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0005-x86-mm-cpa-Allow-range-check-for-static-protections.patch
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0005-x86-mm-cpa-Allow-range-check-for-static-protections.patch
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From c73b6d859bd510a753598eb4a1541a6f4358fa55 Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <[email protected]>
Date: Mon, 17 Sep 2018 16:29:10 +0200
Subject: [PATCH 05/12] x86/mm/cpa: Allow range check for static protections
Checking static protections only page by page is slow especially for huge
pages. To allow quick checks over a complete range, add the ability to do
that.
Make the checks inclusive so the ranges can be directly used for debug output
later.
No functional change.
Signed-off-by: Thomas Gleixner <[email protected]>
Reviewed-by: Dave Hansen <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Bin Yang <[email protected]>
Cc: Mark Gross <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]
Cc: Zhang Ning <[email protected]>
Signed-off-by: Lili Li <[email protected]>
---
arch/x86/mm/pageattr.c | 69 +++++++++++++++++++++++++++---------------
1 file changed, 44 insertions(+), 25 deletions(-)
diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
index 9731aeeebe71..61ff27848452 100644
--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -286,22 +286,29 @@ static void cpa_flush_array(unsigned long *start, int numpages, int cache,
}
}
+static bool overlaps(unsigned long r1_start, unsigned long r1_end,
+ unsigned long r2_start, unsigned long r2_end)
+{
+ return (r1_start <= r2_end && r1_end >= r2_start) ||
+ (r2_start <= r1_end && r2_end >= r1_start);
+}
+
#ifdef CONFIG_PCI_BIOS
/*
* The BIOS area between 640k and 1Mb needs to be executable for PCI BIOS
* based config access (CONFIG_PCI_GOBIOS) support.
*/
#define BIOS_PFN PFN_DOWN(BIOS_BEGIN)
-#define BIOS_PFN_END PFN_DOWN(BIOS_END)
+#define BIOS_PFN_END PFN_DOWN(BIOS_END - 1)
-static pgprotval_t protect_pci_bios(unsigned long pfn)
+static pgprotval_t protect_pci_bios(unsigned long spfn, unsigned long epfn)
{
- if (pcibios_enabled && within(pfn, BIOS_PFN, BIOS_PFN_END))
+ if (pcibios_enabled && overlaps(spfn, epfn, BIOS_PFN, BIOS_PFN_END))
return _PAGE_NX;
return 0;
}
#else
-static pgprotval_t protect_pci_bios(unsigned long pfn)
+static pgprotval_t protect_pci_bios(unsigned long spfn, unsigned long epfn)
{
return 0;
}
@@ -312,12 +319,17 @@ static pgprotval_t protect_pci_bios(unsigned long pfn)
* aliases. This also includes __ro_after_init, so do not enforce until
* kernel_set_to_readonly is true.
*/
-static pgprotval_t protect_rodata(unsigned long pfn)
+static pgprotval_t protect_rodata(unsigned long spfn, unsigned long epfn)
{
- unsigned long start_pfn = __pa_symbol(__start_rodata) >> PAGE_SHIFT;
- unsigned long end_pfn = __pa_symbol(__end_rodata) >> PAGE_SHIFT;
+ unsigned long epfn_ro, spfn_ro = PFN_DOWN(__pa_symbol(__start_rodata));
+
+ /*
+ * Note: __end_rodata is at page aligned and not inclusive, so
+ * subtract 1 to get the last enforced PFN in the rodata area.
+ */
+ epfn_ro = PFN_DOWN(__pa_symbol(__end_rodata)) - 1;
- if (kernel_set_to_readonly && within(pfn, start_pfn, end_pfn))
+ if (kernel_set_to_readonly && overlaps(spfn, epfn, spfn_ro, epfn_ro))
return _PAGE_RW;
return 0;
}
@@ -330,9 +342,12 @@ static pgprotval_t protect_rodata(unsigned long pfn)
*
* This does not cover __inittext since that is gone after boot.
*/
-static pgprotval_t protect_kernel_text(unsigned long address)
+static pgprotval_t protect_kernel_text(unsigned long start, unsigned long end)
{
- if (within(address, (unsigned long)_text, (unsigned long)_etext))
+ unsigned long t_end = (unsigned long)_etext - 1;
+ unsigned long t_start = (unsigned long)_text;
+
+ if (overlaps(start, end, t_start, t_end))
return _PAGE_NX;
return 0;
}
@@ -347,13 +362,14 @@ static pgprotval_t protect_kernel_text(unsigned long address)
* This will preserve the large page mappings for kernel text/data at no
* extra cost.
*/
-static pgprotval_t protect_kernel_text_ro(unsigned long address)
+static pgprotval_t protect_kernel_text_ro(unsigned long start,
+ unsigned long end)
{
- unsigned long end = (unsigned long)__end_rodata_hpage_align;
- unsigned long start = (unsigned long)_text;
+ unsigned long t_end = (unsigned long)__end_rodata_hpage_align - 1;
+ unsigned long t_start = (unsigned long)_text;
unsigned int level;
- if (!kernel_set_to_readonly || !within(address, start, end))
+ if (!kernel_set_to_readonly || !overlaps(start, end, t_start, t_end))
return 0;
/*
* Don't enforce the !RW mapping for the kernel text mapping, if
@@ -367,12 +383,13 @@ static pgprotval_t protect_kernel_text_ro(unsigned long address)
* so the protections for kernel text and identity mappings have to
* be the same.
*/
- if (lookup_address(address, &level) && (level != PG_LEVEL_4K))
+ if (lookup_address(start, &level) && (level != PG_LEVEL_4K))
return _PAGE_RW;
return 0;
}
#else
-static pgprotval_t protect_kernel_text_ro(unsigned long address)
+static pgprotval_t protect_kernel_text_ro(unsigned long start,
+ unsigned long end)
{
return 0;
}
@@ -384,18 +401,20 @@ static pgprotval_t protect_kernel_text_ro(unsigned long address)
* right (again, ioremap() on BIOS memory is not uncommon) so this function
* checks and fixes these known static required protection bits.
*/
-static inline pgprot_t static_protections(pgprot_t prot, unsigned long address,
- unsigned long pfn)
+static inline pgprot_t static_protections(pgprot_t prot, unsigned long start,
+ unsigned long pfn, unsigned long npg)
{
pgprotval_t forbidden;
+ unsigned long end;
/* Operate on the virtual address */
- forbidden = protect_kernel_text(address);
- forbidden |= protect_kernel_text_ro(address);
+ end = start + npg * PAGE_SIZE - 1;
+ forbidden = protect_kernel_text(start, end);
+ forbidden |= protect_kernel_text_ro(start, end);
/* Check the PFN directly */
- forbidden |= protect_pci_bios(pfn);
- forbidden |= protect_rodata(pfn);
+ forbidden |= protect_pci_bios(pfn, pfn + npg - 1);
+ forbidden |= protect_rodata(pfn, pfn + npg - 1);
return __pgprot(pgprot_val(prot) & ~forbidden);
}
@@ -667,10 +686,10 @@ static int __should_split_large_page(pte_t *kpte, unsigned long address,
* in it results in a different pgprot than the first one of the
* requested range. If yes, then the page needs to be split.
*/
- new_prot = static_protections(req_prot, address, pfn);
+ new_prot = static_protections(req_prot, address, pfn, 1);
pfn = old_pfn;
for (i = 0, addr = lpaddr; i < numpages; i++, addr += PAGE_SIZE, pfn++) {
- pgprot_t chk_prot = static_protections(req_prot, addr, pfn);
+ pgprot_t chk_prot = static_protections(req_prot, addr, pfn, 1);
if (pgprot_val(chk_prot) != pgprot_val(new_prot))
return 1;
@@ -1280,7 +1299,7 @@ static int __change_page_attr(struct cpa_data *cpa, int primary)
pgprot_val(new_prot) &= ~pgprot_val(cpa->mask_clr);
pgprot_val(new_prot) |= pgprot_val(cpa->mask_set);
- new_prot = static_protections(new_prot, address, pfn);
+ new_prot = static_protections(new_prot, address, pfn, 1);
new_prot = pgprot_clear_protnone_bits(new_prot);
--
2.19.1