Commit d5974166 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Dave Hansen
Browse files

x86/mm: Inhibit _PAGE_NX changes from cpa_process_alias() 



There is a cludge in change_page_attr_set_clr() that inhibits
propagating NX changes to the aliases (directmap and highmap) -- this
is a cludge twofold:

 - it also inhibits the primary checks in __change_page_attr();
 - it hard depends on single bit changes.

The introduction of set_memory_rox() triggered this last issue for
clearing both _PAGE_RW and _PAGE_NX.

Explicitly ignore _PAGE_NX in cpa_process_alias() instead.

Fixes: b38994948567 ("x86/mm: Implement native set_memory_rox()")
Reported-by: default avatarkernel test robot <oliver.sang@intel.com>
Debugged-by: default avatarDave Hansen <dave.hansen@intel.com>
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20221110125544.594991716%40infradead.org
parent ef9ab81a

arch/x86/mm/pat/set_memory.c

+23 −5
Original line number Diff line number Diff line
@@ -1669,6 +1669,12 @@ static int cpa_process_alias(struct cpa_data *cpa) 
		alias_cpa.flags &= ~(CPA_PAGES_ARRAY | CPA_ARRAY);

		alias_cpa.curpage = 0;



		/* Directmap always has NX set, do not modify. */

		if (__supported_pte_mask & _PAGE_NX) {

			alias_cpa.mask_clr.pgprot &= ~_PAGE_NX;

			alias_cpa.mask_set.pgprot &= ~_PAGE_NX;

		}



		cpa->force_flush_all = 1;



		ret = __change_page_attr_set_clr(&alias_cpa, 0);
@@ -1691,6 +1697,15 @@ static int cpa_process_alias(struct cpa_data *cpa) 
		alias_cpa.flags &= ~(CPA_PAGES_ARRAY | CPA_ARRAY);

		alias_cpa.curpage = 0;



		/*

		 * [_text, _brk_end) also covers data, do not modify NX except

		 * in cases where the highmap is the primary target.

		 */

		if (__supported_pte_mask & _PAGE_NX) {

			alias_cpa.mask_clr.pgprot &= ~_PAGE_NX;

			alias_cpa.mask_set.pgprot &= ~_PAGE_NX;

		}



		cpa->force_flush_all = 1;

		/*

		 * The high mapping range is imprecise, so ignore the
@@ -1709,6 +1724,12 @@ static int __change_page_attr_set_clr(struct cpa_data *cpa, int checkalias) 
	unsigned long rempages = numpages;

	int ret = 0;



	/*

	 * No changes, easy!

	 */

	if (!(pgprot_val(cpa->mask_set) | pgprot_val(cpa->mask_clr)))

		return ret;



	while (rempages) {

		/*

		 * Store the remaining nr of pages for the large page
@@ -1755,7 +1776,7 @@ static int change_page_attr_set_clr(unsigned long *addr, int numpages, 
				    struct page **pages)

{

	struct cpa_data cpa;

	int ret, cache, checkalias;

	int ret, cache;



	memset(&cpa, 0, sizeof(cpa));
@@ -1805,10 +1826,7 @@ static int change_page_attr_set_clr(unsigned long *addr, int numpages, 
	cpa.curpage = 0;

	cpa.force_split = force_split;



	/* No alias checking for _NX bit modifications */

	checkalias = (pgprot_val(mask_set) | pgprot_val(mask_clr)) != _PAGE_NX;



	ret = __change_page_attr_set_clr(&cpa, checkalias);

	ret = __change_page_attr_set_clr(&cpa, 1);



	/*

	 * Check whether we really changed something: