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Various fixes to the ARMv7-A system call logic

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This commit is contained in:
Gregory Nutt 2014-08-29 08:24:00 -06:00
parent 8196b629a4
commit 27e463dfaa
1 changed files with 32 additions and 10 deletions
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42
arch/arm/src/armv7-a/arm_syscall.c
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@ -117,13 +117,13 @@ static void dispatch_syscall(void)
" str r6, [sp, #8]\n" /* Move parameter 6 (if any) into position */
" str lr, [sp, #12]\n" /* Save lr in the stack frame */
" ldr ip, =g_stublookup\n" /* R12=The base of the stub lookup table */
" ldr ip, [ip, r0, lsl #2]\n" /* R12=The address of the stub for this syscall */
" ldr ip, [ip, r0, lsl #2]\n" /* R12=The address of the stub for this SYSCALL */
" blx ip\n" /* Call the stub (modifies lr)*/
" ldr lr, [sp, #12]\n" /* Restore lr */
" add sp, sp, #16\n" /* Destroy the stack frame */
" mov r2, r0\n" /* R2=Save return value in R2 */
" mov r0, #3\n" /* R0=SYS_syscall_return */
" svc 0" /* Return from the syscall */
" svc 0" /* Return from the SYSCALL */
);
}
#endif
@ -156,7 +156,18 @@ uint32_t *arm_syscall(uint32_t *regs)
uint32_t cpsr;
#endif
DEBUGASSERT(regs && regs == current_regs);
/* Nested interrupts are not supported */
DEBUGASSERT(regs && current_regs == NULL);
/* Current regs non-zero indicates that we are processing an interrupt;
* current_regs is also used to manage interrupt level context switches.
*/
current_regs = 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
@ -178,7 +189,7 @@ uint32_t *arm_syscall(uint32_t *regs)
switch (cmd)
{
/* R0=SYS_syscall_return: This a syscall return command:
/* R0=SYS_syscall_return: This a SYSCALL return command:
*
* void up_syscall_return(void);
*
@ -190,22 +201,23 @@ uint32_t *arm_syscall(uint32_t *regs)
* 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. */
/* Make sure that there is a saved SYSCALL return address. */
DEBUGASSERT(index >= 0);
/* Setup to return to the saved syscall return address in
/* Setup to return to the saved SYSCALL return address in
* the original mode.
*/
regs[REG_PC] = rtcb->xcp.syscall[index].sysreturn;
#ifdef CONFIG_NUTTX_KERNEL
regs[REG_CPSR] = rtcb->xcp.syscall[index].cpsr;
#endif
rtcb->xcp.nsyscalls = index;
/* The return value must be in R0-R1. dispatch_syscall() temporarily
@ -215,7 +227,6 @@ uint32_t *arm_syscall(uint32_t *regs)
regs[REG_R0] = regs[REG_R2];
}
break;
#endif
/* R0=SYS_task_start: This a user task start
*
@ -373,7 +384,7 @@ uint32_t *arm_syscall(uint32_t *regs)
DEBUGASSERT(cmd >= CONFIG_SYS_RESERVED && cmd < SYS_maxsyscall);
/* Make sure that there is a no saved syscall return address. We
/* Make sure that there is a no saved SYSCALL return address. We
* cannot yet handle nested system calls.
*/
@ -426,7 +437,18 @@ uint32_t *arm_syscall(uint32_t *regs)
}
#endif
return OK;
/* Set current_regs to NULL to indicate that we are no longer in an
* interrupt handler.
*/
regs = (uint32_t *)current_regs;
current_regs = NULL;
/* Return the last value of curent_regs. This will determine if any
* context switch will be performed on the return from the exception.
*/
return regs;
}
#else