[PATCH] vm_page_prot value

[PATCH] vm_page_prot value

[David Engebretsen]

Following is a patch against 2.4.18-pre3 which fixes a problem where the 
protection on user stack pages are not marked executable even though 
the flags indicate the page is executable.  Some more aggressive cache 
flush optimizations may rely on the execution marking to indicate if a page 
needs to be flushed as it might be present in an icache which is not 
coherent with the dcache.

Pat Mccarthy, Don Reed, Dave Engebretsen


diff -Naur linux.orig/fs/exec.c linuxppc64_2_4/fs/exec.c
--- linux.orig/fs/exec.c	Fri Dec 21 11:41:55 2001
+++ linuxppc64_2_4/fs/exec.c	Thu Jan 10 11:32:48 2002
@@ -313,7 +312,7 @@
 		mpnt->vm_mm = current->mm;
 		mpnt->vm_start = PAGE_MASK & (unsigned long) bprm->p;
 		mpnt->vm_end = STACK_TOP;
-		mpnt->vm_page_prot = PAGE_COPY;
+		mpnt->vm_page_prot = protection_map[VM_STACK_FLAGS & 0xf];
 		mpnt->vm_flags = VM_STACK_FLAGS;
 		mpnt->vm_ops = NULL;
 		mpnt->vm_pgoff = 0;

Re: [PATCH] vm_page_prot value

[David S. Miller]

   From: David Engebretsen <engebret@vnet.ibm.com>
   Date: Thu, 17 Jan 2002 12:47:45 -0600

   Following is a patch against 2.4.18-pre3 which fixes a problem where the 
   protection on user stack pages are not marked executable even though 
   the flags indicate the page is executable.  Some more aggressive cache 
   flush optimizations may rely on the execution marking to indicate if a page 
   needs to be flushed as it might be present in an icache which is not 
   coherent with the dcache.

Actually, PAGE_COPY happens to be executable on many platforms.