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Commit 91ee8f5c authored by Thomas Gleixner's avatar Thomas Gleixner
Browse files

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: default avatarThomas Gleixner <tglx@linutronix.de>
Reviewed-by: default avatarDave 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
parent afd7969a

arch/x86/mm/pageattr.c

+44 −25
Original line number Diff line number Diff line
@@ -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);