ |
| mov sp, x0 |
| |
| /* Restore callee-saved registers on to the stack */ |
| ldp x19, x20, [x0, #(PNCD_C_RT_CTX_X19 - PNCD_C_RT_CTX_SIZE)] |
| ldp x21, x22, [x0, #(PNCD_C_RT_CTX_X21 - PNCD_C_RT_CTX_SIZE)] |
| ldp x23, x24, [x0, #(PNCD_C_RT_CTX_X23 - PNCD_C_RT_CTX_SIZE)] |
| ldp x25, x26, [x0, #(PNCD_C_RT_CTX_X25 - PNCD_C_RT_CTX_SIZE)] |
| ldp x27, x28, [x0, #(PNCD_C_RT_CTX_X27 - PNCD_C_RT_CTX_SIZE)] |
| ldp x29, x30, [x0, #(PNCD_C_RT_CTX_X29 - PNCD_C_RT_CTX_SIZE)] |
| |
| /* --------------------------------------------- |
| * This should take us back to the instruction |
| * after the call to the last pncd_enter_sp(). |
| * 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 pncd_exit_sp |