X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=src%2Fuserprog%2Fexception.c;h=19aca125e331783bad87330e8e7213f72072e580;hb=fd2a5afa946474ba0839de0e9da238dbaecbd6a5;hp=dead766fdbde82b736394f1fc4c8ab92d371ff37;hpb=5fa7a9e2a12522684b0fbaa7d06555544563f124;p=pintos-anon diff --git a/src/userprog/exception.c b/src/userprog/exception.c index dead766..19aca12 100644 --- a/src/userprog/exception.c +++ b/src/userprog/exception.c @@ -5,6 +5,9 @@ #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 *); @@ -21,8 +24,8 @@ static void page_fault (struct intr_frame *); 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) { @@ -30,28 +33,38 @@ 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. */ @@ -95,39 +108,41 @@ kill (struct intr_frame *f) } } -/* 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; @@ -136,7 +151,7 @@ page_fault (struct intr_frame *f) /* 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. */ - printf ("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",