--- /dev/null
+/*
+ * Kernel unwinding support
+ *
+ * (c) 2002-2004 Randolph Chung <tausq@debian.org>
+ *
+ * Derived partially from the IA64 implementation. The PA-RISC
+ * Runtime Architecture Document is also a useful reference to
+ * understand what is happening here
+ */
+
+/*
+ * J. David Anglin writes:
+ *
+ * "You have to adjust the current sp to that at the begining of the function.
+ * There can be up to two stack additions to allocate the frame in the
+ * prologue. Similar things happen in the epilogue. In the presence of
+ * interrupts, you have to be concerned about where you are in the function
+ * and what stack adjustments have taken place."
+ *
+ * For now these cases are not handled, but they should be!
+ */
+
+#include <linux/config.h>
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/slab.h>
+
+#include <asm/uaccess.h>
+
+#include <asm/unwind.h>
+
+/* #define DEBUG 1 */
+#ifdef DEBUG
+#define dbg(x...) printk(x)
+#else
+#define dbg(x...)
+#endif
+
+extern const struct unwind_table_entry __start___unwind[];
+extern const struct unwind_table_entry __stop___unwind[];
+
+static spinlock_t unwind_lock;
+/*
+ * the kernel unwind block is not dynamically allocated so that
+ * we can call unwind_init as early in the bootup process as
+ * possible (before the slab allocator is initialized)
+ */
+static struct unwind_table kernel_unwind_table;
+static struct unwind_table *unwind_tables, *unwind_tables_end;
+
+
+static inline const struct unwind_table_entry *
+find_unwind_entry_in_table(const struct unwind_table *table, unsigned long addr)
+{
+ const struct unwind_table_entry *e = 0;
+ unsigned long lo, hi, mid;
+
+ addr -= table->base_addr;
+
+ for (lo = 0, hi = table->length; lo < hi; )
+ {
+ mid = (lo + hi) / 2;
+ e = &table->table[mid];
+ if (addr < e->region_start)
+ hi = mid;
+ else if (addr > e->region_end)
+ lo = mid + 1;
+ else
+ break;
+ }
+
+ return e;
+}
+
+static inline const struct unwind_table_entry *
+find_unwind_entry(unsigned long addr)
+{
+ struct unwind_table *table = unwind_tables;
+ const struct unwind_table_entry *e = NULL;
+
+ if (addr >= kernel_unwind_table.start &&
+ addr <= kernel_unwind_table.end)
+ e = find_unwind_entry_in_table(&kernel_unwind_table, addr);
+ else
+ for (; table; table = table->next)
+ {
+ if (addr >= table->start &&
+ addr <= table->end)
+ e = find_unwind_entry_in_table(table, addr);
+ if (e)
+ break;
+ }
+
+ return e;
+}
+
+static void
+unwind_table_init(struct unwind_table *table, const char *name,
+ unsigned long base_addr, unsigned long gp,
+ const void *table_start, const void *table_end)
+{
+ const struct unwind_table_entry *start = table_start;
+ const struct unwind_table_entry *end = table_end - 1;
+
+ table->name = name;
+ table->base_addr = base_addr;
+ table->gp = gp;
+ table->start = base_addr + start->region_start;
+ table->end = base_addr + end->region_end;
+ table->table = (struct unwind_table_entry *)table_start;
+ table->length = end - start;
+ table->next = NULL;
+}
+
+void *
+unwind_table_add(const char *name, unsigned long base_addr,
+ unsigned long gp,
+ const void *start, const void *end)
+{
+ struct unwind_table *table;
+ unsigned long flags;
+
+ table = kmalloc(sizeof(struct unwind_table), GFP_USER);
+ if (table == NULL)
+ return 0;
+ unwind_table_init(table, name, base_addr, gp, start, end);
+ spin_lock_irqsave(&unwind_lock, flags);
+ if (unwind_tables)
+ {
+ unwind_tables_end->next = table;
+ unwind_tables_end = table;
+ }
+ else
+ {
+ unwind_tables = unwind_tables_end = table;
+ }
+ spin_unlock_irqrestore(&unwind_lock, flags);
+
+ return table;
+}
+
+/* Called from setup_arch to import the kernel unwind info */
+static int unwind_init(void)
+{
+ long start, stop;
+ register unsigned long gp __asm__ ("r27");
+
+ start = (long)&__start___unwind[0];
+ stop = (long)&__stop___unwind[0];
+
+ printk("unwind_init: start = 0x%lx, end = 0x%lx, entries = %lu\n",
+ start, stop,
+ (stop - start) / sizeof(struct unwind_table_entry));
+
+ unwind_table_init(&kernel_unwind_table, "kernel", KERNEL_START,
+ gp,
+ &__start___unwind[0], &__stop___unwind[0]);
+#if 0
+ {
+ int i;
+ for (i = 0; i < 10; i++)
+ {
+ printk("region 0x%x-0x%x\n",
+ __start___unwind[i].region_start,
+ __start___unwind[i].region_end);
+ }
+ }
+#endif
+ return 0;
+}
+
+static void unwind_frame_regs(struct unwind_frame_info *info)
+{
+ const struct unwind_table_entry *e;
+ unsigned long npc;
+ unsigned int insn;
+ long frame_size = 0;
+ int looking_for_rp, rpoffset = 0;
+
+ e = find_unwind_entry(info->ip);
+ if (!e) {
+ unsigned long sp;
+ extern char _stext[], _etext[];
+
+ dbg("Cannot find unwind entry for 0x%lx; forced unwinding\n", info->ip);
+
+ /* Since we are doing the unwinding blind, we don't know if
+ we are adjusting the stack correctly or extracting the rp
+ correctly. The rp is checked to see if it belongs to the
+ kernel text section, if not we assume we don't have a
+ correct stack frame and we continue to unwind the stack.
+ This is not quite correct, and will fail for loadable
+ modules. */
+ sp = info->sp & ~63;
+ do {
+ info->prev_sp = sp - 64;
+
+ /* FIXME: what happens if we unwind too far so that
+ sp no longer falls in a mapped kernel page? */
+#ifndef __LP64__
+ info->prev_ip = *(unsigned long *)(info->prev_sp - 20);
+#else
+ info->prev_ip = *(unsigned long *)(info->prev_sp - 16);
+#endif
+
+ sp = info->prev_sp;
+ } while (info->prev_ip < (unsigned long)_stext ||
+ info->prev_ip > (unsigned long)_etext);
+ } else {
+
+ dbg("e->start = 0x%x, e->end = 0x%x, Save_SP = %d, Save_RP = %d size = %u\n",
+ e->region_start, e->region_end, e->Save_SP, e->Save_RP, e->Total_frame_size);
+
+ looking_for_rp = e->Save_RP;
+
+ for (npc = e->region_start;
+ (frame_size < (e->Total_frame_size << 3) || looking_for_rp) &&
+ npc < info->ip;
+ npc += 4) {
+
+ insn = *(unsigned int *)npc;
+
+ if ((insn & 0xffffc000) == 0x37de0000 ||
+ (insn & 0xffe00000) == 0x6fc00000) {
+ /* ldo X(sp), sp, or stwm X,D(sp) */
+ frame_size += (insn & 0x1 ? -1 << 13 : 0) |
+ ((insn & 0x3fff) >> 1);
+ } else if ((insn & 0xffe00008) == 0x7ec00008) {
+ /* std,ma X,D(sp) */
+ frame_size += (insn & 0x1 ? -1 << 13 : 0) |
+ (((insn >> 4) & 0x3ff) << 3);
+ } else if (insn == 0x6bc23fd9) {
+ /* stw rp,-20(sp) */
+ rpoffset = 20;
+ looking_for_rp = 0;
+ } else if (insn == 0x0fc212c1) {
+ /* std rp,-16(sr0,sp) */
+ rpoffset = 16;
+ looking_for_rp = 0;
+ }
+ }
+
+ info->prev_sp = info->sp - frame_size;
+ if (rpoffset)
+ info->prev_ip = *(unsigned long *)(info->prev_sp - rpoffset);
+ }
+}
+
+void unwind_frame_init(struct unwind_frame_info *info, struct task_struct *t,
+ struct pt_regs *regs)
+{
+ memset(info, 0, sizeof(struct unwind_frame_info));
+ info->t = t;
+ info->sp = regs->ksp;
+ info->ip = regs->kpc;
+
+ dbg("(%d) Start unwind from sp=%08lx ip=%08lx\n", (int)t->pid, info->sp, info->ip);
+}
+
+void unwind_frame_init_from_blocked_task(struct unwind_frame_info *info, struct task_struct *t)
+{
+ struct pt_regs *regs = &t->thread.regs;
+ unwind_frame_init(info, t, regs);
+}
+
+int unwind_once(struct unwind_frame_info *next_frame)
+{
+ unwind_frame_regs(next_frame);
+
+ if (next_frame->prev_sp == 0 ||
+ next_frame->prev_ip == 0)
+ return -1;
+
+ next_frame->sp = next_frame->prev_sp;
+ next_frame->ip = next_frame->prev_ip;
+ next_frame->prev_sp = 0;
+ next_frame->prev_ip = 0;
+
+ dbg("(%d) Continue unwind to sp=%08lx ip=%08lx\n", (int)next_frame->t->pid, next_frame->sp, next_frame->ip);
+
+ return 0;
+}
+
+int unwind_to_user(struct unwind_frame_info *info)
+{
+ int ret;
+
+ do {
+ ret = unwind_once(info);
+ } while (!ret && !(info->ip & 3));
+
+ return ret;
+}
+
+module_init(unwind_init);
git://git.onelab.eu / linux-2.6.git / blobdiff