On Tue, 5 Jul 2005 16:35:51 -0500 [email protected] wrote:
| randy_dunlap wrote:
| > On Tue, 5 Jul 2005 15:02:26 -0500 [email protected] wrote:
| >
| >> Andi--
| >>
| >> I made another pass at this. This does roughly the same thing, but
| >> it doesn't create the new "change_page_attr_perm()" functions. With
| >> this patch, the change to init.c (cleanup_nx_in_kerneltext()) is
| >> optional. I changed __change_page_attr() so that, if the page to be
| >> changed is part of a large executable page, it splits the page up
| >> *keeping the executability of the extra 511 pages*, and then marks
| >> the new PTE page as reserved so that it won't be reverted.
| >>
| >> So, basically, without the changes to init.c, the NX bits for data in
| >> the first two big pages won't get fixed until someone calls
| >> change_page_attr() on them. If NX is disabled, these patches have
| >> no functional effect at all.
| >>
| >> How does this look?
| >
| > Look? It has lots of bad line breaks and other style issues.
| >
| > But I'll let Andi comment on the technical issues.
| >
| >> -----
| >>
| >> diff -purN linux-2.6.12grep/arch/i386/mm/init.c
| >> linux-2.6.12/arch/i386/mm/init.c
| >> --- linux-2.6.12grep/arch/i386/mm/init.c 2005-07-01
| >> 15:09:27.000000000 -0500 +++
| >> linux-2.6.12/arch/i386/mm/init.c 2005-07-05 14:32:57.000000000
| -0500
| >> @@ -666,6 +666,28 @@ static int noinline do_test_wp_bit(void)
| >> return flag; }
| >>
| >> +/*
| >> + * In kernel_physical_mapping_init(), any big pages that contained
| >> kernel text area were + * set up as big executable pages. This
| >> function should be called + when the initmem
| >> + * is freed, to correctly set up the executable & non-executable +
| >> pages in this area.
| >> + */
| >> +static void cleanup_nx_in_kerneltext(void) {
| >> + unsigned long from, to;
| >> +
| >> + if (!nx_enabled) return;
| >
| > return; on separate line.
| >
| >> + from = PAGE_OFFSET;
| >> + to = (unsigned long)_text & PAGE_MASK;
| >> + for (; from<to; from += PAGE_SIZE)
| > from < to
| >
| > (i.e., use the spacebar)
| >
| >> + change_page_attr(virt_to_page(from), 1, PAGE_KERNEL); +
| >> + from = ((unsigned long)_etext + PAGE_SIZE - 1) & PAGE_MASK;
| >> + to = ((unsigned long)__init_end + LARGE_PAGE_SIZE) &
| >> LARGE_PAGE_MASK; + for (; from<to; from += PAGE_SIZE)
| >
| > add spaces: from < to
| >
| >> + change_page_attr(virt_to_page(from), 1, PAGE_KERNEL); }
| +
| >> void free_initmem(void)
| >> {
| >> unsigned long addr;
| >
| >
| > ---
| > ~Randy
|
| Thanks for the feedback. I know it looks like crap with the line
| wrapping, but I have no way of sending non-automatically-line-broken
| email right now, which is why I attached the file in addition to the
| inline text. I apologize for that.
My apologies also, I completely missed seeing the attachment.
| I'll correct those cosmetic issues, thanks.
---
~Randy
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