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x86/mm/cpa: Allow range check for static protections

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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 <tglx@linutronix.de>
Reviewed-by: Dave Hansen <dave.hansen@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Bin Yang <bin.yang@intel.com>
Cc: Mark Gross <mark.gross@intel.com>
Link: https://lkml.kernel.org/r/20180917143545.995734490@linutronix.de
This commit is contained in:
Thomas Gleixner
2018-09-17 16:29:10 +02:00
parent afd7969a99
commit 91ee8f5c1f
1 changed files with 44 additions and 25 deletions
Download Patch File Download Diff File Expand all files Collapse all files

69
arch/x86/mm/pageattr.c
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@@ -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 #ifdef CONFIG_PCI_BIOS
/* /*
* The BIOS area between 640k and 1Mb needs to be executable for PCI BIOS * The BIOS area between 640k and 1Mb needs to be executable for PCI BIOS
* based config access (CONFIG_PCI_GOBIOS) support. * based config access (CONFIG_PCI_GOBIOS) support.
*/ */
#define BIOS_PFN PFN_DOWN(BIOS_BEGIN) #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 _PAGE_NX;
return 0; return 0;
} }
#else #else
static pgprotval_t protect_pci_bios(unsigned long pfn) static pgprotval_t protect_pci_bios(unsigned long spfn, unsigned long epfn)
{ {
return 0; 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 * aliases. This also includes __ro_after_init, so do not enforce until
* kernel_set_to_readonly is true. * 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 epfn_ro, spfn_ro = PFN_DOWN(__pa_symbol(__start_rodata));
unsigned long end_pfn = __pa_symbol(__end_rodata) >> PAGE_SHIFT;
if (kernel_set_to_readonly && within(pfn, start_pfn, end_pfn)) /*
* 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 && overlaps(spfn, epfn, spfn_ro, epfn_ro))
return _PAGE_RW; return _PAGE_RW;
return 0; 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. * 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 _PAGE_NX;
return 0; 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 * This will preserve the large page mappings for kernel text/data at no
* extra cost. * 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 t_end = (unsigned long)__end_rodata_hpage_align - 1;
unsigned long start = (unsigned long)_text; unsigned long t_start = (unsigned long)_text;
unsigned int level; 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; return 0;
/* /*
* Don't enforce the !RW mapping for the kernel text mapping, if * 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 * so the protections for kernel text and identity mappings have to
* be the same. * 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 _PAGE_RW;
return 0; return 0;
} }
#else #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; 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 * right (again, ioremap() on BIOS memory is not uncommon) so this function
* checks and fixes these known static required protection bits. * checks and fixes these known static required protection bits.
*/ */
static inline pgprot_t static_protections(pgprot_t prot, unsigned long address, static inline pgprot_t static_protections(pgprot_t prot, unsigned long start,
unsigned long pfn) unsigned long pfn, unsigned long npg)
{ {
pgprotval_t forbidden; pgprotval_t forbidden;
unsigned long end;
/* Operate on the virtual address */ /* Operate on the virtual address */
forbidden = protect_kernel_text(address); end = start + npg * PAGE_SIZE - 1;
forbidden |= protect_kernel_text_ro(address); forbidden = protect_kernel_text(start, end);
forbidden |= protect_kernel_text_ro(start, end);
/* Check the PFN directly */ /* Check the PFN directly */
forbidden |= protect_pci_bios(pfn); forbidden |= protect_pci_bios(pfn, pfn + npg - 1);
forbidden |= protect_rodata(pfn); forbidden |= protect_rodata(pfn, pfn + npg - 1);
return __pgprot(pgprot_val(prot) & ~forbidden); 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 * in it results in a different pgprot than the first one of the
* requested range. If yes, then the page needs to be split. * 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; pfn = old_pfn;
for (i = 0, addr = lpaddr; i < numpages; i++, addr += PAGE_SIZE, 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)) if (pgprot_val(chk_prot) != pgprot_val(new_prot))
return 1; return 1;
@@ -1280,7 +1299,7 @@ repeat:
pgprot_val(new_prot) &= ~pgprot_val(cpa->mask_clr); pgprot_val(new_prot) &= ~pgprot_val(cpa->mask_clr);
pgprot_val(new_prot) |= pgprot_val(cpa->mask_set); 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); new_prot = pgprot_clear_protnone_bits(new_prot);