t16-byte align - plan9port - [fork] Plan 9 from user space

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---

commit fa07e3d777fc52a7c564f71c9b7f2bba1d0e7716

parent d9ed72433f25ec45908dede1022425a3f3ed1c67

Author: rsc 

Date:   Sat, 22 Apr 2006 00:50:08 +0000

16-byte align

Diffstat:
  M src/libthread/Darwin-386.c          |       9 +++++++++

1 file changed, 9 insertions(+), 0 deletions(-)
---

diff --git a/src/libthread/Darwin-386.c b/src/libthread/Darwin-386.c

t@@ -3,10 +3,19 @@
 void
 makecontext(ucontext_t *ucp, void (*func)(void), int argc, ...)
 {
+        int n;
         int *sp;
 
         sp = (int*)ucp->uc_stack.ss_sp+ucp->uc_stack.ss_size/4;
         sp -= argc;
+        /*
+         * Stack pointer at call instruction (before return address
+         * gets pushed) must be 16-byte aligned.
+         */
+        if((uintptr)sp%4)
+                abort();
+        while((uintptr)sp%16)
+                sp--;
         memmove(sp, &argc+1, argc*sizeof(int));
         *--sp = 0;                /* return address */
         ucp->uc_mcontext.mc_eip = (long)func;