diff options
Diffstat (limited to 'arch/s390/mm/fault.c')
| -rw-r--r-- | arch/s390/mm/fault.c | 105 |
1 files changed, 47 insertions, 58 deletions
diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c index 641aef36ccc..7462aebd3eb 100644 --- a/arch/s390/mm/fault.c +++ b/arch/s390/mm/fault.c @@ -108,53 +108,40 @@ void bust_spinlocks(int yes) } /* - * Check which address space is addressed by the access - * register in S390_lowcore.exc_access_id. - * Returns 1 for user space and 0 for kernel space. + * Returns the address space associated with the fault. + * Returns 0 for kernel space, 1 for user space and + * 2 for code execution in user space with noexec=on. */ -static int __check_access_register(struct pt_regs *regs, int error_code) -{ - int areg = S390_lowcore.exc_access_id; - - if (areg == 0) - /* Access via access register 0 -> kernel address */ - return 0; - save_access_regs(current->thread.acrs); - if (regs && areg < NUM_ACRS && current->thread.acrs[areg] <= 1) - /* - * access register contains 0 -> kernel address, - * access register contains 1 -> user space address - */ - return current->thread.acrs[areg]; - - /* Something unhealthy was done with the access registers... */ - die("page fault via unknown access register", regs, error_code); - do_exit(SIGKILL); - return 0; -} - -/* - * Check which address space the address belongs to. - * May return 1 or 2 for user space and 0 for kernel space. - * Returns 2 for user space in primary addressing mode with - * CONFIG_S390_EXEC_PROTECT on and kernel parameter noexec=on. - */ -static inline int check_user_space(struct pt_regs *regs, int error_code) +static inline int check_space(struct task_struct *tsk) { /* - * The lowest two bits of S390_lowcore.trans_exc_code indicate - * which paging table was used: - * 0: Primary Segment Table Descriptor - * 1: STD determined via access register - * 2: Secondary Segment Table Descriptor - * 3: Home Segment Table Descriptor + * The lowest two bits of S390_lowcore.trans_exc_code + * indicate which paging table was used. */ - int descriptor = S390_lowcore.trans_exc_code & 3; - if (unlikely(descriptor == 1)) - return __check_access_register(regs, error_code); - if (descriptor == 2) - return current->thread.mm_segment.ar4; - return ((descriptor != 0) ^ (switch_amode)) << s390_noexec; + int desc = S390_lowcore.trans_exc_code & 3; + + if (desc == 3) /* Home Segment Table Descriptor */ + return switch_amode == 0; + if (desc == 2) /* Secondary Segment Table Descriptor */ + return tsk->thread.mm_segment.ar4; +#ifdef CONFIG_S390_SWITCH_AMODE + if (unlikely(desc == 1)) { /* STD determined via access register */ + /* %a0 always indicates primary space. */ + if (S390_lowcore.exc_access_id != 0) { + save_access_regs(tsk->thread.acrs); + /* + * An alet of 0 indicates primary space. + * An alet of 1 indicates secondary space. + * Any other alet values generate an + * alen-translation exception. + */ + if (tsk->thread.acrs[S390_lowcore.exc_access_id]) + return tsk->thread.mm_segment.ar4; + } + } +#endif + /* Primary Segment Table Descriptor */ + return switch_amode << s390_noexec; } /* @@ -265,16 +252,16 @@ out_fault: * 11 Page translation -> Not present (nullification) * 3b Region third trans. -> Not present (nullification) */ -static inline void __kprobes +static inline void do_exception(struct pt_regs *regs, unsigned long error_code, int is_protection) { struct task_struct *tsk; struct mm_struct *mm; struct vm_area_struct * vma; unsigned long address; - int user_address; const struct exception_table_entry *fixup; - int si_code = SEGV_MAPERR; + int si_code; + int space; tsk = current; mm = tsk->mm; @@ -294,7 +281,7 @@ do_exception(struct pt_regs *regs, unsigned long error_code, int is_protection) NULL pointer write access in kernel mode. */ if (!(regs->psw.mask & PSW_MASK_PSTATE)) { address = 0; - user_address = 0; + space = 0; goto no_context; } @@ -309,15 +296,15 @@ do_exception(struct pt_regs *regs, unsigned long error_code, int is_protection) * the address */ address = S390_lowcore.trans_exc_code & __FAIL_ADDR_MASK; - user_address = check_user_space(regs, error_code); + space = check_space(tsk); /* * Verify that the fault happened in user space, that * we are not in an interrupt and that there is a * user context. */ - if (user_address == 0 || in_atomic() || !mm) - goto no_context; + if (unlikely(space == 0 || in_atomic() || !mm)) + goto no_context; /* * When we get here, the fault happened in the current @@ -328,12 +315,13 @@ do_exception(struct pt_regs *regs, unsigned long error_code, int is_protection) down_read(&mm->mmap_sem); - vma = find_vma(mm, address); - if (!vma) - goto bad_area; + si_code = SEGV_MAPERR; + vma = find_vma(mm, address); + if (!vma) + goto bad_area; #ifdef CONFIG_S390_EXEC_PROTECT - if (unlikely((user_address == 2) && !(vma->vm_flags & VM_EXEC))) + if (unlikely((space == 2) && !(vma->vm_flags & VM_EXEC))) if (!signal_return(mm, regs, address, error_code)) /* * signal_return() has done an up_read(&mm->mmap_sem) @@ -389,7 +377,7 @@ survive: * The instruction that caused the program check will * be repeated. Don't signal single step via SIGTRAP. */ - clear_tsk_thread_flag(current, TIF_SINGLE_STEP); + clear_tsk_thread_flag(tsk, TIF_SINGLE_STEP); return; /* @@ -419,7 +407,7 @@ no_context: * Oops. The kernel tried to access some bad page. We'll have to * terminate things with extreme prejudice. */ - if (user_address == 0) + if (space == 0) printk(KERN_ALERT "Unable to handle kernel pointer dereference" " at virtual kernel address %p\n", (void *)address); else @@ -462,13 +450,14 @@ do_sigbus: goto no_context; } -void do_protection_exception(struct pt_regs *regs, unsigned long error_code) +void __kprobes do_protection_exception(struct pt_regs *regs, + unsigned long error_code) { regs->psw.addr -= (error_code >> 16); do_exception(regs, 4, 1); } -void do_dat_exception(struct pt_regs *regs, unsigned long error_code) +void __kprobes do_dat_exception(struct pt_regs *regs, unsigned long error_code) { do_exception(regs, error_code & 0xff, 0); } |