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);
}
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);
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;
}
int up_svcall(int irq, FAR void *context)
{
uint32_t *regs = (uint32_t*)context;
uint32_t cmd;
DEBUGASSERT(regs && regs == current_regs);
cmd = regs[REG_R0];
/* The SVCall software interrupt is called with R0 = system call command
* and R1..R7 = variable number of arguments depending on the system call.
*/
#if defined(CONFIG_DEBUG_SYSCALL) || defined(CONFIG_DEBUG_SVCALL)
# ifndef CONFIG_DEBUG_SVCALL
if (cmd > SYS_switch_context)
# endif
{
svcdbg("SVCALL Entry: regs: %p cmd: %d\n", regs, cmd);
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]);
# ifdef REG_EXC_RETURN
svcdbg(" PSR: %08x EXC_RETURN: %08x\n",
regs[REG_XPSR], regs[REG_EXC_RETURN]);
# else
svcdbg(" PSR: %08x\n", regs[REG_XPSR]);
# endif
}
#endif
/* Handle the SVCall according to the command in R0 */
switch (cmd)
{
/* 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) noreturn_function;
*
* 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 = SYS_switch_context
* 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;
/* R0=SYS_syscall_return: This a syscall return command:
*
* void up_syscall_return(void);
*
* At this point, the following values are saved in context:
*
* R0 = SYS_syscall_return
*
* We need to restore the saved return address and return in
* unprivileged thread mode.
*/
#ifdef CONFIG_NUTTX_KERNEL
case SYS_syscall_return:
{
struct tcb_s *rtcb = sched_self();
int index = (int)rtcb->xcp.nsyscalls - 1;
/* Make sure that there is a saved syscall return address. */
DEBUGASSERT(index >= 0);
/* Setup to return to the saved syscall return address in
* the original mode.
*/
regs[REG_PC] = rtcb->xcp.syscall[index].sysreturn;
regs[REG_EXC_RETURN] = rtcb->xcp.syscall[index].excreturn;
rtcb->xcp.nsyscalls = index;
/* The return value must be in R0-R1. dispatch_syscall() temporarily
* moved the value for R0 into R2.
*/
regs[REG_R0] = regs[REG_R2];
}
break;
#endif
/* R0=SYS_task_start: This a user task start
*
* void up_task_start(main_t taskentry, int argc, FAR char *argv[]) noreturn_function;
*
* At this point, the following values are saved in context:
*
* R0 = SYS_task_start
* R1 = taskentry
* R2 = argc
* R3 = argv
*/
#ifdef CONFIG_NUTTX_KERNEL
case SYS_task_start:
{
/* Set up to return to the user-space task start-up function in
* unprivileged mode.
*/
regs[REG_PC] = (uint32_t)USERSPACE->task_startup;
regs[REG_EXC_RETURN] = EXC_RETURN_UNPRIVTHR;
/* Change the parameter ordering to match the expectation of struct
* userpace_s task_startup:
*/
regs[REG_R0] = regs[REG_R1]; /* Task entry */
regs[REG_R1] = regs[REG_R2]; /* argc */
regs[REG_R2] = regs[REG_R3]; /* argv */
}
break;
#endif
/* R0=SYS_pthread_start: This a user pthread start
*
* void up_pthread_start(pthread_startroutine_t entrypt, pthread_addr_t arg) noreturn_function;
*
* At this point, the following values are saved in context:
*
* R0 = SYS_pthread_start
* R1 = entrypt
* R2 = arg
*/
#if defined(CONFIG_NUTTX_KERNEL) && !defined(CONFIG_DISABLE_PTHREAD)
case SYS_pthread_start:
{
/* Set up to return to the user-space pthread start-up function in
* unprivileged mode.
*/
regs[REG_PC] = (uint32_t)USERSPACE->pthread_startup;
regs[REG_EXC_RETURN] = EXC_RETURN_UNPRIVTHR;
/* Change the parameter ordering to match the expectation of struct
* userpace_s pthread_startup:
*/
regs[REG_R0] = regs[REG_R1]; /* pthread entry */
regs[REG_R1] = regs[REG_R2]; /* arg */
}
break;
#endif
/* R0=SYS_signal_handler: This a user signal handler callback
*
* void signal_handler(_sa_sigaction_t sighand, int signo,
* FAR siginfo_t *info, FAR void *ucontext);
*
* At this point, the following values are saved in context:
*
* R0 = SYS_signal_handler
* R1 = sighand
* R2 = signo
* R3 = info
* ucontext (on the stack)
*/
#if defined(CONFIG_NUTTX_KERNEL) && !defined(CONFIG_DISABLE_SIGNALS)
case SYS_signal_handler:
{
struct tcb_s *rtcb = sched_self();
/* Remember the caller's return address */
DEBUGASSERT(rtcb->xcp.sigreturn == 0);
rtcb->xcp.sigreturn = regs[REG_PC];
/* Set up to return to the user-space pthread start-up function in
* unprivileged mode.
*/
regs[REG_PC] = (uint32_t)USERSPACE->signal_handler;
regs[REG_EXC_RETURN] = EXC_RETURN_UNPRIVTHR;
/* Change the parameter ordering to match the expectation of struct
* userpace_s signal_handler.
*/
regs[REG_R0] = regs[REG_R1]; /* sighand */
regs[REG_R1] = regs[REG_R2]; /* signal */
regs[REG_R2] = regs[REG_R3]; /* info */
/* The last parameter, ucontext, is trickier. The ucontext
* parameter will reside at an offset of 4 from the stack pointer.
*/
regs[REG_R3] = *(uint32_t*)(regs[REG_SP+4]);
}
break;
#endif
/* R0=SYS_signal_handler_return: This a user signal handler callback
*
* void signal_handler_return(void);
*
* At this point, the following values are saved in context:
*
* R0 = SYS_signal_handler_return
*/
#if defined(CONFIG_NUTTX_KERNEL) && !defined(CONFIG_DISABLE_SIGNALS)
case SYS_signal_handler_return:
{
struct tcb_s *rtcb = sched_self();
/* Set up to return to the kernel-mode signal dispatching logic. */
DEBUGASSERT(rtcb->xcp.sigreturn != 0);
regs[REG_PC] = rtcb->xcp.sigreturn;
regs[REG_EXC_RETURN] = EXC_RETURN_PRIVTHR;
rtcb->xcp.sigreturn = 0;
}
break;
#endif
/* 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
FAR struct tcb_s *rtcb = sched_self();
int index = rtcb->xcp.nsyscalls;
/* Verify that the SYS call number is within range */
DEBUGASSERT(cmd >= CONFIG_SYS_RESERVED && cmd < SYS_maxsyscall);
/* Make sure that there is a no saved syscall return address. We
* cannot yet handle nested system calls.
*/
DEBUGASSERT(index < CONFIG_SYS_NNEST);
/* Setup to return to dispatch_syscall in privileged mode. */
rtcb->xcp.syscall[index].sysreturn = regs[REG_PC];
rtcb->xcp.syscall[index].excreturn = regs[REG_EXC_RETURN];
rtcb->xcp.nsyscalls = index + 1;
regs[REG_PC] = (uint32_t)dispatch_syscall;
regs[REG_EXC_RETURN] = EXC_RETURN_PRIVTHR;
/* Offset R0 to account for the reserved values */
regs[REG_R0] -= CONFIG_SYS_RESERVED;
#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 defined(CONFIG_DEBUG_SYSCALL) || defined(CONFIG_DEBUG_SVCALL)
# ifndef CONFIG_DEBUG_SVCALL
if (cmd > SYS_switch_context)
# else
if (regs != current_regs)
# endif
{
svcdbg("SVCall Return:\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]);
# ifdef REG_EXC_RETURN
svcdbg(" PSR: %08x EXC_RETURN: %08x\n",
current_regs[REG_XPSR], current_regs[REG_EXC_RETURN]);
# else
svcdbg(" PSR: %08x\n", current_regs[REG_XPSR]);
# endif
}
# ifdef CONFIG_DEBUG_SVCALL
else
{
svcdbg("SVCall Return: %d\n", regs[REG_R0]);
}
# endif
#endif
return OK;
}
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;
}
uint32_t *arm_syscall(uint32_t *regs)
{
uint32_t cmd;
#ifdef CONFIG_BUILD_KERNEL
uint32_t cpsr;
#endif
/* Nested interrupts are not supported */
DEBUGASSERT(regs);
/* The SYSCALL command is in R0 on entry. Parameters follow in R1..R7 */
cmd = regs[REG_R0];
/* The SVCall software interrupt is called with R0 = system call command
* and R1..R7 = variable number of arguments depending on the system call.
*/
#if defined(CONFIG_DEBUG_SYSCALL)
svcdbg("SYSCALL Entry: regs: %p cmd: %d\n", regs, cmd);
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("CPSR: %08x\n", regs[REG_CPSR]);
#endif
/* Handle the SVCall according to the command in R0 */
switch (cmd)
{
/* R0=SYS_syscall_return: This a SYSCALL return command:
*
* void up_syscall_return(void);
*
* At this point, the following values are saved in context:
*
* R0 = SYS_syscall_return
*
* We need to restore the saved return address and return in
* unprivileged thread mode.
*/
case SYS_syscall_return:
{
FAR struct tcb_s *rtcb = sched_self();
int index = (int)rtcb->xcp.nsyscalls - 1;
/* Make sure that there is a saved SYSCALL return address. */
DEBUGASSERT(index >= 0);
/* Setup to return to the saved SYSCALL return address in
* the original mode.
*/
regs[REG_PC] = rtcb->xcp.syscall[index].sysreturn;
#ifdef CONFIG_BUILD_KERNEL
regs[REG_CPSR] = rtcb->xcp.syscall[index].cpsr;
#endif
/* The return value must be in R0-R1. dispatch_syscall() temporarily
* moved the value for R0 into R2.
*/
regs[REG_R0] = regs[REG_R2];
#ifdef CONFIG_ARCH_KERNEL_STACK
/* If this is the outermost SYSCALL and if there is a saved user stack
* pointer, then restore the user stack pointer on this final return to
* user code.
*/
if (index == 0 && rtcb->xcp.ustkptr != NULL)
{
regs[REG_SP] = (uint32_t)rtcb->xcp.ustkptr;
rtcb->xcp.ustkptr = NULL;
}
#endif
/* Save the new SYSCALL nesting level */
rtcb->xcp.nsyscalls = index;
}
break;
/* R0=SYS_context_restore: Restore task context
*
* void up_fullcontextrestore(uint32_t *restoreregs) noreturn_function;
*
* At this point, the following values are saved in context:
*
* R0 = SYS_context_restore
* R1 = restoreregs
*/
#ifdef CONFIG_BUILD_KERNEL
case SYS_context_restore:
{
/* Replace 'regs' with the pointer to the register set in
* regs[REG_R1]. On return from the system call, that register
* set will determine the restored context.
*/
regs = (uint32_t *)regs[REG_R1];
DEBUGASSERT(regs);
}
break;
#endif
/* R0=SYS_task_start: This a user task start
*
* void up_task_start(main_t taskentry, int argc, FAR char *argv[]) noreturn_function;
*
* At this point, the following values are saved in context:
*
* R0 = SYS_task_start
* R1 = taskentry
* R2 = argc
* R3 = argv
*/
#ifdef CONFIG_BUILD_KERNEL
case SYS_task_start:
{
/* Set up to return to the user-space _start function in
* unprivileged mode. We need:
*
* R0 = argc
* R1 = argv
* PC = taskentry
* CSPR = user mode
*/
regs[REG_PC] = regs[REG_R1];
regs[REG_R0] = regs[REG_R2];
regs[REG_R1] = regs[REG_R3];
cpsr = regs[REG_CPSR] & ~PSR_MODE_MASK;
regs[REG_CPSR] = cpsr | PSR_MODE_USR;
}
break;
#endif
/* R0=SYS_pthread_start: This a user pthread start
*
* void up_pthread_start(pthread_startroutine_t entrypt, pthread_addr_t arg) noreturn_function;
*
* At this point, the following values are saved in context:
*
* R0 = SYS_pthread_start
* R1 = entrypt
* R2 = arg
*/
#if defined(CONFIG_BUILD_KERNEL) && !defined(CONFIG_DISABLE_PTHREAD)
case SYS_pthread_start:
{
/* Set up to return to the user-space pthread start-up function in
* unprivileged mode. We need:
*
* R0 = arg
* PC = entrypt
* CSPR = user mode
*/
regs[REG_PC] = regs[REG_R1];
regs[REG_R0] = regs[REG_R2];
cpsr = regs[REG_CPSR] & ~PSR_MODE_MASK;
regs[REG_CPSR] = cpsr | PSR_MODE_USR;
}
break;
#endif
#if defined(CONFIG_BUILD_KERNEL) && !defined(CONFIG_DISABLE_SIGNALS)
/* R0=SYS_signal_handler: This a user signal handler callback
*
* void signal_handler(_sa_sigaction_t sighand, int signo,
* FAR siginfo_t *info, FAR void *ucontext);
*
* At this point, the following values are saved in context:
*
* R0 = SYS_signal_handler
* R1 = sighand
* R2 = signo
* R3 = info
* ucontext (on the stack)
*/
case SYS_signal_handler:
{
FAR struct tcb_s *rtcb = sched_self();
/* Remember the caller's return address */
DEBUGASSERT(rtcb->xcp.sigreturn == 0);
rtcb->xcp.sigreturn = regs[REG_PC];
/* Set up to return to the user-space pthread start-up function in
* unprivileged mode.
*/
regs[REG_PC] = (uint32_t)ARCH_DATA_RESERVE->ar_sigtramp;
cpsr = regs[REG_CPSR] & ~PSR_MODE_MASK;
regs[REG_CPSR] = cpsr | PSR_MODE_USR;
/* Change the parameter ordering to match the expectation of struct
* userpace_s signal_handler.
*/
regs[REG_R0] = regs[REG_R1]; /* sighand */
regs[REG_R1] = regs[REG_R2]; /* signal */
regs[REG_R2] = regs[REG_R3]; /* info */
/* The last parameter, ucontext, is trickier. The ucontext
* parameter will reside at an offset of 4 from the stack pointer.
*/
regs[REG_R3] = *(uint32_t*)(regs[REG_SP]+4);
#ifdef CONFIG_ARCH_KERNEL_STACK
/* If we are signalling a user process, then we must be operating
* on the kernel stack now. We need to switch back to the user
* stack before dispatching the signal handler to the user code.
* The existence of an allocated kernel stack is sufficient
* information to make this decision.
*/
if (rtcb->xcp.kstack != NULL)
{
DEBUGASSERT(rtcb->xcp.kstkptr == NULL && rtcb->xcp.ustkptr != NULL);
rtcb->xcp.kstkptr = (FAR uint32_t *)regs[REG_SP];
regs[REG_SP] = (uint32_t)rtcb->xcp.ustkptr;
}
#endif
}
break;
#endif
#if defined(CONFIG_BUILD_KERNEL) && !defined(CONFIG_DISABLE_SIGNALS)
/* R0=SYS_signal_handler_return: This a user signal handler callback
*
* void signal_handler_return(void);
*
* At this point, the following values are saved in context:
*
* R0 = SYS_signal_handler_return
*/
case SYS_signal_handler_return:
{
FAR struct tcb_s *rtcb = sched_self();
/* Set up to return to the kernel-mode signal dispatching logic. */
DEBUGASSERT(rtcb->xcp.sigreturn != 0);
regs[REG_PC] = rtcb->xcp.sigreturn;
cpsr = regs[REG_CPSR] & ~PSR_MODE_MASK;
regs[REG_CPSR] = cpsr | PSR_MODE_SVC;
rtcb->xcp.sigreturn = 0;
#ifdef CONFIG_ARCH_KERNEL_STACK
/* We must enter here be using the user stack. We need to switch
* to back to the kernel user stack before returning to the kernel
* mode signal trampoline.
*/
if (rtcb->xcp.kstack != NULL)
{
DEBUGASSERT(rtcb->xcp.kstkptr != NULL &&
(uint32_t)rtcb->xcp.ustkptr == regs[REG_SP]);
regs[REG_SP] = (uint32_t)rtcb->xcp.kstkptr;
rtcb->xcp.kstkptr = NULL;
}
#endif
}
break;
#endif
/* 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_LIB_SYSCALL
FAR struct tcb_s *rtcb = sched_self();
int index = rtcb->xcp.nsyscalls;
/* Verify that the SYS call number is within range */
DEBUGASSERT(cmd >= CONFIG_SYS_RESERVED && cmd < SYS_maxsyscall);
/* Make sure that there is a no saved SYSCALL return address. We
* cannot yet handle nested system calls.
*/
DEBUGASSERT(index < CONFIG_SYS_NNEST);
/* Setup to return to dispatch_syscall in privileged mode. */
rtcb->xcp.syscall[index].sysreturn = regs[REG_PC];
#ifdef CONFIG_BUILD_KERNEL
rtcb->xcp.syscall[index].cpsr = regs[REG_CPSR];
#endif
regs[REG_PC] = (uint32_t)dispatch_syscall;
#ifdef CONFIG_BUILD_KERNEL
cpsr = regs[REG_CPSR] & ~PSR_MODE_MASK;
regs[REG_CPSR] = cpsr | PSR_MODE_SVC;
#endif
/* Offset R0 to account for the reserved values */
regs[REG_R0] -= CONFIG_SYS_RESERVED;
#else
svcdbg("ERROR: Bad SYS call: %d\n", regs[REG_R0]);
#endif
#ifdef CONFIG_ARCH_KERNEL_STACK
/* If this is the first SYSCALL and if there is an allocated
* kernel stack, then switch to the kernel stack.
*/
if (index == 0 && rtcb->xcp.kstack != NULL)
{
rtcb->xcp.ustkptr = (FAR uint32_t *)regs[REG_SP];
regs[REG_SP] = (uint32_t)rtcb->xcp.kstack + ARCH_KERNEL_STACKSIZE;
}
#endif
/* Save the new SYSCALL nesting level */
rtcb->xcp.nsyscalls = index + 1;
}
break;
}
#if defined(CONFIG_DEBUG_SYSCALL)
/* Report what happened */
svcdbg("SYSCALL Exit: regs: %p\n", regs);
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("CPSR: %08x\n", regs[REG_CPSR]);
#endif
/* Return the last value of curent_regs. This supports context switches
* on return from the exception. That capability is only used with the
* SYS_context_switch system call.
*/
return regs;
}
