fix: corner case for x87 context restore on execve

[lunaix-os.git] / lunaix-os / kernel / asm / x86 / interrupt.S

diff --git a/lunaix-os/kernel/asm/x86/interrupt.S b/lunaix-os/kernel/asm/x86/interrupt.S
index dc5c4c395ee750abfb379707cd5c26db5b3193bf..f308503c7aac3722a39f721afcae32f1462259e4 100644 (file)
--- a/lunaix-os/kernel/asm/x86/interrupt.S
+++ b/lunaix-os/kernel/asm/x86/interrupt.S
@@ -1,76 +1,43 @@
 #define __ASM__
 #include <arch/x86/interrupts.h>
 #define __ASM__
 #include <arch/x86/interrupts.h>

-#include <lunaix/common.h>
+#include <arch/x86/i386_asm.h>
+#include <arch/x86/tss.h>

 #include <lunaix/syscall.h>
 #include <lunaix/syscall.h>

-#define __ASM_INTR_DIAGNOSIS
+#include <arch/x86/interrupt.S.inc>

 
 

-.macro isr_template vector, no_error_code=1
-    .global _asm_isr\vector
-    .type _asm_isr\vector, @function
-    _asm_isr\vector:
-        .if \no_error_code
-            pushl $0x0
-        .endif
-        pushl $\vector
-        jmp interrupt_wrapper
-.endm
+#define __ASM_INTR_DIAGNOSIS

 
 #ifdef __ASM_INTR_DIAGNOSIS
 .section .bss
     .global debug_resv
     debug_resv:
         .skip 16
 
 #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:
 #endif
 
 .section .bss
     .align 16
     lo_tmp_stack:

-        .skip 128
+        .skip 256

     tmp_stack:
 
     tmp_stack:
 

-.section .text
-    isr_template FAULT_DIVISION_ERROR
-    isr_template FAULT_GENERAL_PROTECTION, no_error_code=0
-    isr_template FAULT_PAGE_FAULT, no_error_code=0
-    isr_template FAULT_STACK_SEG_FAULT, no_error_code=0
+/*
+    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.

 
 

-    isr_template LUNAIX_SYS_PANIC
-    isr_template LUNAIX_SYS_CALL
+    Be aware the twists, offsets and hidden dependencies!

 
 

-    isr_template APIC_ERROR_IV
-    isr_template APIC_LINT0_IV
-    isr_template APIC_TIMER_IV
-    isr_template APIC_SPIV_IV
-    isr_template RTC_TIMER_IV
-    isr_template PC_KBD_IV
+*/

 
 

+.section .text
+    .global interrupt_wrapper

     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
-           esp
-           gs
-           fs
-           es
-           ds         > offset = 7 * 4 = 28
-           esi
-           ebp
-           edi
-           edx
-           ecx
-           ebx
-    lsa:   eax        > offset = 0
-
-            las: Least Significant Address
-            msa: Most Significant Address
-        */

         cld
         cld

+
+        subl $4, %esp

         pushl %esp
 
         subl $16, %esp
         pushl %esp
 
         subl $16, %esp


@@ -87,25 +54,39 @@
         pushl %ebx
         pushl %eax
 
         pushl %ebx
         pushl %eax
 

-        movl 60(%esp), %eax   /* 取出 %cs */
+        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
 
         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 */
+    /* crossing the user/kernel boundary */
+        movw $KDATA_SEG, %ax

         movw %ax, %gs
         movw %ax, %fs
         movw %ax, %ds
         movw %ax, %es
 
         movw %ax, %gs
         movw %ax, %fs
         movw %ax, %ds
         movw %ax, %es
 

-        # 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, %ebx
+
+        # Save x87 context to user stack, rather than kernel's memory.
+        # XXX what will happen if we triggered a page fault during fxsave?
+        # FIXME can we remove this overhead?
+        movl iuesp(%esp), %eax
+        andl $stack_alignment, %eax 
+        subl $512, %eax
+        fxsave (%eax)
+
+        # 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 %eax, proc_ustack_top(%ebx)     # 存入__current->ustack_top

 
 

+    /* kernel space same-level switch */

     1:
         movl %esp, %eax
     1:
         movl %esp, %eax

-        andl $0xfffffff0, %esp
+        andl $stack_alignment, %esp

         subl $16, %esp
         movl %eax, (%esp)
 
         subl $16, %esp
         movl %eax, (%esp)
 


@@ -119,10 +100,23 @@
 
 #ifdef __ASM_INTR_DIAGNOSIS
         movl %eax, (debug_resv + 8)
 
 #ifdef __ASM_INTR_DIAGNOSIS
         movl %eax, (debug_resv + 8)

-        movl 56(%esp), %eax
-        movl %eax, (debug_resv + 4)
+        movl iesp(%esp), %eax
+        movl exeip(%eax), %eax
+        movl %eax, (debug_resv + 4) # eip

 #endif
 
 #endif
 

+        movl ics(%esp), %eax
+        andl $3, %eax
+        jz 1f 
+
+        movl __current, %eax
+        movl proc_ustack_top(%eax), %eax
+        test %eax, %eax
+        jz 1f
+        fxrstor (%eax)
+
+1:
+        popl %eax   # discard isr_param::depth

         popl %eax
         popl %ebx
         popl %ecx
         popl %eax
         popl %ebx
         popl %ecx


@@ -138,24 +132,30 @@
 
         movl 16(%esp), %esp
 
 
         movl 16(%esp), %esp
 

+        movl %eax, tmp_store
+        movl __current, %eax
+
+        # nested intr: restore saved context
+        popl proc_intr_ctx(%eax)
+

         addl $8, %esp
 
         addl $8, %esp
 

-        pushl %eax

 #ifdef __ASM_INTR_DIAGNOSIS
 #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 %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
         andl $3, %eax
         setnz %al
         shll $3, %eax

-        addl $16, %eax
+        addl $12, %eax

         addl %esp, %eax
         addl %esp, %eax

-        movl %eax, (_tss + 4)
-        popl %eax
+        movl %eax, (_tss + tss_esp0_off)
+        movl tmp_store, %eax
+

         iret
 
     .global switch_to
         iret
 
     .global switch_to


@@ -165,8 +165,8 @@
 
         popl %ebx               # next
         movl __current, %eax    
 
         popl %ebx               # next
         movl __current, %eax    

-        movl 88(%eax), %ecx     # __current->pagetable
-        movl 88(%ebx), %eax     # next->pagetable
+        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
         
         cmpl %ecx, %eax         # if(next->pagtable != __current->pagetable) {
         jz 1f


@@ -178,26 +178,37 @@
         # 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
         # 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

+

         call signal_dispatch    # kernel/signal.c
 
         test %eax, %eax         # do we have signal to handle?
         jz 1f
         call signal_dispatch    # kernel/signal.c
 
         test %eax, %eax         # do we have signal to handle?
         jz 1f

+
+        # 更新 tss
+        movl proc_intr_ctx(%ebx), %ecx      # __current->intr_ctx
+        movl %ecx, (tss_esp0_off + _tss)
+

         jmp handle_signal
         jmp handle_signal

+

     1:
     1:

-        leal 8(%ebx), %eax
+        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！
         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！

-        leal 8(%eax), %ebx      # arg1 in %eax: addr of proc_sig structure in user stack
+        # arg1 in %eax: addr of proc_sig structure in user stack
+        movl psig_saved_ictx(%eax), %ebx      # %ebx = &proc_sig->saved_ictx

 
 

-        pushl $UDATA_SEG        # proc_sig->prev_context.ss
+        pushl $UDATA_SEG

         pushl %eax              # esp
         pushl %eax              # esp

-        pushl 64(%ebx)          # proc_sig->prev_context.eflags
+
+        movl iexecp(%ebx), %ebx
+        pushl exeflags(%ebx)          # proc_sig->saved_ictx->execp->eflags
+        

         pushl $UCODE_SEG        # cs
         pushl $UCODE_SEG        # cs

-        pushl $sig_wrapper      # eip for sig wrapper
+        pushl psig_sigact(%eax)           # %eip = proc_sig->sigact

 
         movw $UDATA_SEG, %cx    # switch data seg to user mode
         movw %cx, %es
 
         movw $UDATA_SEG, %cx    # switch data seg to user mode
         movw %cx, %es


@@ -205,21 +216,4 @@
         movw %cx, %fs
         movw %cx, %gs
 
         movw %cx, %fs
         movw %cx, %gs
 

-        iret  
-
-.section .usrtext
-    sig_wrapper:                # in user mode
-        movl %esp, %eax
-        and $0xfffffff0, %esp
-        subl $8, %esp
-        pushl %eax              # Addr to proc_sig structure 
-        pushl 4(%eax)           # proc_sig->sig_num     ---- 16 bytes aligned
-
-        call (%eax)             # invoke signal handler
-
-        # invoke the sigreturn syscall to exit the signal wrapper
-        movl $__SYSCALL_sigreturn, %eax
-        movl 4(%esp), %ebx
-        int $LUNAIX_SYS_CALL    
-
-        ud2                     # never reach!
\ No newline at end of file
+        iret
\ No newline at end of file