[PATCH] i386: Do better early exception handlers

Add early i386 fault handlers with debug information for common faults.
Handles:

        divide error
        invalid opcode
        protection fault
        page fault

Also adds code to detect early recursive/multiple faults and halt the
system when they happen (taken from x86_64.)

Signed-off-by: Chuck Ebbert <76306.1226@compuserve.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Andi Kleen <ak@muc.de>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>

diff --git a/arch/i386/kernel/head.S b/arch/i386/kernel/head.S
index a6b8bd8..be9d883 100644 (file)
--- a/arch/i386/kernel/head.S
+++ b/arch/i386/kernel/head.S
@@ -371,8 +371,65 @@ rp_sidt:
        addl $8,%edi
        dec %ecx
        jne rp_sidt
+
+.macro set_early_handler handler,trapno
+       lea \handler,%edx
+       movl $(__KERNEL_CS << 16),%eax
+       movw %dx,%ax
+       movw $0x8E00,%dx        /* interrupt gate - dpl=0, present */
+       lea idt_table,%edi
+       movl %eax,8*\trapno(%edi)
+       movl %edx,8*\trapno+4(%edi)
+.endm
+
+       set_early_handler handler=early_divide_err,trapno=0
+       set_early_handler handler=early_illegal_opcode,trapno=6
+       set_early_handler handler=early_protection_fault,trapno=13
+       set_early_handler handler=early_page_fault,trapno=14
+
        ret
 
+early_divide_err:
+       xor %edx,%edx
+       pushl $0        /* fake errcode */
+       jmp early_fault
+
+early_illegal_opcode:
+       movl $6,%edx
+       pushl $0        /* fake errcode */
+       jmp early_fault
+
+early_protection_fault:
+       movl $13,%edx
+       jmp early_fault
+
+early_page_fault:
+       movl $14,%edx
+       jmp early_fault
+
+early_fault:
+       cld
+#ifdef CONFIG_PRINTK
+       movl $(__KERNEL_DS),%eax
+       movl %eax,%ds
+       movl %eax,%es
+       cmpl $2,early_recursion_flag
+       je hlt_loop
+       incl early_recursion_flag
+       movl %cr2,%eax
+       pushl %eax
+       pushl %edx              /* trapno */
+       pushl $fault_msg
+#ifdef CONFIG_EARLY_PRINTK
+       call early_printk
+#else
+       call printk
+#endif
+#endif
+hlt_loop:
+       hlt
+       jmp hlt_loop
+
 /* This is the default interrupt "handler" :-) */
        ALIGN
 ignore_int:
@@ -386,6 +443,9 @@ ignore_int:
        movl $(__KERNEL_DS),%eax
        movl %eax,%ds
        movl %eax,%es
+       cmpl $2,early_recursion_flag
+       je hlt_loop
+       incl early_recursion_flag
        pushl 16(%esp)
        pushl 24(%esp)
        pushl 32(%esp)
@@ -431,9 +491,16 @@ ENTRY(stack_start)
 
 ready: .byte 0
 
+early_recursion_flag:
+       .long 0
+
 int_msg:
        .asciz "Unknown interrupt or fault at EIP %p %p %p\n"
 
+fault_msg:
+       .ascii "Int %d: CR2 %p  err %p  EIP %p  CS %p  flags %p\n"
+       .asciz "Stack: %p %p %p %p %p %p %p %p\n"
+
 /*
  * The IDT and GDT 'descriptors' are a strange 48-bit object
  * only used by the lidt and lgdt instructions. They are not