.global debug_resv
debug_resv:
.skip 16
+ tmp_store:
+ .skip 4
#endif
.section .bss
.skip 128
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!
+
+*/
+
.section .text
.global interrupt_wrapper
interrupt_wrapper:
/*
Stack layout (layout of struct isr_param)
- msa: [ss]
- [esp]
- eflags > offset = 48 + 16 = 64
- cs
- eip
- err_code
- vector > offset = 28 + 16 + 4 = 48
+ msa: [ss] > 76
+ [esp] > 72
+ eflags > 68
+ cs > 64
+ eip > 60
+ err_code > 56
+ vector > offset = 52
+ [saved_prev_ctx] > offset = 0
+ ---
esp
gs
fs
es
- ds > offset = 7 * 4 = 28
+ ds > offset = 7 * 4 = 28 + 4
esi
ebp
edi
edx
ecx
ebx
- lsa: eax > offset = 0
+ eax
+ lsa: depth > offset = 0
las: Least Significant Address
msa: Most Significant Address
*/
cld
+
+ subl $52, %esp
pushl %esp
subl $16, %esp
pushl %ebx
pushl %eax
- movl 60(%esp), %eax /* 取出 %cs */
+ movl __current, %eax
+ movl 8(%eax), %eax
+ incl %eax
+ pushl %eax # nested intr: current depth
+
+ movl 116(%esp), %eax /* 取出 %cs */
andl $0x3, %eax /* 判断 RPL */
jz 1f
# 保存用户栈顶指针。这是因为我们允许系统调用内进行上下文切换，而这样一来，我们就失去了用户栈的信息，
# 这样一来，就无法设置信号上下文。这主要是为了实现了pause()而做的准备
- movl (__current), %eax
- movl 68(%esp), %ebx # 取出esp
- movl %ebx, 84(%eax) # 存入__current->ustack_top
+ movl __current, %eax
+
+ # 保存x87FPU的状态
+ movl 68(%eax), %ebx
+ fxsave (%ebx)
+
+ movl 124(%esp), %ebx # 取出esp
+ movl %ebx, 60(%eax) # 存入__current->ustack_top
1:
movl %esp, %eax
#ifdef __ASM_INTR_DIAGNOSIS
movl %eax, (debug_resv + 8)
- movl 56(%esp), %eax
- movl %eax, (debug_resv + 4)
+ movl 48(%esp), %eax
+ movl 60(%eax), %eax
+ movl %eax, (debug_resv + 4) # eip
#endif
-
+ movl __current, %eax
+ movl 68(%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
movl 16(%esp), %esp
+ movl %eax, tmp_store
+ movl __current, %eax
+ # nested intr: restore saved context
+ popl 8(%eax) # depth
+ popl 12(%eax) # eax
+ popl 16(%eax) # ebx
+ popl 20(%eax) # ecx
+ popl 24(%eax) # edx
+ popl 28(%eax) # edi
+ popl 32(%eax) # ebp
+ popl 36(%eax) # esi
+ popl 40(%eax) # ds
+ popl 44(%eax) # es
+ popl 48(%eax) # fs
+ popl 52(%eax) # gs
+ popl 56(%eax) # esp
+
addl $8, %esp
- pushl %eax
#ifdef __ASM_INTR_DIAGNOSIS
- movl 4(%esp), %eax
+ 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 8(%esp), %eax
+ movl 4(%esp), %eax
andl $3, %eax
setnz %al
shll $3, %eax
- addl $16, %eax
+ addl $12, %eax
addl %esp, %eax
movl %eax, (_tss + 4)
- popl %eax
+ movl tmp_store, %eax
iret
.global switch_to
popl %ebx # next
movl __current, %eax
- movl 88(%eax), %ecx # __current->pagetable
- movl 88(%ebx), %eax # next->pagetable
+ movl 64(%eax), %ecx # __current->pagetable
+ movl 64(%ebx), %eax # next->pagetable
cmpl %ecx, %eax # if(next->pagtable != __current->pagetable) {
jz 1f
# 注意2：handle_signal在调用之前，须确保proc_sig已经写入用户栈！
leal 8(%eax), %ebx # arg1 in %eax: addr of proc_sig structure in user stack
- pushl $UDATA_SEG # proc_sig->prev_context.ss
+ pushl $UDATA_SEG # proc_sig->prev_context.proc_regs.ss
pushl %eax # esp
- pushl 64(%ebx) # proc_sig->prev_context.eflags
+ movl 48(%ebx), %ebx
+ pushl 68(%ebx) # proc_sig->prev_context.proc_regs.execp->eflags
pushl $UCODE_SEG # cs
pushl $sig_wrapper # eip for sig wrapper
pushl %eax # Addr to proc_sig structure
pushl 4(%eax) # proc_sig->sig_num ---- 16 bytes aligned
- call (%eax) # invoke signal handler
+ call *(%eax) # invoke signal handler
# invoke the sigreturn syscall to exit the signal wrapper
movl $__SYSCALL_sigreturn, %eax
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