diff options
| -rw-r--r-- | arch/x86/lib/usercopy.c | 43 | ||||
| -rw-r--r-- | arch/x86/mm/fault.c | 41 |
2 files changed, 36 insertions, 48 deletions
diff --git a/arch/x86/lib/usercopy.c b/arch/x86/lib/usercopy.c index 4f74d94c8d97..5465b8613944 100644 --- a/arch/x86/lib/usercopy.c +++ b/arch/x86/lib/usercopy.c @@ -11,39 +11,26 @@ #include <linux/sched.h> /* - * best effort, GUP based copy_from_user() that is NMI-safe + * We rely on the nested NMI work to allow atomic faults from the NMI path; the + * nested NMI paths are careful to preserve CR2. */ unsigned long copy_from_user_nmi(void *to, const void __user *from, unsigned long n) { - unsigned long offset, addr = (unsigned long)from; - unsigned long size, len = 0; - struct page *page; - void *map; - int ret; + unsigned long ret; if (__range_not_ok(from, n, TASK_SIZE)) - return len; - - do { - ret = __get_user_pages_fast(addr, 1, 0, &page); - if (!ret) - break; - - offset = addr & (PAGE_SIZE - 1); - size = min(PAGE_SIZE - offset, n - len); - - map = kmap_atomic(page); - memcpy(to, map+offset, size); - kunmap_atomic(map); - put_page(page); - - len += size; - to += size; - addr += size; - - } while (len < n); - - return len; + return 0; + + /* + * Even though this function is typically called from NMI/IRQ context + * disable pagefaults so that its behaviour is consistent even when + * called form other contexts. + */ + pagefault_disable(); + ret = __copy_from_user_inatomic(to, from, n); + pagefault_enable(); + + return n - ret; } EXPORT_SYMBOL_GPL(copy_from_user_nmi); diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c index 3aaeffcfd67a..7a517bb41060 100644 --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -51,7 +51,7 @@ kmmio_fault(struct pt_regs *regs, unsigned long addr) return 0; } -static inline int __kprobes notify_page_fault(struct pt_regs *regs) +static inline int __kprobes kprobes_fault(struct pt_regs *regs) { int ret = 0; @@ -1048,7 +1048,7 @@ __do_page_fault(struct pt_regs *regs, unsigned long error_code) return; /* kprobes don't want to hook the spurious faults: */ - if (notify_page_fault(regs)) + if (kprobes_fault(regs)) return; /* * Don't take the mm semaphore here. If we fixup a prefetch @@ -1060,23 +1060,8 @@ __do_page_fault(struct pt_regs *regs, unsigned long error_code) } /* kprobes don't want to hook the spurious faults: */ - if (unlikely(notify_page_fault(regs))) + if (unlikely(kprobes_fault(regs))) return; - /* - * It's safe to allow irq's after cr2 has been saved and the - * vmalloc fault has been handled. - * - * User-mode registers count as a user access even for any - * potential system fault or CPU buglet: - */ - if (user_mode_vm(regs)) { - local_irq_enable(); - error_code |= PF_USER; - flags |= FAULT_FLAG_USER; - } else { - if (regs->flags & X86_EFLAGS_IF) - local_irq_enable(); - } if (unlikely(error_code & PF_RSVD)) pgtable_bad(regs, error_code, address); @@ -1088,8 +1073,6 @@ __do_page_fault(struct pt_regs *regs, unsigned long error_code) } } - perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address); - /* * If we're in an interrupt, have no user context or are running * in an atomic region then we must not take the fault: @@ -1099,6 +1082,24 @@ __do_page_fault(struct pt_regs *regs, unsigned long error_code) return; } + /* + * It's safe to allow irq's after cr2 has been saved and the + * vmalloc fault has been handled. + * + * User-mode registers count as a user access even for any + * potential system fault or CPU buglet: + */ + if (user_mode_vm(regs)) { + local_irq_enable(); + error_code |= PF_USER; + flags |= FAULT_FLAG_USER; + } else { + if (regs->flags & X86_EFLAGS_IF) + local_irq_enable(); + } + + perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address); + if (error_code & PF_WRITE) flags |= FAULT_FLAG_WRITE; |