iv/linux
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

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

Browse Source 
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
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

69
arch/x86/mm/pageattr.c
View File

@ -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));
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 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 @@ repeat:
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);