The following commit has been merged into the x86/mm branch of tip:
Commit-ID: 127960a05548ea699a95791669e8112552eb2452
Gitweb: https://git.kernel.org/tip/127960a05548ea699a95791669e8112552eb2452
Author: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
AuthorDate: Thu, 10 Nov 2022 13:33:57 +01:00
Committer: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
CommitterDate: Tue, 15 Nov 2022 22:29:58 +01:00
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@xxxxxxxxx>
Debugged-by: Dave Hansen <dave.hansen@xxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
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:
|