From: Thomas Leonard <talex5@gmail.com>
Date: Wed, 16 Jul 2014 11:07:41 +0000 (+0100)
Subject: mini-os: x86_64: make thread stacks 16-byte aligned
X-Git-Url: http://xenbits.xensource.com/gitweb?a=commitdiff_plain;h=5bcf79d1e0e5b46497df96b29a27e9b7f8b4ba7d;p=people%2Fpauldu%2Fmini-os.git

mini-os: x86_64: make thread stacks 16-byte aligned

Otherwise, passing doubles to varargs functions causes a crash.

Signed-off-by: Thomas Leonard <talex5@gmail.com>
Acked-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
---

diff --git a/arch/x86/sched.c b/arch/x86/sched.c
index 8a05b58..e4a3dc2 100644
--- a/arch/x86/sched.c
+++ b/arch/x86/sched.c
@@ -107,6 +107,9 @@ struct thread* arch_create_thread(char *name, void (*function)(void *),
     thread->sp = (unsigned long)thread->stack + STACK_SIZE;
     /* Save pointer to the thread on the stack, used by current macro */
     *((unsigned long *)thread->stack) = (unsigned long)thread;
+
+    /* Must ensure that (%rsp + 8) is 16-byte aligned at the start of thread_starter. */
+    thread->sp -= sizeof(unsigned long);
     
     stack_push(thread, (unsigned long) function);
     stack_push(thread, (unsigned long) data);