From b91e47b5185ba70fff0151c34ad8923564a07d81 Mon Sep 17 00:00:00 2001
From: Dirk Ziegelmeier <dirk@ziegelmeier.net>
Date: Thu, 7 Jul 2016 13:35:13 +0200
Subject: [PATCH] Implement portable and overridable allocation of memory
 buffers Fixes bug #48300 (Private mempools allocate foreign memory), bug
 #48354 (Portable alignment defines/include required for static allocation)
 and bug #47092 (Tag memory buffers like memp_memory_xxx and ram_heap with a
 macro so that attributes can be attached to their definitions)

Signed-off-by: Simon Goldschmidt <goldsimon@gmx.de>
---
 src/core/ipv4/ip_frag.c |  2 +-
 src/core/mem.c          |  2 +-
 src/include/lwip/arch.h | 14 ++++++++++++++
 src/include/lwip/memp.h |  4 ++--
 4 files changed, 18 insertions(+), 4 deletions(-)

diff --git a/src/core/ipv4/ip_frag.c b/src/core/ipv4/ip_frag.c
index a6474335..bb0599e6 100644
--- a/src/core/ipv4/ip_frag.c
+++ b/src/core/ipv4/ip_frag.c
@@ -640,7 +640,7 @@ nullreturn:
 
 #if IP_FRAG
 #if IP_FRAG_USES_STATIC_BUF
-static u8_t buf[LWIP_MEM_ALIGN_SIZE(IP_FRAG_MAX_MTU + MEM_ALIGNMENT - 1)];
+static LWIP_DECLARE_MEMORY_ALIGNED(buf, IP_FRAG_MAX_MTU);
 #else /* IP_FRAG_USES_STATIC_BUF */
 
 #if !LWIP_NETIF_TX_SINGLE_PBUF
diff --git a/src/core/mem.c b/src/core/mem.c
index 9ca9e3c4..d3d97e35 100644
--- a/src/core/mem.c
+++ b/src/core/mem.c
@@ -202,7 +202,7 @@ struct mem {
  * how that space is calculated). */
 #ifndef LWIP_RAM_HEAP_POINTER
 /** the heap. we need one struct mem at the end and some room for alignment */
-u8_t ram_heap[MEM_SIZE_ALIGNED + (2U*SIZEOF_STRUCT_MEM) + MEM_ALIGNMENT];
+LWIP_DECLARE_MEMORY_ALIGNED(ram_heap, MEM_SIZE_ALIGNED + (2U*SIZEOF_STRUCT_MEM));
 #define LWIP_RAM_HEAP_POINTER ram_heap
 #endif /* LWIP_RAM_HEAP_POINTER */
 
diff --git a/src/include/lwip/arch.h b/src/include/lwip/arch.h
index 41b123f6..ca708b3c 100644
--- a/src/include/lwip/arch.h
+++ b/src/include/lwip/arch.h
@@ -110,6 +110,20 @@ typedef uintptr_t mem_ptr_t;
 #endif
 #endif
 
+/** Allocates a memory buffer of specified size that is of sufficient size to align
+ * its start address using LWIP_MEM_ALIGN.
+ * You can declare your own version here e.g. to enforce alignment without adding
+ * trailing padding bytes (see LWIP_MEM_ALIGN_BUFFER) or your own section placement
+ * requirements.
+ * e.g. if you use gcc and need 32 bit alignment:
+ * #define LWIP_DECLARE_MEMORY_ALIGNED(variable_name, size) u8_t variable_name[size] __attribute__((aligned(4)))
+ * or more portable:
+ * #define LWIP_DECLARE_MEMORY_ALIGNED(variable_name, size) u32_t variable_name[(size + sizeof(u32_t) - 1) / sizeof(u32_t)]
+ */
+#ifndef LWIP_DECLARE_MEMORY_ALIGNED
+#define LWIP_DECLARE_MEMORY_ALIGNED(variable_name, size) u8_t variable_name[LWIP_MEM_ALIGN_BUFFER(size)]
+#endif
+
 #ifdef __cplusplus
 extern "C" {
 #endif
diff --git a/src/include/lwip/memp.h b/src/include/lwip/memp.h
index d6c29657..285d3b8b 100644
--- a/src/include/lwip/memp.h
+++ b/src/include/lwip/memp.h
@@ -90,8 +90,8 @@ extern const struct memp_desc* const memp_pools[MEMP_MAX];
 
 #else /* MEMP_MEM_MALLOC */
 
-#define LWIP_MEMPOOL_DECLARE(name,num,size,desc) u8_t memp_memory_ ## name ## _base \
-    [((num) * (MEMP_SIZE + MEMP_ALIGN_SIZE(size))) + (MEM_ALIGNMENT-1)]; \
+#define LWIP_MEMPOOL_DECLARE(name,num,size,desc) \
+  LWIP_DECLARE_MEMORY_ALIGNED(memp_memory_ ## name ## _base, ((num) * (MEMP_SIZE + MEMP_ALIGN_SIZE(size)))); \
     \
   static struct memp *memp_tab_ ## name; \
     \