/* * Copyright (c) 2016 Intel Corporation * * SPDX-License-Identifier: Apache-2.0 */ #include #include #include /* exports */ GTEXT(_exception) /* import */ GTEXT(_Fault) GTEXT(__swap) #ifdef CONFIG_IRQ_OFFLOAD GTEXT(_irq_do_offload) GTEXT(_offload_routine) #endif #ifdef CONFIG_TIMESLICING GTEXT(_update_time_slice_before_swap) #endif /* Allows use of r1/at register, otherwise reserved for assembler use */ .set noat /* Placed into special 'exception' section so that the linker can put this code * at ALT_CPU_EXCEPTION_ADDR defined in system.h * * This is the common entry point for processor exceptions and interrupts from * the Internal Interrupt Controller (IIC). * * If the External (EIC) controller is in use, then we will never get here on * behalf of an interrupt, instead the EIC driver will have set up a vector * table and the processor will jump directly into the appropriate table * entry. */ SECTION_FUNC(exception.entry, _exception) /* Reserve thread stack space for saving context */ subi sp, sp, __NANO_ESF_SIZEOF /* Preserve all caller-saved registers onto the thread's stack */ stw ra, __NANO_ESF_ra_OFFSET(sp) stw r1, __NANO_ESF_r1_OFFSET(sp) stw r2, __NANO_ESF_r2_OFFSET(sp) stw r3, __NANO_ESF_r3_OFFSET(sp) stw r4, __NANO_ESF_r4_OFFSET(sp) stw r5, __NANO_ESF_r5_OFFSET(sp) stw r6, __NANO_ESF_r6_OFFSET(sp) stw r7, __NANO_ESF_r7_OFFSET(sp) stw r8, __NANO_ESF_r8_OFFSET(sp) stw r9, __NANO_ESF_r9_OFFSET(sp) stw r10, __NANO_ESF_r10_OFFSET(sp) stw r11, __NANO_ESF_r11_OFFSET(sp) stw r12, __NANO_ESF_r12_OFFSET(sp) stw r13, __NANO_ESF_r13_OFFSET(sp) stw r14, __NANO_ESF_r14_OFFSET(sp) stw r15, __NANO_ESF_r15_OFFSET(sp) /* Store value of estatus control register */ rdctl et, estatus stw et, __NANO_ESF_estatus_OFFSET(sp) /* ea-4 is the address of the instruction when the exception happened, * put this in the stack frame as well */ addi r15, ea, -4 stw r15, __NANO_ESF_instr_OFFSET(sp) /* Figure out whether we are here because of an interrupt or an * exception. If an interrupt, switch stacks and enter IRQ handling * code. If an exception, remain on current stack and enter exception * handing code. From the CPU manual, ipending must be nonzero and * estatis.PIE must be enabled for this to be considered an interrupt. * * Stick ipending in r4 since it will be an arg for _enter_irq */ rdctl r4, ipending beq r4, zero, not_interrupt /* We stashed estatus in et earlier */ andi r15, et, 1 beq r15, zero, not_interrupt is_interrupt: /* If we get here, this is an interrupt */ /* Grab a reference to _kernel in r10 so we can determine the * current irq stack pointer */ movhi r10, %hi(_kernel) ori r10, r10, %lo(_kernel) /* Stash a copy of thread's sp in r12 so that we can put it on the IRQ * stack */ mov r12, sp /* Switch to interrupt stack */ ldw sp, _kernel_offset_to_irq_stack(r10) /* Store thread stack pointer onto IRQ stack */ addi sp, sp, -4 stw r12, 0(sp) on_irq_stack: /* Enter C interrupt handling code. Value of ipending will be the * function parameter since we put it in r4 */ call _enter_irq /* Interrupt handler finished and the interrupt should be serviced * now, the appropriate bits in ipending should be cleared */ /* Get a reference to _kernel again in r10 */ movhi r10, %hi(_kernel) ori r10, r10, %lo(_kernel) #ifdef CONFIG_PREEMPT_ENABLED ldw r11, _kernel_offset_to_current(r10) /* Determine whether the exception of the ISR requires context * switch */ /* Call into the kernel to see if a scheduling decision is necessary */ ldw r2, _kernel_offset_to_ready_q_cache(r10) beq r2, r11, no_reschedule /* * A context reschedule is required: keep the volatile registers of * the interrupted thread on the context's stack. Utilize * the existing __swap() primitive to save the remaining * thread's registers (including floating point) and perform * a switch to the new thread. */ /* We put the thread stack pointer on top of the IRQ stack before * we switched stacks. Restore it to go back to thread stack */ ldw sp, 0(sp) #ifdef CONFIG_TIMESLICING call _update_time_slice_before_swap #endif /* Argument to Swap() is estatus since that's the state of the * status register before the exception happened. When coming * out of the context switch we need this info to restore * IRQ lock state. We put this value in et earlier. */ mov r4, et call __swap jmpi _exception_exit #else jmpi no_reschedule #endif /* CONFIG_PREEMPT_ENABLED */ not_interrupt: /* Since this wasn't an interrupt we're not going to restart the * faulting instruction. * * We earlier put ea - 4 in the stack frame, replace it with just ea */ stw ea, __NANO_ESF_instr_OFFSET(sp) #ifdef CONFIG_IRQ_OFFLOAD /* Check the contents of _offload_routine. If non-NULL, jump into * the interrupt code anyway. */ movhi r10, %hi(_offload_routine) ori r10, r10, %lo(_offload_routine) ldw r11, (r10) bne r11, zero, is_interrupt #endif _exception_enter_fault: /* If we get here, the exception wasn't in interrupt or an * invocation of irq_oflload(). Let _Fault() handle it in * C domain */ mov r4, sp call _Fault jmpi _exception_exit no_reschedule: /* We put the thread stack pointer on top of the IRQ stack before * we switched stacks. Restore it to go back to thread stack */ ldw sp, 0(sp) /* Fall through */ _exception_exit: /* We are on the thread stack. Restore all saved registers * and return to the interrupted context */ /* Return address from the exception */ ldw ea, __NANO_ESF_instr_OFFSET(sp) /* Restore estatus * XXX is this right??? */ ldw r5, __NANO_ESF_estatus_OFFSET(sp) wrctl estatus, r5 /* Restore caller-saved registers */ ldw ra, __NANO_ESF_ra_OFFSET(sp) ldw r1, __NANO_ESF_r1_OFFSET(sp) ldw r2, __NANO_ESF_r2_OFFSET(sp) ldw r3, __NANO_ESF_r3_OFFSET(sp) ldw r4, __NANO_ESF_r4_OFFSET(sp) ldw r5, __NANO_ESF_r5_OFFSET(sp) ldw r6, __NANO_ESF_r6_OFFSET(sp) ldw r7, __NANO_ESF_r7_OFFSET(sp) ldw r8, __NANO_ESF_r8_OFFSET(sp) ldw r9, __NANO_ESF_r9_OFFSET(sp) ldw r10, __NANO_ESF_r10_OFFSET(sp) ldw r11, __NANO_ESF_r11_OFFSET(sp) ldw r12, __NANO_ESF_r12_OFFSET(sp) ldw r13, __NANO_ESF_r13_OFFSET(sp) ldw r14, __NANO_ESF_r14_OFFSET(sp) ldw r15, __NANO_ESF_r15_OFFSET(sp) /* Put the stack pointer back where it was when we entered * exception state */ addi sp, sp, __NANO_ESF_SIZEOF /* All done, copy estatus into status and transfer to ea */ eret