/* * fault.c: Page fault handlers for the Sparc. * * Copyright (C) 1995 David S. Miller (davem@caip.rutgers.edu) * Copyright (C) 1996 Eddie C. Dost (ecd@skynet.be) * Copyright (C) 1997 Jakub Jelinek (jj@sunsite.mff.cuni.cz) */ #include <asm/head.h> #include <linux/string.h> #include <linux/types.h> #include <linux/sched.h> #include <linux/ptrace.h> #include <linux/mman.h> #include <linux/threads.h> #include <linux/kernel.h> #include <linux/signal.h> #include <linux/mm.h> #include <linux/smp.h> #include <linux/perf_event.h> #include <linux/interrupt.h> #include <linux/kdebug.h> #include <asm/system.h> #include <asm/page.h> #include <asm/pgtable.h> #include <asm/memreg.h> #include <asm/openprom.h> #include <asm/oplib.h> #include <asm/smp.h> #include <asm/traps.h> #include <asm/uaccess.h> extern int prom_node_root; int show_unhandled_signals = 1; /* At boot time we determine these two values necessary for setting * up the segment maps and page table entries (pte's). */ int num_segmaps, num_contexts; int invalid_segment; /* various Virtual Address Cache parameters we find at boot time... */ int vac_size, vac_linesize, vac_do_hw_vac_flushes; int vac_entries_per_context, vac_entries_per_segment; int vac_entries_per_page; /* Return how much physical memory we have. */ unsigned long probe_memory(void) { unsigned long total = 0; int i; for (i = 0; sp_banks[i].num_bytes; i++) total += sp_banks[i].num_bytes; return total; } extern void sun4c_complete_all_stores(void); /* Whee, a level 15 NMI interrupt memory error. Let's have fun... */ asmlinkage void sparc_lvl15_nmi(struct pt_regs *regs, unsigned long serr, unsigned long svaddr, unsigned long aerr, unsigned long avaddr) { sun4c_complete_all_stores(); printk("FAULT: NMI received\n"); printk("SREGS: Synchronous Error %08lx\n", serr); printk(" Synchronous Vaddr %08lx\n", svaddr); printk(" Asynchronous Error %08lx\n", aerr); printk(" Asynchronous Vaddr %08lx\n", avaddr); if (sun4c_memerr_reg) printk(" Memory Parity Error %08lx\n", *sun4c_memerr_reg); printk("REGISTER DUMP:\n"); show_regs(regs); prom_halt(); } static void unhandled_fault(unsigned long, struct task_struct *, struct pt_regs *) __attribute__ ((noreturn)); static void unhandled_fault(unsigned long address, struct task_struct *tsk, struct pt_regs *regs) { if((unsigned long) address < PAGE_SIZE) { printk(KERN_ALERT "Unable to handle kernel NULL pointer dereference\n"); } else { printk(KERN_ALERT "Unable to handle kernel paging request " "at virtual address %08lx\n", address); } printk(KERN_ALERT "tsk->{mm,active_mm}->context = %08lx\n", (tsk->mm ? tsk->mm->context : tsk->active_mm->context)); printk(KERN_ALERT "tsk->{mm,active_mm}->pgd = %08lx\n", (tsk->mm ? (unsigned long) tsk->mm->pgd : (unsigned long) tsk->active_mm->pgd)); die_if_kernel("Oops", regs); } asmlinkage int lookup_fault(unsigned long pc, unsigned long ret_pc, unsigned long address) { struct pt_regs regs; unsigned long g2; unsigned int insn; int i; i = search_extables_range(ret_pc, &g2); switch (i) { case 3: /* load & store will be handled by fixup */ return 3; case 1: /* store will be handled by fixup, load will bump out */ /* for _to_ macros */ insn = *((unsigned int *) pc); if ((insn >> 21) & 1) return 1; break; case 2: /* load will be handled by fixup, store will bump out */ /* for _from_ macros */ insn = *((unsigned int *) pc); if (!((insn >> 21) & 1) || ((insn>>19)&0x3f) == 15) return 2; break; default: break; } memset(®s, 0, sizeof (regs)); regs.pc = pc; regs.npc = pc + 4; __asm__ __volatile__( "rd %%psr, %0\n\t" "nop\n\t" "nop\n\t" "nop\n" : "=r" (regs.psr)); unhandled_fault(address, current, ®s); /* Not reached */ return 0; } static inline void show_signal_msg(struct pt_regs *regs, int sig, int code, unsigned long address, struct task_struct *tsk) { if (!unhandled_signal(tsk, sig)) return; if (!printk_ratelimit()) return; printk("%s%s[%d]: segfault at %lx ip %p (rpc %p) sp %p error %x", task_pid_nr(tsk) > 1 ? KERN_INFO : KERN_EMERG, tsk->comm, task_pid_nr(tsk), address, (void *)regs->pc, (void *)regs->u_regs[UREG_I7], (void *)regs->u_regs[UREG_FP], code); print_vma_addr(KERN_CONT " in ", regs->pc); printk(KERN_CONT "\n"); } static void __do_fault_siginfo(int code, int sig, struct pt_regs *regs, unsigned long addr) { siginfo_t info; info.si_signo = sig; info.si_code = code; info.si_errno = 0; info.si_addr = (void __user *) addr; info.si_trapno = 0; if (unlikely(show_unhandled_signals)) show_signal_msg(regs, sig, info.si_code, addr, current); force_sig_info (sig, &info, current); } extern unsigned long safe_compute_effective_address(struct pt_regs *, unsigned int); static unsigned long compute_si_addr(struct pt_regs *regs, int text_fault) { unsigned int insn; if (text_fault) return regs->pc; if (regs->psr & PSR_PS) { insn = *(unsigned int *) regs->pc; } else { __get_user(insn, (unsigned int *) regs->pc); } return safe_compute_effective_address(regs, insn); } static noinline void do_fault_siginfo(int code, int sig, struct pt_regs *regs, int text_fault) { unsigned long addr = compute_si_addr(regs, text_fault); __do_fault_siginfo(code, sig, regs, addr); } asmlinkage void do_sparc_fault(struct pt_regs *regs, int text_fault, int write, unsigned long address) { struct vm_area_struct *vma; struct task_struct *tsk = current; struct mm_struct *mm = tsk->mm; unsigned int fixup; unsigned long g2; int from_user = !(regs->psr & PSR_PS); int fault, code; if(text_fault) address = regs->pc; /* * We fault-in kernel-space virtual memory on-demand. The * 'reference' page table is init_mm.pgd. * * NOTE! We MUST NOT take any locks for this case. We may * be in an interrupt or a critical region, and should * only copy the information from the master page table, * nothing more. */ code = SEGV_MAPERR; if (!ARCH_SUN4C && address >= TASK_SIZE) goto vmalloc_fault; /* * If we're in an interrupt or have no user * context, we must not take the fault.. */ if (in_atomic() || !mm) goto no_context; perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address); down_read(&mm->mmap_sem); /* * The kernel referencing a bad kernel pointer can lock up * a sun4c machine completely, so we must attempt recovery. */ if(!from_user && address >= PAGE_OFFSET) goto bad_area; vma = find_vma(mm, address); if(!vma) 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: code = SEGV_ACCERR; if(write) { if(!(vma->vm_flags & VM_WRITE)) goto bad_area; } else { /* Allow reads even for write-only mappings */ if(!(vma->vm_flags & (VM_READ | VM_EXEC))) goto bad_area; } /* * If for any reason at all we couldn't handle the fault, * make sure we exit gracefully rather than endlessly redo * the fault. */ fault = handle_mm_fault(mm, vma, address, write ? FAULT_FLAG_WRITE : 0); if (unlikely(fault & VM_FAULT_ERROR)) { if (fault & VM_FAULT_OOM) goto out_of_memory; else if (fault & VM_FAULT_SIGBUS) goto do_sigbus; BUG(); } if (fault & VM_FAULT_MAJOR) { current->maj_flt++; perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, regs, address); } else { current->min_flt++; perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, regs, address); } up_read(&mm->mmap_sem); return; /* * Something tried to access memory that isn't in our memory map.. * Fix it, but check if it's kernel or user first.. */ bad_area: up_read(&mm->mmap_sem); bad_area_nosemaphore: /* User mode accesses just cause a SIGSEGV */ if (from_user) { do_fault_siginfo(code, SIGSEGV, regs, text_fault); return; } /* Is this in ex_table? */ no_context: g2 = regs->u_regs[UREG_G2]; if (!from_user) { fixup = search_extables_range(regs->pc, &g2); if (fixup > 10) { /* Values below are reserved for other things */ extern const unsigned __memset_start[]; extern const unsigned __memset_end[]; extern const unsigned __csum_partial_copy_start[]; extern const unsigned __csum_partial_copy_end[]; #ifdef DEBUG_EXCEPTIONS printk("Exception: PC<%08lx> faddr<%08lx>\n", regs->pc, address); printk("EX_TABLE: insn<%08lx> fixup<%08x> g2<%08lx>\n", regs->pc, fixup, g2); #endif if ((regs->pc >= (unsigned long)__memset_start && regs->pc < (unsigned long)__memset_end) || (regs->pc >= (unsigned long)__csum_partial_copy_start && regs->pc < (unsigned long)__csum_partial_copy_end)) { regs->u_regs[UREG_I4] = address; regs->u_regs[UREG_I5] = regs->pc; } regs->u_regs[UREG_G2] = g2; regs->pc = fixup; regs->npc = regs->pc + 4; return; } } unhandled_fault (address, tsk, regs); 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 (from_user) { pagefault_out_of_memory(); return; } goto no_context; do_sigbus: up_read(&mm->mmap_sem); do_fault_siginfo(BUS_ADRERR, SIGBUS, regs, text_fault); if (!from_user) goto no_context; vmalloc_fault: { /* * Synchronize this task's top level page-table * with the 'reference' page table. */ int offset = pgd_index(address); pgd_t *pgd, *pgd_k; pmd_t *pmd, *pmd_k; pgd = tsk->active_mm->pgd + offset; pgd_k = init_mm.pgd + offset; if (!pgd_present(*pgd)) { if (!pgd_present(*pgd_k)) goto bad_area_nosemaphore; pgd_val(*pgd) = pgd_val(*pgd_k); return; } pmd = pmd_offset(pgd, address); pmd_k = pmd_offset(pgd_k, address); if (pmd_present(*pmd) || !pmd_present(*pmd_k)) goto bad_area_nosemaphore; *pmd = *pmd_k; return; } } asmlinkage void do_sun4c_fault(struct pt_regs *regs, int text_fault, int write, unsigned long address) { extern void sun4c_update_mmu_cache(struct vm_area_struct *, unsigned long,pte_t *); extern pte_t *sun4c_pte_offset_kernel(pmd_t *,unsigned long); struct task_struct *tsk = current; struct mm_struct *mm = tsk->mm; pgd_t *pgdp; pte_t *ptep; if (text_fault) { address = regs->pc; } else if (!write && !(regs->psr & PSR_PS)) { unsigned int insn, __user *ip; ip = (unsigned int __user *)regs->pc; if (!get_user(insn, ip)) { if ((insn & 0xc1680000) == 0xc0680000) write = 1; } } if (!mm) { /* We are oopsing. */ do_sparc_fault(regs, text_fault, write, address); BUG(); /* P3 Oops already, you bitch */ } pgdp = pgd_offset(mm, address); ptep = sun4c_pte_offset_kernel((pmd_t *) pgdp, address); if (pgd_val(*pgdp)) { if (write) { if ((pte_val(*ptep) & (_SUN4C_PAGE_WRITE|_SUN4C_PAGE_PRESENT)) == (_SUN4C_PAGE_WRITE|_SUN4C_PAGE_PRESENT)) { unsigned long flags; *ptep = __pte(pte_val(*ptep) | _SUN4C_PAGE_ACCESSED | _SUN4C_PAGE_MODIFIED | _SUN4C_PAGE_VALID | _SUN4C_PAGE_DIRTY); local_irq_save(flags); if (sun4c_get_segmap(address) != invalid_segment) { sun4c_put_pte(address, pte_val(*ptep)); local_irq_restore(flags); return; } local_irq_restore(flags); } } else { if ((pte_val(*ptep) & (_SUN4C_PAGE_READ|_SUN4C_PAGE_PRESENT)) == (_SUN4C_PAGE_READ|_SUN4C_PAGE_PRESENT)) { unsigned long flags; *ptep = __pte(pte_val(*ptep) | _SUN4C_PAGE_ACCESSED | _SUN4C_PAGE_VALID); local_irq_save(flags); if (sun4c_get_segmap(address) != invalid_segment) { sun4c_put_pte(address, pte_val(*ptep)); local_irq_restore(flags); return; } local_irq_restore(flags); } } } /* This conditional is 'interesting'. */ if (pgd_val(*pgdp) && !(write && !(pte_val(*ptep) & _SUN4C_PAGE_WRITE)) && (pte_val(*ptep) & _SUN4C_PAGE_VALID)) /* Note: It is safe to not grab the MMAP semaphore here because * we know that update_mmu_cache() will not sleep for * any reason (at least not in the current implementation) * and therefore there is no danger of another thread getting * on the CPU and doing a shrink_mmap() on this vma. */ sun4c_update_mmu_cache (find_vma(current->mm, address), address, ptep); else do_sparc_fault(regs, text_fault, write, address); } /* This always deals with user addresses. */ static void force_user_fault(unsigned long address, int write) { struct vm_area_struct *vma; struct task_struct *tsk = current; struct mm_struct *mm = tsk->mm; int code; code = SEGV_MAPERR; down_read(&mm->mmap_sem); vma = find_vma(mm, address); if(!vma) 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; good_area: code = SEGV_ACCERR; if(write) { if(!(vma->vm_flags & VM_WRITE)) goto bad_area; } else { if(!(vma->vm_flags & (VM_READ | VM_EXEC))) goto bad_area; } switch (handle_mm_fault(mm, vma, address, write ? FAULT_FLAG_WRITE : 0)) { case VM_FAULT_SIGBUS: case VM_FAULT_OOM: goto do_sigbus; } up_read(&mm->mmap_sem); return; bad_area: up_read(&mm->mmap_sem); __do_fault_siginfo(code, SIGSEGV, tsk->thread.kregs, address); return; do_sigbus: up_read(&mm->mmap_sem); __do_fault_siginfo(BUS_ADRERR, SIGBUS, tsk->thread.kregs, address); } static void check_stack_aligned(unsigned long sp) { if (sp & 0x7UL) force_sig(SIGILL, current); } void window_overflow_fault(void) { unsigned long sp; sp = current_thread_info()->rwbuf_stkptrs[0]; if(((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK)) force_user_fault(sp + 0x38, 1); force_user_fault(sp, 1); check_stack_aligned(sp); } void window_underflow_fault(unsigned long sp) { if(((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK)) force_user_fault(sp + 0x38, 0); force_user_fault(sp, 0); check_stack_aligned(sp); } void window_ret_fault(struct pt_regs *regs) { unsigned long sp; sp = regs->u_regs[UREG_FP]; if(((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK)) force_user_fault(sp + 0x38, 0); force_user_fault(sp, 0); check_stack_aligned(sp); }