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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: kernel test robot <oliver.sang@intel.com>
Debugged-by: Dave Hansen <dave.hansen@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20221110125544.594991716%40infradead.org
This commit is contained in:
Peter Zijlstra 2022-11-10 13:33:57 +01:00 committed by Dave Hansen
parent ef9ab81af6
commit d597416683
1 changed files with 23 additions and 5 deletions
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28
arch/x86/mm/pat/set_memory.c
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@ -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: