Make libpayload alloc() memory pointers volatile

gcc4.6.2 was optimizing the libpayload alloc() function and failing to
reload a pointer after the memory had been manipulated by a pointer in
the inlined function setup(). Change the pointer type to volatile
and now pass it to the setup() function. Also clean up the
declaration so that it isn't cast a bunch times in the function.

Change-Id: I1637bd7bd5d9cf82ac88925cbfe76d319aa3cd82
Signed-off-by: Marc Jones <marc.jones@se-eng.com>
Reviewed-on: http://review.coreboot.org/705
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <patrick@georgi-clan.de>

diff --git a/payloads/libpayload/libc/malloc.c b/payloads/libpayload/libc/malloc.c
index 6389fc937936381aee709a337cdad63cad2eb698..9412cab189d455cc026158769957f3dd7b0bfe0a 100644 (file)
--- a/payloads/libpayload/libc/malloc.c
+++ b/payloads/libpayload/libc/malloc.c
@@ -73,11 +73,9 @@ static int heap_initialized = 0;
 static int minimal_free = 0;
 #endif
 
-static void setup(void)
+static void setup(hdrtype_t volatile *start, int size)
 {
-       int size = (unsigned int)(&_eheap - &_heap) - HDRSIZE;
-
-       *((hdrtype_t *) hstart) = FREE_BLOCK(size);
+       *start = FREE_BLOCK(size);
 
 #ifdef CONFIG_DEBUG_MALLOC
        heap_initialized = 1;
@@ -88,7 +86,7 @@ static void setup(void)
 static void *alloc(int len)
 {
        hdrtype_t header;
-       void *ptr = hstart;
+       hdrtype_t volatile *ptr = (hdrtype_t volatile *) hstart;
 
        /* Align the size. */
        len = (len + 3) & ~3;
@@ -97,12 +95,12 @@ static void *alloc(int len)
                return (void *)NULL;
 
        /* Make sure the region is setup correctly. */
-       if (!HAS_MAGIC(*((hdrtype_t *) ptr)))
-               setup();
+       if (!HAS_MAGIC(*ptr))
+               setup(ptr, len);
 
        /* Find some free space. */
        do {
-               header = *((hdrtype_t *) ptr);
+               header = *ptr;
                int size = SIZE(header);
 
                if (!HAS_MAGIC(header) || size == 0) {
@@ -114,7 +112,7 @@ static void *alloc(int len)
 
                if (header & FLAG_FREE) {
                        if (len <= size) {
-                               void *nptr = ptr + (HDRSIZE + len);
+                               hdrtype_t volatile *nptr = ptr + (HDRSIZE + len);
                                int nsize = size - (HDRSIZE + len);
 
                                /* If there is still room in this block,
@@ -124,14 +122,13 @@ static void *alloc(int len)
 
                                if (nsize > 0) {
                                        /* Mark the block as used. */
-                                       *((hdrtype_t *) ptr) = USED_BLOCK(len);
+                                       *ptr = USED_BLOCK(len);
 
                                        /* Create a new free block. */
-                                       *((hdrtype_t *) nptr) =
-                                           FREE_BLOCK(nsize);
+                                       *nptr = FREE_BLOCK(nsize);
                                } else {
                                        /* Mark the block as used. */
-                                       *((hdrtype_t *) ptr) = USED_BLOCK(size);
+                                       *ptr = USED_BLOCK(size);
                                }
 
                                return (void *)(ptr + HDRSIZE);
@@ -140,7 +137,7 @@ static void *alloc(int len)
 
                ptr += HDRSIZE + size;
 
-       } while (ptr < hend);
+       } while (ptr < (hdrtype_t *) hend);
 
        /* Nothing available. */
        return (void *)NULL;