Use mmap to allocate procedure stack buffers on E2K

(fix of commit 990dcdba1)

Issue #411 (bdwgc).

This commit prevents stack overflow in case of a big procedure stack
to be saved.

If a procedure stack requires less than 1 memory page for the buffer,
then the buffer is still allocated on the local stack.

* include/private/gc_priv.h [E2K] (PS_ALLOCA_BUF, ALLOCA_SAFE_LIMIT,
FREE_PROCEDURE_STACK_LOCAL): Define macro.
* include/private/gc_priv.h [E2K] (PROCEDURE_STACK_ALLOCA_AND_STORE):
Rename to GET_PROCEDURE_STACK_LOCAL; update comment; modify
implementation to call GC_mmap_procedure_stack_buf (and
GC_unmap_procedure_stack_buf) if size > ALLOCA_SAFE_LIMIT.
* include/private/gc_priv.h [E2K] (GC_mmap_procedure_stack_buf,
GC_unmap_procedure_stack_buf): Declare function.
* include/private/gc_priv.h [E2K && THREADS]
(GC_alloc_and_get_procedure_stack): Refine comment.
* mach_dep.c [E2K]: Include sys/mman.h.
* mach_dep.c [E2K] (GC_mmap_procedure_stack_buf,
GC_unmap_procedure_stack_buf): Implement.
* mark_rts.c [E2K && !THREADS] (GC_push_current_stack): Rename
PROCEDURE_STACK_ALLOCA_AND_STORE to GET_PROCEDURE_STACK_LOCAL; call
FREE_PROCEDURE_STACK_LOCAL() when bs_lo is not needed.
* pthread_stop_world.c [!GC_OPENBSD_UTHREADS && !NACL && E2K]
(GC_suspend_handler_inner, GC_push_all_stacks): Likewise.

1 files changed, 20 insertions, 2 deletions

diff --git a/mach_dep.c b/mach_dep.c
index 28e44867..ef2df2be 100644
--- a/mach_dep.c
+++ b/mach_dep.c
@@ -28,9 +28,9 @@
 
 #ifdef E2K
 # include <errno.h>
-# include <sys/syscall.h>
-
 # include <asm/e2k_syswork.h>
+# include <sys/mman.h>
+# include <sys/syscall.h>
 
 # define VA_SIZE 48
 # define E2K_PSHTP_SIZE 12
@@ -103,6 +103,24 @@
     return NULL;
   }
 
+  GC_INNER ptr_t GC_mmap_procedure_stack_buf(size_t aligned_sz)
+  {
+    void *buf = mmap(NULL, aligned_sz, PROT_READ | PROT_WRITE,
+                     MAP_PRIVATE | MAP_ANON, 0 /* fd */, 0 /* offset */);
+    if (MAP_FAILED == buf)
+      ABORT_ARG2("Could not map memory for procedure stack",
+                 ": requested %lu bytes, errno= %d",
+                 (unsigned long)aligned_sz, errno);
+    return (ptr_t)buf;
+  }
+
+  GC_INNER void GC_unmap_procedure_stack_buf(ptr_t buf, size_t sz)
+  {
+    if (munmap(buf, ROUNDUP_PAGESIZE(sz)) == -1)
+      ABORT_ARG1("munmap failed (for procedure stack space)",
+                 ": errno= %d", errno);
+  }
+
 # ifdef THREADS
     GC_INNER size_t GC_alloc_and_get_procedure_stack(ptr_t *pbuf)
     {