/* $Id: fault.c,v 1.122 2001/11/17 07:19:26 davem Exp $ * 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 #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #define ELEMENTS(arr) (sizeof (arr)/sizeof (arr[0])) extern struct sparc_phys_banks sp_banks[SPARC_PHYS_BANKS]; extern int prom_node_root; /* 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; /* Nice, simple, prom library does all the sweating for us. ;) */ int prom_probe_memory (void) { register struct linux_mlist_v0 *mlist; register unsigned long bytes, base_paddr, tally; register int i; i = 0; mlist= *prom_meminfo()->v0_available; bytes = tally = mlist->num_bytes; base_paddr = (unsigned long) mlist->start_adr; sp_banks[0].base_addr = base_paddr; sp_banks[0].num_bytes = bytes; while (mlist->theres_more != (void *) 0){ i++; mlist = mlist->theres_more; bytes = mlist->num_bytes; tally += bytes; if (i >= SPARC_PHYS_BANKS-1) { printk ("The machine has more banks than " "this kernel can support\n" "Increase the SPARC_PHYS_BANKS " "setting (currently %d)\n", SPARC_PHYS_BANKS); i = SPARC_PHYS_BANKS-1; break; } sp_banks[i].base_addr = (unsigned long) mlist->start_adr; sp_banks[i].num_bytes = mlist->num_bytes; } i++; sp_banks[i].base_addr = 0xdeadbeef; sp_banks[i].num_bytes = 0; /* Now mask all bank sizes on a page boundary, it is all we can * use anyways. */ for(i=0; sp_banks[i].num_bytes != 0; i++) sp_banks[i].num_bytes &= PAGE_MASK; return tally; } /* Traverse the memory lists in the prom to see how much physical we * have. */ unsigned long probe_memory(void) { int total; total = prom_probe_memory(); /* Oh man, much nicer, keep the dirt in promlib. */ 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_exception_table(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; } 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); } 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; siginfo_t info; int from_user = !(regs->psr & PSR_PS); 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. */ if (!ARCH_SUN4C_SUN4 && address >= TASK_SIZE) goto vmalloc_fault; info.si_code = SEGV_MAPERR; /* * If we're in an interrupt or have no user * context, we must not take the fault.. */ if (in_interrupt() || !mm) goto no_context; 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: info.si_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. */ switch (handle_mm_fault(mm, vma, address, write)) { case 1: current->min_flt++; break; case 2: current->maj_flt++; break; case 0: goto do_sigbus; default: goto out_of_memory; } 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) { #if 0 printk("Fault whee %s [%d]: segfaults at %08lx pc=%08lx\n", tsk->comm, tsk->pid, address, regs->pc); #endif info.si_signo = SIGSEGV; info.si_errno = 0; /* info.si_code set above to make clear whether this was a SEGV_MAPERR or SEGV_ACCERR fault. */ info.si_addr = (void *) compute_si_addr(regs, text_fault); info.si_trapno = 0; force_sig_info (SIGSEGV, &info, tsk); return; } /* Is this in ex_table? */ no_context: g2 = regs->u_regs[UREG_G2]; if (!from_user && (fixup = search_exception_table (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); printk("VM: killing process %s\n", tsk->comm); if (from_user) do_exit(SIGKILL); goto no_context; do_sigbus: up_read(&mm->mmap_sem); info.si_signo = SIGBUS; info.si_errno = 0; info.si_code = BUS_ADRERR; info.si_addr = (void *) compute_si_addr(regs, text_fault); info.si_trapno = 0; force_sig_info (SIGBUS, &info, tsk); 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_val(*pmd) = pmd_val(*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(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, *ip; ip = (unsigned int *)regs->pc; if (! get_user(insn, ip)) { if ((insn & 0xc1680000) == 0xc0680000) write = 1; } } pgdp = pgd_offset(mm, address); ptep = sun4c_pte_offset((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); save_and_cli(flags); if (sun4c_get_segmap(address) != invalid_segment) { sun4c_put_pte(address, pte_val(*ptep)); restore_flags(flags); return; } restore_flags(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); save_and_cli(flags); if (sun4c_get_segmap(address) != invalid_segment) { sun4c_put_pte(address, pte_val(*ptep)); restore_flags(flags); return; } restore_flags(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. */ inline 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; siginfo_t info; info.si_code = SEGV_MAPERR; #if 0 printk("wf\n", tsk->pid, write, address); #endif 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: info.si_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; } if (!handle_mm_fault(mm, vma, address, write)) goto do_sigbus; up_read(&mm->mmap_sem); return; bad_area: up_read(&mm->mmap_sem); #if 0 printk("Window whee %s [%d]: segfaults at %08lx\n", tsk->comm, tsk->pid, address); #endif info.si_signo = SIGSEGV; info.si_errno = 0; /* info.si_code set above to make clear whether this was a SEGV_MAPERR or SEGV_ACCERR fault. */ info.si_addr = (void *) address; info.si_trapno = 0; force_sig_info (SIGSEGV, &info, tsk); return; do_sigbus: up_read(&mm->mmap_sem); info.si_signo = SIGBUS; info.si_errno = 0; info.si_code = BUS_ADRERR; info.si_addr = (void *) address; info.si_trapno = 0; force_sig_info (SIGBUS, &info, tsk); } void window_overflow_fault(void) { unsigned long sp; sp = current->thread.rwbuf_stkptrs[0]; if(((sp + 0x38) & PAGE_MASK) != (sp & PAGE_MASK)) force_user_fault(sp + 0x38, 1); force_user_fault(sp, 1); } 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); } 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); }