/**************************************************************************** * arch/arm/src/armv7-m/up_svcall.c * * Copyright (C) 2009, 2011-2012 Gregory Nutt. All rights reserved. * Author: Gregory Nutt * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in * the documentation and/or other materials provided with the * distribution. * 3. Neither the name NuttX nor the names of its contributors may be * used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE * POSSIBILITY OF SUCH DAMAGE. * ****************************************************************************/ /**************************************************************************** * Included Files ****************************************************************************/ #include #include #include #include #include #include #include #ifdef CONFIG_NUTTX_KERNEL # include #endif #include "svcall.h" #include "up_internal.h" /**************************************************************************** * Pre-processor Definitions ****************************************************************************/ /* Configuration ************************************************************/ #undef SYSCALL_INTERRUPTIBLE #if defined(CONFIG_NUTTX_KERNEL) # if CONFIG_ARCH_INTERRUPTSTACK > 3 # warning "CONFIG_ARCH_INTERRUPTSTACK and CONFIG_NUTTX_KERNEL are incompatible" # warning "options as currently implemented. Interrupts will have to be disabled" # warning "during SYScall processing to avoid un-handled nested interrupts" # else # define SYSCALL_INTERRUPTIBLE 1 # endif #endif /* Debug ********************************************************************/ /* Debug output from this file may interfere with context switching! To get * debug output you must enabled the following in your NuttX configuration: * * CONFIG_DEBUG and CONFIG_DEBUG_SCHED * * And you must explicitly define DEBUG_SVCALL below: */ #undef DEBUG_SVCALL /* Define to debug SVCall */ #ifdef DEBUG_SVCALL # define svcdbg(format, arg...) slldbg(format, ##arg) #else # define svcdbg(x...) #endif /**************************************************************************** * Private Data ****************************************************************************/ /**************************************************************************** * Public Data ****************************************************************************/ /**************************************************************************** * Private Functions ****************************************************************************/ /**************************************************************************** * Name: dispatch_syscall * * Description: * Dispatch a system call to the appropriate handling logic. * ****************************************************************************/ #ifdef CONFIG_NUTTX_KERNEL static inline void dispatch_syscall(uint32_t *regs) { uint32_t cmd = regs[REG_R0]; FAR _TCB *rtcb = sched_self(); uintptr_t ret = (uintptr_t)ERROR; /* Verify the the SYS call number is within range */ if (cmd < SYS_maxsyscall) { /* Report error and return ERROR */ slldbg("ERROR: Bad SYS call: %d\n", cmd); } else { /* The index into the syscall table is offset by the number of architecture- * specific reserved entries at the beginning of the SYS call number space. */ int index = cmd - CONFIG_SYS_RESERVED; /* Enable interrupts while the SYSCALL executes */ #ifdef SYSCALL_INTERRUPTIBLE irqenable(); #endif /* Call the correct stub for each SYS call, based on the number of parameters */ svcdbg("Calling stub%d at %p\n", index, g_stubloopkup[index].stub0); switch (g_stubnparms[index]) { /* No parameters */ case 0: ret = g_stublookup[index].stub0(); break; /* Number of parameters: 1 */ case 1: ret = g_stublookup[index].stub1(regs[REG_R1]); break; /* Number of parameters: 2 */ case 2: ret = g_stublookup[index].stub2(regs[REG_R1], regs[REG_R2]); break; /* Number of parameters: 3 */ case 3: ret = g_stublookup[index].stub3(regs[REG_R1], regs[REG_R2], regs[REG_R3]); break; /* Number of parameters: 4 */ case 4: ret = g_stublookup[index].stub4(regs[REG_R1], regs[REG_R2], regs[REG_R3], regs[REG_R4]); break; /* Number of parameters: 5 */ case 5: ret = g_stublookup[index].stub5(regs[REG_R1], regs[REG_R2], regs[REG_R3], regs[REG_R4], regs[REG_R5]); break; /* Number of parameters: 6 */ case 6: ret = g_stublookup[index].stub6(regs[REG_R1], regs[REG_R2], regs[REG_R3], regs[REG_R4], regs[REG_R5], regs[REG_R6]); break; /* Unsupported number of paramters. Report error and return ERROR */ default: slldbg("ERROR: Bad SYS call %d number parameters %d\n", cmd, g_stubnparms[index]); break; } #ifdef SYSCALL_INTERRUPTIBLE irqdisable(); #endif } /* Set up the return value. First, check if a context switch occurred. * In this case, regs will no longer be the same as current_regs. In * the case of a context switch, we will have to save the return value * in the TCB where it can be returned later when the task is restarted. */ if (regs != current_regs) { regs = rtcb->xcp.regs; } /* Then return the result in R0 */ svcdbg("Return value regs: %p value: %d\n", regs, ret); regs[REG_R0] = (uint32_t)ret; } #endif /**************************************************************************** * Public Functions ****************************************************************************/ /**************************************************************************** * Name: up_svcall * * Description: * This is SVCall exception handler that performs context switching * ****************************************************************************/ int up_svcall(int irq, FAR void *context) { uint32_t *regs = (uint32_t*)context; DEBUGASSERT(regs && regs == current_regs); /* The SVCall software interrupt is called with R0 = system call command * and R1..R7 = variable number of arguments depending on the system call. */ svcdbg("SVCALL Entry: regs: %p cmd: %d\n", regs, regs[REG_R0]); svcdbg(" R0: %08x %08x %08x %08x %08x %08x %08x %08x\n", regs[REG_R0], regs[REG_R1], regs[REG_R2], regs[REG_R3], regs[REG_R4], regs[REG_R5], regs[REG_R6], regs[REG_R7]); svcdbg(" R8: %08x %08x %08x %08x %08x %08x %08x %08x\n", regs[REG_R8], regs[REG_R9], regs[REG_R10], regs[REG_R11], regs[REG_R12], regs[REG_R13], regs[REG_R14], regs[REG_R15]); svcdbg(" PSR=%08x\n", regs[REG_XPSR]); /* Handle the SVCall according to the command in R0 */ switch (regs[REG_R0]) { /* R0=SYS_save_context: This is a save context command: * * int up_saveusercontext(uint32_t *saveregs); * * At this point, the following values are saved in context: * * R0 = SYS_save_context * R1 = saveregs * * In this case, we simply need to copy the current regsters to the * save register space references in the saved R1 and return. */ case SYS_save_context: { DEBUGASSERT(regs[REG_R1] != 0); memcpy((uint32_t*)regs[REG_R1], regs, XCPTCONTEXT_SIZE); #if defined(CONFIG_ARCH_FPU) && !defined(CONFIG_ARMV7M_CMNVECTOR) up_savefpu((uint32_t*)regs[REG_R1]); #endif } break; /* R0=SYS_restore_context: This a restore context command: * * void up_fullcontextrestore(uint32_t *restoreregs) __attribute__ ((noreturn)); * * At this point, the following values are saved in context: * * R0 = SYS_restore_context * R1 = restoreregs * * In this case, we simply need to set current_regs to restore register * area referenced in the saved R1. context == current_regs is the normal * exception return. By setting current_regs = context[R1], we force * the return to the saved context referenced in R1. */ case SYS_restore_context: { DEBUGASSERT(regs[REG_R1] != 0); current_regs = (uint32_t*)regs[REG_R1]; } break; /* R0=SYS_switch_context: This a switch context command: * * void up_switchcontext(uint32_t *saveregs, uint32_t *restoreregs); * * At this point, the following values are saved in context: * * R0 = 1 * R1 = saveregs * R2 = restoreregs * * In this case, we do both: We save the context registers to the save * register area reference by the saved contents of R1 and then set * current_regs to to the save register area referenced by the saved * contents of R2. */ case SYS_switch_context: { DEBUGASSERT(regs[REG_R1] != 0 && regs[REG_R2] != 0); memcpy((uint32_t*)regs[REG_R1], regs, XCPTCONTEXT_SIZE); #if defined(CONFIG_ARCH_FPU) && !defined(CONFIG_ARMV7M_CMNVECTOR) up_savefpu((uint32_t*)regs[REG_R1]); #endif current_regs = (uint32_t*)regs[REG_R2]; } break; /* This is not an architecture-specific system call. If NuttX is built * as a standalone kernel with a system call interface, then all of the * additional system calls must be handled as in the default case. */ default: #ifdef CONFIG_NUTTX_KERNEL dispatch_syscall(regs); #else slldbg("ERROR: Bad SYS call: %d\n", regs[REG_R0]); #endif break; } /* Report what happened. That might difficult in the case of a context switch */ if (regs != current_regs) { svcdbg("SVCall Return: Context switch!\n"); svcdbg(" R0: %08x %08x %08x %08x %08x %08x %08x %08x\n", current_regs[REG_R0], current_regs[REG_R1], current_regs[REG_R2], current_regs[REG_R3], current_regs[REG_R4], current_regs[REG_R5], current_regs[REG_R6], current_regs[REG_R7]); svcdbg(" R8: %08x %08x %08x %08x %08x %08x %08x %08x\n", current_regs[REG_R8], current_regs[REG_R9], current_regs[REG_R10], current_regs[REG_R11], current_regs[REG_R12], current_regs[REG_R13], current_regs[REG_R14], current_regs[REG_R15]); svcdbg(" PSR=%08x\n", current_regs[REG_XPSR]); } else { svcdbg("SVCall Return: %d\n", regs[REG_R0]); } return OK; }