}
EXPORT_SYMBOL(kdbgetsymval);
-static char *kdb_name_table[100]; /* arbitrary size */
-
-/*
- * kdbnearsym - Return the name of the symbol with the nearest address
- * less than 'addr'.
+/**
+ * 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
*
- * Parameters:
- * addr Address to check for symbol near
- * symtab Structure to receive results
- * Returns:
- * 0 No sections contain this address, symtab zero filled
- * 1 Address mapped to module/symbol/section, data in symtab
- * Remarks:
- * 2.6 kallsyms has a "feature" where it unpacks the name into a
- * string. If that string is reused before the caller expects it
- * then the caller sees its string change without warning. To
- * avoid cluttering up the main kdb code with lots of kdb_strdup,
- * tests and kfree calls, kdbnearsym maintains an LRU list of the
- * last few unique strings. The list is sized large enough to
- * hold active strings, no kdb caller of kdbnearsym makes more
- * than ~20 later calls before using a saved value.
+ * 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;
-#define knt1_size 128 /* must be >= kallsyms table size */
- char *knt1 = NULL;
+ 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;
- knt1 = debug_kmalloc(knt1_size, GFP_ATOMIC);
- if (!knt1) {
- kdb_func_printf("addr=0x%lx cannot kmalloc knt1\n", addr);
- goto out;
- }
+
symtab->sym_name = kallsyms_lookup(addr, &symbolsize , &offset,
- (char **)(&symtab->mod_name), knt1);
+ (char **)(&symtab->mod_name), namebuf);
if (offset > 8*1024*1024) {
symtab->sym_name = NULL;
addr = offset = symbolsize = 0;
symtab->sym_end = symtab->sym_start + symbolsize;
ret = symtab->sym_name != NULL && *(symtab->sym_name) != '\0';
- if (ret) {
- int i;
- /* Another 2.6 kallsyms "feature". Sometimes the sym_name is
- * set but the buffer passed into kallsyms_lookup is not used,
- * so it contains garbage. The caller has to work out which
- * buffer needs to be saved.
- *
- * What was Rusty smoking when he wrote that code?
- */
- if (symtab->sym_name != knt1) {
- strncpy(knt1, symtab->sym_name, knt1_size);
- knt1[knt1_size-1] = '\0';
- }
- for (i = 0; i < ARRAY_SIZE(kdb_name_table); ++i) {
- if (kdb_name_table[i] &&
- strcmp(kdb_name_table[i], knt1) == 0)
- break;
- }
- if (i >= ARRAY_SIZE(kdb_name_table)) {
- debug_kfree(kdb_name_table[0]);
- memmove(kdb_name_table, kdb_name_table+1,
- sizeof(kdb_name_table[0]) *
- (ARRAY_SIZE(kdb_name_table)-1));
- } else {
- debug_kfree(knt1);
- knt1 = kdb_name_table[i];
- memmove(kdb_name_table+i, kdb_name_table+i+1,
- sizeof(kdb_name_table[0]) *
- (ARRAY_SIZE(kdb_name_table)-i-1));
- }
- i = ARRAY_SIZE(kdb_name_table) - 1;
- kdb_name_table[i] = knt1;
- symtab->sym_name = kdb_name_table[i];
- knt1 = NULL;
- }
-
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:
- debug_kfree(knt1);
return ret;
}
-void kdbnearsym_cleanup(void)
-{
- int i;
- for (i = 0; i < ARRAY_SIZE(kdb_name_table); ++i) {
- if (kdb_name_table[i]) {
- debug_kfree(kdb_name_table[i]);
- kdb_name_table[i] = NULL;
- }
- }
-}
-
static char ks_namebuf[KSYM_NAME_LEN+1], ks_namebuf_prev[KSYM_NAME_LEN+1];
/*
return (mask & kdb_task_state_string(state)) != 0;
}
-/* Last ditch allocator for debugging, so we can still debug even when
- * the GFP_ATOMIC pool has been exhausted. The algorithms are tuned
- * for space usage, not for speed. One smallish memory pool, the free
- * chain is always in ascending address order to allow coalescing,
- * allocations are done in brute force best fit.
- */
-
-struct debug_alloc_header {
- u32 next; /* offset of next header from start of pool */
- u32 size;
- void *caller;
-};
-
-/* The memory returned by this allocator must be aligned, which means
- * so must the header size. Do not assume that sizeof(struct
- * debug_alloc_header) is a multiple of the alignment, explicitly
- * calculate the overhead of this header, including the alignment.
- * The rest of this code must not use sizeof() on any header or
- * pointer to a header.
- */
-#define dah_align 8
-#define dah_overhead ALIGN(sizeof(struct debug_alloc_header), dah_align)
-
-static u64 debug_alloc_pool_aligned[256*1024/dah_align]; /* 256K pool */
-static char *debug_alloc_pool = (char *)debug_alloc_pool_aligned;
-static u32 dah_first, dah_first_call = 1, dah_used, dah_used_max;
-
-/* Locking is awkward. The debug code is called from all contexts,
- * including non maskable interrupts. A normal spinlock is not safe
- * in NMI context. Try to get the debug allocator lock, if it cannot
- * be obtained after a second then give up. If the lock could not be
- * previously obtained on this cpu then only try once.
- *
- * sparse has no annotation for "this function _sometimes_ acquires a
- * lock", so fudge the acquire/release notation.
- */
-static DEFINE_SPINLOCK(dap_lock);
-static int get_dap_lock(void)
- __acquires(dap_lock)
-{
- static int dap_locked = -1;
- int count;
- if (dap_locked == smp_processor_id())
- count = 1;
- else
- count = 1000;
- while (1) {
- if (spin_trylock(&dap_lock)) {
- dap_locked = -1;
- return 1;
- }
- if (!count--)
- break;
- udelay(1000);
- }
- dap_locked = smp_processor_id();
- __acquire(dap_lock);
- return 0;
-}
-
-void *debug_kmalloc(size_t size, gfp_t flags)
-{
- unsigned int rem, h_offset;
- struct debug_alloc_header *best, *bestprev, *prev, *h;
- void *p = NULL;
- if (!get_dap_lock()) {
- __release(dap_lock); /* we never actually got it */
- return NULL;
- }
- h = (struct debug_alloc_header *)(debug_alloc_pool + dah_first);
- if (dah_first_call) {
- h->size = sizeof(debug_alloc_pool_aligned) - dah_overhead;
- dah_first_call = 0;
- }
- size = ALIGN(size, dah_align);
- prev = best = bestprev = NULL;
- while (1) {
- if (h->size >= size && (!best || h->size < best->size)) {
- best = h;
- bestprev = prev;
- if (h->size == size)
- break;
- }
- if (!h->next)
- break;
- prev = h;
- h = (struct debug_alloc_header *)(debug_alloc_pool + h->next);
- }
- if (!best)
- goto out;
- rem = best->size - size;
- /* The pool must always contain at least one header */
- if (best->next == 0 && bestprev == NULL && rem < dah_overhead)
- goto out;
- if (rem >= dah_overhead) {
- best->size = size;
- h_offset = ((char *)best - debug_alloc_pool) +
- dah_overhead + best->size;
- h = (struct debug_alloc_header *)(debug_alloc_pool + h_offset);
- h->size = rem - dah_overhead;
- h->next = best->next;
- } else
- h_offset = best->next;
- best->caller = __builtin_return_address(0);
- dah_used += best->size;
- dah_used_max = max(dah_used, dah_used_max);
- if (bestprev)
- bestprev->next = h_offset;
- else
- dah_first = h_offset;
- p = (char *)best + dah_overhead;
- memset(p, POISON_INUSE, best->size - 1);
- *((char *)p + best->size - 1) = POISON_END;
-out:
- spin_unlock(&dap_lock);
- return p;
-}
-
-void debug_kfree(void *p)
-{
- struct debug_alloc_header *h;
- unsigned int h_offset;
- if (!p)
- return;
- if ((char *)p < debug_alloc_pool ||
- (char *)p >= debug_alloc_pool + sizeof(debug_alloc_pool_aligned)) {
- kfree(p);
- return;
- }
- if (!get_dap_lock()) {
- __release(dap_lock); /* we never actually got it */
- return; /* memory leak, cannot be helped */
- }
- h = (struct debug_alloc_header *)((char *)p - dah_overhead);
- memset(p, POISON_FREE, h->size - 1);
- *((char *)p + h->size - 1) = POISON_END;
- h->caller = NULL;
- dah_used -= h->size;
- h_offset = (char *)h - debug_alloc_pool;
- if (h_offset < dah_first) {
- h->next = dah_first;
- dah_first = h_offset;
- } else {
- struct debug_alloc_header *prev;
- unsigned int prev_offset;
- prev = (struct debug_alloc_header *)(debug_alloc_pool +
- dah_first);
- while (1) {
- if (!prev->next || prev->next > h_offset)
- break;
- prev = (struct debug_alloc_header *)
- (debug_alloc_pool + prev->next);
- }
- prev_offset = (char *)prev - debug_alloc_pool;
- if (prev_offset + dah_overhead + prev->size == h_offset) {
- prev->size += dah_overhead + h->size;
- memset(h, POISON_FREE, dah_overhead - 1);
- *((char *)h + dah_overhead - 1) = POISON_END;
- h = prev;
- h_offset = prev_offset;
- } else {
- h->next = prev->next;
- prev->next = h_offset;
- }
- }
- if (h_offset + dah_overhead + h->size == h->next) {
- struct debug_alloc_header *next;
- next = (struct debug_alloc_header *)
- (debug_alloc_pool + h->next);
- h->size += dah_overhead + next->size;
- h->next = next->next;
- memset(next, POISON_FREE, dah_overhead - 1);
- *((char *)next + dah_overhead - 1) = POISON_END;
- }
- spin_unlock(&dap_lock);
-}
-
-void debug_kusage(void)
-{
- struct debug_alloc_header *h_free, *h_used;
-#ifdef CONFIG_IA64
- /* FIXME: using dah for ia64 unwind always results in a memory leak.
- * Fix that memory leak first, then set debug_kusage_one_time = 1 for
- * all architectures.
- */
- static int debug_kusage_one_time;
-#else
- static int debug_kusage_one_time = 1;
-#endif
- if (!get_dap_lock()) {
- __release(dap_lock); /* we never actually got it */
- return;
- }
- h_free = (struct debug_alloc_header *)(debug_alloc_pool + dah_first);
- if (dah_first == 0 &&
- (h_free->size == sizeof(debug_alloc_pool_aligned) - dah_overhead ||
- dah_first_call))
- goto out;
- if (!debug_kusage_one_time)
- goto out;
- debug_kusage_one_time = 0;
- kdb_func_printf("debug_kmalloc memory leak dah_first %d\n", dah_first);
- if (dah_first) {
- h_used = (struct debug_alloc_header *)debug_alloc_pool;
- kdb_func_printf("h_used %px size %d\n", h_used, h_used->size);
- }
- do {
- h_used = (struct debug_alloc_header *)
- ((char *)h_free + dah_overhead + h_free->size);
- kdb_func_printf("h_used %px size %d caller %px\n",
- h_used, h_used->size, h_used->caller);
- h_free = (struct debug_alloc_header *)
- (debug_alloc_pool + h_free->next);
- } while (h_free->next);
- h_used = (struct debug_alloc_header *)
- ((char *)h_free + dah_overhead + h_free->size);
- if ((char *)h_used - debug_alloc_pool !=
- sizeof(debug_alloc_pool_aligned))
- kdb_func_printf("h_used %px size %d caller %px\n",
- h_used, h_used->size, h_used->caller);
-out:
- spin_unlock(&dap_lock);
-}
-
/* Maintain a small stack of kdb_flags to allow recursion without disturbing
* the global kdb state.
*/
projects / linux-2.6-microblaze.git / blobdiff