diff options
Diffstat (limited to 'arch/x86/mm')
-rw-r--r-- | arch/x86/mm/extable.c | 58 | ||||
-rw-r--r-- | arch/x86/mm/pageattr.c | 50 |
2 files changed, 25 insertions, 83 deletions
diff --git a/arch/x86/mm/extable.c b/arch/x86/mm/extable.c index 6521134057e8..856fa409c536 100644 --- a/arch/x86/mm/extable.c +++ b/arch/x86/mm/extable.c @@ -117,67 +117,11 @@ __visible bool ex_handler_fprestore(const struct exception_table_entry *fixup, } EXPORT_SYMBOL_GPL(ex_handler_fprestore); -/* Helper to check whether a uaccess fault indicates a kernel bug. */ -static bool bogus_uaccess(struct pt_regs *regs, int trapnr, - unsigned long fault_addr) -{ - /* This is the normal case: #PF with a fault address in userspace. */ - if (trapnr == X86_TRAP_PF && fault_addr < TASK_SIZE_MAX) - return false; - - /* - * This code can be reached for machine checks, but only if the #MC - * handler has already decided that it looks like a candidate for fixup. - * This e.g. happens when attempting to access userspace memory which - * the CPU can't access because of uncorrectable bad memory. - */ - if (trapnr == X86_TRAP_MC) - return false; - - /* - * There are two remaining exception types we might encounter here: - * - #PF for faulting accesses to kernel addresses - * - #GP for faulting accesses to noncanonical addresses - * Complain about anything else. - */ - if (trapnr != X86_TRAP_PF && trapnr != X86_TRAP_GP) { - WARN(1, "unexpected trap %d in uaccess\n", trapnr); - return false; - } - - /* - * This is a faulting memory access in kernel space, on a kernel - * address, in a usercopy function. This can e.g. be caused by improper - * use of helpers like __put_user and by improper attempts to access - * userspace addresses in KERNEL_DS regions. - * The one (semi-)legitimate exception are probe_kernel_{read,write}(), - * which can be invoked from places like kgdb, /dev/mem (for reading) - * and privileged BPF code (for reading). - * The probe_kernel_*() functions set the kernel_uaccess_faults_ok flag - * to tell us that faulting on kernel addresses, and even noncanonical - * addresses, in a userspace accessor does not necessarily imply a - * kernel bug, root might just be doing weird stuff. - */ - if (current->kernel_uaccess_faults_ok) - return false; - - /* This is bad. Refuse the fixup so that we go into die(). */ - if (trapnr == X86_TRAP_PF) { - pr_emerg("BUG: pagefault on kernel address 0x%lx in non-whitelisted uaccess\n", - fault_addr); - } else { - pr_emerg("BUG: GPF in non-whitelisted uaccess (non-canonical address?)\n"); - } - return true; -} - __visible bool ex_handler_uaccess(const struct exception_table_entry *fixup, struct pt_regs *regs, int trapnr, unsigned long error_code, unsigned long fault_addr) { - if (bogus_uaccess(regs, trapnr, fault_addr)) - return false; regs->ip = ex_fixup_addr(fixup); return true; } @@ -188,8 +132,6 @@ __visible bool ex_handler_ext(const struct exception_table_entry *fixup, unsigned long error_code, unsigned long fault_addr) { - if (bogus_uaccess(regs, trapnr, fault_addr)) - return false; /* Special hack for uaccess_err */ current->thread.uaccess_err = 1; regs->ip = ex_fixup_addr(fixup); diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c index 4f8972311a77..14e6119838a6 100644 --- a/arch/x86/mm/pageattr.c +++ b/arch/x86/mm/pageattr.c @@ -230,6 +230,29 @@ static bool __cpa_pfn_in_highmap(unsigned long pfn) #endif +/* + * See set_mce_nospec(). + * + * Machine check recovery code needs to change cache mode of poisoned pages to + * UC to avoid speculative access logging another error. But passing the + * address of the 1:1 mapping to set_memory_uc() is a fine way to encourage a + * speculative access. So we cheat and flip the top bit of the address. This + * works fine for the code that updates the page tables. But at the end of the + * process we need to flush the TLB and cache and the non-canonical address + * causes a #GP fault when used by the INVLPG and CLFLUSH instructions. + * + * But in the common case we already have a canonical address. This code + * will fix the top bit if needed and is a no-op otherwise. + */ +static inline unsigned long fix_addr(unsigned long addr) +{ +#ifdef CONFIG_X86_64 + return (long)(addr << 1) >> 1; +#else + return addr; +#endif +} + static unsigned long __cpa_addr(struct cpa_data *cpa, unsigned long idx) { if (cpa->flags & CPA_PAGES_ARRAY) { @@ -313,7 +336,7 @@ void __cpa_flush_tlb(void *data) unsigned int i; for (i = 0; i < cpa->numpages; i++) - __flush_tlb_one_kernel(__cpa_addr(cpa, i)); + __flush_tlb_one_kernel(fix_addr(__cpa_addr(cpa, i))); } static void cpa_flush(struct cpa_data *data, int cache) @@ -347,7 +370,7 @@ static void cpa_flush(struct cpa_data *data, int cache) * Only flush present addresses: */ if (pte && (pte_val(*pte) & _PAGE_PRESENT)) - clflush_cache_range_opt((void *)addr, PAGE_SIZE); + clflush_cache_range_opt((void *)fix_addr(addr), PAGE_SIZE); } mb(); } @@ -1627,29 +1650,6 @@ out: return ret; } -/* - * Machine check recovery code needs to change cache mode of poisoned - * pages to UC to avoid speculative access logging another error. But - * passing the address of the 1:1 mapping to set_memory_uc() is a fine - * way to encourage a speculative access. So we cheat and flip the top - * bit of the address. This works fine for the code that updates the - * page tables. But at the end of the process we need to flush the cache - * and the non-canonical address causes a #GP fault when used by the - * CLFLUSH instruction. - * - * But in the common case we already have a canonical address. This code - * will fix the top bit if needed and is a no-op otherwise. - */ -static inline unsigned long make_addr_canonical_again(unsigned long addr) -{ -#ifdef CONFIG_X86_64 - return (long)(addr << 1) >> 1; -#else - return addr; -#endif -} - - static int change_page_attr_set_clr(unsigned long *addr, int numpages, pgprot_t mask_set, pgprot_t mask_clr, int force_split, int in_flag, |