From 5043268cb187b668fff575baa50a8c48a282eb46 Mon Sep 17 00:00:00 2001
From: herman ten brugge <hermantenbrugge@home.nl>
Date: Sun, 24 Jan 2021 11:28:26 +0100
Subject: [PATCH] Fix unaligned access arm (openbsd)

libtcc.c:
Fix unaligned load/store from magic3

tccgen.c:
For packed struct allways use single byte code
If field does not start at at align check it
Align stack correctly with vla
---
 libtcc.c | 18 +++++++++++++-----
 tccgen.c | 10 +++++++---
 2 files changed, 20 insertions(+), 8 deletions(-)

diff --git a/libtcc.c b/libtcc.c
index 84392be7..9d2cbaf9 100644
--- a/libtcc.c
+++ b/libtcc.c
@@ -273,12 +273,20 @@ PUB_FUNC char *tcc_strdup(const char *str)
 #define MEM_DEBUG_MAGIC2 0xFEEDDEB2
 #define MEM_DEBUG_MAGIC3 0xFEEDDEB3
 #define MEM_DEBUG_FILE_LEN 40
+#define MEM_DEBUG_OFF3 offsetof(mem_debug_header_t, magic3)
 #define MEM_DEBUG_CHECK3(header) \
-    ((mem_debug_header_t*)((char*)header + header->size))->magic3
+    ({unsigned magic3; \
+      memcpy(&magic3, (char*)header + MEM_DEBUG_OFF3 + header->size, \
+             sizeof (magic3)); \
+      magic3;})
+#define MEM_DEBUG_SET3(header) \
+    {unsigned magic3 = MEM_DEBUG_MAGIC3; \
+      memcpy((char*)header + MEM_DEBUG_OFF3 + header->size, &magic3, \
+             sizeof (magic3));}
 #define MEM_USER_PTR(header) \
-    ((char *)header + offsetof(mem_debug_header_t, magic3))
+    ((char *)header + MEM_DEBUG_OFF3)
 #define MEM_HEADER_PTR(ptr) \
-    (mem_debug_header_t *)((char*)ptr - offsetof(mem_debug_header_t, magic3))
+    (mem_debug_header_t *)((char*)ptr - MEM_DEBUG_OFF3)
 
 struct mem_debug_header {
     unsigned magic1;
@@ -325,7 +333,7 @@ PUB_FUNC void *tcc_malloc_debug(unsigned long size, const char *file, int line)
     header->magic1 = MEM_DEBUG_MAGIC1;
     header->magic2 = MEM_DEBUG_MAGIC2;
     header->size = size;
-    MEM_DEBUG_CHECK3(header) = MEM_DEBUG_MAGIC3;
+    MEM_DEBUG_SET3(header);
     header->line_num = line;
     ofs = strlen(file) - MEM_DEBUG_FILE_LEN;
     strncpy(header->file_name, file + (ofs > 0 ? ofs : 0), MEM_DEBUG_FILE_LEN);
@@ -382,7 +390,7 @@ PUB_FUNC void *tcc_realloc_debug(void *ptr, unsigned long size, const char *file
     if (!header)
         _tcc_error("memory full (realloc)");
     header->size = size;
-    MEM_DEBUG_CHECK3(header) = MEM_DEBUG_MAGIC3;
+    MEM_DEBUG_SET3(header);
     if (header->next)
         header->next->prev = header;
     if (header->prev)
diff --git a/tccgen.c b/tccgen.c
index 29e21669..2728af45 100644
--- a/tccgen.c
+++ b/tccgen.c
@@ -4727,7 +4727,10 @@ static void struct_layout(CType *type, AttributeDef *ad)
             continue;
         bit_pos = BIT_POS(f->type.t);
         size = type_size(&f->type, &align);
-        if (bit_pos + bit_size <= size * 8 && f->c + size <= c)
+        if (c & 3) /* packed struct */
+	    goto single_byte;
+        if (bit_pos + bit_size <= size * 8 && f->c + size <= c &&
+	    (f->c & (align - 1)) == 0)
             continue;
 
         /* try to access the field using a different type */
@@ -4768,6 +4771,7 @@ static void struct_layout(CType *type, AttributeDef *ad)
                 cx, s, align, px, bit_size);
 #endif
         } else {
+single_byte:
             /* fall back to load/store single-byte wise */
             f->auxtype = VT_STRUCT;
 #ifdef BF_DEBUG
@@ -8269,7 +8273,7 @@ static void decl_initializer_alloc(CType *type, AttributeDef *ad, int r,
 #ifdef CONFIG_TCC_BCHECK
         if (bcheck && v) {
             /* add padding between stack variables for bound checking */
-            loc--;
+            loc -= align;
         }
 #endif
         loc = (loc - size) & -align;
@@ -8278,7 +8282,7 @@ static void decl_initializer_alloc(CType *type, AttributeDef *ad, int r,
 #ifdef CONFIG_TCC_BCHECK
         if (bcheck && v) {
             /* add padding between stack variables for bound checking */
-            loc--;
+            loc -= align;
         }
 #endif
         if (v) {