From 28c4f97f0908367dc8b44ecd0dcf00b78eba2ff9 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Mon, 17 Sep 2018 16:29:10 +0200 Subject: [PATCH] x86/mm/cpa: Allow range check for static protections commit 91ee8f5c1f50a1f4096c178a93a8da46ce3f6cc8 upstream. 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 Reviewed-by: Dave Hansen Cc: Peter Zijlstra Cc: Bin Yang Cc: Mark Gross Link: https://lkml.kernel.org/r/20180917143545.995734490@linutronix.de Signed-off-by: Shile Zhang Acked-by: Joseph Qi --- 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 fca0e0e396e0..b0e1dd6ce89d 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); -- GitLab