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-rw-r--r--kernel/debug/kdb/kdb_support.c927
1 files changed, 927 insertions, 0 deletions
diff --git a/kernel/debug/kdb/kdb_support.c b/kernel/debug/kdb/kdb_support.c
new file mode 100644
index 000000000000..45344d5c53dd
--- /dev/null
+++ b/kernel/debug/kdb/kdb_support.c
@@ -0,0 +1,927 @@
+/*
+ * 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 <stdarg.h>
+#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/module.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 "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)
+{
+ if (KDB_DEBUG(AR))
+ kdb_printf("kdbgetsymval: symname=%s, symtab=%p\n", symname,
+ symtab);
+ memset(symtab, 0, sizeof(*symtab));
+ symtab->sym_start = kallsyms_lookup_name(symname);
+ if (symtab->sym_start) {
+ if (KDB_DEBUG(AR))
+ kdb_printf("kdbgetsymval: returns 1, "
+ "symtab->sym_start=0x%lx\n",
+ symtab->sym_start);
+ return 1;
+ }
+ if (KDB_DEBUG(AR))
+ kdb_printf("kdbgetsymval: returns 0\n");
+ return 0;
+}
+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'.
+ *
+ * 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.
+ */
+int kdbnearsym(unsigned long addr, kdb_symtab_t *symtab)
+{
+ int ret = 0;
+ unsigned long symbolsize;
+ unsigned long offset;
+#define knt1_size 128 /* must be >= kallsyms table size */
+ char *knt1 = NULL;
+
+ if (KDB_DEBUG(AR))
+ kdb_printf("kdbnearsym: addr=0x%lx, symtab=%p\n", addr, symtab);
+ memset(symtab, 0, sizeof(*symtab));
+
+ if (addr < 4096)
+ goto out;
+ knt1 = debug_kmalloc(knt1_size, GFP_ATOMIC);
+ if (!knt1) {
+ kdb_printf("kdbnearsym: addr=0x%lx cannot kmalloc knt1\n",
+ addr);
+ goto out;
+ }
+ symtab->sym_name = kallsyms_lookup(addr, &symbolsize , &offset,
+ (char **)(&symtab->mod_name), knt1);
+ 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 (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]);
+ memcpy(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];
+ memcpy(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";
+ if (KDB_DEBUG(AR))
+ kdb_printf("kdbnearsym: returns %d symtab->sym_start=0x%lx, "
+ "symtab->mod_name=%p, symtab->sym_name=%p (%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];
+
+/*
+ * 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) {
+ strcpy(ks_namebuf, name);
+ /* 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.
+ * Returns:
+ * 1 if a symbol matches the given prefix.
+ * 0 if no string found
+ */
+int kallsyms_symbol_next(char *prefix_name, int flag)
+{
+ 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) == 0) {
+ strncpy(prefix_name, name, strlen(name)+1);
+ return 1;
+ }
+ }
+ 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 = probe_kernel_read((char *)res, (char *)addr, size);
+ if (ret) {
+ if (!KDB_STATE(SUPPRESS)) {
+ kdb_printf("kdb_getarea: 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 = probe_kernel_read((char *)addr, (char *)res, size);
+ if (ret) {
+ if (!KDB_STATE(SUPPRESS)) {
+ kdb_printf("kdb_putarea: 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, KM_KDB);
+ memcpy(res, vaddr + (addr & (PAGE_SIZE - 1)), size);
+ kunmap_atomic(vaddr, KM_KDB);
+
+ 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;
+ }
+ /* drop through */
+ default:
+ diag = KDB_BADWIDTH;
+ kdb_printf("kdb_getphysword: bad width %ld\n", (long) 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;
+ }
+ /* drop through */
+ default:
+ diag = KDB_BADWIDTH;
+ kdb_printf("kdb_getword: bad width %ld\n", (long) 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;
+ }
+ /* drop through */
+ default:
+ diag = KDB_BADWIDTH;
+ kdb_printf("kdb_putword: bad width %ld\n", (long) size);
+ }
+ return diag;
+}
+
+/*
+ * kdb_task_state_string - Convert a string containing any of the
+ * letters DRSTCZEUIMA to a mask for the process state field and
+ * return the value. If no argument is supplied, return the mask
+ * that corresponds to environment variable PS, DRSTCZEU by
+ * default.
+ * Inputs:
+ * s String to convert
+ * Returns:
+ * Mask for process state.
+ * Notes:
+ * The mask folds data from several sources into a single long value, so
+ * be carefull not to overlap the bits. TASK_* bits are in the LSB,
+ * special cases like UNRUNNABLE are in the MSB. As of 2.6.10-rc1 there
+ * is no overlap between TASK_* and EXIT_* but that may not always be
+ * true, so EXIT_* bits are shifted left 16 bits before being stored in
+ * the mask.
+ */
+
+/* unrunnable is < 0 */
+#define UNRUNNABLE (1UL << (8*sizeof(unsigned long) - 1))
+#define RUNNING (1UL << (8*sizeof(unsigned long) - 2))
+#define IDLE (1UL << (8*sizeof(unsigned long) - 3))
+#define DAEMON (1UL << (8*sizeof(unsigned long) - 4))
+
+unsigned long kdb_task_state_string(const char *s)
+{
+ long res = 0;
+ if (!s) {
+ s = kdbgetenv("PS");
+ if (!s)
+ s = "DRSTCZEU"; /* default value for ps */
+ }
+ while (*s) {
+ switch (*s) {
+ case 'D':
+ res |= TASK_UNINTERRUPTIBLE;
+ break;
+ case 'R':
+ res |= RUNNING;
+ break;
+ case 'S':
+ res |= TASK_INTERRUPTIBLE;
+ break;
+ case 'T':
+ res |= TASK_STOPPED;
+ break;
+ case 'C':
+ res |= TASK_TRACED;
+ break;
+ case 'Z':
+ res |= EXIT_ZOMBIE << 16;
+ break;
+ case 'E':
+ res |= EXIT_DEAD << 16;
+ break;
+ case 'U':
+ res |= UNRUNNABLE;
+ break;
+ case 'I':
+ res |= IDLE;
+ break;
+ case 'M':
+ res |= DAEMON;
+ break;
+ case 'A':
+ res = ~0UL;
+ break;
+ default:
+ kdb_printf("%s: unknown flag '%c' ignored\n",
+ __func__, *s);
+ break;
+ }
+ ++s;
+ }
+ return res;
+}
+
+/*
+ * 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)
+{
+ int cpu;
+ char state;
+ unsigned long tmp;
+
+ if (!p || probe_kernel_read(&tmp, (char *)p, sizeof(unsigned long)))
+ return 'E';
+
+ cpu = kdb_process_cpu(p);
+ state = (p->state == 0) ? 'R' :
+ (p->state < 0) ? 'U' :
+ (p->state & TASK_UNINTERRUPTIBLE) ? 'D' :
+ (p->state & TASK_STOPPED) ? 'T' :
+ (p->state & TASK_TRACED) ? 'C' :
+ (p->exit_state & EXIT_ZOMBIE) ? 'Z' :
+ (p->exit_state & EXIT_DEAD) ? 'E' :
+ (p->state & TASK_INTERRUPTIBLE) ? 'S' : '?';
+ if (p->pid == 0) {
+ /* Idle task. Is it really idle, apart from the kdb
+ * interrupt? */
+ if (!kdb_task_has_cpu(p) || kgdb_info[cpu].irq_depth == 1) {
+ if (cpu != kdb_initial_cpu)
+ state = 'I'; /* idle task */
+ }
+ } else if (!p->mm && state == 'S') {
+ state = 'M'; /* 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 mask from kdb_task_state_string to select processes
+ * Returns:
+ * True if the process matches at least one criteria defined by the mask.
+ */
+unsigned long kdb_task_state(const struct task_struct *p, unsigned long mask)
+{
+ char state[] = { kdb_task_state_char(p), '\0' };
+ return (mask & kdb_task_state_string(state)) != 0;
+}
+
+/*
+ * kdb_print_nameval - Print a name and its value, converting the
+ * value to a symbol lookup if possible.
+ * Inputs:
+ * name field name to print
+ * val value of field
+ */
+void kdb_print_nameval(const char *name, unsigned long val)
+{
+ kdb_symtab_t symtab;
+ kdb_printf(" %-11.11s ", name);
+ if (kdbnearsym(val, &symtab))
+ kdb_symbol_print(val, &symtab,
+ KDB_SP_VALUE|KDB_SP_SYMSIZE|KDB_SP_NEWLINE);
+ else
+ kdb_printf("0x%lx\n", val);
+}
+
+/* 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_printf("%s: debug_kmalloc memory leak dah_first %d\n",
+ __func__, dah_first);
+ if (dah_first) {
+ h_used = (struct debug_alloc_header *)debug_alloc_pool;
+ kdb_printf("%s: h_used %p size %d\n", __func__, h_used,
+ h_used->size);
+ }
+ do {
+ h_used = (struct debug_alloc_header *)
+ ((char *)h_free + dah_overhead + h_free->size);
+ kdb_printf("%s: h_used %p size %d caller %p\n",
+ __func__, 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_printf("%s: h_used %p size %d caller %p\n",
+ __func__, 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.
+ */
+
+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];
+}

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