423A35C7/os_kernel_lab
1
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity

add lab answers

Browse Source
This commit is contained in:
chyyuu
2014-08-20 15:42:20 +08:00
parent d9ec12887b
commit f9773095fe
731 changed files with 92876 additions and 0 deletions
Download Patch File Download Diff File Expand all files Collapse all files

27
labcodes_answer/lab5_result/kern/debug/assert.h Normal file
View File

@@ -0,0 +1,27 @@
#ifndef __KERN_DEBUG_ASSERT_H__
#define __KERN_DEBUG_ASSERT_H__
#include <defs.h>
void __warn(const char *file, int line, const char *fmt, ...);
void __noreturn __panic(const char *file, int line, const char *fmt, ...);
#define warn(...) \
__warn(__FILE__, __LINE__, __VA_ARGS__)
#define panic(...) \
__panic(__FILE__, __LINE__, __VA_ARGS__)
#define assert(x) \
do { \
if (!(x)) { \
panic("assertion failed: %s", #x); \
} \
} while (0)
// static_assert(x) will generate a compile-time error if 'x' is false.
#define static_assert(x) \
switch (x) { case 0: case (x): ; }
#endif /* !__KERN_DEBUG_ASSERT_H__ */

365
labcodes_answer/lab5_result/kern/debug/kdebug.c Normal file
View File

@@ -0,0 +1,365 @@
#include <defs.h>
#include <x86.h>
#include <stab.h>
#include <stdio.h>
#include <string.h>
#include <memlayout.h>
#include <sync.h>
#include <vmm.h>
#include <proc.h>
#include <kdebug.h>
#include <kmonitor.h>
#include <assert.h>
#define STACKFRAME_DEPTH 20
extern const struct stab __STAB_BEGIN__[]; // beginning of stabs table
extern const struct stab __STAB_END__[]; // end of stabs table
extern const char __STABSTR_BEGIN__[]; // beginning of string table
extern const char __STABSTR_END__[]; // end of string table
/* debug information about a particular instruction pointer */
struct eipdebuginfo {
const char *eip_file; // source code filename for eip
int eip_line; // source code line number for eip
const char *eip_fn_name; // name of function containing eip
int eip_fn_namelen; // length of function's name
uintptr_t eip_fn_addr; // start address of function
int eip_fn_narg; // number of function arguments
};
/* user STABS data structure */
struct userstabdata {
const struct stab *stabs;
const struct stab *stab_end;
const char *stabstr;
const char *stabstr_end;
};
/* *
* stab_binsearch - according to the input, the initial value of
* range [*@region_left, *@region_right], find a single stab entry
* that includes the address @addr and matches the type @type,
* and then save its boundary to the locations that pointed
* by @region_left and @region_right.
*
* Some stab types are arranged in increasing order by instruction address.
* For example, N_FUN stabs (stab entries with n_type == N_FUN), which
* mark functions, and N_SO stabs, which mark source files.
*
* Given an instruction address, this function finds the single stab entry
* of type @type that contains that address.
*
* The search takes place within the range [*@region_left, *@region_right].
* Thus, to search an entire set of N stabs, you might do:
*
* left = 0;
* right = N - 1; (rightmost stab)
* stab_binsearch(stabs, &left, &right, type, addr);
*
* The search modifies *region_left and *region_right to bracket the @addr.
* *@region_left points to the matching stab that contains @addr,
* and *@region_right points just before the next stab.
* If *@region_left > *region_right, then @addr is not contained in any
* matching stab.
*
* For example, given these N_SO stabs:
* Index Type Address
* 0 SO f0100000
* 13 SO f0100040
* 117 SO f0100176
* 118 SO f0100178
* 555 SO f0100652
* 556 SO f0100654
* 657 SO f0100849
* this code:
* left = 0, right = 657;
* stab_binsearch(stabs, &left, &right, N_SO, 0xf0100184);
* will exit setting left = 118, right = 554.
* */
static void
stab_binsearch(const struct stab *stabs, int *region_left, int *region_right,
int type, uintptr_t addr) {
int l = *region_left, r = *region_right, any_matches = 0;
while (l <= r) {
int true_m = (l + r) / 2, m = true_m;
// search for earliest stab with right type
while (m >= l && stabs[m].n_type != type) {
m --;
}
if (m < l) { // no match in [l, m]
l = true_m + 1;
continue;
}
// actual binary search
any_matches = 1;
if (stabs[m].n_value < addr) {
*region_left = m;
l = true_m + 1;
} else if (stabs[m].n_value > addr) {
*region_right = m - 1;
r = m - 1;
} else {
// exact match for 'addr', but continue loop to find
// *region_right
*region_left = m;
l = m;
addr ++;
}
}
if (!any_matches) {
*region_right = *region_left - 1;
}
else {
// find rightmost region containing 'addr'
l = *region_right;
for (; l > *region_left && stabs[l].n_type != type; l --)
/* do nothing */;
*region_left = l;
}
}
/* *
* debuginfo_eip - Fill in the @info structure with information about
* the specified instruction address, @addr. Returns 0 if information
* was found, and negative if not. But even if it returns negative it
* has stored some information into '*info'.
* */
int
debuginfo_eip(uintptr_t addr, struct eipdebuginfo *info) {
const struct stab *stabs, *stab_end;
const char *stabstr, *stabstr_end;
info->eip_file = "<unknown>";
info->eip_line = 0;
info->eip_fn_name = "<unknown>";
info->eip_fn_namelen = 9;
info->eip_fn_addr = addr;
info->eip_fn_narg = 0;
// find the relevant set of stabs
if (addr >= KERNBASE) {
stabs = __STAB_BEGIN__;
stab_end = __STAB_END__;
stabstr = __STABSTR_BEGIN__;
stabstr_end = __STABSTR_END__;
}
else {
// user-program linker script, tools/user.ld puts the information about the
// program's stabs (included __STAB_BEGIN__, __STAB_END__, __STABSTR_BEGIN__,
// and __STABSTR_END__) in a structure located at virtual address USTAB.
const struct userstabdata *usd = (struct userstabdata *)USTAB;
// make sure that debugger (current process) can access this memory
struct mm_struct *mm;
if (current == NULL || (mm = current->mm) == NULL) {
return -1;
}
if (!user_mem_check(mm, (uintptr_t)usd, sizeof(struct userstabdata), 0)) {
return -1;
}
stabs = usd->stabs;
stab_end = usd->stab_end;
stabstr = usd->stabstr;
stabstr_end = usd->stabstr_end;
// make sure the STABS and string table memory is valid
if (!user_mem_check(mm, (uintptr_t)stabs, (uintptr_t)stab_end - (uintptr_t)stabs, 0)) {
return -1;
}
if (!user_mem_check(mm, (uintptr_t)stabstr, stabstr_end - stabstr, 0)) {
return -1;
}
}
// String table validity checks
if (stabstr_end <= stabstr || stabstr_end[-1] != 0) {
return -1;
}
// Now we find the right stabs that define the function containing
// 'eip'. First, we find the basic source file containing 'eip'.
// Then, we look in that source file for the function. Then we look
// for the line number.
// Search the entire set of stabs for the source file (type N_SO).
int lfile = 0, rfile = (stab_end - stabs) - 1;
stab_binsearch(stabs, &lfile, &rfile, N_SO, addr);
if (lfile == 0)
return -1;
// Search within that file's stabs for the function definition
// (N_FUN).
int lfun = lfile, rfun = rfile;
int lline, rline;
stab_binsearch(stabs, &lfun, &rfun, N_FUN, addr);
if (lfun <= rfun) {
// stabs[lfun] points to the function name
// in the string table, but check bounds just in case.
if (stabs[lfun].n_strx < stabstr_end - stabstr) {
info->eip_fn_name = stabstr + stabs[lfun].n_strx;
}
info->eip_fn_addr = stabs[lfun].n_value;
addr -= info->eip_fn_addr;
// Search within the function definition for the line number.
lline = lfun;
rline = rfun;
} else {
// Couldn't find function stab! Maybe we're in an assembly
// file. Search the whole file for the line number.
info->eip_fn_addr = addr;
lline = lfile;
rline = rfile;
}
info->eip_fn_namelen = strfind(info->eip_fn_name, ':') - info->eip_fn_name;
// Search within [lline, rline] for the line number stab.
// If found, set info->eip_line to the right line number.
// If not found, return -1.
stab_binsearch(stabs, &lline, &rline, N_SLINE, addr);
if (lline <= rline) {
info->eip_line = stabs[rline].n_desc;
} else {
return -1;
}
// Search backwards from the line number for the relevant filename stab.
// We can't just use the "lfile" stab because inlined functions
// can interpolate code from a different file!
// Such included source files use the N_SOL stab type.
while (lline >= lfile
&& stabs[lline].n_type != N_SOL
&& (stabs[lline].n_type != N_SO || !stabs[lline].n_value)) {
lline --;
}
if (lline >= lfile && stabs[lline].n_strx < stabstr_end - stabstr) {
info->eip_file = stabstr + stabs[lline].n_strx;
}
// Set eip_fn_narg to the number of arguments taken by the function,
// or 0 if there was no containing function.
if (lfun < rfun) {
for (lline = lfun + 1;
lline < rfun && stabs[lline].n_type == N_PSYM;
lline ++) {
info->eip_fn_narg ++;
}
}
return 0;
}
/* *
* print_kerninfo - print the information about kernel, including the location
* of kernel entry, the start addresses of data and text segements, the start
* address of free memory and how many memory that kernel has used.
* */
void
print_kerninfo(void) {
extern char etext[], edata[], end[], kern_init[];
cprintf("Special kernel symbols:\n");
cprintf(" entry 0x%08x (phys)\n", kern_init);
cprintf(" etext 0x%08x (phys)\n", etext);
cprintf(" edata 0x%08x (phys)\n", edata);
cprintf(" end 0x%08x (phys)\n", end);
cprintf("Kernel executable memory footprint: %dKB\n", (end - kern_init + 1023)/1024);
}
/* *
* print_debuginfo - read and print the stat information for the address @eip,
* and info.eip_fn_addr should be the first address of the related function.
* */
void
print_debuginfo(uintptr_t eip) {
struct eipdebuginfo info;
if (debuginfo_eip(eip, &info) != 0) {
cprintf(" <unknow>: -- 0x%08x --\n", eip);
}
else {
char fnname[256];
int j;
for (j = 0; j < info.eip_fn_namelen; j ++) {
fnname[j] = info.eip_fn_name[j];
}
fnname[j] = '\0';
cprintf(" %s:%d: %s+%d\n", info.eip_file, info.eip_line,
fnname, eip - info.eip_fn_addr);
}
}
static __noinline uint32_t
read_eip(void) {
uint32_t eip;
asm volatile("movl 4(%%ebp), %0" : "=r" (eip));
return eip;
}
/* *
* print_stackframe - print a list of the saved eip values from the nested 'call'
* instructions that led to the current point of execution
*
* The x86 stack pointer, namely esp, points to the lowest location on the stack
* that is currently in use. Everything below that location in stack is free. Pushing
* a value onto the stack will invole decreasing the stack pointer and then writing
* the value to the place that stack pointer pointes to. And popping a value do the
* opposite.
*
* The ebp (base pointer) register, in contrast, is associated with the stack
* primarily by software convention. On entry to a C function, the function's
* prologue code normally saves the previous function's base pointer by pushing
* it onto the stack, and then copies the current esp value into ebp for the duration
* of the function. If all the functions in a program obey this convention,
* then at any given point during the program's execution, it is possible to trace
* back through the stack by following the chain of saved ebp pointers and determining
* exactly what nested sequence of function calls caused this particular point in the
* program to be reached. This capability can be particularly useful, for example,
* when a particular function causes an assert failure or panic because bad arguments
* were passed to it, but you aren't sure who passed the bad arguments. A stack
* backtrace lets you find the offending function.
*
* The inline function read_ebp() can tell us the value of current ebp. And the
* non-inline function read_eip() is useful, it can read the value of current eip,
* since while calling this function, read_eip() can read the caller's eip from
* stack easily.
*
* In print_debuginfo(), the function debuginfo_eip() can get enough information about
* calling-chain. Finally print_stackframe() will trace and print them for debugging.
*
* Note that, the length of ebp-chain is limited. In boot/bootasm.S, before jumping
* to the kernel entry, the value of ebp has been set to zero, that's the boundary.
* */
void
print_stackframe(void) {
/* LAB1 YOUR CODE : STEP 1 */
/* (1) call read_ebp() to get the value of ebp. the type is (uint32_t);
* (2) call read_eip() to get the value of eip. the type is (uint32_t);
* (3) from 0 .. STACKFRAME_DEPTH
* (3.1) printf value of ebp, eip
* (3.2) (uint32_t)calling arguments [0..4] = the contents in address (unit32_t)ebp +2 [0..4]
* (3.3) cprintf("\n");
* (3.4) call print_debuginfo(eip-1) to print the C calling function name and line number, etc.
* (3.5) popup a calling stackframe
* NOTICE: the calling funciton's return addr eip = ss:[ebp+4]
* the calling funciton's ebp = ss:[ebp]
*/
uint32_t ebp = read_ebp(), eip = read_eip();
int i, j;
for (i = 0; ebp != 0 && i < STACKFRAME_DEPTH; i ++) {
cprintf("ebp:0x%08x eip:0x%08x args:", ebp, eip);
uint32_t *args = (uint32_t *)ebp + 2;
for (j = 0; j < 4; j ++) {
cprintf("0x%08x ", args[j]);
}
cprintf("\n");
print_debuginfo(eip - 1);
eip = ((uint32_t *)ebp)[1];
ebp = ((uint32_t *)ebp)[0];
}
}

12
labcodes_answer/lab5_result/kern/debug/kdebug.h Normal file
View File

@@ -0,0 +1,12 @@
#ifndef __KERN_DEBUG_KDEBUG_H__
#define __KERN_DEBUG_KDEBUG_H__
#include <defs.h>
#include <trap.h>
void print_kerninfo(void);
void print_stackframe(void);
void print_debuginfo(uintptr_t eip);
#endif /* !__KERN_DEBUG_KDEBUG_H__ */

132
labcodes_answer/lab5_result/kern/debug/kmonitor.c Normal file
View File

@@ -0,0 +1,132 @@
#include <stdio.h>
#include <string.h>
#include <mmu.h>
#include <trap.h>
#include <kmonitor.h>
#include <kdebug.h>
/* *
* Simple command-line kernel monitor useful for controlling the
* kernel and exploring the system interactively.
* */
struct command {
const char *name;
const char *desc;
// return -1 to force monitor to exit
int(*func)(int argc, char **argv, struct trapframe *tf);
};
static struct command commands[] = {
{"help", "Display this list of commands.", mon_help},
{"kerninfo", "Display information about the kernel.", mon_kerninfo},
{"backtrace", "Print backtrace of stack frame.", mon_backtrace},
};
/* return if kernel is panic, in kern/debug/panic.c */
bool is_kernel_panic(void);
#define NCOMMANDS (sizeof(commands)/sizeof(struct command))
/***** Kernel monitor command interpreter *****/
#define MAXARGS 16
#define WHITESPACE " \t\n\r"
/* parse - parse the command buffer into whitespace-separated arguments */
static int
parse(char *buf, char **argv) {
int argc = 0;
while (1) {
// find global whitespace
while (*buf != '\0' && strchr(WHITESPACE, *buf) != NULL) {
*buf ++ = '\0';
}
if (*buf == '\0') {
break;
}
// save and scan past next arg
if (argc == MAXARGS - 1) {
cprintf("Too many arguments (max %d).\n", MAXARGS);
}
argv[argc ++] = buf;
while (*buf != '\0' && strchr(WHITESPACE, *buf) == NULL) {
buf ++;
}
}
return argc;
}
/* *
* runcmd - parse the input string, split it into separated arguments
* and then lookup and invoke some related commands/
* */
static int
runcmd(char *buf, struct trapframe *tf) {
char *argv[MAXARGS];
int argc = parse(buf, argv);
if (argc == 0) {
return 0;
}
int i;
for (i = 0; i < NCOMMANDS; i ++) {
if (strcmp(commands[i].name, argv[0]) == 0) {
return commands[i].func(argc - 1, argv + 1, tf);
}
}
cprintf("Unknown command '%s'\n", argv[0]);
return 0;
}
/***** Implementations of basic kernel monitor commands *****/
void
kmonitor(struct trapframe *tf) {
cprintf("Welcome to the kernel debug monitor!!\n");
cprintf("Type 'help' for a list of commands.\n");
if (tf != NULL) {
print_trapframe(tf);
}
char *buf;
while (1) {
if ((buf = readline("K> ")) != NULL) {
if (runcmd(buf, tf) < 0) {
break;
}
}
}
}
/* mon_help - print the information about mon_* functions */
int
mon_help(int argc, char **argv, struct trapframe *tf) {
int i;
for (i = 0; i < NCOMMANDS; i ++) {
cprintf("%s - %s\n", commands[i].name, commands[i].desc);
}
return 0;
}
/* *
* mon_kerninfo - call print_kerninfo in kern/debug/kdebug.c to
* print the memory occupancy in kernel.
* */
int
mon_kerninfo(int argc, char **argv, struct trapframe *tf) {
print_kerninfo();
return 0;
}
/* *
* mon_backtrace - call print_stackframe in kern/debug/kdebug.c to
* print a backtrace of the stack.
* */
int
mon_backtrace(int argc, char **argv, struct trapframe *tf) {
print_stackframe();
return 0;
}

19
labcodes_answer/lab5_result/kern/debug/kmonitor.h Normal file
View File

@@ -0,0 +1,19 @@
#ifndef __KERN_DEBUG_MONITOR_H__
#define __KERN_DEBUG_MONITOR_H__
#include <trap.h>
void kmonitor(struct trapframe *tf);
int mon_help(int argc, char **argv, struct trapframe *tf);
int mon_kerninfo(int argc, char **argv, struct trapframe *tf);
int mon_backtrace(int argc, char **argv, struct trapframe *tf);
int mon_continue(int argc, char **argv, struct trapframe *tf);
int mon_step(int argc, char **argv, struct trapframe *tf);
int mon_breakpoint(int argc, char **argv, struct trapframe *tf);
int mon_watchpoint(int argc, char **argv, struct trapframe *tf);
int mon_delete_dr(int argc, char **argv, struct trapframe *tf);
int mon_list_dr(int argc, char **argv, struct trapframe *tf);
#endif /* !__KERN_DEBUG_MONITOR_H__ */

49
labcodes_answer/lab5_result/kern/debug/panic.c Normal file
View File

@@ -0,0 +1,49 @@
#include <defs.h>
#include <stdio.h>
#include <intr.h>
#include <kmonitor.h>
static bool is_panic = 0;
/* *
* __panic - __panic is called on unresolvable fatal errors. it prints
* "panic: 'message'", and then enters the kernel monitor.
* */
void
__panic(const char *file, int line, const char *fmt, ...) {
if (is_panic) {
goto panic_dead;
}
is_panic = 1;
// print the 'message'
va_list ap;
va_start(ap, fmt);
cprintf("kernel panic at %s:%d:\n ", file, line);
vcprintf(fmt, ap);
cprintf("\n");
va_end(ap);
panic_dead:
intr_disable();
while (1) {
kmonitor(NULL);
}
}
/* __warn - like panic, but don't */
void
__warn(const char *file, int line, const char *fmt, ...) {
va_list ap;
va_start(ap, fmt);
cprintf("kernel warning at %s:%d:\n ", file, line);
vcprintf(fmt, ap);
cprintf("\n");
va_end(ap);
}
bool
is_kernel_panic(void) {
return is_panic;
}

54
labcodes_answer/lab5_result/kern/debug/stab.h Normal file
View File

@@ -0,0 +1,54 @@
#ifndef __KERN_DEBUG_STAB_H__
#define __KERN_DEBUG_STAB_H__
#include <defs.h>
/* *
* STABS debugging info
*
* The kernel debugger can understand some debugging information in
* the STABS format. For more information on this format, see
* http://sources.redhat.com/gdb/onlinedocs/stabs_toc.html
*
* The constants below define some symbol types used by various debuggers
* and compilers. Kernel uses the N_SO, N_SOL, N_FUN, and N_SLINE types.
* */
#define N_GSYM 0x20 // global symbol
#define N_FNAME 0x22 // F77 function name
#define N_FUN 0x24 // procedure name
#define N_STSYM 0x26 // data segment variable
#define N_LCSYM 0x28 // bss segment variable
#define N_MAIN 0x2a // main function name
#define N_PC 0x30 // global Pascal symbol
#define N_RSYM 0x40 // register variable
#define N_SLINE 0x44 // text segment line number
#define N_DSLINE 0x46 // data segment line number
#define N_BSLINE 0x48 // bss segment line number
#define N_SSYM 0x60 // structure/union element
#define N_SO 0x64 // main source file name
#define N_LSYM 0x80 // stack variable
#define N_BINCL 0x82 // include file beginning
#define N_SOL 0x84 // included source file name
#define N_PSYM 0xa0 // parameter variable
#define N_EINCL 0xa2 // include file end
#define N_ENTRY 0xa4 // alternate entry point
#define N_LBRAC 0xc0 // left bracket
#define N_EXCL 0xc2 // deleted include file
#define N_RBRAC 0xe0 // right bracket
#define N_BCOMM 0xe2 // begin common
#define N_ECOMM 0xe4 // end common
#define N_ECOML 0xe8 // end common (local name)
#define N_LENG 0xfe // length of preceding entry
/* Entries in the STABS table are formatted as follows. */
struct stab {
uint32_t n_strx; // index into string table of name
uint8_t n_type; // type of symbol
uint8_t n_other; // misc info (usually empty)
uint16_t n_desc; // description field
uintptr_t n_value; // value of symbol
};
#endif /* !__KERN_DEBUG_STAB_H__ */