From 9820e1c3376c641299624dd24646aed3167ad5b1 Mon Sep 17 00:00:00 2001 From: Dmitry V. Levin Date: Thu, 5 Apr 2018 07:32:10 +0300 Subject: x86/uapi: Fix asm/bootparam.h userspace compilation errors Consistently use types provided by to fix the following asm/bootparam.h userspace compilation errors: /usr/include/asm/bootparam.h:140:2: error: unknown type name 'u16' u16 version; /usr/include/asm/bootparam.h:141:2: error: unknown type name 'u16' u16 compatible_version; /usr/include/asm/bootparam.h:142:2: error: unknown type name 'u16' u16 pm_timer_address; /usr/include/asm/bootparam.h:143:2: error: unknown type name 'u16' u16 num_cpus; /usr/include/asm/bootparam.h:144:2: error: unknown type name 'u64' u64 pci_mmconfig_base; /usr/include/asm/bootparam.h:145:2: error: unknown type name 'u32' u32 tsc_khz; /usr/include/asm/bootparam.h:146:2: error: unknown type name 'u32' u32 apic_khz; /usr/include/asm/bootparam.h:147:2: error: unknown type name 'u8' u8 standard_ioapic; /usr/include/asm/bootparam.h:148:2: error: unknown type name 'u8' u8 cpu_ids[255]; Signed-off-by: Dmitry V. Levin Acked-by: Jan Kiszka Cc: # v4.16 Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Fixes: 4a362601baa6 ("x86/jailhouse: Add infrastructure for running in non-root cell") Link: http://lkml.kernel.org/r/20180405043210.GA13254@altlinux.org Signed-off-by: Ingo Molnar --- arch/x86/include/uapi/asm/bootparam.h | 18 +++++++++--------- 1 file changed, 9 insertions(+), 9 deletions(-) (limited to 'arch/x86') diff --git a/arch/x86/include/uapi/asm/bootparam.h b/arch/x86/include/uapi/asm/bootparam.h index aebf60357758..a06cbf019744 100644 --- a/arch/x86/include/uapi/asm/bootparam.h +++ b/arch/x86/include/uapi/asm/bootparam.h @@ -137,15 +137,15 @@ struct boot_e820_entry { * setup data structure. */ struct jailhouse_setup_data { - u16 version; - u16 compatible_version; - u16 pm_timer_address; - u16 num_cpus; - u64 pci_mmconfig_base; - u32 tsc_khz; - u32 apic_khz; - u8 standard_ioapic; - u8 cpu_ids[255]; + __u16 version; + __u16 compatible_version; + __u16 pm_timer_address; + __u16 num_cpus; + __u64 pci_mmconfig_base; + __u32 tsc_khz; + __u32 apic_khz; + __u8 standard_ioapic; + __u8 cpu_ids[255]; } __attribute__((packed)); /* The so-called "zeropage" */ -- cgit v1.2.3 From 071ccc966ba5db1ac8f5c24b0faebb37698f68db Mon Sep 17 00:00:00 2001 From: Andy Lutomirski Date: Tue, 3 Apr 2018 15:39:26 -0700 Subject: x86/entry/64: Drop idtentry's manual stack switch for user entries For non-paranoid entries, idtentry knows how to switch from the kernel stack to the user stack, as does error_entry. This results in pointless duplication and code bloat. Make idtentry stop thinking about stacks for non-paranoid entries. This reduces text size by 5377 bytes. This goes back to the following commit: 7f2590a110b8 ("x86/entry/64: Use a per-CPU trampoline stack for IDT entries") Signed-off-by: Andy Lutomirski Cc: Borislav Petkov Cc: Dominik Brodowski Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/90aab80c1f906e70742eaa4512e3c9b5e62d59d4.1522794757.git.luto@kernel.org Signed-off-by: Ingo Molnar --- arch/x86/entry/entry_64.S | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'arch/x86') diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S index 9b114675fbc0..e237913a056b 100644 --- a/arch/x86/entry/entry_64.S +++ b/arch/x86/entry/entry_64.S @@ -908,7 +908,7 @@ ENTRY(\sym) pushq $-1 /* ORIG_RAX: no syscall to restart */ .endif - .if \paranoid < 2 + .if \paranoid == 1 testb $3, CS-ORIG_RAX(%rsp) /* If coming from userspace, switch stacks */ jnz .Lfrom_usermode_switch_stack_\@ .endif @@ -955,7 +955,7 @@ ENTRY(\sym) jmp error_exit .endif - .if \paranoid < 2 + .if \paranoid == 1 /* * Entry from userspace. Switch stacks and treat it * as a normal entry. This means that paranoid handlers -- cgit v1.2.3 From d1440b23c922d845ff039f64694a32ff356e89fa Mon Sep 17 00:00:00 2001 From: Dave Hansen Date: Fri, 6 Apr 2018 13:55:02 -0700 Subject: x86/mm: Factor out pageattr _PAGE_GLOBAL setting The pageattr code has a pattern repeated where it sets _PAGE_GLOBAL for present PTEs but clears it for non-present PTEs. The intention is to keep _PAGE_GLOBAL from getting confused with _PAGE_PROTNONE since _PAGE_GLOBAL is for present PTEs and _PAGE_PROTNONE is for non-present But, this pattern makes no sense. Effectively, it says, if you use the pageattr code, always set _PAGE_GLOBAL when _PAGE_PRESENT. canon_pgprot() will clear it if unsupported (because it masks the value with __supported_pte_mask) but we *always* set it. Even if canon_pgprot() did not filter _PAGE_GLOBAL, it would be OK. _PAGE_GLOBAL is ignored when CR4.PGE=0 by the hardware. This unconditional setting of _PAGE_GLOBAL is a problem when we have PTI and non-PTI and we want some areas to have _PAGE_GLOBAL and some not. This updated version of the code says: 1. Clear _PAGE_GLOBAL when !_PAGE_PRESENT 2. Never set _PAGE_GLOBAL implicitly 3. Allow _PAGE_GLOBAL to be in cpa.set_mask 4. Allow _PAGE_GLOBAL to be inherited from previous PTE Signed-off-by: Dave Hansen Cc: Andrea Arcangeli Cc: Andy Lutomirski Cc: Arjan van de Ven Cc: Borislav Petkov Cc: Dan Williams Cc: David Woodhouse Cc: Greg Kroah-Hartman Cc: Hugh Dickins Cc: Josh Poimboeuf Cc: Juergen Gross Cc: Kees Cook Cc: Linus Torvalds Cc: Nadav Amit Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: linux-mm@kvack.org Link: http://lkml.kernel.org/r/20180406205502.86E199DA@viggo.jf.intel.com Signed-off-by: Ingo Molnar --- arch/x86/mm/pageattr.c | 66 ++++++++++++++++++-------------------------------- 1 file changed, 23 insertions(+), 43 deletions(-) (limited to 'arch/x86') diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c index 85cf12219dea..4d369d5c04c5 100644 --- a/arch/x86/mm/pageattr.c +++ b/arch/x86/mm/pageattr.c @@ -512,6 +512,23 @@ static void __set_pmd_pte(pte_t *kpte, unsigned long address, pte_t pte) #endif } +static pgprot_t pgprot_clear_protnone_bits(pgprot_t prot) +{ + /* + * _PAGE_GLOBAL means "global page" for present PTEs. + * But, it is also used to indicate _PAGE_PROTNONE + * for non-present PTEs. + * + * This ensures that a _PAGE_GLOBAL PTE going from + * present to non-present is not confused as + * _PAGE_PROTNONE. + */ + if (!(pgprot_val(prot) & _PAGE_PRESENT)) + pgprot_val(prot) &= ~_PAGE_GLOBAL; + + return prot; +} + static int try_preserve_large_page(pte_t *kpte, unsigned long address, struct cpa_data *cpa) @@ -577,18 +594,11 @@ try_preserve_large_page(pte_t *kpte, unsigned long address, * different bit positions in the two formats. */ req_prot = pgprot_4k_2_large(req_prot); - - /* - * Set the PSE and GLOBAL flags only if the PRESENT flag is - * set otherwise pmd_present/pmd_huge will return true even on - * a non present pmd. The canon_pgprot will clear _PAGE_GLOBAL - * for the ancient hardware that doesn't support it. - */ + req_prot = pgprot_clear_protnone_bits(req_prot); if (pgprot_val(req_prot) & _PAGE_PRESENT) - pgprot_val(req_prot) |= _PAGE_PSE | _PAGE_GLOBAL; + pgprot_val(req_prot) |= _PAGE_PSE; else - pgprot_val(req_prot) &= ~(_PAGE_PSE | _PAGE_GLOBAL); - + pgprot_val(req_prot) &= ~_PAGE_PSE; req_prot = canon_pgprot(req_prot); /* @@ -698,16 +708,7 @@ __split_large_page(struct cpa_data *cpa, pte_t *kpte, unsigned long address, return 1; } - /* - * Set the GLOBAL flags only if the PRESENT flag is set - * otherwise pmd/pte_present will return true even on a non - * present pmd/pte. The canon_pgprot will clear _PAGE_GLOBAL - * for the ancient hardware that doesn't support it. - */ - if (pgprot_val(ref_prot) & _PAGE_PRESENT) - pgprot_val(ref_prot) |= _PAGE_GLOBAL; - else - pgprot_val(ref_prot) &= ~_PAGE_GLOBAL; + ref_prot = pgprot_clear_protnone_bits(ref_prot); /* * Get the target pfn from the original entry: @@ -930,18 +931,7 @@ static void populate_pte(struct cpa_data *cpa, pte = pte_offset_kernel(pmd, start); - /* - * Set the GLOBAL flags only if the PRESENT flag is - * set otherwise pte_present will return true even on - * a non present pte. The canon_pgprot will clear - * _PAGE_GLOBAL for the ancient hardware that doesn't - * support it. - */ - if (pgprot_val(pgprot) & _PAGE_PRESENT) - pgprot_val(pgprot) |= _PAGE_GLOBAL; - else - pgprot_val(pgprot) &= ~_PAGE_GLOBAL; - + pgprot = pgprot_clear_protnone_bits(pgprot); pgprot = canon_pgprot(pgprot); while (num_pages-- && start < end) { @@ -1234,17 +1224,7 @@ repeat: new_prot = static_protections(new_prot, address, pfn); - /* - * Set the GLOBAL flags only if the PRESENT flag is - * set otherwise pte_present will return true even on - * a non present pte. The canon_pgprot will clear - * _PAGE_GLOBAL for the ancient hardware that doesn't - * support it. - */ - if (pgprot_val(new_prot) & _PAGE_PRESENT) - pgprot_val(new_prot) |= _PAGE_GLOBAL; - else - pgprot_val(new_prot) &= ~_PAGE_GLOBAL; + new_prot = pgprot_clear_protnone_bits(new_prot); /* * We need to keep the pfn from the existing PTE, -- cgit v1.2.3 From 606c7193d5fbf8ea3dafc8a9468f719fbf1d7160 Mon Sep 17 00:00:00 2001 From: Dave Hansen Date: Fri, 6 Apr 2018 13:55:04 -0700 Subject: x86/mm: Undo double _PAGE_PSE clearing When clearing _PAGE_PRESENT on a huge page, we need to be careful to also clear _PAGE_PSE, otherwise it might still get confused for a valid large page table entry. We do that near the spot where we *set* _PAGE_PSE. That's fine, but it's unnecessary. pgprot_large_2_4k() already did it. BTW, I also noticed that pgprot_large_2_4k() and pgprot_4k_2_large() are not symmetric. pgprot_large_2_4k() clears _PAGE_PSE (because it is aliased to _PAGE_PAT) but pgprot_4k_2_large() does not put _PAGE_PSE back. Bummer. Also, add some comments and change "promote" to "move". "Promote" seems an odd word to move when we are logically moving a bit to a lower bit position. Also add an extra line return to make it clear to which line the comment applies. Signed-off-by: Dave Hansen Cc: Andrea Arcangeli Cc: Andy Lutomirski Cc: Arjan van de Ven Cc: Borislav Petkov Cc: Dan Williams Cc: David Woodhouse Cc: Greg Kroah-Hartman Cc: Hugh Dickins Cc: Josh Poimboeuf Cc: Juergen Gross Cc: Kees Cook Cc: Linus Torvalds Cc: Nadav Amit Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: linux-mm@kvack.org Link: http://lkml.kernel.org/r/20180406205504.9B0F44A9@viggo.jf.intel.com Signed-off-by: Ingo Molnar --- arch/x86/mm/pageattr.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) (limited to 'arch/x86') diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c index 4d369d5c04c5..d3442dfdfced 100644 --- a/arch/x86/mm/pageattr.c +++ b/arch/x86/mm/pageattr.c @@ -583,6 +583,7 @@ try_preserve_large_page(pte_t *kpte, unsigned long address, * up accordingly. */ old_pte = *kpte; + /* Clear PSE (aka _PAGE_PAT) and move PAT bit to correct position */ req_prot = pgprot_large_2_4k(old_prot); pgprot_val(req_prot) &= ~pgprot_val(cpa->mask_clr); @@ -597,8 +598,6 @@ try_preserve_large_page(pte_t *kpte, unsigned long address, req_prot = pgprot_clear_protnone_bits(req_prot); if (pgprot_val(req_prot) & _PAGE_PRESENT) pgprot_val(req_prot) |= _PAGE_PSE; - else - pgprot_val(req_prot) &= ~_PAGE_PSE; req_prot = canon_pgprot(req_prot); /* @@ -684,8 +683,12 @@ __split_large_page(struct cpa_data *cpa, pte_t *kpte, unsigned long address, switch (level) { case PG_LEVEL_2M: ref_prot = pmd_pgprot(*(pmd_t *)kpte); - /* clear PSE and promote PAT bit to correct position */ + /* + * Clear PSE (aka _PAGE_PAT) and move + * PAT bit to correct position. + */ ref_prot = pgprot_large_2_4k(ref_prot); + ref_pfn = pmd_pfn(*(pmd_t *)kpte); break; -- cgit v1.2.3 From 8a57f4849f4fa22ed18a941164a214083fc020a2 Mon Sep 17 00:00:00 2001 From: Dave Hansen Date: Fri, 6 Apr 2018 13:55:06 -0700 Subject: x86/mm: Introduce "default" kernel PTE mask The __PAGE_KERNEL_* page permissions are "raw". They contain bits that may or may not be supported on the current processor. They need to be filtered by a mask (currently __supported_pte_mask) to turn them into a value that we can actually set in a PTE. These __PAGE_KERNEL_* values all contain _PAGE_GLOBAL. But, with PTI, we want to be able to support _PAGE_GLOBAL (have the bit set in __supported_pte_mask) but not have it appear in any of these masks by default. This patch creates a new mask, __default_kernel_pte_mask, and applies it when creating all of the PAGE_KERNEL_* masks. This makes PAGE_KERNEL_* safe to use anywhere (they only contain supported bits). It also ensures that PAGE_KERNEL_* contains _PAGE_GLOBAL on PTI=n kernels but clears _PAGE_GLOBAL when PTI=y. We also make __default_kernel_pte_mask a non-GPL exported symbol because there are plenty of driver-available interfaces that take PAGE_KERNEL_* permissions. Signed-off-by: Dave Hansen Cc: Andrea Arcangeli Cc: Andy Lutomirski Cc: Arjan van de Ven Cc: Borislav Petkov Cc: Dan Williams Cc: David Woodhouse Cc: Greg Kroah-Hartman Cc: Hugh Dickins Cc: Josh Poimboeuf Cc: Juergen Gross Cc: Kees Cook Cc: Linus Torvalds Cc: Nadav Amit Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: linux-mm@kvack.org Link: http://lkml.kernel.org/r/20180406205506.030DB6B6@viggo.jf.intel.com Signed-off-by: Ingo Molnar --- arch/x86/include/asm/pgtable_types.h | 29 ++++++++++++++++------------- arch/x86/mm/init.c | 6 ++++++ arch/x86/mm/init_32.c | 8 +++++++- arch/x86/mm/init_64.c | 5 +++++ 4 files changed, 34 insertions(+), 14 deletions(-) (limited to 'arch/x86') diff --git a/arch/x86/include/asm/pgtable_types.h b/arch/x86/include/asm/pgtable_types.h index acfe755562a6..1e5a40673953 100644 --- a/arch/x86/include/asm/pgtable_types.h +++ b/arch/x86/include/asm/pgtable_types.h @@ -196,19 +196,21 @@ enum page_cache_mode { #define __PAGE_KERNEL_NOENC (__PAGE_KERNEL) #define __PAGE_KERNEL_NOENC_WP (__PAGE_KERNEL_WP) -#define PAGE_KERNEL __pgprot(__PAGE_KERNEL | _PAGE_ENC) -#define PAGE_KERNEL_NOENC __pgprot(__PAGE_KERNEL) -#define PAGE_KERNEL_RO __pgprot(__PAGE_KERNEL_RO | _PAGE_ENC) -#define PAGE_KERNEL_EXEC __pgprot(__PAGE_KERNEL_EXEC | _PAGE_ENC) -#define PAGE_KERNEL_EXEC_NOENC __pgprot(__PAGE_KERNEL_EXEC) -#define PAGE_KERNEL_RX __pgprot(__PAGE_KERNEL_RX | _PAGE_ENC) -#define PAGE_KERNEL_NOCACHE __pgprot(__PAGE_KERNEL_NOCACHE | _PAGE_ENC) -#define PAGE_KERNEL_LARGE __pgprot(__PAGE_KERNEL_LARGE | _PAGE_ENC) -#define PAGE_KERNEL_LARGE_EXEC __pgprot(__PAGE_KERNEL_LARGE_EXEC | _PAGE_ENC) -#define PAGE_KERNEL_VVAR __pgprot(__PAGE_KERNEL_VVAR | _PAGE_ENC) - -#define PAGE_KERNEL_IO __pgprot(__PAGE_KERNEL_IO) -#define PAGE_KERNEL_IO_NOCACHE __pgprot(__PAGE_KERNEL_IO_NOCACHE) +#define default_pgprot(x) __pgprot((x) & __default_kernel_pte_mask) + +#define PAGE_KERNEL default_pgprot(__PAGE_KERNEL | _PAGE_ENC) +#define PAGE_KERNEL_NOENC default_pgprot(__PAGE_KERNEL) +#define PAGE_KERNEL_RO default_pgprot(__PAGE_KERNEL_RO | _PAGE_ENC) +#define PAGE_KERNEL_EXEC default_pgprot(__PAGE_KERNEL_EXEC | _PAGE_ENC) +#define PAGE_KERNEL_EXEC_NOENC default_pgprot(__PAGE_KERNEL_EXEC) +#define PAGE_KERNEL_RX default_pgprot(__PAGE_KERNEL_RX | _PAGE_ENC) +#define PAGE_KERNEL_NOCACHE default_pgprot(__PAGE_KERNEL_NOCACHE | _PAGE_ENC) +#define PAGE_KERNEL_LARGE default_pgprot(__PAGE_KERNEL_LARGE | _PAGE_ENC) +#define PAGE_KERNEL_LARGE_EXEC default_pgprot(__PAGE_KERNEL_LARGE_EXEC | _PAGE_ENC) +#define PAGE_KERNEL_VVAR default_pgprot(__PAGE_KERNEL_VVAR | _PAGE_ENC) + +#define PAGE_KERNEL_IO default_pgprot(__PAGE_KERNEL_IO) +#define PAGE_KERNEL_IO_NOCACHE default_pgprot(__PAGE_KERNEL_IO_NOCACHE) #endif /* __ASSEMBLY__ */ @@ -483,6 +485,7 @@ static inline pgprot_t pgprot_large_2_4k(pgprot_t pgprot) typedef struct page *pgtable_t; extern pteval_t __supported_pte_mask; +extern pteval_t __default_kernel_pte_mask; extern void set_nx(void); extern int nx_enabled; diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c index 82f5252c723a..583a88c8a6ee 100644 --- a/arch/x86/mm/init.c +++ b/arch/x86/mm/init.c @@ -190,6 +190,12 @@ static void __init probe_page_size_mask(void) enable_global_pages(); } + /* By the default is everything supported: */ + __default_kernel_pte_mask = __supported_pte_mask; + /* Except when with PTI where the kernel is mostly non-Global: */ + if (cpu_feature_enabled(X86_FEATURE_PTI)) + __default_kernel_pte_mask &= ~_PAGE_GLOBAL; + /* Enable 1 GB linear kernel mappings if available: */ if (direct_gbpages && boot_cpu_has(X86_FEATURE_GBPAGES)) { printk(KERN_INFO "Using GB pages for direct mapping\n"); diff --git a/arch/x86/mm/init_32.c b/arch/x86/mm/init_32.c index 396e1f0151ac..07cdc2ed4965 100644 --- a/arch/x86/mm/init_32.c +++ b/arch/x86/mm/init_32.c @@ -558,8 +558,14 @@ static void __init pagetable_init(void) permanent_kmaps_init(pgd_base); } -pteval_t __supported_pte_mask __read_mostly = ~(_PAGE_NX | _PAGE_GLOBAL); +#define DEFAULT_PTE_MASK ~(_PAGE_NX | _PAGE_GLOBAL) +/* Bits supported by the hardware: */ +pteval_t __supported_pte_mask __read_mostly = DEFAULT_PTE_MASK; +/* Bits allowed in normal kernel mappings: */ +pteval_t __default_kernel_pte_mask __read_mostly = DEFAULT_PTE_MASK; EXPORT_SYMBOL_GPL(__supported_pte_mask); +/* Used in PAGE_KERNEL_* macros which are reasonably used out-of-tree: */ +EXPORT_SYMBOL(__default_kernel_pte_mask); /* user-defined highmem size */ static unsigned int highmem_pages = -1; diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c index 45241de66785..e6c52dbbf649 100644 --- a/arch/x86/mm/init_64.c +++ b/arch/x86/mm/init_64.c @@ -65,8 +65,13 @@ * around without checking the pgd every time. */ +/* Bits supported by the hardware: */ pteval_t __supported_pte_mask __read_mostly = ~0; +/* Bits allowed in normal kernel mappings: */ +pteval_t __default_kernel_pte_mask __read_mostly = ~0; EXPORT_SYMBOL_GPL(__supported_pte_mask); +/* Used in PAGE_KERNEL_* macros which are reasonably used out-of-tree: */ +EXPORT_SYMBOL(__default_kernel_pte_mask); int force_personality32; -- cgit v1.2.3 From 6baf4bec02dbc41645c3a5130ee15a8e1d62b80f Mon Sep 17 00:00:00 2001 From: Dave Hansen Date: Fri, 6 Apr 2018 13:55:07 -0700 Subject: x86/espfix: Document use of _PAGE_GLOBAL The "normal" kernel page table creation mechanisms using PAGE_KERNEL_* page protections will never set _PAGE_GLOBAL with PTI. The few places in the kernel that always want _PAGE_GLOBAL must avoid using PAGE_KERNEL_*. Document that we want it here and its use is not accidental. Signed-off-by: Dave Hansen Cc: Andrea Arcangeli Cc: Andy Lutomirski Cc: Arjan van de Ven Cc: Borislav Petkov Cc: Dan Williams Cc: David Woodhouse Cc: Greg Kroah-Hartman Cc: Hugh Dickins Cc: Josh Poimboeuf Cc: Juergen Gross Cc: Kees Cook Cc: Linus Torvalds Cc: Nadav Amit Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: linux-mm@kvack.org Link: http://lkml.kernel.org/r/20180406205507.BCF4D4F0@viggo.jf.intel.com Signed-off-by: Ingo Molnar --- arch/x86/kernel/espfix_64.c | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'arch/x86') diff --git a/arch/x86/kernel/espfix_64.c b/arch/x86/kernel/espfix_64.c index e5ec3cafa72e..aebd0d5bc086 100644 --- a/arch/x86/kernel/espfix_64.c +++ b/arch/x86/kernel/espfix_64.c @@ -195,6 +195,10 @@ void init_espfix_ap(int cpu) pte_p = pte_offset_kernel(&pmd, addr); stack_page = page_address(alloc_pages_node(node, GFP_KERNEL, 0)); + /* + * __PAGE_KERNEL_* includes _PAGE_GLOBAL, which we want since + * this is mapped to userspace. + */ pte = __pte(__pa(stack_page) | ((__PAGE_KERNEL_RO | _PAGE_ENC) & ptemask)); for (n = 0; n < ESPFIX_PTE_CLONES; n++) set_pte(&pte_p[n*PTE_STRIDE], pte); -- cgit v1.2.3 From fb43d6cb91ef57d9e58d5f69b423784ff4a4c374 Mon Sep 17 00:00:00 2001 From: Dave Hansen Date: Fri, 6 Apr 2018 13:55:09 -0700 Subject: x86/mm: Do not auto-massage page protections A PTE is constructed from a physical address and a pgprotval_t. __PAGE_KERNEL, for instance, is a pgprot_t and must be converted into a pgprotval_t before it can be used to create a PTE. This is done implicitly within functions like pfn_pte() by massage_pgprot(). However, this makes it very challenging to set bits (and keep them set) if your bit is being filtered out by massage_pgprot(). This moves the bit filtering out of pfn_pte() and friends. For users of PAGE_KERNEL*, filtering will be done automatically inside those macros but for users of __PAGE_KERNEL*, they need to do their own filtering now. Note that we also just move pfn_pte/pmd/pud() over to check_pgprot() instead of massage_pgprot(). This way, we still *look* for unsupported bits and properly warn about them if we find them. This might happen if an unfiltered __PAGE_KERNEL* value was passed in, for instance. - printk format warning fix from: Arnd Bergmann - boot crash fix from: Tom Lendacky - crash bisected by: Mike Galbraith Signed-off-by: Dave Hansen Reported-and-fixed-by: Arnd Bergmann Fixed-by: Tom Lendacky Bisected-by: Mike Galbraith Cc: Andrea Arcangeli Cc: Andy Lutomirski Cc: Arjan van de Ven Cc: Borislav Petkov Cc: Dan Williams Cc: David Woodhouse Cc: Greg Kroah-Hartman Cc: Hugh Dickins Cc: Josh Poimboeuf Cc: Juergen Gross Cc: Kees Cook Cc: Linus Torvalds Cc: Nadav Amit Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: linux-mm@kvack.org Link: http://lkml.kernel.org/r/20180406205509.77E1D7F6@viggo.jf.intel.com Signed-off-by: Ingo Molnar --- arch/x86/boot/compressed/kaslr.c | 3 +++ arch/x86/include/asm/pgtable.h | 27 ++++++++++++++++++++++----- arch/x86/kernel/head64.c | 2 ++ arch/x86/kernel/ldt.c | 6 +++++- arch/x86/mm/ident_map.c | 3 +++ arch/x86/mm/iomap_32.c | 6 ++++++ arch/x86/mm/ioremap.c | 3 +++ arch/x86/mm/kasan_init_64.c | 14 +++++++++++++- arch/x86/mm/pgtable.c | 3 +++ arch/x86/power/hibernate_64.c | 20 +++++++++++++++----- 10 files changed, 75 insertions(+), 12 deletions(-) (limited to 'arch/x86') diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c index 66e42a098d70..a0a50b91ecef 100644 --- a/arch/x86/boot/compressed/kaslr.c +++ b/arch/x86/boot/compressed/kaslr.c @@ -54,6 +54,9 @@ unsigned int ptrs_per_p4d __ro_after_init = 1; extern unsigned long get_cmd_line_ptr(void); +/* Used by PAGE_KERN* macros: */ +pteval_t __default_kernel_pte_mask __read_mostly = ~0; + /* Simplified build-specific string for starting entropy. */ static const char build_str[] = UTS_RELEASE " (" LINUX_COMPILE_BY "@" LINUX_COMPILE_HOST ") (" LINUX_COMPILER ") " UTS_VERSION; diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h index 89d5c8886c85..5f49b4ff0c24 100644 --- a/arch/x86/include/asm/pgtable.h +++ b/arch/x86/include/asm/pgtable.h @@ -526,22 +526,39 @@ static inline pgprotval_t massage_pgprot(pgprot_t pgprot) return protval; } +static inline pgprotval_t check_pgprot(pgprot_t pgprot) +{ + pgprotval_t massaged_val = massage_pgprot(pgprot); + + /* mmdebug.h can not be included here because of dependencies */ +#ifdef CONFIG_DEBUG_VM + WARN_ONCE(pgprot_val(pgprot) != massaged_val, + "attempted to set unsupported pgprot: %016llx " + "bits: %016llx supported: %016llx\n", + (u64)pgprot_val(pgprot), + (u64)pgprot_val(pgprot) ^ massaged_val, + (u64)__supported_pte_mask); +#endif + + return massaged_val; +} + static inline pte_t pfn_pte(unsigned long page_nr, pgprot_t pgprot) { return __pte(((phys_addr_t)page_nr << PAGE_SHIFT) | - massage_pgprot(pgprot)); + check_pgprot(pgprot)); } static inline pmd_t pfn_pmd(unsigned long page_nr, pgprot_t pgprot) { return __pmd(((phys_addr_t)page_nr << PAGE_SHIFT) | - massage_pgprot(pgprot)); + check_pgprot(pgprot)); } static inline pud_t pfn_pud(unsigned long page_nr, pgprot_t pgprot) { return __pud(((phys_addr_t)page_nr << PAGE_SHIFT) | - massage_pgprot(pgprot)); + check_pgprot(pgprot)); } static inline pte_t pte_modify(pte_t pte, pgprot_t newprot) @@ -553,7 +570,7 @@ static inline pte_t pte_modify(pte_t pte, pgprot_t newprot) * the newprot (if present): */ val &= _PAGE_CHG_MASK; - val |= massage_pgprot(newprot) & ~_PAGE_CHG_MASK; + val |= check_pgprot(newprot) & ~_PAGE_CHG_MASK; return __pte(val); } @@ -563,7 +580,7 @@ static inline pmd_t pmd_modify(pmd_t pmd, pgprot_t newprot) pmdval_t val = pmd_val(pmd); val &= _HPAGE_CHG_MASK; - val |= massage_pgprot(newprot) & ~_HPAGE_CHG_MASK; + val |= check_pgprot(newprot) & ~_HPAGE_CHG_MASK; return __pmd(val); } diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c index 0c855deee165..0c408f8c4ed4 100644 --- a/arch/x86/kernel/head64.c +++ b/arch/x86/kernel/head64.c @@ -195,6 +195,8 @@ unsigned long __head __startup_64(unsigned long physaddr, pud[i + 1] = (pudval_t)pmd + pgtable_flags; pmd_entry = __PAGE_KERNEL_LARGE_EXEC & ~_PAGE_GLOBAL; + /* Filter out unsupported __PAGE_KERNEL_* bits: */ + pmd_entry &= __supported_pte_mask; pmd_entry += sme_get_me_mask(); pmd_entry += physaddr; diff --git a/arch/x86/kernel/ldt.c b/arch/x86/kernel/ldt.c index 26d713ecad34..d41d896481b8 100644 --- a/arch/x86/kernel/ldt.c +++ b/arch/x86/kernel/ldt.c @@ -145,6 +145,7 @@ map_ldt_struct(struct mm_struct *mm, struct ldt_struct *ldt, int slot) unsigned long offset = i << PAGE_SHIFT; const void *src = (char *)ldt->entries + offset; unsigned long pfn; + pgprot_t pte_prot; pte_t pte, *ptep; va = (unsigned long)ldt_slot_va(slot) + offset; @@ -163,7 +164,10 @@ map_ldt_struct(struct mm_struct *mm, struct ldt_struct *ldt, int slot) * target via some kernel interface which misses a * permission check. */ - pte = pfn_pte(pfn, __pgprot(__PAGE_KERNEL_RO & ~_PAGE_GLOBAL)); + pte_prot = __pgprot(__PAGE_KERNEL_RO & ~_PAGE_GLOBAL); + /* Filter out unsuppored __PAGE_KERNEL* bits: */ + pgprot_val(pte_prot) |= __supported_pte_mask; + pte = pfn_pte(pfn, pte_prot); set_pte_at(mm, va, ptep, pte); pte_unmap_unlock(ptep, ptl); } diff --git a/arch/x86/mm/ident_map.c b/arch/x86/mm/ident_map.c index 9aa22be8331e..a2f0c7e20fb0 100644 --- a/arch/x86/mm/ident_map.c +++ b/arch/x86/mm/ident_map.c @@ -98,6 +98,9 @@ int kernel_ident_mapping_init(struct x86_mapping_info *info, pgd_t *pgd_page, if (!info->kernpg_flag) info->kernpg_flag = _KERNPG_TABLE; + /* Filter out unsupported __PAGE_KERNEL_* bits: */ + info->kernpg_flag &= __default_kernel_pte_mask; + for (; addr < end; addr = next) { pgd_t *pgd = pgd_page + pgd_index(addr); p4d_t *p4d; diff --git a/arch/x86/mm/iomap_32.c b/arch/x86/mm/iomap_32.c index ada98b39b8ad..b3294d36769d 100644 --- a/arch/x86/mm/iomap_32.c +++ b/arch/x86/mm/iomap_32.c @@ -44,6 +44,9 @@ int iomap_create_wc(resource_size_t base, unsigned long size, pgprot_t *prot) return ret; *prot = __pgprot(__PAGE_KERNEL | cachemode2protval(pcm)); + /* Filter out unsupported __PAGE_KERNEL* bits: */ + pgprot_val(*prot) &= __default_kernel_pte_mask; + return 0; } EXPORT_SYMBOL_GPL(iomap_create_wc); @@ -88,6 +91,9 @@ iomap_atomic_prot_pfn(unsigned long pfn, pgprot_t prot) prot = __pgprot(__PAGE_KERNEL | cachemode2protval(_PAGE_CACHE_MODE_UC_MINUS)); + /* Filter out unsupported __PAGE_KERNEL* bits: */ + pgprot_val(prot) &= __default_kernel_pte_mask; + return (void __force __iomem *) kmap_atomic_prot_pfn(pfn, prot); } EXPORT_SYMBOL_GPL(iomap_atomic_prot_pfn); diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c index e2db83bebc3b..c63a545ec199 100644 --- a/arch/x86/mm/ioremap.c +++ b/arch/x86/mm/ioremap.c @@ -816,6 +816,9 @@ void __init __early_set_fixmap(enum fixed_addresses idx, } pte = early_ioremap_pte(addr); + /* Sanitize 'prot' against any unsupported bits: */ + pgprot_val(flags) &= __default_kernel_pte_mask; + if (pgprot_val(flags)) set_pte(pte, pfn_pte(phys >> PAGE_SHIFT, flags)); else diff --git a/arch/x86/mm/kasan_init_64.c b/arch/x86/mm/kasan_init_64.c index d8ff013ea9d0..980dbebd0ca7 100644 --- a/arch/x86/mm/kasan_init_64.c +++ b/arch/x86/mm/kasan_init_64.c @@ -269,6 +269,12 @@ void __init kasan_early_init(void) pudval_t pud_val = __pa_nodebug(kasan_zero_pmd) | _KERNPG_TABLE; p4dval_t p4d_val = __pa_nodebug(kasan_zero_pud) | _KERNPG_TABLE; + /* Mask out unsupported __PAGE_KERNEL bits: */ + pte_val &= __default_kernel_pte_mask; + pmd_val &= __default_kernel_pte_mask; + pud_val &= __default_kernel_pte_mask; + p4d_val &= __default_kernel_pte_mask; + for (i = 0; i < PTRS_PER_PTE; i++) kasan_zero_pte[i] = __pte(pte_val); @@ -371,7 +377,13 @@ void __init kasan_init(void) */ memset(kasan_zero_page, 0, PAGE_SIZE); for (i = 0; i < PTRS_PER_PTE; i++) { - pte_t pte = __pte(__pa(kasan_zero_page) | __PAGE_KERNEL_RO | _PAGE_ENC); + pte_t pte; + pgprot_t prot; + + prot = __pgprot(__PAGE_KERNEL_RO | _PAGE_ENC); + pgprot_val(prot) &= __default_kernel_pte_mask; + + pte = __pte(__pa(kasan_zero_page) | pgprot_val(prot)); set_pte(&kasan_zero_pte[i], pte); } /* Flush TLBs again to be sure that write protection applied. */ diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c index 34cda7e0551b..d10a40aceeaa 100644 --- a/arch/x86/mm/pgtable.c +++ b/arch/x86/mm/pgtable.c @@ -583,6 +583,9 @@ void __native_set_fixmap(enum fixed_addresses idx, pte_t pte) void native_set_fixmap(enum fixed_addresses idx, phys_addr_t phys, pgprot_t flags) { + /* Sanitize 'prot' against any unsupported bits: */ + pgprot_val(flags) &= __default_kernel_pte_mask; + __native_set_fixmap(idx, pfn_pte(phys >> PAGE_SHIFT, flags)); } diff --git a/arch/x86/power/hibernate_64.c b/arch/x86/power/hibernate_64.c index 74a532989308..48b14b534897 100644 --- a/arch/x86/power/hibernate_64.c +++ b/arch/x86/power/hibernate_64.c @@ -51,6 +51,12 @@ static int set_up_temporary_text_mapping(pgd_t *pgd) pmd_t *pmd; pud_t *pud; p4d_t *p4d = NULL; + pgprot_t pgtable_prot = __pgprot(_KERNPG_TABLE); + pgprot_t pmd_text_prot = __pgprot(__PAGE_KERNEL_LARGE_EXEC); + + /* Filter out unsupported __PAGE_KERNEL* bits: */ + pgprot_val(pmd_text_prot) &= __default_kernel_pte_mask; + pgprot_val(pgtable_prot) &= __default_kernel_pte_mask; /* * The new mapping only has to cover the page containing the image @@ -81,15 +87,19 @@ static int set_up_temporary_text_mapping(pgd_t *pgd) return -ENOMEM; set_pmd(pmd + pmd_index(restore_jump_address), - __pmd((jump_address_phys & PMD_MASK) | __PAGE_KERNEL_LARGE_EXEC)); + __pmd((jump_address_phys & PMD_MASK) | pgprot_val(pmd_text_prot))); set_pud(pud + pud_index(restore_jump_address), - __pud(__pa(pmd) | _KERNPG_TABLE)); + __pud(__pa(pmd) | pgprot_val(pgtable_prot))); if (p4d) { - set_p4d(p4d + p4d_index(restore_jump_address), __p4d(__pa(pud) | _KERNPG_TABLE)); - set_pgd(pgd + pgd_index(restore_jump_address), __pgd(__pa(p4d) | _KERNPG_TABLE)); + p4d_t new_p4d = __p4d(__pa(pud) | pgprot_val(pgtable_prot)); + pgd_t new_pgd = __pgd(__pa(p4d) | pgprot_val(pgtable_prot)); + + set_p4d(p4d + p4d_index(restore_jump_address), new_p4d); + set_pgd(pgd + pgd_index(restore_jump_address), new_pgd); } else { /* No p4d for 4-level paging: point the pgd to the pud page table */ - set_pgd(pgd + pgd_index(restore_jump_address), __pgd(__pa(pud) | _KERNPG_TABLE)); + pgd_t new_pgd = __pgd(__pa(p4d) | pgprot_val(pgtable_prot)); + set_pgd(pgd + pgd_index(restore_jump_address), new_pgd); } return 0; -- cgit v1.2.3 From 1a54420aeb4da1ba5b28283aa5696898220c9a27 Mon Sep 17 00:00:00 2001 From: Dave Hansen Date: Fri, 6 Apr 2018 13:55:11 -0700 Subject: x86/mm: Remove extra filtering in pageattr code The pageattr code has a mode where it can set or clear PTE bits in existing PTEs, so the page protections of the *new* PTEs come from one of two places: 1. The set/clear masks: cpa->mask_clr / cpa->mask_set 2. The existing PTE We filter ->mask_set/clr for supported PTE bits at entry to __change_page_attr() so we never need to filter them again. The only other place permissions can come from is an existing PTE and those already presumably have good bits. We do not need to filter them again. Signed-off-by: Dave Hansen Cc: Andrea Arcangeli Cc: Andy Lutomirski Cc: Arjan van de Ven Cc: Borislav Petkov Cc: Dan Williams Cc: David Woodhouse Cc: Greg Kroah-Hartman Cc: Hugh Dickins Cc: Josh Poimboeuf Cc: Juergen Gross Cc: Kees Cook Cc: Linus Torvalds Cc: Nadav Amit Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: linux-mm@kvack.org Link: http://lkml.kernel.org/r/20180406205511.BC072352@viggo.jf.intel.com Signed-off-by: Ingo Molnar --- arch/x86/mm/pageattr.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) (limited to 'arch/x86') diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c index d3442dfdfced..968f51a2e39b 100644 --- a/arch/x86/mm/pageattr.c +++ b/arch/x86/mm/pageattr.c @@ -598,7 +598,6 @@ try_preserve_large_page(pte_t *kpte, unsigned long address, req_prot = pgprot_clear_protnone_bits(req_prot); if (pgprot_val(req_prot) & _PAGE_PRESENT) pgprot_val(req_prot) |= _PAGE_PSE; - req_prot = canon_pgprot(req_prot); /* * old_pfn points to the large page base pfn. So we need @@ -718,7 +717,7 @@ __split_large_page(struct cpa_data *cpa, pte_t *kpte, unsigned long address, */ pfn = ref_pfn; for (i = 0; i < PTRS_PER_PTE; i++, pfn += pfninc) - set_pte(&pbase[i], pfn_pte(pfn, canon_pgprot(ref_prot))); + set_pte(&pbase[i], pfn_pte(pfn, ref_prot)); if (virt_addr_valid(address)) { unsigned long pfn = PFN_DOWN(__pa(address)); @@ -935,7 +934,6 @@ static void populate_pte(struct cpa_data *cpa, pte = pte_offset_kernel(pmd, start); pgprot = pgprot_clear_protnone_bits(pgprot); - pgprot = canon_pgprot(pgprot); while (num_pages-- && start < end) { set_pte(pte, pfn_pte(cpa->pfn, pgprot)); @@ -1234,7 +1232,7 @@ repeat: * after all we're only going to change it's attributes * not the memory it points to */ - new_pte = pfn_pte(pfn, canon_pgprot(new_prot)); + new_pte = pfn_pte(pfn, new_prot); cpa->pfn = pfn; /* * Do we really change anything ? -- cgit v1.2.3 From 430d4005b8b41c19966dd3bfdb33004bdb2de01c Mon Sep 17 00:00:00 2001 From: Dave Hansen Date: Fri, 6 Apr 2018 13:55:13 -0700 Subject: x86/mm: Comment _PAGE_GLOBAL mystery I was mystified as to where the _PAGE_GLOBAL in the kernel page tables for kernel text came from. I audited all the places I could find, but I missed one: head_64.S. The page tables that we create in here live for a long time, and they also have _PAGE_GLOBAL set, despite whether the processor supports it or not. It's harmless, and we got *lucky* that the pageattr code accidentally clears it when we wipe it out of __supported_pte_mask and then later try to mark kernel text read-only. Comment some of these properties to make it easier to find and understand in the future. Signed-off-by: Dave Hansen Cc: Andrea Arcangeli Cc: Andy Lutomirski Cc: Arjan van de Ven Cc: Borislav Petkov Cc: Dan Williams Cc: David Woodhouse Cc: Greg Kroah-Hartman Cc: Hugh Dickins Cc: Josh Poimboeuf Cc: Juergen Gross Cc: Kees Cook Cc: Linus Torvalds Cc: Nadav Amit Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: linux-mm@kvack.org Link: http://lkml.kernel.org/r/20180406205513.079BB265@viggo.jf.intel.com Signed-off-by: Ingo Molnar --- arch/x86/kernel/head_64.S | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) (limited to 'arch/x86') diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S index 48385c1074a5..8344dd2f310a 100644 --- a/arch/x86/kernel/head_64.S +++ b/arch/x86/kernel/head_64.S @@ -399,8 +399,13 @@ NEXT_PAGE(level3_ident_pgt) .quad level2_ident_pgt - __START_KERNEL_map + _KERNPG_TABLE_NOENC .fill 511, 8, 0 NEXT_PAGE(level2_ident_pgt) - /* Since I easily can, map the first 1G. + /* + * Since I easily can, map the first 1G. * Don't set NX because code runs from these pages. + * + * Note: This sets _PAGE_GLOBAL despite whether + * the CPU supports it or it is enabled. But, + * the CPU should ignore the bit. */ PMDS(0, __PAGE_KERNEL_IDENT_LARGE_EXEC, PTRS_PER_PMD) #else @@ -431,6 +436,10 @@ NEXT_PAGE(level2_kernel_pgt) * (NOTE: at +512MB starts the module area, see MODULES_VADDR. * If you want to increase this then increase MODULES_VADDR * too.) + * + * This table is eventually used by the kernel during normal + * runtime. Care must be taken to clear out undesired bits + * later, like _PAGE_RW or _PAGE_GLOBAL in some cases. */ PMDS(0, __PAGE_KERNEL_LARGE_EXEC, KERNEL_IMAGE_SIZE/PMD_SIZE) -- cgit v1.2.3 From 639d6aafe437a7464399d2a77d006049053df06f Mon Sep 17 00:00:00 2001 From: Dave Hansen Date: Fri, 6 Apr 2018 13:55:14 -0700 Subject: x86/mm: Do not forbid _PAGE_RW before init for __ro_after_init __ro_after_init data gets stuck in the .rodata section. That's normally fine because the kernel itself manages the R/W properties. But, if we run __change_page_attr() on an area which is __ro_after_init, the .rodata checks will trigger and force the area to be immediately read-only, even if it is early-ish in boot. This caused problems when trying to clear the _PAGE_GLOBAL bit for these area in the PTI code: it cleared _PAGE_GLOBAL like I asked, but also took it up on itself to clear _PAGE_RW. The kernel then oopses the next time it wrote to a __ro_after_init data structure. To fix this, add the kernel_set_to_readonly check, just like we have for kernel text, just a few lines below in this function. Signed-off-by: Dave Hansen Acked-by: Kees Cook Cc: Andrea Arcangeli Cc: Andy Lutomirski Cc: Arjan van de Ven Cc: Borislav Petkov Cc: Dan Williams Cc: David Woodhouse Cc: Greg Kroah-Hartman Cc: Hugh Dickins Cc: Josh Poimboeuf Cc: Juergen Gross Cc: Linus Torvalds Cc: Nadav Amit Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: linux-mm@kvack.org Link: http://lkml.kernel.org/r/20180406205514.8D898241@viggo.jf.intel.com Signed-off-by: Ingo Molnar --- arch/x86/mm/pageattr.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) (limited to 'arch/x86') diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c index 968f51a2e39b..a7324045d87d 100644 --- a/arch/x86/mm/pageattr.c +++ b/arch/x86/mm/pageattr.c @@ -298,9 +298,11 @@ static inline pgprot_t static_protections(pgprot_t prot, unsigned long address, /* * The .rodata section needs to be read-only. Using the pfn - * catches all aliases. + * catches all aliases. This also includes __ro_after_init, + * so do not enforce until kernel_set_to_readonly is true. */ - if (within(pfn, __pa_symbol(__start_rodata) >> PAGE_SHIFT, + if (kernel_set_to_readonly && + within(pfn, __pa_symbol(__start_rodata) >> PAGE_SHIFT, __pa_symbol(__end_rodata) >> PAGE_SHIFT)) pgprot_val(forbidden) |= _PAGE_RW; -- cgit v1.2.3 From 0f561fce4d6979a50415616896512f87a6d1d5c8 Mon Sep 17 00:00:00 2001 From: Dave Hansen Date: Fri, 6 Apr 2018 13:55:15 -0700 Subject: x86/pti: Enable global pages for shared areas The entry/exit text and cpu_entry_area are mapped into userspace and the kernel. But, they are not _PAGE_GLOBAL. This creates unnecessary TLB misses. Add the _PAGE_GLOBAL flag for these areas. Signed-off-by: Dave Hansen Cc: Andrea Arcangeli Cc: Andy Lutomirski Cc: Arjan van de Ven Cc: Borislav Petkov Cc: Dan Williams Cc: David Woodhouse Cc: Greg Kroah-Hartman Cc: Hugh Dickins Cc: Josh Poimboeuf Cc: Juergen Gross Cc: Kees Cook Cc: Linus Torvalds Cc: Nadav Amit Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: linux-mm@kvack.org Link: http://lkml.kernel.org/r/20180406205515.2977EE7D@viggo.jf.intel.com Signed-off-by: Ingo Molnar --- arch/x86/mm/cpu_entry_area.c | 14 +++++++++++++- arch/x86/mm/pti.c | 23 ++++++++++++++++++++++- 2 files changed, 35 insertions(+), 2 deletions(-) (limited to 'arch/x86') diff --git a/arch/x86/mm/cpu_entry_area.c b/arch/x86/mm/cpu_entry_area.c index 476d810639a8..b45f5aaefd74 100644 --- a/arch/x86/mm/cpu_entry_area.c +++ b/arch/x86/mm/cpu_entry_area.c @@ -27,8 +27,20 @@ EXPORT_SYMBOL(get_cpu_entry_area); void cea_set_pte(void *cea_vaddr, phys_addr_t pa, pgprot_t flags) { unsigned long va = (unsigned long) cea_vaddr; + pte_t pte = pfn_pte(pa >> PAGE_SHIFT, flags); - set_pte_vaddr(va, pfn_pte(pa >> PAGE_SHIFT, flags)); + /* + * The cpu_entry_area is shared between the user and kernel + * page tables. All of its ptes can safely be global. + * _PAGE_GLOBAL gets reused to help indicate PROT_NONE for + * non-present PTEs, so be careful not to set it in that + * case to avoid confusion. + */ + if (boot_cpu_has(X86_FEATURE_PGE) && + (pgprot_val(flags) & _PAGE_PRESENT)) + pte = pte_set_flags(pte, _PAGE_GLOBAL); + + set_pte_vaddr(va, pte); } static void __init diff --git a/arch/x86/mm/pti.c b/arch/x86/mm/pti.c index 631507f0c198..8082f8b0c10e 100644 --- a/arch/x86/mm/pti.c +++ b/arch/x86/mm/pti.c @@ -299,6 +299,27 @@ pti_clone_pmds(unsigned long start, unsigned long end, pmdval_t clear) if (WARN_ON(!target_pmd)) return; + /* + * Only clone present PMDs. This ensures only setting + * _PAGE_GLOBAL on present PMDs. This should only be + * called on well-known addresses anyway, so a non- + * present PMD would be a surprise. + */ + if (WARN_ON(!(pmd_flags(*pmd) & _PAGE_PRESENT))) + return; + + /* + * Setting 'target_pmd' below creates a mapping in both + * the user and kernel page tables. It is effectively + * global, so set it as global in both copies. Note: + * the X86_FEATURE_PGE check is not _required_ because + * the CPU ignores _PAGE_GLOBAL when PGE is not + * supported. The check keeps consistentency with + * code that only set this bit when supported. + */ + if (boot_cpu_has(X86_FEATURE_PGE)) + *pmd = pmd_set_flags(*pmd, _PAGE_GLOBAL); + /* * Copy the PMD. That is, the kernelmode and usermode * tables will share the last-level page tables of this @@ -348,7 +369,7 @@ static void __init pti_clone_entry_text(void) { pti_clone_pmds((unsigned long) __entry_text_start, (unsigned long) __irqentry_text_end, - _PAGE_RW | _PAGE_GLOBAL); + _PAGE_RW); } /* -- cgit v1.2.3 From 39114b7a743e6759bab4d96b7d9651d44d17e3f9 Mon Sep 17 00:00:00 2001 From: Dave Hansen Date: Fri, 6 Apr 2018 13:55:17 -0700 Subject: x86/pti: Never implicitly clear _PAGE_GLOBAL for kernel image Summary: In current kernels, with PTI enabled, no pages are marked Global. This potentially increases TLB misses. But, the mechanism by which the Global bit is set and cleared is rather haphazard. This patch makes the process more explicit. In the end, it leaves us with Global entries in the page tables for the areas truly shared by userspace and kernel and increases TLB hit rates. The place this patch really shines in on systems without PCIDs. In this case, we are using an lseek microbenchmark[1] to see how a reasonably non-trivial syscall behaves. Higher is better: No Global pages (baseline): 6077741 lseeks/sec 88 Global Pages (this set): 7528609 lseeks/sec (+23.9%) On a modern Skylake desktop with PCIDs, the benefits are tangible, but not huge for a kernel compile (lower is better): No Global pages (baseline): 186.951 seconds time elapsed ( +- 0.35% ) 28 Global pages (this set): 185.756 seconds time elapsed ( +- 0.09% ) -1.195 seconds (-0.64%) I also re-checked everything using the lseek1 test[1]: No Global pages (baseline): 15783951 lseeks/sec 28 Global pages (this set): 16054688 lseeks/sec +270737 lseeks/sec (+1.71%) The effect is more visible, but still modest. Details: The kernel page tables are inherited from head_64.S which rudely marks them as _PAGE_GLOBAL. For PTI, we have been relying on the grace of $DEITY and some insane behavior in pageattr.c to clear _PAGE_GLOBAL. This patch tries to do better. First, stop filtering out "unsupported" bits from being cleared in the pageattr code. It's fine to filter out *setting* these bits but it is insane to keep us from clearing them. Then, *explicitly* go clear _PAGE_GLOBAL from the kernel identity map. Do not rely on pageattr to do it magically. After this patch, we can see that "GLB" shows up in each copy of the page tables, that we have the same number of global entries in each and that they are the *same* entries. /sys/kernel/debug/page_tables/current_kernel:11 /sys/kernel/debug/page_tables/current_user:11 /sys/kernel/debug/page_tables/kernel:11 9caae8ad6a1fb53aca2407ec037f612d current_kernel.GLB 9caae8ad6a1fb53aca2407ec037f612d current_user.GLB 9caae8ad6a1fb53aca2407ec037f612d kernel.GLB A quick visual audit also shows that all the entries make sense. 0xfffffe0000000000 is the cpu_entry_area and 0xffffffff81c00000 is the entry/exit text: 0xfffffe0000000000-0xfffffe0000002000 8K ro GLB NX pte 0xfffffe0000002000-0xfffffe0000003000 4K RW GLB NX pte 0xfffffe0000003000-0xfffffe0000006000 12K ro GLB NX pte 0xfffffe0000006000-0xfffffe0000007000 4K ro GLB x pte 0xfffffe0000007000-0xfffffe000000d000 24K RW GLB NX pte 0xfffffe000002d000-0xfffffe000002e000 4K ro GLB NX pte 0xfffffe000002e000-0xfffffe000002f000 4K RW GLB NX pte 0xfffffe000002f000-0xfffffe0000032000 12K ro GLB NX pte 0xfffffe0000032000-0xfffffe0000033000 4K ro GLB x pte 0xfffffe0000033000-0xfffffe0000039000 24K RW GLB NX pte 0xffffffff81c00000-0xffffffff81e00000 2M ro PSE GLB x pmd [1.] https://github.com/antonblanchard/will-it-scale/blob/master/tests/lseek1.c Signed-off-by: Dave Hansen Cc: Andrea Arcangeli Cc: Andy Lutomirski Cc: Arjan van de Ven Cc: Borislav Petkov Cc: Dan Williams Cc: David Woodhouse Cc: Greg Kroah-Hartman Cc: Hugh Dickins Cc: Josh Poimboeuf Cc: Juergen Gross Cc: Kees Cook Cc: Linus Torvalds Cc: Nadav Amit Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: linux-mm@kvack.org Link: http://lkml.kernel.org/r/20180406205517.C80FBE05@viggo.jf.intel.com Signed-off-by: Ingo Molnar --- arch/x86/mm/init.c | 8 +------- arch/x86/mm/pageattr.c | 12 +++++++++--- arch/x86/mm/pti.c | 25 +++++++++++++++++++++++++ 3 files changed, 35 insertions(+), 10 deletions(-) (limited to 'arch/x86') diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c index 583a88c8a6ee..fec82b577c18 100644 --- a/arch/x86/mm/init.c +++ b/arch/x86/mm/init.c @@ -161,12 +161,6 @@ struct map_range { static int page_size_mask; -static void enable_global_pages(void) -{ - if (!static_cpu_has(X86_FEATURE_PTI)) - __supported_pte_mask |= _PAGE_GLOBAL; -} - static void __init probe_page_size_mask(void) { /* @@ -187,7 +181,7 @@ static void __init probe_page_size_mask(void) __supported_pte_mask &= ~_PAGE_GLOBAL; if (boot_cpu_has(X86_FEATURE_PGE)) { cr4_set_bits_and_update_boot(X86_CR4_PGE); - enable_global_pages(); + __supported_pte_mask |= _PAGE_GLOBAL; } /* By the default is everything supported: */ diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c index a7324045d87d..0f3d50f4c48c 100644 --- a/arch/x86/mm/pageattr.c +++ b/arch/x86/mm/pageattr.c @@ -1411,11 +1411,11 @@ static int change_page_attr_set_clr(unsigned long *addr, int numpages, memset(&cpa, 0, sizeof(cpa)); /* - * Check, if we are requested to change a not supported - * feature: + * Check, if we are requested to set a not supported + * feature. Clearing non-supported features is OK. */ mask_set = canon_pgprot(mask_set); - mask_clr = canon_pgprot(mask_clr); + if (!pgprot_val(mask_set) && !pgprot_val(mask_clr) && !force_split) return 0; @@ -1758,6 +1758,12 @@ int set_memory_4k(unsigned long addr, int numpages) __pgprot(0), 1, 0, NULL); } +int set_memory_nonglobal(unsigned long addr, int numpages) +{ + return change_page_attr_clear(&addr, numpages, + __pgprot(_PAGE_GLOBAL), 0); +} + static int __set_memory_enc_dec(unsigned long addr, int numpages, bool enc) { struct cpa_data cpa; diff --git a/arch/x86/mm/pti.c b/arch/x86/mm/pti.c index 8082f8b0c10e..1470b173963f 100644 --- a/arch/x86/mm/pti.c +++ b/arch/x86/mm/pti.c @@ -372,6 +372,27 @@ static void __init pti_clone_entry_text(void) _PAGE_RW); } +/* + * This is the only user for it and it is not arch-generic like + * the other set_memory.h functions. Just extern it. + */ +extern int set_memory_nonglobal(unsigned long addr, int numpages); +void pti_set_kernel_image_nonglobal(void) +{ + /* + * The identity map is created with PMDs, regardless of the + * actual length of the kernel. We need to clear + * _PAGE_GLOBAL up to a PMD boundary, not just to the end + * of the image. + */ + unsigned long start = PFN_ALIGN(_text); + unsigned long end = ALIGN((unsigned long)_end, PMD_PAGE_SIZE); + + pr_debug("set kernel image non-global\n"); + + set_memory_nonglobal(start, (end - start) >> PAGE_SHIFT); +} + /* * Initialize kernel page table isolation */ @@ -383,6 +404,10 @@ void __init pti_init(void) pr_info("enabled\n"); pti_clone_user_shared(); + + /* Undo all global bits from the init pagetables in head_64.S: */ + pti_set_kernel_image_nonglobal(); + /* Replace some of the global bits just for shared entry text: */ pti_clone_entry_text(); pti_setup_espfix64(); pti_setup_vsyscall(); -- cgit v1.2.3 From 8c06c7740d191b9055cb9be920579d5ecdd26303 Mon Sep 17 00:00:00 2001 From: Dave Hansen Date: Fri, 6 Apr 2018 13:55:18 -0700 Subject: x86/pti: Leave kernel text global for !PCID Global pages are bad for hardening because they potentially let an exploit read the kernel image via a Meltdown-style attack which makes it easier to find gadgets. But, global pages are good for performance because they reduce TLB misses when making user/kernel transitions, especially when PCIDs are not available, such as on older hardware, or where a hypervisor has disabled them for some reason. This patch implements a basic, sane policy: If you have PCIDs, you only map a minimal amount of kernel text global. If you do not have PCIDs, you map all kernel text global. This policy effectively makes PCIDs something that not only adds performance but a little bit of hardening as well. I ran a simple "lseek" microbenchmark[1] to test the benefit on a modern Atom microserver. Most of the benefit comes from applying the series before this patch ("entry only"), but there is still a signifiant benefit from this patch. No Global Lines (baseline ): 6077741 lseeks/sec 88 Global Lines (entry only): 7528609 lseeks/sec (+23.9%) 94 Global Lines (this patch): 8433111 lseeks/sec (+38.8%) [1.] https://github.com/antonblanchard/will-it-scale/blob/master/tests/lseek1.c Signed-off-by: Dave Hansen Cc: Andrea Arcangeli Cc: Andy Lutomirski Cc: Arjan van de Ven Cc: Borislav Petkov Cc: Dan Williams Cc: David Woodhouse Cc: Greg Kroah-Hartman Cc: Hugh Dickins Cc: Josh Poimboeuf Cc: Juergen Gross Cc: Kees Cook Cc: Linus Torvalds Cc: Nadav Amit Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: linux-mm@kvack.org Link: http://lkml.kernel.org/r/20180406205518.E3D989EB@viggo.jf.intel.com Signed-off-by: Ingo Molnar --- arch/x86/include/asm/pti.h | 2 ++ arch/x86/mm/init_64.c | 6 ++++ arch/x86/mm/pti.c | 78 +++++++++++++++++++++++++++++++++++++++++++--- 3 files changed, 82 insertions(+), 4 deletions(-) (limited to 'arch/x86') diff --git a/arch/x86/include/asm/pti.h b/arch/x86/include/asm/pti.h index 0b5ef05b2d2d..38a17f1d5c9d 100644 --- a/arch/x86/include/asm/pti.h +++ b/arch/x86/include/asm/pti.h @@ -6,8 +6,10 @@ #ifdef CONFIG_PAGE_TABLE_ISOLATION extern void pti_init(void); extern void pti_check_boottime_disable(void); +extern void pti_clone_kernel_text(void); #else static inline void pti_check_boottime_disable(void) { } +static inline void pti_clone_kernel_text(void) { } #endif #endif /* __ASSEMBLY__ */ diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c index e6c52dbbf649..6d1ff39c2438 100644 --- a/arch/x86/mm/init_64.c +++ b/arch/x86/mm/init_64.c @@ -1290,6 +1290,12 @@ void mark_rodata_ro(void) (unsigned long) __va(__pa_symbol(_sdata))); debug_checkwx(); + + /* + * Do this after all of the manipulation of the + * kernel text page tables are complete. + */ + pti_clone_kernel_text(); } int kern_addr_valid(unsigned long addr) diff --git a/arch/x86/mm/pti.c b/arch/x86/mm/pti.c index 1470b173963f..f1fd52f449e0 100644 --- a/arch/x86/mm/pti.c +++ b/arch/x86/mm/pti.c @@ -66,12 +66,22 @@ static void __init pti_print_if_secure(const char *reason) pr_info("%s\n", reason); } +enum pti_mode { + PTI_AUTO = 0, + PTI_FORCE_OFF, + PTI_FORCE_ON +} pti_mode; + void __init pti_check_boottime_disable(void) { char arg[5]; int ret; + /* Assume mode is auto unless overridden. */ + pti_mode = PTI_AUTO; + if (hypervisor_is_type(X86_HYPER_XEN_PV)) { + pti_mode = PTI_FORCE_OFF; pti_print_if_insecure("disabled on XEN PV."); return; } @@ -79,18 +89,23 @@ void __init pti_check_boottime_disable(void) ret = cmdline_find_option(boot_command_line, "pti", arg, sizeof(arg)); if (ret > 0) { if (ret == 3 && !strncmp(arg, "off", 3)) { + pti_mode = PTI_FORCE_OFF; pti_print_if_insecure("disabled on command line."); return; } if (ret == 2 && !strncmp(arg, "on", 2)) { + pti_mode = PTI_FORCE_ON; pti_print_if_secure("force enabled on command line."); goto enable; } - if (ret == 4 && !strncmp(arg, "auto", 4)) + if (ret == 4 && !strncmp(arg, "auto", 4)) { + pti_mode = PTI_AUTO; goto autosel; + } } if (cmdline_find_option_bool(boot_command_line, "nopti")) { + pti_mode = PTI_FORCE_OFF; pti_print_if_insecure("disabled on command line."); return; } @@ -149,7 +164,7 @@ pgd_t __pti_set_user_pgd(pgd_t *pgdp, pgd_t pgd) * * Returns a pointer to a P4D on success, or NULL on failure. */ -static __init p4d_t *pti_user_pagetable_walk_p4d(unsigned long address) +static p4d_t *pti_user_pagetable_walk_p4d(unsigned long address) { pgd_t *pgd = kernel_to_user_pgdp(pgd_offset_k(address)); gfp_t gfp = (GFP_KERNEL | __GFP_NOTRACK | __GFP_ZERO); @@ -177,7 +192,7 @@ static __init p4d_t *pti_user_pagetable_walk_p4d(unsigned long address) * * Returns a pointer to a PMD on success, or NULL on failure. */ -static __init pmd_t *pti_user_pagetable_walk_pmd(unsigned long address) +static pmd_t *pti_user_pagetable_walk_pmd(unsigned long address) { gfp_t gfp = (GFP_KERNEL | __GFP_NOTRACK | __GFP_ZERO); p4d_t *p4d = pti_user_pagetable_walk_p4d(address); @@ -267,7 +282,7 @@ static void __init pti_setup_vsyscall(void) static void __init pti_setup_vsyscall(void) { } #endif -static void __init +static void pti_clone_pmds(unsigned long start, unsigned long end, pmdval_t clear) { unsigned long addr; @@ -372,6 +387,58 @@ static void __init pti_clone_entry_text(void) _PAGE_RW); } +/* + * Global pages and PCIDs are both ways to make kernel TLB entries + * live longer, reduce TLB misses and improve kernel performance. + * But, leaving all kernel text Global makes it potentially accessible + * to Meltdown-style attacks which make it trivial to find gadgets or + * defeat KASLR. + * + * Only use global pages when it is really worth it. + */ +static inline bool pti_kernel_image_global_ok(void) +{ + /* + * Systems with PCIDs get litlle benefit from global + * kernel text and are not worth the downsides. + */ + if (cpu_feature_enabled(X86_FEATURE_PCID)) + return false; + + /* + * Only do global kernel image for pti=auto. Do the most + * secure thing (not global) if pti=on specified. + */ + if (pti_mode != PTI_AUTO) + return false; + + /* + * K8 may not tolerate the cleared _PAGE_RW on the userspace + * global kernel image pages. Do the safe thing (disable + * global kernel image). This is unlikely to ever be + * noticed because PTI is disabled by default on AMD CPUs. + */ + if (boot_cpu_has(X86_FEATURE_K8)) + return false; + + return true; +} + +/* + * For some configurations, map all of kernel text into the user page + * tables. This reduces TLB misses, especially on non-PCID systems. + */ +void pti_clone_kernel_text(void) +{ + unsigned long start = PFN_ALIGN(_text); + unsigned long end = ALIGN((unsigned long)_end, PMD_PAGE_SIZE); + + if (!pti_kernel_image_global_ok()) + return; + + pti_clone_pmds(start, end, _PAGE_RW); +} + /* * This is the only user for it and it is not arch-generic like * the other set_memory.h functions. Just extern it. @@ -388,6 +455,9 @@ void pti_set_kernel_image_nonglobal(void) unsigned long start = PFN_ALIGN(_text); unsigned long end = ALIGN((unsigned long)_end, PMD_PAGE_SIZE); + if (pti_kernel_image_global_ok()) + return; + pr_debug("set kernel image non-global\n"); set_memory_nonglobal(start, (end - start) >> PAGE_SHIFT); -- cgit v1.2.3 From e3e288121408c3abeed5af60b87b95c847143845 Mon Sep 17 00:00:00 2001 From: Joerg Roedel Date: Wed, 11 Apr 2018 17:24:38 +0200 Subject: x86/pgtable: Don't set huge PUD/PMD on non-leaf entries The pmd_set_huge() and pud_set_huge() functions are used from the generic ioremap() code to establish large mappings where this is possible. But the generic ioremap() code does not check whether the PMD/PUD entries are already populated with a non-leaf entry, so that any page-table pages these entries point to will be lost. Further, on x86-32 with SHARED_KERNEL_PMD=0, this causes a BUG_ON() in vmalloc_sync_one() when PMD entries are synced from swapper_pg_dir to the current page-table. This happens because the PMD entry from swapper_pg_dir was promoted to a huge-page entry while the current PGD still contains the non-leaf entry. Because both entries are present and point to a different page, the BUG_ON() triggers. This was actually triggered with pti-x32 enabled in a KVM virtual machine by the graphics driver. A real and better fix for that would be to improve the page-table handling in the generic ioremap() code. But that is out-of-scope for this patch-set and left for later work. Reported-by: David H. Gutteridge Signed-off-by: Joerg Roedel Reviewed-by: Thomas Gleixner Cc: Andrea Arcangeli Cc: Andy Lutomirski Cc: Boris Ostrovsky Cc: Borislav Petkov Cc: Brian Gerst Cc: Dave Hansen Cc: David Laight Cc: Denys Vlasenko Cc: Eduardo Valentin Cc: Greg KH Cc: Jiri Kosina Cc: Josh Poimboeuf Cc: Juergen Gross Cc: Linus Torvalds Cc: Pavel Machek Cc: Peter Zijlstra Cc: Waiman Long Cc: Will Deacon Cc: aliguori@amazon.com Cc: daniel.gruss@iaik.tugraz.at Cc: hughd@google.com Cc: keescook@google.com Cc: linux-mm@kvack.org Link: http://lkml.kernel.org/r/20180411152437.GC15462@8bytes.org Signed-off-by: Ingo Molnar --- arch/x86/mm/pgtable.c | 9 +++++++++ 1 file changed, 9 insertions(+) (limited to 'arch/x86') diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c index d10a40aceeaa..ffc8c13c50e4 100644 --- a/arch/x86/mm/pgtable.c +++ b/arch/x86/mm/pgtable.c @@ -1,6 +1,7 @@ // SPDX-License-Identifier: GPL-2.0 #include #include +#include #include #include #include @@ -639,6 +640,10 @@ int pud_set_huge(pud_t *pud, phys_addr_t addr, pgprot_t prot) (mtrr != MTRR_TYPE_WRBACK)) return 0; + /* Bail out if we are we on a populated non-leaf entry: */ + if (pud_present(*pud) && !pud_huge(*pud)) + return 0; + prot = pgprot_4k_2_large(prot); set_pte((pte_t *)pud, pfn_pte( @@ -667,6 +672,10 @@ int pmd_set_huge(pmd_t *pmd, phys_addr_t addr, pgprot_t prot) return 0; } + /* Bail out if we are we on a populated non-leaf entry: */ + if (pmd_present(*pmd) && !pmd_huge(*pmd)) + return 0; + prot = pgprot_4k_2_large(prot); set_pte((pte_t *)pmd, pfn_pte( -- cgit v1.2.3