1 files changed, 84 insertions, 45 deletions

diff --git a/arch/arm/kernel/unwind.c b/arch/arm/kernel/unwind.c
index e7e8365795c3..00df012c4678 100644
--- a/arch/arm/kernel/unwind.c
+++ b/arch/arm/kernel/unwind.c
@@ -67,7 +67,7 @@ EXPORT_SYMBOL(__aeabi_unwind_cpp_pr2);
 
 struct unwind_ctrl_block {
         unsigned long vrs[16];          /* virtual register set */
-        unsigned long *insn;            /* pointer to the current instructions word */
+        const unsigned long *insn;      /* pointer to the current instructions word */
         int entries;                    /* number of entries left to interpret */
         int byte;                       /* current byte number in the instructions word */
 };
@@ -83,8 +83,9 @@ enum regs {
         PC = 15
 };
 
-extern struct unwind_idx __start_unwind_idx[];
-extern struct unwind_idx __stop_unwind_idx[];
+extern const struct unwind_idx __start_unwind_idx[];
+static const struct unwind_idx *__origin_unwind_idx;
+extern const struct unwind_idx __stop_unwind_idx[];
 
 static DEFINE_SPINLOCK(unwind_lock);
 static LIST_HEAD(unwind_tables);
@@ -98,45 +99,99 @@ static LIST_HEAD(unwind_tables);
 })
 
 /*
- * Binary search in the unwind index. The entries entries are
+ * Binary search in the unwind index. The entries are
  * guaranteed to be sorted in ascending order by the linker.
+ *
+ * start = first entry
+ * origin = first entry with positive offset (or stop if there is no such entry)
+ * stop - 1 = last entry
  */
-static struct unwind_idx *search_index(unsigned long addr,
-                                       struct unwind_idx *first,
-                                       struct unwind_idx *last)
+static const struct unwind_idx *search_index(unsigned long addr,
+                                       const struct unwind_idx *start,
+                                       const struct unwind_idx *origin,
+                                       const struct unwind_idx *stop)
 {
-        pr_debug("%s(%08lx, %p, %p)\n", __func__, addr, first, last);
+        unsigned long addr_prel31;
+
+        pr_debug("%s(%08lx, %p, %p, %p)\n",
+                        __func__, addr, start, origin, stop);
+
+        /*
+         * only search in the section with the matching sign. This way the
+         * prel31 numbers can be compared as unsigned longs.
+         */
+        if (addr < (unsigned long)start)
+                /* negative offsets: [start; origin) */
+                stop = origin;
+        else
+                /* positive offsets: [origin; stop) */
+                start = origin;
+
+        /* prel31 for address relavive to start */
+        addr_prel31 = (addr - (unsigned long)start) & 0x7fffffff;
 
-        if (addr < first->addr) {
+        while (start < stop - 1) {
+                const struct unwind_idx *mid = start + ((stop - start) >> 1);
+
+                /*
+                 * As addr_prel31 is relative to start an offset is needed to
+                 * make it relative to mid.
+                 */
+                if (addr_prel31 - ((unsigned long)mid - (unsigned long)start) <
+                                mid->addr_offset)
+                        stop = mid;
+                else {
+                        /* keep addr_prel31 relative to start */
+                        addr_prel31 -= ((unsigned long)mid -
+                                        (unsigned long)start);
+                        start = mid;
+                }
+        }
+
+        if (likely(start->addr_offset <= addr_prel31))
+                return start;
+        else {
                 pr_warning("unwind: Unknown symbol address %08lx\n", addr);
                 return NULL;
-        } else if (addr >= last->addr)
-                return last;
+        }
+}
 
-        while (first < last - 1) {
-                struct unwind_idx *mid = first + ((last - first + 1) >> 1);
+static const struct unwind_idx *unwind_find_origin(
+                const struct unwind_idx *start, const struct unwind_idx *stop)
+{
+        pr_debug("%s(%p, %p)\n", __func__, start, stop);
+        while (start < stop) {
+                const struct unwind_idx *mid = start + ((stop - start) >> 1);
 
-                if (addr < mid->addr)
-                        last = mid;
+                if (mid->addr_offset >= 0x40000000)
+                        /* negative offset */
+                        start = mid + 1;
                 else
-                        first = mid;
+                        /* positive offset */
+                        stop = mid;
         }
-
-        return first;
+        pr_debug("%s -> %p\n", __func__, stop);
+        return stop;
 }
 
-static struct unwind_idx *unwind_find_idx(unsigned long addr)
+static const struct unwind_idx *unwind_find_idx(unsigned long addr)
 {
-        struct unwind_idx *idx = NULL;
+        const struct unwind_idx *idx = NULL;
         unsigned long flags;
 
         pr_debug("%s(%08lx)\n", __func__, addr);
 
-        if (core_kernel_text(addr))
+        if (core_kernel_text(addr)) {
+                if (unlikely(!__origin_unwind_idx))
+                        __origin_unwind_idx =
+                                unwind_find_origin(__start_unwind_idx,
+                                                __stop_unwind_idx);
+
                 /* main unwind table */
                 idx = search_index(addr, __start_unwind_idx,
-                                   __stop_unwind_idx - 1);
-        else {
+                                   __origin_unwind_idx,
+                                   __stop_unwind_idx);
+        } else {
                 /* module unwind tables */
                 struct unwind_table *table;
 
@@ -145,7 +200,8 @@ static struct unwind_idx *unwind_find_idx(unsigned long addr)
                         if (addr >= table->begin_addr &&
                             addr < table->end_addr) {
                                 idx = search_index(addr, table->start,
-                                                   table->stop - 1);
+                                                   table->origin,
+                                                   table->stop);
                                 /* Move-to-front to exploit common traces */
                                 list_move(&table->list, &unwind_tables);
                                 break;
@@ -274,7 +330,7 @@ static int unwind_exec_insn(struct unwind_ctrl_block *ctrl)
 int unwind_frame(struct stackframe *frame)
 {
         unsigned long high, low;
-        struct unwind_idx *idx;
+        const struct unwind_idx *idx;
         struct unwind_ctrl_block ctrl;
 
         /* only go to a higher address on the stack */
@@ -399,7 +455,6 @@ struct unwind_table *unwind_table_add(unsigned long start, unsigned long size,
                                       unsigned long text_size)
 {
         unsigned long flags;
-        struct unwind_idx *idx;
         struct unwind_table *tab = kmalloc(sizeof(*tab), GFP_KERNEL);
 
         pr_debug("%s(%08lx, %08lx, %08lx, %08lx)\n", __func__, start, size,
@@ -408,15 +463,12 @@ struct unwind_table *unwind_table_add(unsigned long start, unsigned long size,
         if (!tab)
                 return tab;
 
-        tab->start = (struct unwind_idx *)start;
-        tab->stop = (struct unwind_idx *)(start + size);
+        tab->start = (const struct unwind_idx *)start;
+        tab->stop = (const struct unwind_idx *)(start + size);
+        tab->origin = unwind_find_origin(tab->start, tab->stop);
         tab->begin_addr = text_addr;
         tab->end_addr = text_addr + text_size;
 
-        /* Convert the symbol addresses to absolute values */
-        for (idx = tab->start; idx < tab->stop; idx++)
-                idx->addr = prel31_to_addr(&idx->addr);
-
         spin_lock_irqsave(&unwind_lock, flags);
         list_add_tail(&tab->list, &unwind_tables);
         spin_unlock_irqrestore(&unwind_lock, flags);
@@ -437,16 +489,3 @@ void unwind_table_del(struct unwind_table *tab)
 
         kfree(tab);
 }
-
-int __init unwind_init(void)
-{
-        struct unwind_idx *idx;
-
-        /* Convert the symbol addresses to absolute values */
-        for (idx = __start_unwind_idx; idx < __stop_unwind_idx; idx++)
-                idx->addr = prel31_to_addr(&idx->addr);
-
-        pr_debug("unwind: ARM stack unwinding initialised\n");
-
-        return 0;
-}