The Cell SPU ABI defines using word element 1 of the stack pointer
register to keep track of the number of available stack bytes.
malloc/sbrk is meant to update this (see patch) so that GCC's stack
check instrumentation can detect stack/heap collisions.
Okay to commit?
Ben
2007-03-01 Ben Elliston <bje@au.ibm.com>
* spu/sbrk.c (sbrk): Adjust the stack pointer vector correctly so
that GCC runtime stack checking works. Handle the backchain, too.
Index: spu/sbrk.c
===================================================================
RCS file: /cvs/src/src/libgloss/spu/sbrk.c,v
retrieving revision 1.1
diff -u -p -r1.1 sbrk.c
--- spu/sbrk.c 16 Aug 2006 21:15:03 -0000 1.1
+++ spu/sbrk.c 1 Mar 2007 04:22:32 -0000
@@ -32,6 +32,7 @@ Author: Andreas Neukoetter (ti95neuk@de.
#include <sys/types.h>
#include <errno.h>
+#include <spu_intrinsics.h>
extern int errno;
@@ -44,20 +45,39 @@ sbrk (ptrdiff_t increment)
{
static caddr_t heap_ptr = NULL;
caddr_t base;
+ vector unsigned int sp_reg, sp_delta;
+ vector unsigned int *sp_ptr;
+ /* The stack pointer register. */
+ volatile register vector unsigned int sp_r1 __asm__("1");
+
if (heap_ptr == NULL)
- {
- heap_ptr = (caddr_t) & _end;
- }
+ heap_ptr = (caddr_t) & _end;
+
if (((RAMSIZE - STACKSIZE) - (int) heap_ptr) >= increment)
{
- base = heap_ptr;
- heap_ptr += increment;
- return (base);
+ base = heap_ptr;
+ heap_ptr += increment;
+
+ sp_delta = (vector unsigned int) spu_insert (increment, spu_splats (0), 1);
+
+ /* Subtract sp_delta from the SP limit (word 1). */
+ sp_r1 = spu_sub (sp_r1, sp_delta);
+
+ /* Fix-up backchain. */
+ sp_ptr = (vector unsigned int *) spu_extract (sp_r1, 0);
+ do
+ {
+ sp_reg = *sp_ptr;
+ *sp_ptr = (vector unsigned int) spu_sub (sp_reg, sp_delta);
+ }
+ while ((sp_ptr = (vector unsigned int *) spu_extract (sp_reg, 0)));
+
+ return (base);
}
else
{
- errno = ENOMEM;
- return ((void *) -1);
+ errno = ENOMEM;
+ return ((void *) -1);
}
}