/* * hal_exception.c - implementation of exception handler for TSAR-MIPS32. * * Author Alain Greiner (2016, 2017) * * Copyright (c) UPMC Sorbonne Universites * * This file is part of ALMOS-MKH. * * ALMOS-MKH is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License as published by * the Free Software Foundation; version 2.0 of the License. * * ALMOS-MKH is distributed in the hope that it will be useful, but * WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * General Public License for more details. * * You should have received a copy of the GNU General Public License * along with ALMOS-MKH; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include ////////////////////////////////////////////////////////////////////////////////////////// // Extern global variables ////////////////////////////////////////////////////////////////////////////////////////// extern chdev_directory_t chdev_dir; // allocated in the kernel_init.c file. ////////////////////////////////////////////////////////////////////////////////////////// // This enum defines the global exception types after analysis by the exception handler. ////////////////////////////////////////////////////////////////////////////////////////// typedef enum { EXCP_NON_FATAL, EXCP_USER_ERROR, EXCP_KERNEL_PANIC, } exception_handling_type_t; ////////////////////////////////////////////////////////////////////////////////////////// // This enum defines the relevant subtypes for a MMU exception reported by the mips32. ////////////////////////////////////////////////////////////////////////////////////////// typedef enum { MMU_EXCP_PAGE_UNMAPPED, MMU_EXCP_USER_PRIVILEGE, MMU_EXCP_USER_EXEC, MMU_EXCP_USER_WRITE, } mmu_exception_subtype_t; ////////////////////////////////////////////////////////////////////////////////////////// // This enum defines the relevant values for XCODE field in mips32 CP0_CR register. ////////////////////////////////////////////////////////////////////////////////////////// typedef enum { XCODE_ADEL = 0x4, // Illegal address for data load XCODE_ADES = 0x5, // Illegal address for data store XCODE_IBE = 0x6, // Instruction MMU exception (can be NON-FATAL) XCODE_DBE = 0x7, // Data MMU exception (can be NON-FATAL) XCODE_RI = 0xA, // Reserved instruction exception XCODE_CPU = 0xB, // Coprocessor unusable exception (can be NON-FATAl) XCODE_OVR = 0xC, // Arithmetic Overflow exception } xcode_values_t; ////////////////////////////////////////////////////////////////////////////////////////// // This static function is called when a FPU Coprocessor Unavailable exception has been // detected for the calling thread. // It enables the FPU, It saves the current FPU context in the current owner thread // descriptor if required, and restore the FPU context from the calling thread descriptor. ////////////////////////////////////////////////////////////////////////////////////////// // @ this : pointer on faulty thread descriptor. // @ return always EXCP_NON_FATAL ////////////////////////////////////////////////////////////////////////////////////////// static error_t hal_fpu_exception( thread_t * this ) { core_t * core = this->core; // enable FPU hal_fpu_enable(); // save FPU context in current owner thread if required if( core->fpu_owner != NULL ) { if( core->fpu_owner != this ) { hal_fpu_context_save ( core->fpu_owner->fpu_context ); } } // attach the FPU to the requesting thread hal_fpu_context_restore( this->fpu_context ); core->fpu_owner = this; return EXCP_NON_FATAL; } // end hal_fpu_exception() ////////////////////////////////////////////////////////////////////////////////////////// // This static function is called when an MMU exception has been detected. // It get the relevant exception arguments from the MMU. // It signal a fatal error in case of illegal access. In case of page unmapped // it checks that the faulty address belongs to a registered vseg. It update the local // vseg list from the reference cluster if required, and signal a fatal user error // in case of illegal virtual address. Finally, it updates the local page table from the // reference cluster. ////////////////////////////////////////////////////////////////////////////////////////// // @ this : pointer on faulty thread descriptor. // @ return EXCP_NON_FATAL / EXCP_USER_ERROR / EXCP_KERNEL_PANIC ////////////////////////////////////////////////////////////////////////////////////////// static error_t hal_mmu_exception( thread_t * this ) { vseg_t * vseg; // vseg containing the bad_vaddr process_t * process; // local process descriptor error_t error; // return value reg_t mmu_ins_excp_code; reg_t mmu_ins_bad_vaddr; reg_t mmu_dat_excp_code; reg_t mmu_dat_bad_vaddr; intptr_t bad_vaddr; uint32_t excp_code; process = this->process; // get relevant values from MMU hal_get_mmu_excp( &mmu_ins_excp_code, &mmu_ins_bad_vaddr, &mmu_dat_excp_code, &mmu_dat_bad_vaddr ); // get exception code and faulty vaddr if( mmu_ins_excp_code ) { excp_code = mmu_ins_excp_code; bad_vaddr = mmu_ins_bad_vaddr; } else if( mmu_dat_excp_code ) { excp_code = mmu_dat_excp_code; bad_vaddr = mmu_dat_bad_vaddr; } else { return EXCP_NON_FATAL; } vmm_dmsg("\n[INFO] %s : enters for thread %x / process %x" " / bad_vaddr = %x / excep_code = %x\n", __FUNCTION__, this->trdid , process->pid , bad_vaddr , excp_code ); // on TSAR, a kernel thread should not rise an MMU exception assert( (this->type != THREAD_USER) , __FUNCTION__ , "thread %x is a kernel thread / vaddr = %x\n", this->trdid , bad_vaddr ); // vaddr must be contained in a registered vseg error = vmm_get_vseg( process , bad_vaddr , &vseg ); vmm_dmsg("\n[INFO] %s : found vseg for thread %x / vseg_min = %x / vseg_max = %x\n", __FUNCTION__ , this->trdid , vseg->min , vseg->max ); // analyse exception code if( excp_code & MMU_EXCP_PAGE_UNMAPPED ) { // enable IRQs before handling page fault hal_enable_irq( NULL ); // try to map the unmapped PTE error = vmm_handle_page_fault( process, vseg, bad_vaddr >> CONFIG_PPM_PAGE_SHIFT ); // vpn // disable IRQs hal_disable_irq( NULL ); if( error ) // not enough memory { printk("\n[ERROR] in %s for thread %x : cannot map legal vaddr = %x\n", __FUNCTION__ , this->trdid , bad_vaddr ); return EXCP_USER_ERROR; } else // page fault successfully handled { vmm_dmsg("\n[INFO] %s : page fault handled for vaddr = %x in thread %x\n", __FUNCTION__ , bad_vaddr , this->trdid ); return EXCP_NON_FATAL; } } else if( excp_code & MMU_EXCP_USER_PRIVILEGE ) { printk("\n[ERROR] in %s for thread %x : user access to kernel vseg at vaddr = %x\n", __FUNCTION__ , this->trdid , bad_vaddr ); return EXCP_USER_ERROR; } else if( excp_code & MMU_EXCP_USER_EXEC ) { printk("\n[ERROR] in %s for thread %x : access to non-exec vseg at vaddr = %x\n", __FUNCTION__ , this->trdid , bad_vaddr ); return EXCP_USER_ERROR; } else if( excp_code & MMU_EXCP_USER_WRITE ) { printk("\n[ERROR] in %s for thread %x : write to non-writable vseg at vaddr = %x\n", __FUNCTION__ , this->trdid , bad_vaddr ); return EXCP_USER_ERROR; } else // this is a kernel error => panic { printk("\n[PANIC] in %s for thread %x : kernel exception = %x / vaddr = %x\n", __FUNCTION__ , this->trdid , excp_code , bad_vaddr ); return EXCP_KERNEL_PANIC; } } // end hal_mmu_exception() ////////////////////////////////////////////////////////////////////////////////////////// // This static function prints on the kernel terminal the saved context (core registers) // and the thread state of a faulty thread. ////////////////////////////////////////////////////////////////////////////////////////// // @ this : pointer on faulty thread descriptor. // @ regs_tbl : pointer on register array. // @ return always EXCP_NON_FATAL ////////////////////////////////////////////////////////////////////////////////////////// static void hal_exception_dump( thread_t * this, reg_t * regs_tbl ) { uint32_t save_sr; // get pointers on TXT0 chdev xptr_t txt0_xp = chdev_dir.txt[0]; cxy_t txt0_cxy = GET_CXY( txt0_xp ); chdev_t * txt0_ptr = GET_PTR( txt0_xp ); // get extended pointer on remote TXT0 chdev lock xptr_t lock_xp = XPTR( txt0_cxy , &txt0_ptr->wait_lock ); // get TXT0 lock in busy waiting mode remote_spinlock_lock_busy( lock_xp , &save_sr ); if( this->type == THREAD_USER ) nolock_printk("\n================= USER ERROR / cycle %d ====================\n", hal_time_stamp() ); else nolock_printk("\n================= KERNEL PANIC / cycle %d ==================\n", hal_time_stamp() ); nolock_printk(" thread type = %s / trdid = %x / pid %x / core[%x,%d]\n" " local locks = %d / remote locks = %d / blocked_vector = %X\n\n", thread_type_str(this->type), this->trdid, this->process->pid, local_cxy, this->core->lid, this->local_locks, this->remote_locks, this->blocked ); nolock_printk("CR %X EPC %X SR %X SP %X\n", regs_tbl[UZ_CR], regs_tbl[UZ_EPC], regs_tbl[UZ_SR], regs_tbl[UZ_SP]); nolock_printk("at_1 %X v0_2 %X v1_3 %X a0_4 %X a1_5 %X\n", regs_tbl[UZ_AT], regs_tbl[UZ_V0], regs_tbl[UZ_V1], regs_tbl[UZ_A0], regs_tbl[UZ_A1]); nolock_printk("a2_6 %X a3_7 %X t0_8 %X t1_9 %X t2_10 %X\n", regs_tbl[UZ_A2],regs_tbl[UZ_A3],regs_tbl[UZ_T0],regs_tbl[UZ_T1],regs_tbl[UZ_T2]); nolock_printk("t3_11 %X t4_12 %X t5_13 %X t6_14 %X t7_15 %X\n", regs_tbl[UZ_T3],regs_tbl[UZ_T4],regs_tbl[UZ_T5],regs_tbl[UZ_T6],regs_tbl[UZ_T7]); nolock_printk("t8_24 %X t9_25 %X gp_28 %X c0_hi %X c0_lo %X\n", regs_tbl[UZ_T8],regs_tbl[UZ_T9],regs_tbl[UZ_GP],regs_tbl[UZ_HI],regs_tbl[UZ_LO]); nolock_printk("s0_16 %X s1_17 %X s2_18 %X s3_19 %X s4_20 %X\n", regs_tbl[UZ_S0],regs_tbl[UZ_S1],regs_tbl[UZ_S2],regs_tbl[UZ_S3],regs_tbl[UZ_S4]); nolock_printk("s5_21 %X s6_22 %X s7_23 %X s8_30 %X ra_31 %X\n", regs_tbl[UZ_S5],regs_tbl[UZ_S6],regs_tbl[UZ_S7],regs_tbl[UZ_S8],regs_tbl[UZ_RA]); // release the lock remote_spinlock_unlock_busy( lock_xp , save_sr ); } // end hal_exception_dump() /////////////////////////////////////////////////////////////////////////////// // TODO replace the hal_core_sleep() by the generic panic() function. /////////////////////////////////////////////////////////////////////////////// void hal_do_exception( thread_t * this, reg_t * regs_tbl ) { error_t error; uint32_t excCode; // 4 bits XCODE from CP0_CR // get 4 bits XCODE from CP0_CR register excCode = (regs_tbl[UZ_CR] >> 2) & 0xF; switch(excCode) { case XCODE_DBE: // can be non fatal case XCODE_IBE: // can be non fatal { error = hal_mmu_exception( this ); } break; case XCODE_CPU: // can be non fatal { if( ((regs_tbl[UZ_CR] >> 28) & 0x3) == 1 ) // unavailable FPU { error = hal_fpu_exception( this ); } else { error = EXCP_USER_ERROR; } } break; case XCODE_OVR: // user fatal error case XCODE_RI: // user fatal error case XCODE_ADEL: // user fatal error case XCODE_ADES: // user fatal error { error = EXCP_USER_ERROR; } break; default: { error = EXCP_KERNEL_PANIC; } } // analyse error code if( error == EXCP_USER_ERROR ) // user error => kill user process { hal_exception_dump( this , regs_tbl ); sys_kill( this->process->pid , SIGKILL ); } else if( error == EXCP_KERNEL_PANIC ) // kernel error => kernel panic { hal_exception_dump( this , regs_tbl ); hal_core_sleep(); } } // end hal_do_exception()