diff options
Diffstat (limited to 'arch/x86/mm/fault.c')
| -rw-r--r-- | arch/x86/mm/fault.c | 167 |
1 files changed, 58 insertions, 109 deletions
diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c index 2b1519bc5381..b24eb4eb9984 100644 --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -157,79 +157,6 @@ is_prefetch(struct pt_regs *regs, unsigned long error_code, unsigned long addr) return prefetch; } -/* - * A protection key fault means that the PKRU value did not allow - * access to some PTE. Userspace can figure out what PKRU was - * from the XSAVE state, and this function fills out a field in - * siginfo so userspace can discover which protection key was set - * on the PTE. - * - * If we get here, we know that the hardware signaled a X86_PF_PK - * fault and that there was a VMA once we got in the fault - * handler. It does *not* guarantee that the VMA we find here - * was the one that we faulted on. - * - * 1. T1 : mprotect_key(foo, PAGE_SIZE, pkey=4); - * 2. T1 : set PKRU to deny access to pkey=4, touches page - * 3. T1 : faults... - * 4. T2: mprotect_key(foo, PAGE_SIZE, pkey=5); - * 5. T1 : enters fault handler, takes mmap_sem, etc... - * 6. T1 : reaches here, sees vma_pkey(vma)=5, when we really - * faulted on a pte with its pkey=4. - */ -static void fill_sig_info_pkey(int si_signo, int si_code, siginfo_t *info, - u32 *pkey) -{ - /* This is effectively an #ifdef */ - if (!boot_cpu_has(X86_FEATURE_OSPKE)) - return; - - /* Fault not from Protection Keys: nothing to do */ - if ((si_code != SEGV_PKUERR) || (si_signo != SIGSEGV)) - return; - /* - * force_sig_info_fault() is called from a number of - * contexts, some of which have a VMA and some of which - * do not. The X86_PF_PK handing happens after we have a - * valid VMA, so we should never reach this without a - * valid VMA. - */ - if (!pkey) { - WARN_ONCE(1, "PKU fault with no VMA passed in"); - info->si_pkey = 0; - return; - } - /* - * si_pkey should be thought of as a strong hint, but not - * absolutely guranteed to be 100% accurate because of - * the race explained above. - */ - info->si_pkey = *pkey; -} - -static void -force_sig_info_fault(int si_signo, int si_code, unsigned long address, - struct task_struct *tsk, u32 *pkey, int fault) -{ - unsigned lsb = 0; - siginfo_t info; - - clear_siginfo(&info); - info.si_signo = si_signo; - info.si_errno = 0; - info.si_code = si_code; - info.si_addr = (void __user *)address; - if (fault & VM_FAULT_HWPOISON_LARGE) - lsb = hstate_index_to_shift(VM_FAULT_GET_HINDEX(fault)); - if (fault & VM_FAULT_HWPOISON) - lsb = PAGE_SHIFT; - info.si_addr_lsb = lsb; - - fill_sig_info_pkey(si_signo, si_code, &info, pkey); - - force_sig_info(si_signo, &info, tsk); -} - DEFINE_SPINLOCK(pgd_lock); LIST_HEAD(pgd_list); @@ -734,8 +661,8 @@ no_context(struct pt_regs *regs, unsigned long error_code, tsk->thread.cr2 = address; /* XXX: hwpoison faults will set the wrong code. */ - force_sig_info_fault(signal, si_code, address, - tsk, NULL, 0); + force_sig_fault(signal, si_code, (void __user *)address, + tsk); } /* @@ -862,7 +789,7 @@ static bool is_vsyscall_vaddr(unsigned long vaddr) static void __bad_area_nosemaphore(struct pt_regs *regs, unsigned long error_code, - unsigned long address, u32 *pkey, int si_code) + unsigned long address, u32 pkey, int si_code) { struct task_struct *tsk = current; @@ -898,7 +825,10 @@ __bad_area_nosemaphore(struct pt_regs *regs, unsigned long error_code, tsk->thread.error_code = error_code; tsk->thread.trap_nr = X86_TRAP_PF; - force_sig_info_fault(SIGSEGV, si_code, address, tsk, pkey, 0); + if (si_code == SEGV_PKUERR) + force_sig_pkuerr((void __user *)address, pkey); + + force_sig_fault(SIGSEGV, si_code, (void __user *)address, tsk); return; } @@ -911,35 +841,29 @@ __bad_area_nosemaphore(struct pt_regs *regs, unsigned long error_code, static noinline void bad_area_nosemaphore(struct pt_regs *regs, unsigned long error_code, - unsigned long address, u32 *pkey) + unsigned long address) { - __bad_area_nosemaphore(regs, error_code, address, pkey, SEGV_MAPERR); + __bad_area_nosemaphore(regs, error_code, address, 0, SEGV_MAPERR); } static void __bad_area(struct pt_regs *regs, unsigned long error_code, - unsigned long address, struct vm_area_struct *vma, int si_code) + unsigned long address, u32 pkey, int si_code) { struct mm_struct *mm = current->mm; - u32 pkey; - - if (vma) - pkey = vma_pkey(vma); - /* * Something tried to access memory that isn't in our memory map.. * Fix it, but check if it's kernel or user first.. */ up_read(&mm->mmap_sem); - __bad_area_nosemaphore(regs, error_code, address, - (vma) ? &pkey : NULL, si_code); + __bad_area_nosemaphore(regs, error_code, address, pkey, si_code); } static noinline void bad_area(struct pt_regs *regs, unsigned long error_code, unsigned long address) { - __bad_area(regs, error_code, address, NULL, SEGV_MAPERR); + __bad_area(regs, error_code, address, 0, SEGV_MAPERR); } static inline bool bad_area_access_from_pkeys(unsigned long error_code, @@ -968,18 +892,40 @@ bad_area_access_error(struct pt_regs *regs, unsigned long error_code, * But, doing it this way allows compiler optimizations * if pkeys are compiled out. */ - if (bad_area_access_from_pkeys(error_code, vma)) - __bad_area(regs, error_code, address, vma, SEGV_PKUERR); - else - __bad_area(regs, error_code, address, vma, SEGV_ACCERR); + if (bad_area_access_from_pkeys(error_code, vma)) { + /* + * A protection key fault means that the PKRU value did not allow + * access to some PTE. Userspace can figure out what PKRU was + * from the XSAVE state. This function captures the pkey from + * the vma and passes it to userspace so userspace can discover + * which protection key was set on the PTE. + * + * If we get here, we know that the hardware signaled a X86_PF_PK + * fault and that there was a VMA once we got in the fault + * handler. It does *not* guarantee that the VMA we find here + * was the one that we faulted on. + * + * 1. T1 : mprotect_key(foo, PAGE_SIZE, pkey=4); + * 2. T1 : set PKRU to deny access to pkey=4, touches page + * 3. T1 : faults... + * 4. T2: mprotect_key(foo, PAGE_SIZE, pkey=5); + * 5. T1 : enters fault handler, takes mmap_sem, etc... + * 6. T1 : reaches here, sees vma_pkey(vma)=5, when we really + * faulted on a pte with its pkey=4. + */ + u32 pkey = vma_pkey(vma); + + __bad_area(regs, error_code, address, pkey, SEGV_PKUERR); + } else { + __bad_area(regs, error_code, address, 0, SEGV_ACCERR); + } } static void do_sigbus(struct pt_regs *regs, unsigned long error_code, unsigned long address, - u32 *pkey, unsigned int fault) + unsigned int fault) { struct task_struct *tsk = current; - int code = BUS_ADRERR; /* Kernel mode? Handle exceptions or die: */ if (!(error_code & X86_PF_USER)) { @@ -997,18 +943,25 @@ do_sigbus(struct pt_regs *regs, unsigned long error_code, unsigned long address, #ifdef CONFIG_MEMORY_FAILURE if (fault & (VM_FAULT_HWPOISON|VM_FAULT_HWPOISON_LARGE)) { - printk(KERN_ERR + unsigned lsb = 0; + + pr_err( "MCE: Killing %s:%d due to hardware memory corruption fault at %lx\n", tsk->comm, tsk->pid, address); - code = BUS_MCEERR_AR; + if (fault & VM_FAULT_HWPOISON_LARGE) + lsb = hstate_index_to_shift(VM_FAULT_GET_HINDEX(fault)); + if (fault & VM_FAULT_HWPOISON) + lsb = PAGE_SHIFT; + force_sig_mceerr(BUS_MCEERR_AR, (void __user *)address, lsb, tsk); + return; } #endif - force_sig_info_fault(SIGBUS, code, address, tsk, pkey, fault); + force_sig_fault(SIGBUS, BUS_ADRERR, (void __user *)address, tsk); } static noinline void mm_fault_error(struct pt_regs *regs, unsigned long error_code, - unsigned long address, u32 *pkey, vm_fault_t fault) + unsigned long address, vm_fault_t fault) { if (fatal_signal_pending(current) && !(error_code & X86_PF_USER)) { no_context(regs, error_code, address, 0, 0); @@ -1032,9 +985,9 @@ mm_fault_error(struct pt_regs *regs, unsigned long error_code, } else { if (fault & (VM_FAULT_SIGBUS|VM_FAULT_HWPOISON| VM_FAULT_HWPOISON_LARGE)) - do_sigbus(regs, error_code, address, pkey, fault); + do_sigbus(regs, error_code, address, fault); else if (fault & VM_FAULT_SIGSEGV) - bad_area_nosemaphore(regs, error_code, address, pkey); + bad_area_nosemaphore(regs, error_code, address); else BUG(); } @@ -1267,7 +1220,7 @@ do_kern_addr_fault(struct pt_regs *regs, unsigned long hw_error_code, * Don't take the mm semaphore here. If we fixup a prefetch * fault we could otherwise deadlock: */ - bad_area_nosemaphore(regs, hw_error_code, address, NULL); + bad_area_nosemaphore(regs, hw_error_code, address); } NOKPROBE_SYMBOL(do_kern_addr_fault); @@ -1283,7 +1236,6 @@ void do_user_addr_fault(struct pt_regs *regs, struct mm_struct *mm; vm_fault_t fault, major = 0; unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE; - u32 pkey; tsk = current; mm = tsk->mm; @@ -1304,7 +1256,7 @@ void do_user_addr_fault(struct pt_regs *regs, * pages in the user address space. */ if (unlikely(smap_violation(hw_error_code, regs))) { - bad_area_nosemaphore(regs, hw_error_code, address, NULL); + bad_area_nosemaphore(regs, hw_error_code, address); return; } @@ -1313,7 +1265,7 @@ void do_user_addr_fault(struct pt_regs *regs, * in a region with pagefaults disabled then we must not take the fault */ if (unlikely(faulthandler_disabled() || !mm)) { - bad_area_nosemaphore(regs, hw_error_code, address, NULL); + bad_area_nosemaphore(regs, hw_error_code, address); return; } @@ -1403,7 +1355,7 @@ void do_user_addr_fault(struct pt_regs *regs, * Fault from code in kernel from * which we do not expect faults. */ - bad_area_nosemaphore(regs, sw_error_code, address, NULL); + bad_area_nosemaphore(regs, sw_error_code, address); return; } retry: @@ -1467,10 +1419,7 @@ good_area: * (potentially after handling any pending signal during the return to * userland). The return to userland is identified whenever * FAULT_FLAG_USER|FAULT_FLAG_KILLABLE are both set in flags. - * Thus we have to be careful about not touching vma after handling the - * fault, so we read the pkey beforehand. */ - pkey = vma_pkey(vma); fault = handle_mm_fault(vma, address, flags); major |= fault & VM_FAULT_MAJOR; @@ -1499,7 +1448,7 @@ good_area: up_read(&mm->mmap_sem); if (unlikely(fault & VM_FAULT_ERROR)) { - mm_fault_error(regs, sw_error_code, address, &pkey, fault); + mm_fault_error(regs, sw_error_code, address, fault); return; } |