#define __ASM__ #include #include #include #include #define __ASM_INTR_DIAGNOSIS #ifdef __ASM_INTR_DIAGNOSIS .section .bss .global debug_resv debug_resv: .skip 16 tmp_store: .skip 4 #endif .section .bss .align 16 lo_tmp_stack: .skip 256 tmp_stack: /* This perhaps the ugliest part in the project. It contains code to handle arbitrary depth of nested interrupt and all those corner cases and nasty gotchas. Be aware the twists, offsets and hidden dependencies! */ #define regsize 4 /* stack layout: saved interrupt context */ .struct 0 idepth: .struct idepth + regsize ieax: .struct ieax + regsize iebx: .struct iebx + regsize iecx: .struct iecx + regsize iedx: .struct iedx + regsize iedi: .struct iedi + regsize iebp: .struct iebp + regsize iesi: .struct iesi + regsize ids: .struct ids + regsize ies: .struct ies + regsize ifs: .struct ifs + regsize igs: .struct igs + regsize iesp: .struct iesp + regsize isave_prev: .struct isave_prev + regsize ivec: .struct ivec + regsize iecode: .struct iecode + regsize ieip: .struct ieip + regsize ics: .struct ics + regsize ieflags: .struct ieflags + regsize iuesp: .struct iuesp + regsize iuss: /* stack layout: execution (flow-control) state context */ .struct 0 exsave_prev: .struct exsave_prev + regsize exvec: .struct exvec + regsize execode: .struct execode + regsize exeip: .struct exeip + regsize excs: .struct excs + regsize exeflags: .struct exeflags + regsize exuesp: .struct exuesp + regsize exuss: /* struct layout: critical section of struct proc_info */ .struct 0 proc_pid: .struct proc_pid + regsize proc_parent: .struct proc_parent + regsize proc_intr_ctx: .struct proc_intr_ctx + regsize proc_ustack_top: .struct proc_ustack_top + regsize proc_page_table: .struct proc_page_table + regsize proc_fxstate: .section .text .global interrupt_wrapper interrupt_wrapper: /* Stack layout (layout of struct isr_param) msa: [ss] > 76 -> 28 [esp] > 72 -> 24 eflags > 68 -> 20 cs > 64 -> 16 eip > 60 -> 12 err_code > 56 -> 8 vector > offset = 52 -> 4 [saved_prev_ctx] > offset = 0 --- esp > 12 * 4 = 48 gs fs es ds > offset = 8 * 4 = 32 esi ebp edi edx ecx ebx eax lsa: depth > offset = 0 las: Least Significant Address msa: Most Significant Address */ cld subl $4, %esp pushl %esp subl $16, %esp movw %gs, 12(%esp) movw %fs, 8(%esp) movw %es, 4(%esp) movw %ds, (%esp) pushl %esi pushl %ebp pushl %edi pushl %edx pushl %ecx pushl %ebx pushl %eax movl __current, %eax movl proc_intr_ctx(%eax), %eax incl %eax pushl %eax # nested intr: current depth movl ics(%esp), %eax /* 取出 %cs */ andl $0x3, %eax /* 判断 RPL */ jz 1f movw $KDATA_SEG, %ax /* 如果从用户模式转来，则切换至内核数据段 */ movw %ax, %gs movw %ax, %fs movw %ax, %ds movw %ax, %es movl __current, %eax # FIXME: Save x87 context to user stack, rather than kernel's memory. # 保存x87FPU的状态 movl proc_fxstate(%eax), %ebx fxsave (%ebx) # 保存用户栈顶指针。因为我们允许同级中断的产生，所以需要该手段跟踪用户栈的地址。 movl iuesp(%esp), %ebx # 取出esp movl %ebx, proc_ustack_top(%eax) # 存入__current->ustack_top 1: movl %esp, %eax andl $0xfffffff0, %esp subl $16, %esp movl %eax, (%esp) call intr_handler movl (%esp), %eax .global soft_iret soft_iret: movl %eax, %esp #ifdef __ASM_INTR_DIAGNOSIS movl %eax, (debug_resv + 8) movl iesp(%esp), %eax movl exeip(%eax), %eax movl %eax, (debug_resv + 4) # eip #endif movl __current, %eax movl proc_fxstate(%eax), %eax test %eax, %eax # do we have stored x87 context? jz 1f fxrstor (%eax) 1: popl %eax # discard isr_param::depth popl %eax popl %ebx popl %ecx popl %edx popl %edi popl %ebp popl %esi movw (%esp), %ds movw 4(%esp), %es movw 8(%esp), %fs movw 12(%esp), %gs movl 16(%esp), %esp movl %eax, tmp_store movl __current, %eax # nested intr: restore saved context popl proc_intr_ctx(%eax) addl $8, %esp #ifdef __ASM_INTR_DIAGNOSIS movl (%esp), %eax movl %eax, debug_resv #endif # 处理TSS.ESP的一些边界条件。如果是正常iret（即从内核模式*优雅地*退出） # 那么TSS.ESP0应该为iret进行弹栈后，%esp的值。 # 所以这里的边界条件是：如返回用户模式，iret会额外弹出8个字节（ss,esp） movl 4(%esp), %eax andl $3, %eax setnz %al shll $3, %eax addl $12, %eax addl %esp, %eax movl %eax, (_tss + tss_esp0_off) movl tmp_store, %eax iret .global switch_to switch_to: # 约定 # arg1: 目标进程PCB地址 (next popl %ebx # next movl __current, %eax movl proc_page_table(%eax), %ecx # __current->pagetable movl proc_page_table(%ebx), %eax # next->pagetable cmpl %ecx, %eax # if(next->pagtable != __current->pagetable) { jz 1f movl %eax, %cr3 # cpu_lcr3(next->pagetable) # } 1: movl %ebx, __current # __current = next # 我们已经处在了新的地址空间，为了避免影响其先前的栈布局 # 需要使用一个临时的栈空间 movl $tmp_stack, %esp # 更新 tss movl proc_intr_ctx(%ebx), %eax # proc->intr_ctx movl iesp(%eax), %eax # intr_ctx->esp movl %eax, (tss_esp0_off + _tss) call signal_dispatch # kernel/signal.c test %eax, %eax # do we have signal to handle? jz 1f jmp handle_signal 1: movl proc_intr_ctx(%ebx), %eax jmp soft_iret .global handle_signal handle_signal: # 注意1：任何对proc_sig的布局改动，都须及时的保证这里的一致性！ # 注意2：handle_signal在调用之前，须确保proc_sig已经写入用户栈！ # arg1 in %eax: addr of proc_sig structure in user stack leal 12(%eax), %ebx # %ebx = &proc_sig->prev_context pushl $UDATA_SEG # proc_sig->prev_context.proc_regs.ss pushl %eax # esp movl 48(%ebx), %ebx pushl 68(%ebx) # proc_sig->prev_context.proc_regs.execp->eflags pushl $UCODE_SEG # cs pushl 4(%eax) # %eip = proc_sig->sigact movw $UDATA_SEG, %cx # switch data seg to user mode movw %cx, %es movw %cx, %ds movw %cx, %fs movw %cx, %gs iret