| /* |
| * PowerPC version |
| * Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org) |
| * |
| * Derived from "arch/i386/mm/fault.c" |
| * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds |
| * |
| * Modified by Cort Dougan and Paul Mackerras. |
| * |
| * This program is free software; you can redistribute it and/or |
| * modify it under the terms of the GNU General Public License |
| * as published by the Free Software Foundation; either version |
| * 2 of the License, or (at your option) any later version. |
| */ |
| |
| #include <linux/signal.h> |
| #include <linux/sched.h> |
| #include <linux/kernel.h> |
| #include <linux/errno.h> |
| #include <linux/string.h> |
| #include <linux/types.h> |
| #include <linux/ptrace.h> |
| #include <linux/mman.h> |
| #include <linux/mm.h> |
| #include <linux/interrupt.h> |
| #include <linux/highmem.h> |
| #include <linux/module.h> |
| |
| #include <asm/page.h> |
| #include <asm/pgtable.h> |
| #include <asm/mmu.h> |
| #include <asm/mmu_context.h> |
| #include <asm/system.h> |
| #include <asm/uaccess.h> |
| #include <asm/tlbflush.h> |
| |
| #if defined(CONFIG_XMON) || defined(CONFIG_KGDB) |
| extern void (*debugger)(struct pt_regs *); |
| extern void (*debugger_fault_handler)(struct pt_regs *); |
| extern int (*debugger_dabr_match)(struct pt_regs *); |
| int debugger_kernel_faults = 1; |
| #endif |
| |
| unsigned long htab_reloads; /* updated by hashtable.S:hash_page() */ |
| unsigned long htab_evicts; /* updated by hashtable.S:hash_page() */ |
| unsigned long htab_preloads; /* updated by hashtable.S:add_hash_page() */ |
| unsigned long pte_misses; /* updated by do_page_fault() */ |
| unsigned long pte_errors; /* updated by do_page_fault() */ |
| unsigned int probingmem; |
| |
| /* |
| * Check whether the instruction at regs->nip is a store using |
| * an update addressing form which will update r1. |
| */ |
| static int store_updates_sp(struct pt_regs *regs) |
| { |
| unsigned int inst; |
| |
| if (get_user(inst, (unsigned int __user *)regs->nip)) |
| return 0; |
| /* check for 1 in the rA field */ |
| if (((inst >> 16) & 0x1f) != 1) |
| return 0; |
| /* check major opcode */ |
| switch (inst >> 26) { |
| case 37: /* stwu */ |
| case 39: /* stbu */ |
| case 45: /* sthu */ |
| case 53: /* stfsu */ |
| case 55: /* stfdu */ |
| return 1; |
| case 31: |
| /* check minor opcode */ |
| switch ((inst >> 1) & 0x3ff) { |
| case 183: /* stwux */ |
| case 247: /* stbux */ |
| case 439: /* sthux */ |
| case 695: /* stfsux */ |
| case 759: /* stfdux */ |
| return 1; |
| } |
| } |
| return 0; |
| } |
| |
| /* |
| * For 600- and 800-family processors, the error_code parameter is DSISR |
| * for a data fault, SRR1 for an instruction fault. For 400-family processors |
| * the error_code parameter is ESR for a data fault, 0 for an instruction |
| * fault. |
| */ |
| int do_page_fault(struct pt_regs *regs, unsigned long address, |
| unsigned long error_code) |
| { |
| struct vm_area_struct * vma; |
| struct mm_struct *mm = current->mm; |
| siginfo_t info; |
| int code = SEGV_MAPERR; |
| int fault; |
| #if defined(CONFIG_4xx) || defined (CONFIG_BOOKE) |
| int is_write = error_code & ESR_DST; |
| #else |
| int is_write = 0; |
| |
| /* |
| * Fortunately the bit assignments in SRR1 for an instruction |
| * fault and DSISR for a data fault are mostly the same for the |
| * bits we are interested in. But there are some bits which |
| * indicate errors in DSISR but can validly be set in SRR1. |
| */ |
| if (TRAP(regs) == 0x400) |
| error_code &= 0x48200000; |
| else |
| is_write = error_code & 0x02000000; |
| #endif /* CONFIG_4xx || CONFIG_BOOKE */ |
| |
| #if defined(CONFIG_XMON) || defined(CONFIG_KGDB) |
| if (debugger_fault_handler && TRAP(regs) == 0x300) { |
| debugger_fault_handler(regs); |
| return 0; |
| } |
| #if !(defined(CONFIG_4xx) || defined(CONFIG_BOOKE)) |
| if (error_code & 0x00400000) { |
| /* DABR match */ |
| if (debugger_dabr_match(regs)) |
| return 0; |
| } |
| #endif /* !(CONFIG_4xx || CONFIG_BOOKE)*/ |
| #endif /* CONFIG_XMON || CONFIG_KGDB */ |
| |
| if (in_atomic() || mm == NULL) |
| return SIGSEGV; |
| |
| 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 (!is_write) |
| goto bad_area; |
| |
| /* |
| * N.B. The rs6000/xcoff ABI allows programs to access up to |
| * a few hundred bytes below the stack pointer. |
| * The kernel signal delivery code writes up to about 1.5kB |
| * below the stack pointer (r1) before decrementing it. |
| * The exec code can write slightly over 640kB to the stack |
| * before setting the user r1. Thus we allow the stack to |
| * expand to 1MB without further checks. |
| */ |
| if (address + 0x100000 < vma->vm_end) { |
| /* get user regs even if this fault is in kernel mode */ |
| struct pt_regs *uregs = current->thread.regs; |
| if (uregs == NULL) |
| goto bad_area; |
| |
| /* |
| * A user-mode access to an address a long way below |
| * the stack pointer is only valid if the instruction |
| * is one which would update the stack pointer to the |
| * address accessed if the instruction completed, |
| * i.e. either stwu rs,n(r1) or stwux rs,r1,rb |
| * (or the byte, halfword, float or double forms). |
| * |
| * If we don't check this then any write to the area |
| * between the last mapped region and the stack will |
| * expand the stack rather than segfaulting. |
| */ |
| if (address + 2048 < uregs->gpr[1] |
| && (!user_mode(regs) || !store_updates_sp(regs))) |
| goto bad_area; |
| } |
| if (expand_stack(vma, address)) |
| goto bad_area; |
| |
| good_area: |
| code = SEGV_ACCERR; |
| #if defined(CONFIG_6xx) |
| if (error_code & 0x95700000) |
| /* an error such as lwarx to I/O controller space, |
| address matching DABR, eciwx, etc. */ |
| goto bad_area; |
| #endif /* CONFIG_6xx */ |
| #if defined(CONFIG_8xx) |
| /* The MPC8xx seems to always set 0x80000000, which is |
| * "undefined". Of those that can be set, this is the only |
| * one which seems bad. |
| */ |
| if (error_code & 0x10000000) |
| /* Guarded storage error. */ |
| goto bad_area; |
| #endif /* CONFIG_8xx */ |
| |
| /* a write */ |
| if (is_write) { |
| if (!(vma->vm_flags & VM_WRITE)) |
| goto bad_area; |
| #if defined(CONFIG_4xx) || defined(CONFIG_BOOKE) |
| /* an exec - 4xx/Book-E allows for per-page execute permission */ |
| } else if (TRAP(regs) == 0x400) { |
| pte_t *ptep; |
| pmd_t *pmdp; |
| |
| #if 0 |
| /* It would be nice to actually enforce the VM execute |
| permission on CPUs which can do so, but far too |
| much stuff in userspace doesn't get the permissions |
| right, so we let any page be executed for now. */ |
| if (! (vma->vm_flags & VM_EXEC)) |
| goto bad_area; |
| #endif |
| |
| /* Since 4xx/Book-E supports per-page execute permission, |
| * we lazily flush dcache to icache. */ |
| ptep = NULL; |
| if (get_pteptr(mm, address, &ptep, &pmdp)) { |
| spinlock_t *ptl = pte_lockptr(mm, pmdp); |
| spin_lock(ptl); |
| if (pte_present(*ptep)) { |
| struct page *page = pte_page(*ptep); |
| |
| if (!test_bit(PG_arch_1, &page->flags)) { |
| flush_dcache_icache_page(page); |
| set_bit(PG_arch_1, &page->flags); |
| } |
| pte_update(ptep, 0, _PAGE_HWEXEC); |
| _tlbie(address); |
| pte_unmap_unlock(ptep, ptl); |
| up_read(&mm->mmap_sem); |
| return 0; |
| } |
| pte_unmap_unlock(ptep, ptl); |
| } |
| #endif |
| /* a read */ |
| } else { |
| /* protection fault */ |
| if (error_code & 0x08000000) |
| goto bad_area; |
| if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE))) |
| 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. |
| */ |
| survive: |
| fault = handle_mm_fault(mm, vma, address, is_write); |
| 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++; |
| else |
| current->min_flt++; |
| |
| up_read(&mm->mmap_sem); |
| /* |
| * keep track of tlb+htab misses that are good addrs but |
| * just need pte's created via handle_mm_fault() |
| * -- Cort |
| */ |
| pte_misses++; |
| return 0; |
| |
| bad_area: |
| up_read(&mm->mmap_sem); |
| pte_errors++; |
| |
| /* User mode accesses cause a SIGSEGV */ |
| if (user_mode(regs)) { |
| _exception(SIGSEGV, regs, code, address); |
| return 0; |
| } |
| |
| return SIGSEGV; |
| |
| /* |
| * 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(current)) { |
| yield(); |
| down_read(&mm->mmap_sem); |
| goto survive; |
| } |
| printk("VM: killing process %s\n", current->comm); |
| if (user_mode(regs)) |
| do_group_exit(SIGKILL); |
| return SIGKILL; |
| |
| do_sigbus: |
| up_read(&mm->mmap_sem); |
| info.si_signo = SIGBUS; |
| info.si_errno = 0; |
| info.si_code = BUS_ADRERR; |
| info.si_addr = (void __user *)address; |
| force_sig_info (SIGBUS, &info, current); |
| if (!user_mode(regs)) |
| return SIGBUS; |
| return 0; |
| } |
| |
| /* |
| * bad_page_fault is called when we have a bad access from the kernel. |
| * It is called from the DSI and ISI handlers in head.S and from some |
| * of the procedures in traps.c. |
| */ |
| void |
| bad_page_fault(struct pt_regs *regs, unsigned long address, int sig) |
| { |
| const struct exception_table_entry *entry; |
| |
| /* Are we prepared to handle this fault? */ |
| if ((entry = search_exception_tables(regs->nip)) != NULL) { |
| regs->nip = entry->fixup; |
| return; |
| } |
| |
| /* kernel has accessed a bad area */ |
| #if defined(CONFIG_XMON) || defined(CONFIG_KGDB) |
| if (debugger_kernel_faults) |
| debugger(regs); |
| #endif |
| die("kernel access of bad area", regs, sig); |
| } |
| |
| #ifdef CONFIG_8xx |
| |
| /* The pgtable.h claims some functions generically exist, but I |
| * can't find them...... |
| */ |
| pte_t *va_to_pte(unsigned long address) |
| { |
| pgd_t *dir; |
| pmd_t *pmd; |
| pte_t *pte; |
| |
| if (address < TASK_SIZE) |
| return NULL; |
| |
| dir = pgd_offset(&init_mm, address); |
| if (dir) { |
| pmd = pmd_offset(dir, address & PAGE_MASK); |
| if (pmd && pmd_present(*pmd)) { |
| pte = pte_offset_kernel(pmd, address & PAGE_MASK); |
| if (pte && pte_present(*pte)) |
| return(pte); |
| } |
| } |
| return NULL; |
| } |
| |
| unsigned long va_to_phys(unsigned long address) |
| { |
| pte_t *pte; |
| |
| pte = va_to_pte(address); |
| if (pte) |
| return(((unsigned long)(pte_val(*pte)) & PAGE_MASK) | (address & ~(PAGE_MASK))); |
| return (0); |
| } |
| |
| void |
| print_8xx_pte(struct mm_struct *mm, unsigned long addr) |
| { |
| pgd_t * pgd; |
| pmd_t * pmd; |
| pte_t * pte; |
| |
| printk(" pte @ 0x%8lx: ", addr); |
| pgd = pgd_offset(mm, addr & PAGE_MASK); |
| if (pgd) { |
| pmd = pmd_offset(pgd, addr & PAGE_MASK); |
| if (pmd && pmd_present(*pmd)) { |
| pte = pte_offset_kernel(pmd, addr & PAGE_MASK); |
| if (pte) { |
| printk(" (0x%08lx)->(0x%08lx)->0x%08lx\n", |
| (long)pgd, (long)pte, (long)pte_val(*pte)); |
| #define pp ((long)pte_val(*pte)) |
| printk(" RPN: %05lx PP: %lx SPS: %lx SH: %lx " |
| "CI: %lx v: %lx\n", |
| pp>>12, /* rpn */ |
| (pp>>10)&3, /* pp */ |
| (pp>>3)&1, /* small */ |
| (pp>>2)&1, /* shared */ |
| (pp>>1)&1, /* cache inhibit */ |
| pp&1 /* valid */ |
| ); |
| #undef pp |
| } |
| else { |
| printk("no pte\n"); |
| } |
| } |
| else { |
| printk("no pmd\n"); |
| } |
| } |
| else { |
| printk("no pgd\n"); |
| } |
| } |
| |
| int |
| get_8xx_pte(struct mm_struct *mm, unsigned long addr) |
| { |
| pgd_t * pgd; |
| pmd_t * pmd; |
| pte_t * pte; |
| int retval = 0; |
| |
| pgd = pgd_offset(mm, addr & PAGE_MASK); |
| if (pgd) { |
| pmd = pmd_offset(pgd, addr & PAGE_MASK); |
| if (pmd && pmd_present(*pmd)) { |
| pte = pte_offset_kernel(pmd, addr & PAGE_MASK); |
| if (pte) { |
| retval = (int)pte_val(*pte); |
| } |
| } |
| } |
| return(retval); |
| } |
| #endif /* CONFIG_8xx */ |