-#include "exception.h"
+#include "userprog/exception.h"
#include <inttypes.h>
-#include "lib.h"
-#include "gdt.h"
-#include "interrupt.h"
-#include "thread.h"
+#include <stdio.h>
+#include "userprog/gdt.h"
+#include "threads/interrupt.h"
+#include "threads/thread.h"
+
+/* Number of page faults processed. */
+static long long page_fault_cnt;
static void kill (struct intr_frame *);
static void page_fault (struct intr_frame *);
programs.
In a real Unix-like OS, most of these interrupts would be
- passed along to the user process in the form of signals, but
- we don't implement signals. Instead, we'll make them simply
- kill the user process.
+ passed along to the user process in the form of signals, as
+ described in [SV-386] 3-24 and 3-25, but we don't implement
+ signals. Instead, we'll make them simply kill the user
+ process.
Page faults are an exception. Here they are treated the same
way as other exceptions, but this will need to change to
implement virtual memory.
- Refer to [IA32-v3] section 5.14 for a description of each of
- these exceptions. */
+ Refer to [IA32-v3a] section 5.15 "Exception and Interrupt
+ Reference" for a description of each of these exceptions. */
void
exception_init (void)
{
e.g. via the INT, INT3, INTO, and BOUND instructions. Thus,
we set DPL==3, meaning that user programs are allowed to
invoke them via these instructions. */
- intr_register (3, 3, INTR_ON, kill, "#BP Breakpoint Exception");
- intr_register (4, 3, INTR_ON, kill, "#OF Overflow Exception");
- intr_register (5, 3, INTR_ON, kill, "#BR BOUND Range Exceeded Exception");
+ intr_register_int (3, 3, INTR_ON, kill, "#BP Breakpoint Exception");
+ intr_register_int (4, 3, INTR_ON, kill, "#OF Overflow Exception");
+ intr_register_int (5, 3, INTR_ON, kill,
+ "#BR BOUND Range Exceeded Exception");
/* These exceptions have DPL==0, preventing user processes from
invoking them via the INT instruction. They can still be
caused indirectly, e.g. #DE can be caused by dividing by
0. */
- intr_register (0, 0, INTR_ON, kill, "#DE Divide Error");
- intr_register (1, 0, INTR_ON, kill, "#DB Debug Exception");
- intr_register (6, 0, INTR_ON, kill, "#UD Invalid Opcode Exception");
- intr_register (7, 0, INTR_ON, kill, "#NM Device Not Available Exception");
- intr_register (11, 0, INTR_ON, kill, "#NP Segment Not Present");
- intr_register (12, 0, INTR_ON, kill, "#SS Stack Fault Exception");
- intr_register (13, 0, INTR_ON, kill, "#GP General Protection Exception");
- intr_register (16, 0, INTR_ON, kill, "#MF x87 FPU Floating-Point Error");
- intr_register (19, 0, INTR_ON, kill, "#XF SIMD Floating-Point Exception");
+ intr_register_int (0, 0, INTR_ON, kill, "#DE Divide Error");
+ intr_register_int (1, 0, INTR_ON, kill, "#DB Debug Exception");
+ intr_register_int (6, 0, INTR_ON, kill, "#UD Invalid Opcode Exception");
+ intr_register_int (7, 0, INTR_ON, kill,
+ "#NM Device Not Available Exception");
+ intr_register_int (11, 0, INTR_ON, kill, "#NP Segment Not Present");
+ intr_register_int (12, 0, INTR_ON, kill, "#SS Stack Fault Exception");
+ intr_register_int (13, 0, INTR_ON, kill, "#GP General Protection Exception");
+ intr_register_int (16, 0, INTR_ON, kill, "#MF x87 FPU Floating-Point Error");
+ intr_register_int (19, 0, INTR_ON, kill,
+ "#XF SIMD Floating-Point Exception");
/* Most exceptions can be handled with interrupts turned on.
We need to disable interrupts for page faults because the
fault address is stored in CR2 and needs to be preserved. */
- intr_register (14, 0, INTR_OFF, page_fault, "#PF Page-Fault Exception");
+ intr_register_int (14, 0, INTR_OFF, page_fault, "#PF Page-Fault Exception");
+}
+
+/* Prints exception statistics. */
+void
+exception_print_stats (void)
+{
+ printf ("Exception: %lld page faults\n", page_fault_cnt);
}
/* Handler for an exception (probably) caused by a user process. */
case SEL_UCSEG:
/* User's code segment, so it's a user exception, as we
expected. Kill the user process. */
- printk ("%s: dying due to interrupt %#04x (%s).\n",
- thread_name (thread_current ()),
- f->vec_no, intr_name (f->vec_no));
+ printf ("%s: dying due to interrupt %#04x (%s).\n",
+ thread_name (), f->vec_no, intr_name (f->vec_no));
intr_dump_frame (f);
thread_exit ();
default:
/* Some other code segment? Shouldn't happen. Panic the
kernel. */
- printk ("Interrupt %#04x (%s) in unknown segment %04x\n",
+ printf ("Interrupt %#04x (%s) in unknown segment %04x\n",
f->vec_no, intr_name (f->vec_no), f->cs);
thread_exit ();
}
}
-/* Page fault error code bits that describe the cause of the exception. */
-#define PF_P 0x1 /* 0: not-present page. 1: access rights violation. */
-#define PF_W 0x2 /* 0: read, 1: write. */
-#define PF_U 0x4 /* 0: kernel, 1: user process. */
-
/* Page fault handler. This is a skeleton that must be filled in
- to implement virtual memory.
+ to implement virtual memory. Some solutions to project 2 may
+ also require modifying this code.
At entry, the address that faulted is in CR2 (Control Register
2) and information about the fault, formatted as described in
- the PF_* macros above, is in F's error_code member. The
+ the PF_* macros in exception.h, is in F's error_code member. The
example code here shows how to parse that information. You
can find more information about both of these in the
description of "Interrupt 14--Page Fault Exception (#PF)" in
- [IA32-v3] section 5.14, which is pages 5-46 to 5-49. */
+ [IA32-v3a] section 5.15 "Exception and Interrupt Reference". */
static void
page_fault (struct intr_frame *f)
{
- bool not_present, write, user;
- uint32_t fault_addr;
-
- /* Obtain faulting address, then turn interrupts back on.
- (Interrupts were only off so that we could be assured of
- reading CR2 before it changed.)
-
- The faulting address is not necesarily the address of the
- instruction that caused the fault--that's in F's eip
- member. Rather, it's the linear address that was accessed
- to cause the fault, which is probably an address of data,
- not code. */
+ bool not_present; /* True: not-present page, false: writing r/o page. */
+ bool write; /* True: access was write, false: access was read. */
+ bool user; /* True: access by user, false: access by kernel. */
+ void *fault_addr; /* Fault address. */
+
+ /* Obtain faulting address, the virtual address that was
+ accessed to cause the fault. It may point to code or to
+ data. It is not necessarily the address of the instruction
+ that caused the fault (that's f->eip).
+ See [IA32-v2a] "MOV--Move to/from Control Registers" and
+ [IA32-v3a] 5.15 "Interrupt 14--Page Fault Exception
+ (#PF)". */
asm ("movl %%cr2, %0" : "=r" (fault_addr));
+
+ /* Turn interrupts back on (they were only off so that we could
+ be assured of reading CR2 before it changed). */
intr_enable ();
+ /* Count page faults. */
+ page_fault_cnt++;
+
/* Determine cause. */
not_present = (f->error_code & PF_P) == 0;
write = (f->error_code & PF_W) != 0;
/* To implement virtual memory, delete the rest of the function
body, and replace it with code that brings in the page to
which fault_addr refers. */
- printk ("Page fault at %08"PRIx32": %s error %s page in %s context.\n",
+ printf ("Page fault at %p: %s error %s page in %s context.\n",
fault_addr,
not_present ? "not present" : "rights violation",
write ? "writing" : "reading",
projects / pintos-anon / blobdiff