Messages in this thread Patch in this message |  | | Date | Sat, 17 Dec 2022 18:55:30 -0000 | From | "tip-bot2 for Peter Zijlstra" <> | Subject | [tip: x86/mm] x86/mm: Inhibit _PAGE_NX changes from cpa_process_alias() |
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The following commit has been merged into the x86/mm branch of tip:
Commit-ID: d597416683d587e940faa35945fba162329b5a71 Gitweb: https://git.kernel.org/tip/d597416683d587e940faa35945fba162329b5a71 Author: Peter Zijlstra <peterz@infradead.org> AuthorDate: Thu, 10 Nov 2022 13:33:57 +01:00 Committer: Dave Hansen <dave.hansen@linux.intel.com> CommitterDate: Thu, 15 Dec 2022 10:37:28 -08:00
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 --- arch/x86/mm/pat/set_memory.c | 28 +++++++++++++++++++++++----- 1 file changed, 23 insertions(+), 5 deletions(-)
diff --git a/arch/x86/mm/pat/set_memory.c b/arch/x86/mm/pat/set_memory.c index 4943f6c..beef774 100644 --- a/arch/x86/mm/pat/set_memory.c +++ b/arch/x86/mm/pat/set_memory.c @@ -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:
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