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If we are configured to use a kernel stack while in SYSCALL handling, then we need to switch back to the user stack to deliver a signal

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This commit is contained in:
Gregory Nutt 2014-09-15 11:38:48 -06:00
parent 949cc1b20c
commit 9aae0adffa
2 changed files with 45 additions and 0 deletions
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3
arch/arm/include/armv7-a/irq.h
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@ -296,6 +296,9 @@ struct xcptcontext
FAR uint32_t *ustkptr; /* Saved user stack pointer */
FAR uint32_t *kstack; /* Allocate base of the (aligned) kernel stack */
#ifndef CONFIG_DISABLE_SIGNALS
FAR uint32_t *kstkptr; /* Saved kernel stack pointer */
#endif
#endif
#endif
};

42
arch/arm/src/armv7-a/arm_syscall.c
View File

@ -352,6 +352,9 @@ uint32_t *arm_syscall(uint32_t *regs)
case SYS_signal_handler:
{
FAR struct tcb_s *rtcb = sched_self();
#ifdef CONFIG_ARCH_KERNEL_STACK
int depth;
#endif
/* Remember the caller's return address */
@ -379,6 +382,24 @@ uint32_t *arm_syscall(uint32_t *regs)
*/
regs[REG_R3] = *(uint32_t*)(regs[REG_SP]+4);
#ifdef CONFIG_ARCH_KERNEL_STACK
/* If this is a nested SYSCALL and if there is an allocated kernel
* stack, then we must be operating on the kernal stack now. We
* need to switch back to the user stack before dispatching the
* signal handler to the user code.
*/
depth = rtcb->xcp.nsyscalls;
if (depth > 0 && rtcb->xcp.kstack != NULL)
{
DEBUGASSERT(rtcb->xcp.kstkptr == NULL &&
rtcb->xcp.ustkptr[depth - 1] != 0);
rtcb->xcp.kstkptr = (FAR uint32_t *)regs[REG_SP];
regs[REG_SP] = (uint32_t)rtcb->xcp.ustkptr[depth - 1];
}
#endif
}
break;
#endif
@ -396,6 +417,9 @@ uint32_t *arm_syscall(uint32_t *regs)
case SYS_signal_handler_return:
{
FAR struct tcb_s *rtcb = sched_self();
#ifdef CONFIG_ARCH_KERNEL_STACK
int depth;
#endif
/* Set up to return to the kernel-mode signal dispatching logic. */
@ -405,6 +429,24 @@ uint32_t *arm_syscall(uint32_t *regs)
cpsr = regs[REG_CPSR] & ~PSR_MODE_MASK;
regs[REG_CPSR] = cpsr | PSR_MODE_SVC;
rtcb->xcp.sigreturn = 0;
#ifdef CONFIG_ARCH_KERNEL_STACK
/* If this is a nested SYSCALL and if there is an allocated kernel
* stack, we must be using the user stack to dispatch to the signal
* handler. We need to switch to back to the kernel user stack
* before returning to the kernel mode signal trampoline.
*/
depth = rtcb->xcp.nsyscalls;
if (depth > 0 && rtcb->xcp.kstack != NULL)
{
DEBUGASSERT(rtcb->xcp.kstkptr != NULL &&
(uint32_t)rtcb->xcp.ustkptr[depth - 1] == regs[REG_SP]);
regs[REG_SP] = (uint32_t)rtcb->xcp.kstkptr;
rtcb->xcp.kstkptr = NULL;
}
#endif
}
break;
#endif