diff options
| -rw-r--r-- | arch/s390/mm/fault.c | 259 |
1 files changed, 141 insertions, 118 deletions
diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c index 7462aebd3eb..8bc35183db5 100644 --- a/arch/s390/mm/fault.c +++ b/arch/s390/mm/fault.c @@ -63,21 +63,25 @@ int unregister_page_fault_notifier(struct notifier_block *nb) return atomic_notifier_chain_unregister(¬ify_page_fault_chain, nb); } -static inline int notify_page_fault(enum die_val val, const char *str, - struct pt_regs *regs, long err, int trap, int sig) +static int __kprobes __notify_page_fault(struct pt_regs *regs, long err) { - struct die_args args = { - .regs = regs, - .str = str, - .err = err, - .trapnr = trap, - .signr = sig - }; - return atomic_notifier_call_chain(¬ify_page_fault_chain, val, &args); + struct die_args args = { .str = "page fault", + .trapnr = 14, + .signr = SIGSEGV }; + args.regs = regs; + args.err = err; + return atomic_notifier_call_chain(¬ify_page_fault_chain, + DIE_PAGE_FAULT, &args); +} + +static inline int notify_page_fault(struct pt_regs *regs, long err) +{ + if (unlikely(kprobe_running())) + return __notify_page_fault(regs, err); + return NOTIFY_DONE; } #else -static inline int notify_page_fault(enum die_val val, const char *str, - struct pt_regs *regs, long err, int trap, int sig) +static inline int notify_page_fault(struct pt_regs *regs, long err) { return NOTIFY_DONE; } @@ -170,6 +174,89 @@ static void do_sigsegv(struct pt_regs *regs, unsigned long error_code, force_sig_info(SIGSEGV, &si, current); } +static void do_no_context(struct pt_regs *regs, unsigned long error_code, + unsigned long address) +{ + const struct exception_table_entry *fixup; + + /* Are we prepared to handle this kernel fault? */ + fixup = search_exception_tables(regs->psw.addr & __FIXUP_MASK); + if (fixup) { + regs->psw.addr = fixup->fixup | PSW_ADDR_AMODE; + return; + } + + /* + * Oops. The kernel tried to access some bad page. We'll have to + * terminate things with extreme prejudice. + */ + if (check_space(current) == 0) + printk(KERN_ALERT "Unable to handle kernel pointer dereference" + " at virtual kernel address %p\n", (void *)address); + else + printk(KERN_ALERT "Unable to handle kernel paging request" + " at virtual user address %p\n", (void *)address); + + die("Oops", regs, error_code); + do_exit(SIGKILL); +} + +static void do_low_address(struct pt_regs *regs, unsigned long error_code) +{ + /* Low-address protection hit in kernel mode means + NULL pointer write access in kernel mode. */ + if (regs->psw.mask & PSW_MASK_PSTATE) { + /* Low-address protection hit in user mode 'cannot happen'. */ + die ("Low-address protection", regs, error_code); + do_exit(SIGKILL); + } + + do_no_context(regs, error_code, 0); +} + +/* + * We ran out of memory, or some other thing happened to us that made + * us unable to handle the page fault gracefully. + */ +static int do_out_of_memory(struct pt_regs *regs, unsigned long error_code, + unsigned long address) +{ + struct task_struct *tsk = current; + struct mm_struct *mm = tsk->mm; + + up_read(&mm->mmap_sem); + if (is_init(tsk)) { + yield(); + down_read(&mm->mmap_sem); + return 1; + } + printk("VM: killing process %s\n", tsk->comm); + if (regs->psw.mask & PSW_MASK_PSTATE) + do_exit(SIGKILL); + do_no_context(regs, error_code, address); + return 0; +} + +static void do_sigbus(struct pt_regs *regs, unsigned long error_code, + unsigned long address) +{ + struct task_struct *tsk = current; + struct mm_struct *mm = tsk->mm; + + up_read(&mm->mmap_sem); + /* + * Send a sigbus, regardless of whether we were in kernel + * or user mode. + */ + tsk->thread.prot_addr = address; + tsk->thread.trap_no = error_code; + force_sig(SIGBUS, tsk); + + /* Kernel mode? Handle exceptions or die */ + if (!(regs->psw.mask & PSW_MASK_PSTATE)) + do_no_context(regs, error_code, address); +} + #ifdef CONFIG_S390_EXEC_PROTECT extern long sys_sigreturn(struct pt_regs *regs); extern long sys_rt_sigreturn(struct pt_regs *regs); @@ -253,49 +340,23 @@ out_fault: * 3b Region third trans. -> Not present (nullification) */ static inline void -do_exception(struct pt_regs *regs, unsigned long error_code, int is_protection) +do_exception(struct pt_regs *regs, unsigned long error_code, int write) { - struct task_struct *tsk; - struct mm_struct *mm; - struct vm_area_struct * vma; - unsigned long address; - const struct exception_table_entry *fixup; - int si_code; + struct task_struct *tsk; + struct mm_struct *mm; + struct vm_area_struct *vma; + unsigned long address; int space; + int si_code; - tsk = current; - mm = tsk->mm; - - if (notify_page_fault(DIE_PAGE_FAULT, "page fault", regs, error_code, 14, - SIGSEGV) == NOTIFY_STOP) + if (notify_page_fault(regs, error_code) == NOTIFY_STOP) return; - /* - * Check for low-address protection. This needs to be treated - * as a special case because the translation exception code - * field is not guaranteed to contain valid data in this case. - */ - if (is_protection && !(S390_lowcore.trans_exc_code & 4)) { - - /* Low-address protection hit in kernel mode means - NULL pointer write access in kernel mode. */ - if (!(regs->psw.mask & PSW_MASK_PSTATE)) { - address = 0; - space = 0; - goto no_context; - } - - /* Low-address protection hit in user mode 'cannot happen'. */ - die ("Low-address protection", regs, error_code); - do_exit(SIGKILL); - } + tsk = current; + mm = tsk->mm; - /* - * get the failing address - * more specific the segment and page table portion of - * the address - */ - address = S390_lowcore.trans_exc_code & __FAIL_ADDR_MASK; + /* get the failing address and the affected space */ + address = S390_lowcore.trans_exc_code & __FAIL_ADDR_MASK; space = check_space(tsk); /* @@ -313,7 +374,7 @@ do_exception(struct pt_regs *regs, unsigned long error_code, int is_protection) */ local_irq_enable(); - down_read(&mm->mmap_sem); + down_read(&mm->mmap_sem); si_code = SEGV_MAPERR; vma = find_vma(mm, address); @@ -330,19 +391,19 @@ do_exception(struct pt_regs *regs, unsigned long error_code, int is_protection) return; #endif - if (vma->vm_start <= address) - goto good_area; - if (!(vma->vm_flags & VM_GROWSDOWN)) - goto bad_area; - if (expand_stack(vma, address)) - goto bad_area; + if (vma->vm_start <= address) + goto good_area; + if (!(vma->vm_flags & VM_GROWSDOWN)) + goto bad_area; + if (expand_stack(vma, address)) + goto bad_area; /* * Ok, we have a good vm_area for this memory access, so * we can handle it.. */ good_area: si_code = SEGV_ACCERR; - if (!is_protection) { + if (!write) { /* page not present, check vm flags */ if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE))) goto bad_area; @@ -357,7 +418,7 @@ survive: * make sure we exit gracefully rather than endlessly redo * the fault. */ - switch (handle_mm_fault(mm, vma, address, is_protection)) { + switch (handle_mm_fault(mm, vma, address, write)) { case VM_FAULT_MINOR: tsk->min_flt++; break; @@ -365,9 +426,12 @@ survive: tsk->maj_flt++; break; case VM_FAULT_SIGBUS: - goto do_sigbus; + do_sigbus(regs, error_code, address); + return; case VM_FAULT_OOM: - goto out_of_memory; + if (do_out_of_memory(regs, error_code, address)) + goto survive; + return; default: BUG(); } @@ -385,75 +449,34 @@ survive: * Fix it, but check if it's kernel or user first.. */ bad_area: - up_read(&mm->mmap_sem); + up_read(&mm->mmap_sem); - /* User mode accesses just cause a SIGSEGV */ - if (regs->psw.mask & PSW_MASK_PSTATE) { - tsk->thread.prot_addr = address; - tsk->thread.trap_no = error_code; + /* User mode accesses just cause a SIGSEGV */ + if (regs->psw.mask & PSW_MASK_PSTATE) { + tsk->thread.prot_addr = address; + tsk->thread.trap_no = error_code; do_sigsegv(regs, error_code, si_code, address); - return; + return; } no_context: - /* Are we prepared to handle this kernel fault? */ - fixup = search_exception_tables(regs->psw.addr & __FIXUP_MASK); - if (fixup) { - regs->psw.addr = fixup->fixup | PSW_ADDR_AMODE; - return; - } - -/* - * Oops. The kernel tried to access some bad page. We'll have to - * terminate things with extreme prejudice. - */ - if (space == 0) - printk(KERN_ALERT "Unable to handle kernel pointer dereference" - " at virtual kernel address %p\n", (void *)address); - else - printk(KERN_ALERT "Unable to handle kernel paging request" - " at virtual user address %p\n", (void *)address); - - die("Oops", regs, error_code); - do_exit(SIGKILL); - - -/* - * We ran out of memory, or some other thing happened to us that made - * us unable to handle the page fault gracefully. -*/ -out_of_memory: - up_read(&mm->mmap_sem); - if (is_init(tsk)) { - yield(); - down_read(&mm->mmap_sem); - goto survive; - } - printk("VM: killing process %s\n", tsk->comm); - if (regs->psw.mask & PSW_MASK_PSTATE) - do_exit(SIGKILL); - goto no_context; - -do_sigbus: - up_read(&mm->mmap_sem); - - /* - * Send a sigbus, regardless of whether we were in kernel - * or user mode. - */ - tsk->thread.prot_addr = address; - tsk->thread.trap_no = error_code; - force_sig(SIGBUS, tsk); - - /* Kernel mode? Handle exceptions or die */ - if (!(regs->psw.mask & PSW_MASK_PSTATE)) - goto no_context; + do_no_context(regs, error_code, address); } void __kprobes do_protection_exception(struct pt_regs *regs, unsigned long error_code) { + /* Protection exception is supressing, decrement psw address. */ regs->psw.addr -= (error_code >> 16); + /* + * Check for low-address protection. This needs to be treated + * as a special case because the translation exception code + * field is not guaranteed to contain valid data in this case. + */ + if (unlikely(!(S390_lowcore.trans_exc_code & 4))) { + do_low_address(regs, error_code); + return; + } do_exception(regs, 4, 1); } |