[PATCH] exec: Use a define for maximum process stack size in STACK_GROWSUP case.

[Will Newton]

Create a new define for the maximum allowed process stack size for
STACK_GROWSUP architectures. This allows the value to be overridden in
architecture specific code where necessary.

Signed-off-by: Will Newton <will.newton@xxxxxxxxx>
---

The only in-tree architecture this affects is parisc. I don't have a
parisc box here to test with, but I have tested this change on an
out-of-tree Linux port with STACK_GROWSUP set.

 fs/exec.c |    9 ++++++---
 1 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/fs/exec.c b/fs/exec.c
index 632b02e..d37a626 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -573,10 +573,13 @@ int setup_arg_pages(struct linux_binprm *bprm,
 	unsigned long stack_base;

 #ifdef CONFIG_STACK_GROWSUP
-	/* Limit stack size to 1GB */
+	/* Limit stack size to 1GB by default. */
+#ifndef STACK_MAX_SIZE
+#define STACK_MAX_SIZE (1 << 30)
+#endif
 	stack_base = current->signal->rlim[RLIMIT_STACK].rlim_max;
-	if (stack_base > (1 << 30))
-		stack_base = 1 << 30;
+	if (stack_base > STACK_MAX_SIZE)
+		stack_base = STACK_MAX_SIZE;

 	/* Make sure we didn't let the argument array grow too large. */
 	if (vma->vm_end - vma->vm_start > stack_base)
-- 
1.5.5.2

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