core/thread: Fix up stack and TLS alignments

Make sure both the stack and TLS blocks are correctly aligned by
adjusting the TLS base address to the most strict alignment of the TLS
block and the stack.

Signed-off-by: Keith Packard <[email protected]>

Author: keith-packard

core/thread.c

@@ -226,9 +226,19 @@ kernel_pid_t thread_create(char *stack, int stacksize, uint8_t priority,
     thread_t *thread = (thread_t *)(uintptr_t)(stack + stacksize);
 
 #ifdef PICOLIBC_TLS
-    stacksize -= _tls_size();
+#if __PICOLIBC_MAJOR__ > 1 || __PICOLIBC_MINOR__ >= 8
+#define TLS_ALIGN       (alignof(thread_t) > _tls_align() ? alignof(thread_t) : _tls_align())
+#else
+#define TLS_ALIGN       alignof(thread_t)
+#endif
+    char *tls = stack + stacksize - _tls_size();
+    /*
+     * Make sure the TLS area is aligned as required and that the
+     * resulting stack will also be aligned as required
+     */
+    thread->tls = (void *) ((uintptr_t) tls & ~ (TLS_ALIGN - 1));
+    stacksize = (char *) thread->tls - stack;
 
-    thread->tls = stack + stacksize;
     _init_tls(thread->tls);
 #endif