393 lines
9.8 KiB
C
393 lines
9.8 KiB
C
/*
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* Kernel unwinding support
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*
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* (c) 2002-2004 Randolph Chung <tausq@debian.org>
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*
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* Derived partially from the IA64 implementation. The PA-RISC
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* Runtime Architecture Document is also a useful reference to
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* understand what is happening here
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*/
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#include <linux/kernel.h>
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#include <linux/init.h>
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#include <linux/slab.h>
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#include <linux/kallsyms.h>
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#include <asm/uaccess.h>
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#include <asm/assembly.h>
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#include <asm/unwind.h>
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/* #define DEBUG 1 */
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#ifdef DEBUG
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#define dbg(x...) printk(x)
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#else
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#define dbg(x...)
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#endif
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extern struct unwind_table_entry __start___unwind[];
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extern struct unwind_table_entry __stop___unwind[];
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static spinlock_t unwind_lock;
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/*
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* the kernel unwind block is not dynamically allocated so that
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* we can call unwind_init as early in the bootup process as
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* possible (before the slab allocator is initialized)
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*/
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static struct unwind_table kernel_unwind_table __read_mostly;
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static LIST_HEAD(unwind_tables);
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static inline const struct unwind_table_entry *
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find_unwind_entry_in_table(const struct unwind_table *table, unsigned long addr)
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{
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const struct unwind_table_entry *e = NULL;
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unsigned long lo, hi, mid;
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lo = 0;
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hi = table->length - 1;
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while (lo <= hi) {
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mid = (hi - lo) / 2 + lo;
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e = &table->table[mid];
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if (addr < e->region_start)
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hi = mid - 1;
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else if (addr > e->region_end)
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lo = mid + 1;
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else
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return e;
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}
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return NULL;
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}
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static const struct unwind_table_entry *
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find_unwind_entry(unsigned long addr)
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{
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struct unwind_table *table;
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const struct unwind_table_entry *e = NULL;
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if (addr >= kernel_unwind_table.start &&
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addr <= kernel_unwind_table.end)
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e = find_unwind_entry_in_table(&kernel_unwind_table, addr);
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else
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list_for_each_entry(table, &unwind_tables, list) {
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if (addr >= table->start &&
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addr <= table->end)
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e = find_unwind_entry_in_table(table, addr);
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if (e)
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break;
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}
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return e;
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}
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static void
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unwind_table_init(struct unwind_table *table, const char *name,
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unsigned long base_addr, unsigned long gp,
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void *table_start, void *table_end)
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{
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struct unwind_table_entry *start = table_start;
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struct unwind_table_entry *end =
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(struct unwind_table_entry *)table_end - 1;
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table->name = name;
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table->base_addr = base_addr;
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table->gp = gp;
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table->start = base_addr + start->region_start;
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table->end = base_addr + end->region_end;
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table->table = (struct unwind_table_entry *)table_start;
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table->length = end - start + 1;
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INIT_LIST_HEAD(&table->list);
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for (; start <= end; start++) {
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if (start < end &&
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start->region_end > (start+1)->region_start) {
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printk("WARNING: Out of order unwind entry! %p and %p\n", start, start+1);
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}
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start->region_start += base_addr;
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start->region_end += base_addr;
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}
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}
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static void
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unwind_table_sort(struct unwind_table_entry *start,
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struct unwind_table_entry *finish)
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{
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struct unwind_table_entry el, *p, *q;
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for (p = start + 1; p < finish; ++p) {
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if (p[0].region_start < p[-1].region_start) {
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el = *p;
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q = p;
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do {
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q[0] = q[-1];
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--q;
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} while (q > start &&
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el.region_start < q[-1].region_start);
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*q = el;
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}
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}
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}
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struct unwind_table *
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unwind_table_add(const char *name, unsigned long base_addr,
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unsigned long gp,
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void *start, void *end)
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{
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struct unwind_table *table;
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unsigned long flags;
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struct unwind_table_entry *s = (struct unwind_table_entry *)start;
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struct unwind_table_entry *e = (struct unwind_table_entry *)end;
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unwind_table_sort(s, e);
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table = kmalloc(sizeof(struct unwind_table), GFP_USER);
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if (table == NULL)
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return NULL;
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unwind_table_init(table, name, base_addr, gp, start, end);
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spin_lock_irqsave(&unwind_lock, flags);
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list_add_tail(&table->list, &unwind_tables);
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spin_unlock_irqrestore(&unwind_lock, flags);
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return table;
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}
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void unwind_table_remove(struct unwind_table *table)
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{
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unsigned long flags;
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spin_lock_irqsave(&unwind_lock, flags);
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list_del(&table->list);
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spin_unlock_irqrestore(&unwind_lock, flags);
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kfree(table);
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}
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/* Called from setup_arch to import the kernel unwind info */
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static int unwind_init(void)
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{
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long start, stop;
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register unsigned long gp __asm__ ("r27");
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start = (long)&__start___unwind[0];
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stop = (long)&__stop___unwind[0];
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spin_lock_init(&unwind_lock);
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printk("unwind_init: start = 0x%lx, end = 0x%lx, entries = %lu\n",
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start, stop,
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(stop - start) / sizeof(struct unwind_table_entry));
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unwind_table_init(&kernel_unwind_table, "kernel", KERNEL_START,
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gp,
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&__start___unwind[0], &__stop___unwind[0]);
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#if 0
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{
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int i;
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for (i = 0; i < 10; i++)
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{
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printk("region 0x%x-0x%x\n",
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__start___unwind[i].region_start,
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__start___unwind[i].region_end);
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}
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}
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#endif
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return 0;
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}
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static void unwind_frame_regs(struct unwind_frame_info *info)
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{
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const struct unwind_table_entry *e;
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unsigned long npc;
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unsigned int insn;
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long frame_size = 0;
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int looking_for_rp, rpoffset = 0;
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e = find_unwind_entry(info->ip);
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if (e == NULL) {
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unsigned long sp;
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extern char _stext[], _etext[];
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dbg("Cannot find unwind entry for 0x%lx; forced unwinding\n", info->ip);
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#ifdef CONFIG_KALLSYMS
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/* Handle some frequent special cases.... */
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{
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char symname[KSYM_NAME_LEN+1];
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char *modname;
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unsigned long symsize, offset;
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kallsyms_lookup(info->ip, &symsize, &offset,
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&modname, symname);
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dbg("info->ip = 0x%lx, name = %s\n", info->ip, symname);
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if (strcmp(symname, "_switch_to_ret") == 0) {
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info->prev_sp = info->sp - CALLEE_SAVE_FRAME_SIZE;
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info->prev_ip = *(unsigned long *)(info->prev_sp - RP_OFFSET);
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dbg("_switch_to_ret @ %lx - setting "
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"prev_sp=%lx prev_ip=%lx\n",
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info->ip, info->prev_sp,
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info->prev_ip);
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return;
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} else if (strcmp(symname, "ret_from_kernel_thread") == 0 ||
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strcmp(symname, "syscall_exit") == 0) {
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info->prev_ip = info->prev_sp = 0;
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return;
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}
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}
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#endif
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/* Since we are doing the unwinding blind, we don't know if
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we are adjusting the stack correctly or extracting the rp
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correctly. The rp is checked to see if it belongs to the
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kernel text section, if not we assume we don't have a
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correct stack frame and we continue to unwind the stack.
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This is not quite correct, and will fail for loadable
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modules. */
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sp = info->sp & ~63;
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do {
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unsigned long tmp;
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info->prev_sp = sp - 64;
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info->prev_ip = 0;
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if (get_user(tmp, (unsigned long *)(info->prev_sp - RP_OFFSET)))
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break;
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info->prev_ip = tmp;
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sp = info->prev_sp;
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} while (info->prev_ip < (unsigned long)_stext ||
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info->prev_ip > (unsigned long)_etext);
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info->rp = 0;
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dbg("analyzing func @ %lx with no unwind info, setting "
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"prev_sp=%lx prev_ip=%lx\n", info->ip,
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info->prev_sp, info->prev_ip);
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} else {
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dbg("e->start = 0x%x, e->end = 0x%x, Save_SP = %d, "
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"Save_RP = %d, Millicode = %d size = %u\n",
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e->region_start, e->region_end, e->Save_SP, e->Save_RP,
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e->Millicode, e->Total_frame_size);
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looking_for_rp = e->Save_RP;
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for (npc = e->region_start;
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(frame_size < (e->Total_frame_size << 3) ||
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looking_for_rp) &&
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npc < info->ip;
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npc += 4) {
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insn = *(unsigned int *)npc;
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if ((insn & 0xffffc000) == 0x37de0000 ||
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(insn & 0xffe00000) == 0x6fc00000) {
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/* ldo X(sp), sp, or stwm X,D(sp) */
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frame_size += (insn & 0x1 ? -1 << 13 : 0) |
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((insn & 0x3fff) >> 1);
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dbg("analyzing func @ %lx, insn=%08x @ "
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"%lx, frame_size = %ld\n", info->ip,
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insn, npc, frame_size);
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} else if ((insn & 0xffe00008) == 0x73c00008) {
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/* std,ma X,D(sp) */
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frame_size += (insn & 0x1 ? -1 << 13 : 0) |
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(((insn >> 4) & 0x3ff) << 3);
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dbg("analyzing func @ %lx, insn=%08x @ "
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"%lx, frame_size = %ld\n", info->ip,
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insn, npc, frame_size);
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} else if (insn == 0x6bc23fd9) {
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/* stw rp,-20(sp) */
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rpoffset = 20;
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looking_for_rp = 0;
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dbg("analyzing func @ %lx, insn=stw rp,"
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"-20(sp) @ %lx\n", info->ip, npc);
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} else if (insn == 0x0fc212c1) {
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/* std rp,-16(sr0,sp) */
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rpoffset = 16;
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looking_for_rp = 0;
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dbg("analyzing func @ %lx, insn=std rp,"
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"-16(sp) @ %lx\n", info->ip, npc);
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}
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}
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info->prev_sp = info->sp - frame_size;
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if (e->Millicode)
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info->rp = info->r31;
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else if (rpoffset)
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info->rp = *(unsigned long *)(info->prev_sp - rpoffset);
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info->prev_ip = info->rp;
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info->rp = 0;
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dbg("analyzing func @ %lx, setting prev_sp=%lx "
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"prev_ip=%lx npc=%lx\n", info->ip, info->prev_sp,
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info->prev_ip, npc);
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}
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}
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void unwind_frame_init(struct unwind_frame_info *info, struct task_struct *t,
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struct pt_regs *regs)
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{
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memset(info, 0, sizeof(struct unwind_frame_info));
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info->t = t;
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info->sp = regs->gr[30];
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info->ip = regs->iaoq[0];
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info->rp = regs->gr[2];
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info->r31 = regs->gr[31];
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dbg("(%d) Start unwind from sp=%08lx ip=%08lx\n",
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t ? (int)t->pid : -1, info->sp, info->ip);
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}
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void unwind_frame_init_from_blocked_task(struct unwind_frame_info *info, struct task_struct *t)
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{
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struct pt_regs *r = &t->thread.regs;
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struct pt_regs *r2;
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r2 = kmalloc(sizeof(struct pt_regs), GFP_KERNEL);
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if (!r2)
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return;
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*r2 = *r;
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r2->gr[30] = r->ksp;
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r2->iaoq[0] = r->kpc;
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unwind_frame_init(info, t, r2);
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kfree(r2);
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}
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void unwind_frame_init_running(struct unwind_frame_info *info, struct pt_regs *regs)
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{
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unwind_frame_init(info, current, regs);
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}
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int unwind_once(struct unwind_frame_info *next_frame)
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{
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unwind_frame_regs(next_frame);
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if (next_frame->prev_sp == 0 ||
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next_frame->prev_ip == 0)
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return -1;
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next_frame->sp = next_frame->prev_sp;
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next_frame->ip = next_frame->prev_ip;
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next_frame->prev_sp = 0;
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next_frame->prev_ip = 0;
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dbg("(%d) Continue unwind to sp=%08lx ip=%08lx\n",
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next_frame->t ? (int)next_frame->t->pid : -1,
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next_frame->sp, next_frame->ip);
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return 0;
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}
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int unwind_to_user(struct unwind_frame_info *info)
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{
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int ret;
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do {
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ret = unwind_once(info);
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} while (!ret && !(info->ip & 3));
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return ret;
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}
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module_init(unwind_init);
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