sh: unwinder: Fix memory leak and create our own kmem cache

Plug a memory leak in dwarf_unwinder_dump() where we didn't free the
memory that we had previously allocated for the DWARF frames and DWARF
registers.

Now is also a opportune time to implement our own mempool and kmem
cache. It's a good idea to have a certain number of frame and register
objects in reserve at all times, so that we are guaranteed to have our
allocation satisfied even when memory is scarce. Since we have pools to
allocate from we can implement the registers for each frame as a linked
list as opposed to a sparsely populated array. Whilst it's true that the
lookup time for a linked list is larger than for arrays, there's only
usually a maximum of 8 registers per frame. So the overhead isn't that
much of a concern.

Signed-off-by: Matt Fleming <matt@console-pimps.org>

1 files changed, 6 insertions, 16 deletions

diff --git a/arch/sh/include/asm/dwarf.h b/arch/sh/include/asm/dwarf.h
index 2fbe8720411e..a22fbe98303f 100644
--- a/arch/sh/include/asm/dwarf.h
+++ b/arch/sh/include/asm/dwarf.h
@@ -265,10 +265,7 @@ struct dwarf_frame {
 
         unsigned long pc;
 
-        struct dwarf_reg *regs;
-        unsigned int num_regs;  /* how many regs are allocated? */
-
-        unsigned int depth;     /* what level are we in the callstack? */
+        struct list_head reg_list;
 
         unsigned long cfa;
 
@@ -292,22 +289,15 @@ struct dwarf_frame {
  *      @flags: Describes how to calculate the value of this register
  */
 struct dwarf_reg {
+        struct list_head link;
+
+        unsigned int number;
+
         unsigned long addr;
         unsigned long flags;
 #define DWARF_REG_OFFSET        (1 << 0)
 };
 
-/**
- *      dwarf_stack - a DWARF stack contains a collection of DWARF frames
- *      @depth: the number of frames in the stack
- *      @level: an array of DWARF frames, indexed by stack level
- *
- */
-struct dwarf_stack {
-        unsigned int depth;
-        struct dwarf_frame **level;
-};
-
 /*
  * Call Frame instruction opcodes.
  */
@@ -372,7 +362,7 @@ static inline unsigned int DW_CFA_operand(unsigned long insn)
 
 extern struct dwarf_frame *dwarf_unwind_stack(unsigned long,
                                               struct dwarf_frame *);
-#endif /* __ASSEMBLY__ */
+#endif /* !__ASSEMBLY__ */
 
 #define CFI_STARTPROC   .cfi_startproc
 #define CFI_ENDPROC     .cfi_endproc