Page Fault Error Code
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Stack-Segment Fault 1.1.8 General Protection Fault 1.1.9 Page Fault 1.1.9.1 Error code 1.1.10 x87 Floating-Point Exception 1.1.11 Alignment Check 1.1.12 SIMD Floating-Point Exception 1.2 Traps exception 13 general protection fault 1.2.1 Debug 1.2.2 Breakpoint 1.2.3 Overflow 1.3 Aborts 1.3.1 Double Fault 1.3.2
General Protection Fault Error Code
Machine Check 1.3.3 Triple Fault 2 Selector Error Code 2.1 Legacy 2.1.1 FPU Error Interrupt 2.1.2 Coprocessor Segment
X86 Exceptions
Overrun 3 See Also 3.1 External Links Exceptions as described in this article are generated by the CPU when an 'error' occurs. Some exceptions are not really errors in
Invalid Opcode Exception X64 Exception Type 06
most cases, such as page faults. Exceptions are a type of interrupt. Exceptions are classified as: Faults: These can be corrected and the program may continue as if nothing happened. Traps: Traps are reported immediately after the execution of the trapping instruction. Aborts: Some severe unrecoverable error. Some exceptions will push a 32-bit "error code" on to the top linux general protection fault of the stack, which provides additional information about the error. This value must be pulled from the stack before returning control back to the currently running program. (i.e. before calling IRET) Name Vector nr. Type Mnemonic Error code? Divide-by-zero Error 0 (0x0) Fault #DE No Debug 1 (0x1) Fault/Trap #DB No Non-maskable Interrupt 2 (0x2) Interrupt - No Breakpoint 3 (0x3) Trap #BP No Overflow 4 (0x4) Trap #OF No Bound Range Exceeded 5 (0x5) Fault #BR No Invalid Opcode 6 (0x6) Fault #UD No Device Not Available 7 (0x7) Fault #NM No Double Fault 8 (0x8) Abort #DF Yes (Zero) Coprocessor Segment Overrun 9 (0x9) Fault - No Invalid TSS 10 (0xA) Fault #TS Yes Segment Not Present 11 (0xB) Fault #NP Yes Stack-Segment Fault 12 (0xC) Fault #SS Yes General Protection Fault 13 (0xD) Fault #GP Yes Page Fault 14 (0xE) Fault #PF Yes Reserved 15 (0xF) - - No x87 Floating-Point Exception 16 (0x10) Fault #MF No Alignment Check 17 (0x11) Fault #AC Yes Machine Check 18 (0x12) Abort #MC No SIMD Floating-
EiB). Paging is a system which allows each process to see the full virtual address space, without actually requiring the full amount x86 exception handling of physical memory to be available or present. In fact, current osdev page fault implementations of x86-64 have a limit of 1 TiB and a theoretical limit of 4 PiB of gpf not handled opcode from v86 physical RAM. In addition to this, paging introduces the benefit of page-level protection. In this system, user processes can only see and modify data which is paged in http://wiki.osdev.org/Exceptions on their own address space, providing hardware-based isolation. System pages are also protected from user processes. On the x86-64 architecture, page-level protection now completely supersedes Segmentation as the memory protection mechanism. On the IA-32 architecture, both paging and segmentation exist, but segmentation is now considered 'legacy'. Once an Operating System has paging, it can also make use http://wiki.osdev.org/Paging of other benefits and workarounds, such as linear framebuffer simulation for memory-mapped IO and paging out to disk, where disk storage space is used to free up physical RAM. Contents 1 MMU 1.1 Page Directory 1.2 Page Table 1.3 Example 2 Enabling 3 Physical Address Extension 4 Usage 4.1 Virtual Address Spaces 4.2 Virtual Memory 5 Manipulation 6 Page Faults 6.1 Handling 7 INVLPG 8 Paging Tricks 9 See Also 9.1 Articles 9.2 External Links MMU Paging is achieved through the use of the MMU (temporary: article 1, article 2). On the x86, the MMU maps memory through a series of tables, two to be exact. They are the paging directory (PD), and the paging table (PT). Both tables contain 1024 4-byte entries, making them 4 KiB each. In the page directory, each entry points to a page table. In the page table, each entry points to a physical address that is then mapped to the virtual address found by calculating the offset within the directory and the
introducing more precise citations. (February 2008) (Learn how and when to remove this template message) A page fault (sometimes called #PF, PF or hard fault[a]) https://en.wikipedia.org/wiki/Page_fault is a type of interrupt, called trap, raised by computer hardware when a running program accesses a memory page that is mapped into the virtual address space, but not actually loaded http://www.delorie.com/djgpp/doc/dpmi/ch4.5.html into main memory. The hardware that detects a page fault is the processor's memory management unit (MMU), while the exception handling software that handles page faults is generally a part general protection of the operating system kernel. When handling a page fault, the operating system generally tries to make the required page accessible at the location in physical memory, or terminates the program in case of an illegal memory access. Contrary to what "fault" might suggest, valid page faults are not errors, and are common and necessary to increase the amount of general protection fault memory available to programs in any operating system that utilizes virtual memory, including OpenVMS, Microsoft Windows, Unix-like systems (including Mac OS X, Linux, *BSD, Solaris, AIX, and HP-UX), and z/OS. Contents 1 Types 1.1 Minor 1.2 Major 1.3 Invalid 2 Invalid conditions 3 See also 4 Notes 5 References 6 External links Types[edit] Minor[edit] If the page is loaded in memory at the time the fault is generated, but is not marked in the memory management unit as being loaded in memory, then it is called a minor or soft page fault. The page fault handler in the operating system merely needs to make the entry for that page in the memory management unit point to the page in memory and indicate that the page is loaded in memory; it does not need to read the page into memory. This could happen if the memory is shared by different programs and the page is already brought into memory for other programs. The page could also have been removed from the working set of a process, but not yet written t
are: use of an invalid selector, use of a selector for which the program has insufficient privileges, use of an offset outside the limits of a segment, execution of an illegal opcode, or division by zero. The DPMI host distinguishes between exceptions and external hardware interrupts or software interrupts. Handlers for exceptions can only be installed with Int 31H Functions 0203H, 0212H, or 0213H. If the client does not install a handler for a particular exception, or installs a handler but chains to the host's default handler, the host reflects the exception as a real mode interrupt for exceptions 0,1,2,3,4,5, and 7. The default behavior of exceptions 6 and 8-1FH is to terminate the client (some hosts may decide that they have to terminate the VM because the fault came from real mode code or it is in a non-terminatable state). Function 0203H was defined in DPMI version 0.9 and continues to be supported in DPMI version 1.0 for compatibility reasons. Exception handlers installed with Function 0203H are only called for exceptions that occur in protected mode. All exceptions are examined by the DPMI host. The host processes any exception that it is responsible for, such as page fault for virtual memory management. These transparent exceptions are never passed to the client exception handlers. All other exceptions become visible exceptions to a client and are passed to the client exception handler (if any) from the DPMI host. The client exception handlers must return with a FAR RETURN, with interrupts disabled on a locked stack, and with SS, (E)SP, CS, and (E)IP registers at the point of exception pushed on the stack. All other registers are unchanged from their contents at the point of exception. The stack frame for 16-bit handlers installed with Function 0203H has the following format: 15 0 +---------------+ | SS | |---------------| 0EH | SP | |---------------| 0CH | Flags | |---------------| 0AH | CS | |---------------| 08H | IP | |---------------| 06H | Error Code | |---------------| 04H | Return CS | |---------------| 02H | Return IP | |---------------| 00H <-- SS:SP The stack frame for 32-bit handlers installed with Function 0203H has the following format: 31 15 0 +---------------+---------------| | Reserved | SS | +---------------+--------------