54 lines
1.1 KiB
ArmAsm
54 lines
1.1 KiB
ArmAsm
/*
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# Page fault
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Generate and handle a page fault.
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Expected output:
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Page fault handled. Error code:
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00000002
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*/
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#include "common.h"
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BEGIN
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CLEAR
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STAGE2
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PROTECTED_MODE
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IDT_SETUP_ENTRY $14, $interrupt_handler
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lidt idt_descriptor
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SETUP_PAGING_4M
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/* Make page 0 not present, so that any access to it will segfault. */
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andb $0xFE, page_table
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PAGING_ON
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/* Access page 0, generating a segfault. */
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movb $0, 0
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PAGING_OFF
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jmp .
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IDT_START
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IDT_SKIP 14
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IDT_ENTRY
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IDT_END
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interrupt_handler:
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VGA_PRINT_STRING $message
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/*
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Mandatory because page faults push the error code to the stack.
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If we don't do this, then the stack will be wrong for iret,
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likely leading to a general fault exception:
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http://stackoverflow.com/questions/10581224/why-does-iret-from-a-page-fault-handler-generate-interrupt-13-general-protectio/33398064#33398064
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*/
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pop %eax
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VGA_PRINT_HEX_4 <%eax>
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/*
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Make the page present. because iret will return to before the mov,
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and we'd get and infinite loop.
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*/
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orb $1, page_table
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iret
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message:
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.asciz "Page fault handled. Error code:"
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