[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>

1 files changed, 67 insertions, 0 deletions

diff --git a/arch/i386/kernel/head.S b/arch/i386/kernel/head.S
index a6b8bd89aa27..be9d883c62ce 100644
--- 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