linux/kernel/debug/kdb/kdb_support.c
Aaron Tomlin f64205a420 module: Move kdb module related code out of main kdb code
No functional change.

This patch migrates the kdb 'lsmod' command support out of main
kdb code into its own file under kernel/module. In addition to
the above, a minor style warning i.e. missing a blank line after
declarations, was resolved too. The new file was added to
MAINTAINERS. Finally we remove linux/module.h as it is entirely
redundant.

Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Acked-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Aaron Tomlin <atomlin@redhat.com>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
2022-04-05 08:43:04 -07:00

557 lines
14 KiB
C

/*
* Kernel Debugger Architecture Independent Support Functions
*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*
* Copyright (c) 1999-2004 Silicon Graphics, Inc. All Rights Reserved.
* Copyright (c) 2009 Wind River Systems, Inc. All Rights Reserved.
* 03/02/13 added new 2.5 kallsyms <xavier.bru@bull.net>
*/
#include <linux/types.h>
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/kallsyms.h>
#include <linux/stddef.h>
#include <linux/vmalloc.h>
#include <linux/ptrace.h>
#include <linux/highmem.h>
#include <linux/hardirq.h>
#include <linux/delay.h>
#include <linux/uaccess.h>
#include <linux/kdb.h>
#include <linux/slab.h>
#include <linux/ctype.h>
#include "kdb_private.h"
/*
* kdbgetsymval - Return the address of the given symbol.
*
* Parameters:
* symname Character string containing symbol name
* symtab Structure to receive results
* Returns:
* 0 Symbol not found, symtab zero filled
* 1 Symbol mapped to module/symbol/section, data in symtab
*/
int kdbgetsymval(const char *symname, kdb_symtab_t *symtab)
{
kdb_dbg_printf(AR, "symname=%s, symtab=%px\n", symname, symtab);
memset(symtab, 0, sizeof(*symtab));
symtab->sym_start = kallsyms_lookup_name(symname);
if (symtab->sym_start) {
kdb_dbg_printf(AR, "returns 1, symtab->sym_start=0x%lx\n",
symtab->sym_start);
return 1;
}
kdb_dbg_printf(AR, "returns 0\n");
return 0;
}
EXPORT_SYMBOL(kdbgetsymval);
/**
* kdbnearsym() - Return the name of the symbol with the nearest address
* less than @addr.
* @addr: Address to check for near symbol
* @symtab: Structure to receive results
*
* WARNING: This function may return a pointer to a single statically
* allocated buffer (namebuf). kdb's unusual calling context (single
* threaded, all other CPUs halted) provides us sufficient locking for
* this to be safe. The only constraint imposed by the static buffer is
* that the caller must consume any previous reply prior to another call
* to lookup a new symbol.
*
* Note that, strictly speaking, some architectures may re-enter the kdb
* trap if the system turns out to be very badly damaged and this breaks
* the single-threaded assumption above. In these circumstances successful
* continuation and exit from the inner trap is unlikely to work and any
* user attempting this receives a prominent warning before being allowed
* to progress. In these circumstances we remain memory safe because
* namebuf[KSYM_NAME_LEN-1] will never change from '\0' although we do
* tolerate the possibility of garbled symbol display from the outer kdb
* trap.
*
* Return:
* * 0 - No sections contain this address, symtab zero filled
* * 1 - Address mapped to module/symbol/section, data in symtab
*/
int kdbnearsym(unsigned long addr, kdb_symtab_t *symtab)
{
int ret = 0;
unsigned long symbolsize = 0;
unsigned long offset = 0;
static char namebuf[KSYM_NAME_LEN];
kdb_dbg_printf(AR, "addr=0x%lx, symtab=%px\n", addr, symtab);
memset(symtab, 0, sizeof(*symtab));
if (addr < 4096)
goto out;
symtab->sym_name = kallsyms_lookup(addr, &symbolsize , &offset,
(char **)(&symtab->mod_name), namebuf);
if (offset > 8*1024*1024) {
symtab->sym_name = NULL;
addr = offset = symbolsize = 0;
}
symtab->sym_start = addr - offset;
symtab->sym_end = symtab->sym_start + symbolsize;
ret = symtab->sym_name != NULL && *(symtab->sym_name) != '\0';
if (symtab->mod_name == NULL)
symtab->mod_name = "kernel";
kdb_dbg_printf(AR, "returns %d symtab->sym_start=0x%lx, symtab->mod_name=%px, symtab->sym_name=%px (%s)\n",
ret, symtab->sym_start, symtab->mod_name, symtab->sym_name, symtab->sym_name);
out:
return ret;
}
static char ks_namebuf[KSYM_NAME_LEN+1], ks_namebuf_prev[KSYM_NAME_LEN+1];
/*
* kallsyms_symbol_complete
*
* Parameters:
* prefix_name prefix of a symbol name to lookup
* max_len maximum length that can be returned
* Returns:
* Number of symbols which match the given prefix.
* Notes:
* prefix_name is changed to contain the longest unique prefix that
* starts with this prefix (tab completion).
*/
int kallsyms_symbol_complete(char *prefix_name, int max_len)
{
loff_t pos = 0;
int prefix_len = strlen(prefix_name), prev_len = 0;
int i, number = 0;
const char *name;
while ((name = kdb_walk_kallsyms(&pos))) {
if (strncmp(name, prefix_name, prefix_len) == 0) {
strscpy(ks_namebuf, name, sizeof(ks_namebuf));
/* Work out the longest name that matches the prefix */
if (++number == 1) {
prev_len = min_t(int, max_len-1,
strlen(ks_namebuf));
memcpy(ks_namebuf_prev, ks_namebuf, prev_len);
ks_namebuf_prev[prev_len] = '\0';
continue;
}
for (i = 0; i < prev_len; i++) {
if (ks_namebuf[i] != ks_namebuf_prev[i]) {
prev_len = i;
ks_namebuf_prev[i] = '\0';
break;
}
}
}
}
if (prev_len > prefix_len)
memcpy(prefix_name, ks_namebuf_prev, prev_len+1);
return number;
}
/*
* kallsyms_symbol_next
*
* Parameters:
* prefix_name prefix of a symbol name to lookup
* flag 0 means search from the head, 1 means continue search.
* buf_size maximum length that can be written to prefix_name
* buffer
* Returns:
* 1 if a symbol matches the given prefix.
* 0 if no string found
*/
int kallsyms_symbol_next(char *prefix_name, int flag, int buf_size)
{
int prefix_len = strlen(prefix_name);
static loff_t pos;
const char *name;
if (!flag)
pos = 0;
while ((name = kdb_walk_kallsyms(&pos))) {
if (!strncmp(name, prefix_name, prefix_len))
return strscpy(prefix_name, name, buf_size);
}
return 0;
}
/*
* kdb_symbol_print - Standard method for printing a symbol name and offset.
* Inputs:
* addr Address to be printed.
* symtab Address of symbol data, if NULL this routine does its
* own lookup.
* punc Punctuation for string, bit field.
* Remarks:
* The string and its punctuation is only printed if the address
* is inside the kernel, except that the value is always printed
* when requested.
*/
void kdb_symbol_print(unsigned long addr, const kdb_symtab_t *symtab_p,
unsigned int punc)
{
kdb_symtab_t symtab, *symtab_p2;
if (symtab_p) {
symtab_p2 = (kdb_symtab_t *)symtab_p;
} else {
symtab_p2 = &symtab;
kdbnearsym(addr, symtab_p2);
}
if (!(symtab_p2->sym_name || (punc & KDB_SP_VALUE)))
return;
if (punc & KDB_SP_SPACEB)
kdb_printf(" ");
if (punc & KDB_SP_VALUE)
kdb_printf(kdb_machreg_fmt0, addr);
if (symtab_p2->sym_name) {
if (punc & KDB_SP_VALUE)
kdb_printf(" ");
if (punc & KDB_SP_PAREN)
kdb_printf("(");
if (strcmp(symtab_p2->mod_name, "kernel"))
kdb_printf("[%s]", symtab_p2->mod_name);
kdb_printf("%s", symtab_p2->sym_name);
if (addr != symtab_p2->sym_start)
kdb_printf("+0x%lx", addr - symtab_p2->sym_start);
if (punc & KDB_SP_SYMSIZE)
kdb_printf("/0x%lx",
symtab_p2->sym_end - symtab_p2->sym_start);
if (punc & KDB_SP_PAREN)
kdb_printf(")");
}
if (punc & KDB_SP_SPACEA)
kdb_printf(" ");
if (punc & KDB_SP_NEWLINE)
kdb_printf("\n");
}
/*
* kdb_strdup - kdb equivalent of strdup, for disasm code.
* Inputs:
* str The string to duplicate.
* type Flags to kmalloc for the new string.
* Returns:
* Address of the new string, NULL if storage could not be allocated.
* Remarks:
* This is not in lib/string.c because it uses kmalloc which is not
* available when string.o is used in boot loaders.
*/
char *kdb_strdup(const char *str, gfp_t type)
{
int n = strlen(str)+1;
char *s = kmalloc(n, type);
if (!s)
return NULL;
return strcpy(s, str);
}
/*
* kdb_getarea_size - Read an area of data. The kdb equivalent of
* copy_from_user, with kdb messages for invalid addresses.
* Inputs:
* res Pointer to the area to receive the result.
* addr Address of the area to copy.
* size Size of the area.
* Returns:
* 0 for success, < 0 for error.
*/
int kdb_getarea_size(void *res, unsigned long addr, size_t size)
{
int ret = copy_from_kernel_nofault((char *)res, (char *)addr, size);
if (ret) {
if (!KDB_STATE(SUPPRESS)) {
kdb_func_printf("Bad address 0x%lx\n", addr);
KDB_STATE_SET(SUPPRESS);
}
ret = KDB_BADADDR;
} else {
KDB_STATE_CLEAR(SUPPRESS);
}
return ret;
}
/*
* kdb_putarea_size - Write an area of data. The kdb equivalent of
* copy_to_user, with kdb messages for invalid addresses.
* Inputs:
* addr Address of the area to write to.
* res Pointer to the area holding the data.
* size Size of the area.
* Returns:
* 0 for success, < 0 for error.
*/
int kdb_putarea_size(unsigned long addr, void *res, size_t size)
{
int ret = copy_to_kernel_nofault((char *)addr, (char *)res, size);
if (ret) {
if (!KDB_STATE(SUPPRESS)) {
kdb_func_printf("Bad address 0x%lx\n", addr);
KDB_STATE_SET(SUPPRESS);
}
ret = KDB_BADADDR;
} else {
KDB_STATE_CLEAR(SUPPRESS);
}
return ret;
}
/*
* kdb_getphys - Read data from a physical address. Validate the
* address is in range, use kmap_atomic() to get data
* similar to kdb_getarea() - but for phys addresses
* Inputs:
* res Pointer to the word to receive the result
* addr Physical address of the area to copy
* size Size of the area
* Returns:
* 0 for success, < 0 for error.
*/
static int kdb_getphys(void *res, unsigned long addr, size_t size)
{
unsigned long pfn;
void *vaddr;
struct page *page;
pfn = (addr >> PAGE_SHIFT);
if (!pfn_valid(pfn))
return 1;
page = pfn_to_page(pfn);
vaddr = kmap_atomic(page);
memcpy(res, vaddr + (addr & (PAGE_SIZE - 1)), size);
kunmap_atomic(vaddr);
return 0;
}
/*
* kdb_getphysword
* Inputs:
* word Pointer to the word to receive the result.
* addr Address of the area to copy.
* size Size of the area.
* Returns:
* 0 for success, < 0 for error.
*/
int kdb_getphysword(unsigned long *word, unsigned long addr, size_t size)
{
int diag;
__u8 w1;
__u16 w2;
__u32 w4;
__u64 w8;
*word = 0; /* Default value if addr or size is invalid */
switch (size) {
case 1:
diag = kdb_getphys(&w1, addr, sizeof(w1));
if (!diag)
*word = w1;
break;
case 2:
diag = kdb_getphys(&w2, addr, sizeof(w2));
if (!diag)
*word = w2;
break;
case 4:
diag = kdb_getphys(&w4, addr, sizeof(w4));
if (!diag)
*word = w4;
break;
case 8:
if (size <= sizeof(*word)) {
diag = kdb_getphys(&w8, addr, sizeof(w8));
if (!diag)
*word = w8;
break;
}
fallthrough;
default:
diag = KDB_BADWIDTH;
kdb_func_printf("bad width %zu\n", size);
}
return diag;
}
/*
* kdb_getword - Read a binary value. Unlike kdb_getarea, this treats
* data as numbers.
* Inputs:
* word Pointer to the word to receive the result.
* addr Address of the area to copy.
* size Size of the area.
* Returns:
* 0 for success, < 0 for error.
*/
int kdb_getword(unsigned long *word, unsigned long addr, size_t size)
{
int diag;
__u8 w1;
__u16 w2;
__u32 w4;
__u64 w8;
*word = 0; /* Default value if addr or size is invalid */
switch (size) {
case 1:
diag = kdb_getarea(w1, addr);
if (!diag)
*word = w1;
break;
case 2:
diag = kdb_getarea(w2, addr);
if (!diag)
*word = w2;
break;
case 4:
diag = kdb_getarea(w4, addr);
if (!diag)
*word = w4;
break;
case 8:
if (size <= sizeof(*word)) {
diag = kdb_getarea(w8, addr);
if (!diag)
*word = w8;
break;
}
fallthrough;
default:
diag = KDB_BADWIDTH;
kdb_func_printf("bad width %zu\n", size);
}
return diag;
}
/*
* kdb_putword - Write a binary value. Unlike kdb_putarea, this
* treats data as numbers.
* Inputs:
* addr Address of the area to write to..
* word The value to set.
* size Size of the area.
* Returns:
* 0 for success, < 0 for error.
*/
int kdb_putword(unsigned long addr, unsigned long word, size_t size)
{
int diag;
__u8 w1;
__u16 w2;
__u32 w4;
__u64 w8;
switch (size) {
case 1:
w1 = word;
diag = kdb_putarea(addr, w1);
break;
case 2:
w2 = word;
diag = kdb_putarea(addr, w2);
break;
case 4:
w4 = word;
diag = kdb_putarea(addr, w4);
break;
case 8:
if (size <= sizeof(word)) {
w8 = word;
diag = kdb_putarea(addr, w8);
break;
}
fallthrough;
default:
diag = KDB_BADWIDTH;
kdb_func_printf("bad width %zu\n", size);
}
return diag;
}
/*
* kdb_task_state_char - Return the character that represents the task state.
* Inputs:
* p struct task for the process
* Returns:
* One character to represent the task state.
*/
char kdb_task_state_char (const struct task_struct *p)
{
unsigned long tmp;
char state;
int cpu;
if (!p ||
copy_from_kernel_nofault(&tmp, (char *)p, sizeof(unsigned long)))
return 'E';
state = task_state_to_char((struct task_struct *) p);
if (is_idle_task(p)) {
/* Idle task. Is it really idle, apart from the kdb
* interrupt? */
cpu = kdb_process_cpu(p);
if (!kdb_task_has_cpu(p) || kgdb_info[cpu].irq_depth == 1) {
if (cpu != kdb_initial_cpu)
state = '-'; /* idle task */
}
} else if (!p->mm && strchr("IMS", state)) {
state = tolower(state); /* sleeping system daemon */
}
return state;
}
/*
* kdb_task_state - Return true if a process has the desired state
* given by the mask.
* Inputs:
* p struct task for the process
* mask set of characters used to select processes; both NULL
* and the empty string mean adopt a default filter, which
* is to suppress sleeping system daemons and the idle tasks
* Returns:
* True if the process matches at least one criteria defined by the mask.
*/
bool kdb_task_state(const struct task_struct *p, const char *mask)
{
char state = kdb_task_state_char(p);
/* If there is no mask, then we will filter code that runs when the
* scheduler is idling and any system daemons that are currently
* sleeping.
*/
if (!mask || mask[0] == '\0')
return !strchr("-ims", state);
/* A is a special case that matches all states */
if (strchr(mask, 'A'))
return true;
return strchr(mask, state);
}
/* Maintain a small stack of kdb_flags to allow recursion without disturbing
* the global kdb state.
*/
static int kdb_flags_stack[4], kdb_flags_index;
void kdb_save_flags(void)
{
BUG_ON(kdb_flags_index >= ARRAY_SIZE(kdb_flags_stack));
kdb_flags_stack[kdb_flags_index++] = kdb_flags;
}
void kdb_restore_flags(void)
{
BUG_ON(kdb_flags_index <= 0);
kdb_flags = kdb_flags_stack[--kdb_flags_index];
}