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Subject[tip: x86/mm] x86/mm: Untangle __change_page_attr_set_clr(.checkalias)
The following commit has been merged into the x86/mm branch of tip:

Commit-ID: ef9ab81af6e1f7b7ff589aa1504434aa5915c1df
Gitweb: https://git.kernel.org/tip/ef9ab81af6e1f7b7ff589aa1504434aa5915c1df
Author: Peter Zijlstra <peterz@infradead.org>
AuthorDate: Thu, 10 Nov 2022 13:33:54 +01:00
Committer: Dave Hansen <dave.hansen@linux.intel.com>
CommitterDate: Thu, 15 Dec 2022 10:37:28 -08:00

x86/mm: Untangle __change_page_attr_set_clr(.checkalias)

The .checkalias argument to __change_page_attr_set_clr() is overloaded
and serves two different purposes:

- it inhibits the call to cpa_process_alias() -- as suggested by the
name; however,

- it also serves as 'primary' indicator for __change_page_attr()
( which in turn also serves as a recursion terminator for
cpa_process_alias() ).

Untangle these by extending the use of CPA_NO_CHECK_ALIAS to all
callsites that currently use .checkalias=0 for this purpose.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20221110125544.527267183%40infradead.org
---
arch/x86/mm/pat/set_memory.c | 30 +++++++++++-------------------
1 file changed, 11 insertions(+), 19 deletions(-)

diff --git a/arch/x86/mm/pat/set_memory.c b/arch/x86/mm/pat/set_memory.c
index 50f81ea..4943f6c 100644
--- a/arch/x86/mm/pat/set_memory.c
+++ b/arch/x86/mm/pat/set_memory.c
@@ -1727,7 +1727,7 @@ static int __change_page_attr_set_clr(struct cpa_data *cpa, int checkalias)
if (ret)
goto out;

- if (checkalias) {
+ if (checkalias && !(cpa->flags & CPA_NO_CHECK_ALIAS)) {
ret = cpa_process_alias(cpa);
if (ret)
goto out;
@@ -1801,18 +1801,12 @@ static int change_page_attr_set_clr(unsigned long *addr, int numpages,
cpa.numpages = numpages;
cpa.mask_set = mask_set;
cpa.mask_clr = mask_clr;
- cpa.flags = 0;
+ cpa.flags = in_flag;
cpa.curpage = 0;
cpa.force_split = force_split;

- if (in_flag & (CPA_ARRAY | CPA_PAGES_ARRAY))
- cpa.flags |= in_flag;
-
/* No alias checking for _NX bit modifications */
checkalias = (pgprot_val(mask_set) | pgprot_val(mask_clr)) != _PAGE_NX;
- /* Has caller explicitly disabled alias checking? */
- if (in_flag & CPA_NO_CHECK_ALIAS)
- checkalias = 0;

ret = __change_page_attr_set_clr(&cpa, checkalias);

@@ -2067,11 +2061,9 @@ int set_memory_np(unsigned long addr, int numpages)

int set_memory_np_noalias(unsigned long addr, int numpages)
{
- int cpa_flags = CPA_NO_CHECK_ALIAS;
-
return change_page_attr_set_clr(&addr, numpages, __pgprot(0),
__pgprot(_PAGE_PRESENT), 0,
- cpa_flags, NULL);
+ CPA_NO_CHECK_ALIAS, NULL);
}

int set_memory_4k(unsigned long addr, int numpages)
@@ -2288,7 +2280,7 @@ static int __set_pages_p(struct page *page, int numpages)
.numpages = numpages,
.mask_set = __pgprot(_PAGE_PRESENT | _PAGE_RW),
.mask_clr = __pgprot(0),
- .flags = 0};
+ .flags = CPA_NO_CHECK_ALIAS };

/*
* No alias checking needed for setting present flag. otherwise,
@@ -2296,7 +2288,7 @@ static int __set_pages_p(struct page *page, int numpages)
* mappings (this adds to complexity if we want to do this from
* atomic context especially). Let's keep it simple!
*/
- return __change_page_attr_set_clr(&cpa, 0);
+ return __change_page_attr_set_clr(&cpa, 1);
}

static int __set_pages_np(struct page *page, int numpages)
@@ -2307,7 +2299,7 @@ static int __set_pages_np(struct page *page, int numpages)
.numpages = numpages,
.mask_set = __pgprot(0),
.mask_clr = __pgprot(_PAGE_PRESENT | _PAGE_RW),
- .flags = 0};
+ .flags = CPA_NO_CHECK_ALIAS };

/*
* No alias checking needed for setting not present flag. otherwise,
@@ -2315,7 +2307,7 @@ static int __set_pages_np(struct page *page, int numpages)
* mappings (this adds to complexity if we want to do this from
* atomic context especially). Let's keep it simple!
*/
- return __change_page_attr_set_clr(&cpa, 0);
+ return __change_page_attr_set_clr(&cpa, 1);
}

int set_direct_map_invalid_noflush(struct page *page)
@@ -2386,7 +2378,7 @@ int __init kernel_map_pages_in_pgd(pgd_t *pgd, u64 pfn, unsigned long address,
.numpages = numpages,
.mask_set = __pgprot(0),
.mask_clr = __pgprot(~page_flags & (_PAGE_NX|_PAGE_RW)),
- .flags = 0,
+ .flags = CPA_NO_CHECK_ALIAS,
};

WARN_ONCE(num_online_cpus() > 1, "Don't call after initializing SMP");
@@ -2399,7 +2391,7 @@ int __init kernel_map_pages_in_pgd(pgd_t *pgd, u64 pfn, unsigned long address,

cpa.mask_set = __pgprot(_PAGE_PRESENT | page_flags);

- retval = __change_page_attr_set_clr(&cpa, 0);
+ retval = __change_page_attr_set_clr(&cpa, 1);
__flush_tlb_all();

out:
@@ -2429,12 +2421,12 @@ int __init kernel_unmap_pages_in_pgd(pgd_t *pgd, unsigned long address,
.numpages = numpages,
.mask_set = __pgprot(0),
.mask_clr = __pgprot(_PAGE_PRESENT | _PAGE_RW),
- .flags = 0,
+ .flags = CPA_NO_CHECK_ALIAS,
};

WARN_ONCE(num_online_cpus() > 1, "Don't call after initializing SMP");

- retval = __change_page_attr_set_clr(&cpa, 0);
+ retval = __change_page_attr_set_clr(&cpa, 1);
__flush_tlb_all();

return retval;
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