Add optional (define BUFFER_ALLOC_DEBUG to enable it) code to check for code overflowing buffer_alloc()-allocated buffers.

Also add a panicf() if buffer_alloc() doesn't have enough space left to allocate a requested buffer


git-svn-id: svn://svn.rockbox.org/rockbox/trunk@28173 a1c6a512-1295-4272-9138-f99709370657

firmware/buffer.c

@@ -20,6 +20,8 @@
  ****************************************************************************/
 #include <stdio.h>
 #include "buffer.h"
+#include "panic.h"
+#include "logf.h"
 
 #if (CONFIG_PLATFORM & PLATFORM_HOSTED)
 unsigned char audiobuffer[(MEM*1024-256)*1024];
@@ -31,20 +33,94 @@ extern unsigned char audiobuffer[];
 
 unsigned char *audiobuf;
 
+#ifdef BUFFER_ALLOC_DEBUG
+static unsigned char *audiobuf_orig_start;
+
+struct buffer_start_marker
+{
+    unsigned int magic;
+    size_t buffer_size;
+};
+#define BUF_MAGIC 0xDEADD0D0
+
+struct buffer_end_marker
+{
+    unsigned int magic;
+    int last;
+};
+#endif /* BUFFER_ALLOC_DEBUG */
+
 void buffer_init(void)
 {
     /* 32-bit aligned */
     audiobuf = (void *)(((unsigned long)audiobuffer + 3) & ~3);
+#ifdef BUFFER_ALLOC_DEBUG
+    audiobuf_orig_start = audiobuf;
+#endif /* BUFFER_ALLOC_DEBUG */
 }
 
 void *buffer_alloc(size_t size)
 {
     void *retval = audiobuf;
+#ifdef BUFFER_ALLOC_DEBUG
+    struct buffer_start_marker *start;
+    struct buffer_end_marker *end;
+#endif /* BUFFER_ALLOC_DEBUG */
 
-    audiobuf += size;
     /* 32-bit aligned */
-    audiobuf = (void *)(((unsigned long)audiobuf + 3) & ~3);
+    size = (size + 3) & ~3;
+
+#ifdef BUFFER_ALLOC_DEBUG
+    retval +=sizeof(struct buffer_start_marker);
+    end=(struct buffer_end_marker*)(audiobuf - sizeof(struct buffer_end_marker));
+    if(end->magic == BUF_MAGIC)
+    {
+        end->last=0;
+    }
+    start=(struct buffer_start_marker*)audiobuf;
+    start->magic = BUF_MAGIC;
+    start->buffer_size = size;
+    end=(struct buffer_end_marker*)(audiobuf+sizeof(struct buffer_start_marker)+size);
+    end->magic = BUF_MAGIC;
+    end->last = 1;
+
+    audiobuf = ((unsigned char *)end) + sizeof(struct buffer_end_marker);
+
+    logf("Alloc %x %d",(unsigned int)retval,size);
+#else /* !BUFFER_ALLOC_DEBUG */
+    audiobuf += size;
+#endif /* BUFFER_ALLOC_DEBUG */
+
+    if (audiobuf > audiobufend) {
+        panicf("OOM: %d bytes", (int) size);
+    }
     
     return retval;
 }
 
+#ifdef BUFFER_ALLOC_DEBUG
+void buffer_alloc_check(char *name)
+{
+    unsigned char *buf_ptr = audiobuf_orig_start;
+    struct buffer_start_marker *start;
+    struct buffer_end_marker *end;
+
+
+    while(buf_ptr < audiobuf)
+    {
+        start=(struct buffer_start_marker*)buf_ptr;
+        if(start->magic != BUF_MAGIC)
+        {
+            panicf("%s corrupted buffer %x start", name,(unsigned int)buf_ptr+sizeof(struct buffer_start_marker));
+        }
+        end=(struct buffer_end_marker*)(buf_ptr+sizeof(struct buffer_start_marker)+start->buffer_size);
+        if(end->magic != BUF_MAGIC)
+        {
+            panicf("%s corrupted %x end", name,(unsigned int)buf_ptr+sizeof(struct buffer_start_marker));
+        }
+        if(end->last)
+            break;
+        buf_ptr=((unsigned char *)end)+sizeof(struct buffer_end_marker);
+    }
+}
+#endif /* BUFFER_ALLOC_DEBUG */

firmware/export/buffer.h

@@ -39,4 +39,8 @@ extern unsigned char *audiobuf;
 void buffer_init(void) INIT_ATTR;
 void *buffer_alloc(size_t size);
 
+#ifdef BUFFER_ALLOC_DEBUG
+void buffer_alloc_check(char *name);
+#endif
+
 #endif

firmware/thread.c

@@ -27,6 +27,7 @@
 #include "kernel.h"
 #include "cpu.h"
 #include "string.h"
+#include "buffer.h"
 #ifdef RB_PROFILE
 #include <profile.h>
 #endif
@@ -1160,6 +1161,16 @@ void switch_thread(void)
     if (UNLIKELY(thread->stack[0] != DEADBEEF) && thread->stack_size > 0)
         thread_stkov(thread);
 
+#ifdef BUFFER_ALLOC_DEBUG
+    /* Check if the current thread just did bad things with buffer_alloc()ed
+     * memory */
+    {
+        static char name[32];
+        thread_get_name(name, 32, thread);
+        buffer_alloc_check(name);
+    }
+#endif
+
 #if NUM_CORES > 1
     /* Run any blocking operations requested before switching/sleeping */
     run_blocking_ops(core, thread);