/* ChibiOS - Copyright (C) 2006..2018 Giovanni Di Sirio Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0 Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License. */ /** * @file ARMCAx-TZ/compilers/GCC/monitor.S * @brief ARMCAx-TZ monitor code * * @addtogroup ARM_CORE * @{ */ #define TRUE 1 #define FALSE 0 #define _FROM_ASM_ #include "chlicense.h" #include "chconf.h" #include "armparams.h" /* * We are facing an architecure with security extension exploited. * The following execution paths are taken by the execution units * running in secure state when an irq is fired (sm_irq), and in non-secure * state when a fiq interrupt is fired (sm_fiq). * They originate by the monitor irq/fiq vector and run in monitor mode, * ie in secure state. * It assumes the following, intially set at boot time, or wherever it needs: * SCR.FW == 0 and SCR.FIQ == 1 and SCR.IRQ == 0 in non-secure state, * ie FIQs are taken to monitor mode, IRQs are taken locally * SCR.FW == 0 and SCR.FIQ == 0 and SCR.IRQ == 1 in secure state, * ie FIQs are taken locally, IRQs are taken to monitor mode * MVBAR holds the address of the monitor vectors base. * The code and the stacks memory reside both in secure memory. */ #if !defined(__DOXYGEN__) .set MODE_USR, 0x10 .set MODE_FIQ, 0x11 .set MODE_IRQ, 0x12 .set MODE_SVC, 0x13 .set MODE_MON, 0x16 .set MODE_ABT, 0x17 .set MODE_UND, 0x1B .set MODE_SYS, 0x1F .set SCR_NS, 0x01 .set SCR_IRQ, 0x02 .set SCR_FIQ, 0x04 .set SCR_EA, 0x08 .set SCR_FW, 0x10 .set SCR_AW, 0x20 .set MON_S_SCR, (SCR_IRQ) // (SCR_EA|SCR_IRQ) .set MON_NS_SCR, (SCR_FIQ|SCR_NS) .set SMC_SVC_INTR, -4 .comm sm_secctx, 20*4, 4 .comm sm_nsecctx, 20*4, 4 .global _ns_thread .section .text .code 32 .balign 4 /* * Helper macros */ /* * Store banked registers in a world area pointed by rm */ .macro sm_store_ooctx_regs rm // cps #MODE_SYS // Assume mode SYS stm \rm!, {sp, lr} cps #MODE_FIQ mrs r12, spsr stm \rm!, {r12, sp, lr} cps #MODE_IRQ mrs r12, spsr stm \rm!, {r12, sp, lr} cps #MODE_ABT mrs r12, spsr stm \rm!, {r12, sp, lr} cps #MODE_SVC mrs r12, spsr stm \rm!, {r12, sp, lr} cps #MODE_UND mrs r12, spsr stm \rm!, {r12, sp, lr} .endm /* * Retrieve banked registers from a world area pointed by rm */ .macro sm_load_ooctx_regs rm // cps #MODE_SYS // Assume mode SYS ldm \rm!, {sp, lr} cps #MODE_FIQ ldm \rm!, {r12, sp, lr} msr spsr_fsxc, r12 cps #MODE_IRQ ldm \rm!, {r12, sp, lr} msr spsr_fsxc, r12 cps #MODE_ABT ldm \rm!, {r12, sp, lr} msr spsr_fsxc, r12 cps #MODE_SVC ldm \rm!, {r12, sp, lr} msr spsr_fsxc, r12 cps #MODE_UND ldm \rm!, {r12, sp, lr} msr spsr_fsxc, r12 .endm /* * Monitor vectors */ .global _monitor_vectors .balign 32 _monitor_vectors: b . // Reset vector, not used b . // Undefined instruction, not used b sm_call // Secure monitor call b . // Prefetch abort, not taken to Monitor mode b . // Data abort, not taken to Monitor mode b . // Reserved b sm_irq // IRQ b sm_fiq // FIQ /* * SMC entry */ sm_call: stmfd sp!, {r4, r12} ldr r12, =MON_S_SCR // enter in the secure world mcr p15, 0, r12, c1, c1, 0 ands r0, r0 // OS special service, // 0 == jump trampoline to non secure world // r1 contains the address where it jumps beq 1f mrs r4, SPSR mov r12, lr stmfd sp!, {r4, r12} // push r4=spsr_mon, r12=lr_mon. cps #MODE_SYS // switch to sys mode, ints disabled ldr r4, =sm_nsecctx sm_store_ooctx_regs r4 cps #MODE_SYS ldr r4, =sm_secctx sm_load_ooctx_regs r4 cps #MODE_SYS bl smcEntry // call the C smc handler ldr r4, =sm_secctx sm_store_ooctx_regs r4 cps #MODE_SYS ldr r4, =sm_nsecctx sm_load_ooctx_regs r4 cps #MODE_MON // switch to monitor mode ldmfd sp!, {r4, r12} // pop r4=spsr_mon, r12=lr_mon. msr SPSR_fsxc, r4 mov lr, r12 ldr r12, =MON_NS_SCR // enter in the non-secure world mcr p15, 0, r12, c1, c1, 0 ldmfd sp!, {r4, r12} subs pc, lr, #0 // return from smc 1: mov lr, r1 // use the address in r1 as return address // in the non secure world ldr r12, =MON_NS_SCR // enter in the non-secure world mcr p15, 0, r12, c1, c1, 0 ldmfd sp!, {r4, r12} subs pc, lr, #0 // return from smc /* * FIQ entry * * Here the fiq is taken from non-secure state, via the FIQ vector * that is in the monitor vector table. * Current mode is monitor (so current state is secure). * We switch immediately to system mode, enabling FIQ. * The FIQ is then served while the ns_thread is running. * Because the ns_thread has the highest priority, the handler returns here * without scheduling. */ sm_fiq: // check point: SCR.NS == 1 stmfd sp!, {r0, r12} ldr r0, =MON_S_SCR // enter in the secure world mcr p15, 0, r0, c1, c1, 0 cps #MODE_SYS ldr r0, =sm_nsecctx sm_store_ooctx_regs r0 cps #MODE_SYS ldr r0, =sm_secctx sm_load_ooctx_regs r0 cpsie f, #MODE_SYS // FIQ enabled, served via base table cpsid f, #MODE_SYS // the handler returns here, FIQ disabled. ldr r0, =sm_secctx sm_store_ooctx_regs r0 cps #MODE_SYS ldr r0, =sm_nsecctx sm_load_ooctx_regs r0 cps #MODE_MON // switch to monitor mode ldr r0, =MON_NS_SCR // set non-secure SCR before return mcr p15, 0, r0, c1, c1, 0 ldmfd sp!, {r0, r12} subs pc, lr, #4 // return into non-secure world /* * IRQ entry * * Here the IRQ is taken from secure state. * Current mode is monitor (so current state is secure), * the previous mode and status is in spsr_mon and * the return address+4 is in lr_mon. * Because we are running in secure state, we are sure that * the main thread is suspended in the smc handler. * The main thread is then resumed with SMC_SVC_INTR * The non secure world has then the responsibility to return into * secure state via a smc. * */ sm_irq: // check point: SCR.NS == 0 cps #MODE_SYS stmfd sp!, {r0-r3, r12, lr} // save scratch registers and lr cps #MODE_MON // switch to monitor mode mrs r0, spsr mov r1, lr cps #MODE_SYS stmfd sp!, {r0, r1} // push r0=spsr_mon, r1=lr_mon. // check point: ns_tread != 0 #if (CH_DBG_SYSTEM_STATE_CHECK == TRUE) bl _dbg_check_lock #endif ldr r0, =_ns_thread mov r1, #SMC_SVC_INTR bl chThdResumeS // resume the ns_thread and serve the IRQ // into non-secure world #if (CH_DBG_SYSTEM_STATE_CHECK == TRUE) bl _dbg_check_unlock #endif // The ns_thread reentered smc, that set SRC.NS to 0 // re-establish the original conditions ldmfd sp!, {r0, r1} // pop r0=spsr_mon, r1=lr_mon. cps #MODE_MON // switch to monitor mode msr SPSR_fsxc, r0 mov lr, r1 cps #MODE_SYS ldmfd sp!, {r0-r3, r12, lr} cps #MODE_MON // switch to monitor mode subs pc, lr, #4 // return into secure world .global _ns_trampoline _ns_trampoline: mov r1, r0 ldr r0, =sm_secctx sm_store_ooctx_regs r0 cps #MODE_SYS ldr r0, =#0 /* mov r2, r0 */ // r2 could contain the address of the fdt mov r3, r0 mov r4, r0 mov r5, r0 mov r6, r0 mov r7, r0 mov r8, r0 mov r9, r0 mov r10, r0 mov r11, r0 mov r12, r0 mov sp, r0 mov lr, r0 smc #0 #endif /* !defined(__DOXYGEN__) */ /** @} */