Messages in this thread Patch in this message | | | Date | Thu, 10 Nov 2022 13:52:56 +0100 | From | Peter Zijlstra <> | Subject | [PATCH 3/4] 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> --- arch/x86/mm/pat/set_memory.c | 28 +++++++++++++++++++++++----- 1 file changed, 23 insertions(+), 5 deletions(-)
--- a/arch/x86/mm/pat/set_memory.c +++ b/arch/x86/mm/pat/set_memory.c @@ -1663,6 +1663,12 @@ static int cpa_process_alias(struct 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); @@ -1685,6 +1691,15 @@ static int cpa_process_alias(struct 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 @@ -1703,6 +1718,12 @@ static int __change_page_attr_set_clr(st 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 @@ -1749,7 +1770,7 @@ static int change_page_attr_set_clr(unsi struct page **pages) { struct cpa_data cpa; - int ret, cache, checkalias; + int ret, cache; memset(&cpa, 0, sizeof(cpa)); @@ -1799,10 +1820,7 @@ static int change_page_attr_set_clr(unsi 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:
| |