1 files changed, 136 insertions, 65 deletions

diff --git a/arch/sh/kernel/dwarf.c b/arch/sh/kernel/dwarf.c
index d0652153f576..e4810375207d 100644
--- a/arch/sh/kernel/dwarf.c
+++ b/arch/sh/kernel/dwarf.c
@@ -17,6 +17,7 @@
 #include <linux/kernel.h>
 #include <linux/io.h>
 #include <linux/list.h>
+#include <linux/mempool.h>
 #include <linux/mm.h>
 #include <asm/dwarf.h>
 #include <asm/unwinder.h>
@@ -25,6 +26,17 @@
 #include <asm/dwarf.h>
 #include <asm/stacktrace.h>
 
+/* Reserve enough memory for two stack frames */
+#define DWARF_FRAME_MIN_REQ     2
+/* ... with 4 registers per frame. */
+#define DWARF_REG_MIN_REQ       (DWARF_FRAME_MIN_REQ * 4)
+
+static struct kmem_cache *dwarf_frame_cachep;
+static mempool_t *dwarf_frame_pool;
+
+static struct kmem_cache *dwarf_reg_cachep;
+static mempool_t *dwarf_reg_pool;
+
 static LIST_HEAD(dwarf_cie_list);
 static DEFINE_SPINLOCK(dwarf_cie_lock);
 
@@ -33,33 +45,25 @@ static DEFINE_SPINLOCK(dwarf_fde_lock);
 
 static struct dwarf_cie *cached_cie;
 
-/*
- * Figure out whether we need to allocate some dwarf registers. If dwarf
- * registers have already been allocated then we may need to realloc
- * them. "reg" is a register number that we need to be able to access
- * after this call.
+/**
+ *      dwarf_frame_alloc_reg - allocate memory for a DWARF register
+ *      @frame: the DWARF frame whose list of registers we insert on
+ *      @reg_num: the register number
+ *
+ *      Allocate space for, and initialise, a dwarf reg from
+ *      dwarf_reg_pool and insert it onto the (unsorted) linked-list of
+ *      dwarf registers for @frame.
  *
- * Register numbers start at zero, therefore we need to allocate space
- * for "reg" + 1 registers.
+ *      Return the initialised DWARF reg.
  */
-static void dwarf_frame_alloc_regs(struct dwarf_frame *frame,
-                                   unsigned int reg)
+static struct dwarf_reg *dwarf_frame_alloc_reg(struct dwarf_frame *frame,
+                                               unsigned int reg_num)
 {
-        struct dwarf_reg *regs;
-        unsigned int num_regs = reg + 1;
-        size_t new_size;
-        size_t old_size;
+        struct dwarf_reg *reg;
 
-        new_size = num_regs * sizeof(*regs);
-        old_size = frame->num_regs * sizeof(*regs);
-
-        /* Fast path: don't allocate any regs if we've already got enough. */
-        if (frame->num_regs >= num_regs)
-                return;
-
-        regs = kzalloc(new_size, GFP_ATOMIC);
-        if (!regs) {
-                printk(KERN_WARNING "Unable to allocate DWARF registers\n");
+        reg = mempool_alloc(dwarf_reg_pool, GFP_ATOMIC);
+        if (!reg) {
+                printk(KERN_WARNING "Unable to allocate a DWARF register\n");
                 /*
                  * Let's just bomb hard here, we have no way to
                  * gracefully recover.
@@ -67,13 +71,44 @@ static void dwarf_frame_alloc_regs(struct dwarf_frame *frame,
                 BUG();
         }
 
-        if (frame->regs) {
-                memcpy(regs, frame->regs, old_size);
-                kfree(frame->regs);
+        reg->number = reg_num;
+        reg->addr = 0;
+        reg->flags = 0;
+
+        list_add(&reg->link, &frame->reg_list);
+
+        return reg;
+}
+
+static void dwarf_frame_free_regs(struct dwarf_frame *frame)
+{
+        struct dwarf_reg *reg, *n;
+
+        list_for_each_entry_safe(reg, n, &frame->reg_list, link) {
+                list_del(&reg->link);
+                mempool_free(reg, dwarf_reg_pool);
+        }
+}
+
+/**
+ *      dwarf_frame_reg - return a DWARF register
+ *      @frame: the DWARF frame to search in for @reg_num
+ *      @reg_num: the register number to search for
+ *
+ *      Lookup and return the dwarf reg @reg_num for this frame. Return
+ *      NULL if @reg_num is an register invalid number.
+ */
+static struct dwarf_reg *dwarf_frame_reg(struct dwarf_frame *frame,
+                                         unsigned int reg_num)
+{
+        struct dwarf_reg *reg;
+
+        list_for_each_entry(reg, &frame->reg_list, link) {
+                if (reg->number == reg_num)
+                        return reg;
         }
 
-        frame->regs = regs;
-        frame->num_regs = num_regs;
+        return NULL;
 }
 
 /**
@@ -347,6 +382,7 @@ static int dwarf_cfa_execute_insns(unsigned char *insn_start,
         unsigned char insn;
         unsigned char *current_insn;
         unsigned int count, delta, reg, expr_len, offset;
+        struct dwarf_reg *regp;
 
         current_insn = insn_start;
 
@@ -369,9 +405,9 @@ static int dwarf_cfa_execute_insns(unsigned char *insn_start,
                         count = dwarf_read_uleb128(current_insn, &offset);
                         current_insn += count;
                         offset *= cie->data_alignment_factor;
-                        dwarf_frame_alloc_regs(frame, reg);
-                        frame->regs[reg].addr = offset;
-                        frame->regs[reg].flags |= DWARF_REG_OFFSET;
+                        regp = dwarf_frame_alloc_reg(frame, reg);
+                        regp->addr = offset;
+                        regp->flags |= DWARF_REG_OFFSET;
                         continue;
                         /* NOTREACHED */
                 case DW_CFA_restore:
@@ -453,17 +489,18 @@ static int dwarf_cfa_execute_insns(unsigned char *insn_start,
                         count = dwarf_read_leb128(current_insn, &offset);
                         current_insn += count;
                         offset *= cie->data_alignment_factor;
-                        dwarf_frame_alloc_regs(frame, reg);
-                        frame->regs[reg].flags |= DWARF_REG_OFFSET;
-                        frame->regs[reg].addr = offset;
+                        regp = dwarf_frame_alloc_reg(frame, reg);
+                        regp->flags |= DWARF_REG_OFFSET;
+                        regp->addr = offset;
                         break;
                 case DW_CFA_val_offset:
                         count = dwarf_read_uleb128(current_insn, &reg);
                         current_insn += count;
                         count = dwarf_read_leb128(current_insn, &offset);
                         offset *= cie->data_alignment_factor;
-                        frame->regs[reg].flags |= DWARF_REG_OFFSET;
-                        frame->regs[reg].addr = offset;
+                        regp = dwarf_frame_alloc_reg(frame, reg);
+                        regp->flags |= DWARF_REG_OFFSET;
+                        regp->addr = offset;
                         break;
                 case DW_CFA_GNU_args_size:
                         count = dwarf_read_uleb128(current_insn, &offset);
@@ -474,9 +511,10 @@ static int dwarf_cfa_execute_insns(unsigned char *insn_start,
                         current_insn += count;
                         count = dwarf_read_uleb128(current_insn, &offset);
                         offset *= cie->data_alignment_factor;
-                        dwarf_frame_alloc_regs(frame, reg);
-                        frame->regs[reg].flags |= DWARF_REG_OFFSET;
-                        frame->regs[reg].addr = -offset;
+
+                        regp = dwarf_frame_alloc_reg(frame, reg);
+                        regp->flags |= DWARF_REG_OFFSET;
+                        regp->addr = -offset;
                         break;
                 default:
                         pr_debug("unhandled DWARF instruction 0x%x\n", insn);
@@ -502,8 +540,8 @@ struct dwarf_frame *dwarf_unwind_stack(unsigned long pc,
         struct dwarf_frame *frame;
         struct dwarf_cie *cie;
         struct dwarf_fde *fde;
+        struct dwarf_reg *reg;
         unsigned long addr;
-        int i, offset;
 
         /*
          * If this is the first invocation of this recursive function we
@@ -516,11 +554,16 @@ struct dwarf_frame *dwarf_unwind_stack(unsigned long pc,
         if (!pc && !prev)
                 pc = (unsigned long)current_text_addr();
 
-        frame = kzalloc(sizeof(*frame), GFP_ATOMIC);
-        if (!frame)
-                return NULL;
+        frame = mempool_alloc(dwarf_frame_pool, GFP_ATOMIC);
+        if (!frame) {
+                printk(KERN_ERR "Unable to allocate a dwarf frame\n");
+                BUG();
+        }
 
+        INIT_LIST_HEAD(&frame->reg_list);
+        frame->flags = 0;
         frame->prev = prev;
+        frame->return_addr = 0;
 
         fde = dwarf_lookup_fde(pc);
         if (!fde) {
@@ -540,7 +583,7 @@ struct dwarf_frame *dwarf_unwind_stack(unsigned long pc,
                  *      case above, which sucks because we could print a
                  *      warning here.
                  */
-                return NULL;
+                goto bail;
         }
 
         cie = dwarf_lookup_cie(fde->cie_pointer);
@@ -560,10 +603,10 @@ struct dwarf_frame *dwarf_unwind_stack(unsigned long pc,
         switch (frame->flags) {
         case DWARF_FRAME_CFA_REG_OFFSET:
                 if (prev) {
-                        BUG_ON(!prev->regs[frame->cfa_register].flags);
+                        reg = dwarf_frame_reg(prev, frame->cfa_register);
+                        BUG_ON(!reg);
 
-                        addr = prev->cfa;
-                        addr += prev->regs[frame->cfa_register].addr;
+                        addr = prev->cfa + reg->addr;
                         frame->cfa = __raw_readl(addr);
 
                 } else {
@@ -584,23 +627,18 @@ struct dwarf_frame *dwarf_unwind_stack(unsigned long pc,
         }
 
         /* If we haven't seen the return address reg, we're screwed. */
-        BUG_ON(!frame->regs[DWARF_ARCH_RA_REG].flags);
-
-        for (i = 0; i <= frame->num_regs; i++) {
-                struct dwarf_reg *reg = &frame->regs[i];
-
-                if (!reg->flags)
-                        continue;
+        reg = dwarf_frame_reg(frame, DWARF_ARCH_RA_REG);
+        BUG_ON(!reg);
 
-                offset = reg->addr;
-                offset += frame->cfa;
-        }
-
-        addr = frame->cfa + frame->regs[DWARF_ARCH_RA_REG].addr;
+        addr = frame->cfa + reg->addr;
         frame->return_addr = __raw_readl(addr);
 
-        frame->next = dwarf_unwind_stack(frame->return_addr, frame);
         return frame;
+
+bail:
+        dwarf_frame_free_regs(frame);
+        mempool_free(frame, dwarf_frame_pool);
+        return NULL;
 }
 
 static int dwarf_parse_cie(void *entry, void *p, unsigned long len,
@@ -770,14 +808,29 @@ static void dwarf_unwinder_dump(struct task_struct *task, struct pt_regs *regs,
                                 unsigned long *sp,
                                 const struct stacktrace_ops *ops, void *data)
 {
-        struct dwarf_frame *frame;
+        struct dwarf_frame *frame, *_frame;
+        unsigned long return_addr;
+
+        _frame = NULL;
+        return_addr = 0;
 
-        frame = dwarf_unwind_stack(0, NULL);
+        while (1) {
+                frame = dwarf_unwind_stack(return_addr, _frame);
+
+                if (_frame) {
+                        dwarf_frame_free_regs(_frame);
+                        mempool_free(_frame, dwarf_frame_pool);
+                }
+
+                _frame = frame;
+
+                if (!frame || !frame->return_addr)
+                        break;
 
-        while (frame && frame->return_addr) {
-                ops->address(data, frame->return_addr, 1);
-                frame = frame->next;
+                return_addr = frame->return_addr;
+                ops->address(data, return_addr, 1);
         }
+
 }
 
 static struct unwinder dwarf_unwinder = {
@@ -801,6 +854,9 @@ static void dwarf_unwinder_cleanup(void)
 
         list_for_each_entry(fde, &dwarf_fde_list, link)
                 kfree(fde);
+
+        kmem_cache_destroy(dwarf_reg_cachep);
+        kmem_cache_destroy(dwarf_frame_cachep);
 }
 
 /**
@@ -827,6 +883,21 @@ static int __init dwarf_unwinder_init(void)
         f_entries = 0;
         entry = &__start_eh_frame;
 
+        dwarf_frame_cachep = kmem_cache_create("dwarf_frames",
+                        sizeof(struct dwarf_frame), 0, SLAB_PANIC, NULL);
+        dwarf_reg_cachep = kmem_cache_create("dwarf_regs",
+                        sizeof(struct dwarf_reg), 0, SLAB_PANIC, NULL);
+
+        dwarf_frame_pool = mempool_create(DWARF_FRAME_MIN_REQ,
+                                          mempool_alloc_slab,
+                                          mempool_free_slab,
+                                          dwarf_frame_cachep);
+
+        dwarf_reg_pool = mempool_create(DWARF_REG_MIN_REQ,
+                                         mempool_alloc_slab,
+                                         mempool_free_slab,
+                                         dwarf_reg_cachep);
+
         while ((char *)entry < __stop_eh_frame) {
                 p = entry;