aboutsummaryrefslogtreecommitdiff
path: root/arch/unicore32/mm/fault.c
diff options
context:
space:
mode:
Diffstat (limited to 'arch/unicore32/mm/fault.c')
-rw-r--r--arch/unicore32/mm/fault.c499
1 files changed, 499 insertions, 0 deletions
diff --git a/arch/unicore32/mm/fault.c b/arch/unicore32/mm/fault.c
new file mode 100644
index 00000000000..0dc922dba91
--- /dev/null
+++ b/arch/unicore32/mm/fault.c
@@ -0,0 +1,499 @@
+/*
+ * linux/arch/unicore32/mm/fault.c
+ *
+ * Code specific to PKUnity SoC and UniCore ISA
+ *
+ * Copyright (C) 2001-2010 GUAN Xue-tao
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#include <linux/module.h>
+#include <linux/signal.h>
+#include <linux/mm.h>
+#include <linux/hardirq.h>
+#include <linux/init.h>
+#include <linux/kprobes.h>
+#include <linux/uaccess.h>
+#include <linux/page-flags.h>
+#include <linux/sched.h>
+#include <linux/io.h>
+
+#include <asm/pgtable.h>
+#include <asm/tlbflush.h>
+
+/*
+ * Fault status register encodings. We steal bit 31 for our own purposes.
+ */
+#define FSR_LNX_PF (1 << 31)
+
+static inline int fsr_fs(unsigned int fsr)
+{
+ /* xyabcde will be abcde+xy */
+ return (fsr & 31) + ((fsr & (3 << 5)) >> 5);
+}
+
+/*
+ * This is useful to dump out the page tables associated with
+ * 'addr' in mm 'mm'.
+ */
+void show_pte(struct mm_struct *mm, unsigned long addr)
+{
+ pgd_t *pgd;
+
+ if (!mm)
+ mm = &init_mm;
+
+ printk(KERN_ALERT "pgd = %p\n", mm->pgd);
+ pgd = pgd_offset(mm, addr);
+ printk(KERN_ALERT "[%08lx] *pgd=%08lx", addr, pgd_val(*pgd));
+
+ do {
+ pmd_t *pmd;
+ pte_t *pte;
+
+ if (pgd_none(*pgd))
+ break;
+
+ if (pgd_bad(*pgd)) {
+ printk("(bad)");
+ break;
+ }
+
+ pmd = pmd_offset((pud_t *) pgd, addr);
+ if (PTRS_PER_PMD != 1)
+ printk(", *pmd=%08lx", pmd_val(*pmd));
+
+ if (pmd_none(*pmd))
+ break;
+
+ if (pmd_bad(*pmd)) {
+ printk("(bad)");
+ break;
+ }
+
+ /* We must not map this if we have highmem enabled */
+ if (PageHighMem(pfn_to_page(pmd_val(*pmd) >> PAGE_SHIFT)))
+ break;
+
+ pte = pte_offset_map(pmd, addr);
+ printk(", *pte=%08lx", pte_val(*pte));
+ pte_unmap(pte);
+ } while (0);
+
+ printk("\n");
+}
+
+/*
+ * Oops. The kernel tried to access some page that wasn't present.
+ */
+static void __do_kernel_fault(struct mm_struct *mm, unsigned long addr,
+ unsigned int fsr, struct pt_regs *regs)
+{
+ /*
+ * Are we prepared to handle this kernel fault?
+ */
+ if (fixup_exception(regs))
+ return;
+
+ /*
+ * No handler, we'll have to terminate things with extreme prejudice.
+ */
+ bust_spinlocks(1);
+ printk(KERN_ALERT
+ "Unable to handle kernel %s at virtual address %08lx\n",
+ (addr < PAGE_SIZE) ? "NULL pointer dereference" :
+ "paging request", addr);
+
+ show_pte(mm, addr);
+ die("Oops", regs, fsr);
+ bust_spinlocks(0);
+ do_exit(SIGKILL);
+}
+
+/*
+ * Something tried to access memory that isn't in our memory map..
+ * User mode accesses just cause a SIGSEGV
+ */
+static void __do_user_fault(struct task_struct *tsk, unsigned long addr,
+ unsigned int fsr, unsigned int sig, int code,
+ struct pt_regs *regs)
+{
+ struct siginfo si;
+
+ tsk->thread.address = addr;
+ tsk->thread.error_code = fsr;
+ tsk->thread.trap_no = 14;
+ si.si_signo = sig;
+ si.si_errno = 0;
+ si.si_code = code;
+ si.si_addr = (void __user *)addr;
+ force_sig_info(sig, &si, tsk);
+}
+
+void do_bad_area(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
+{
+ struct task_struct *tsk = current;
+ struct mm_struct *mm = tsk->active_mm;
+
+ /*
+ * If we are in kernel mode at this point, we
+ * have no context to handle this fault with.
+ */
+ if (user_mode(regs))
+ __do_user_fault(tsk, addr, fsr, SIGSEGV, SEGV_MAPERR, regs);
+ else
+ __do_kernel_fault(mm, addr, fsr, regs);
+}
+
+#define VM_FAULT_BADMAP 0x010000
+#define VM_FAULT_BADACCESS 0x020000
+
+/*
+ * Check that the permissions on the VMA allow for the fault which occurred.
+ * If we encountered a write fault, we must have write permission, otherwise
+ * we allow any permission.
+ */
+static inline bool access_error(unsigned int fsr, struct vm_area_struct *vma)
+{
+ unsigned int mask = VM_READ | VM_WRITE | VM_EXEC;
+
+ if (!(fsr ^ 0x12)) /* write? */
+ mask = VM_WRITE;
+ if (fsr & FSR_LNX_PF)
+ mask = VM_EXEC;
+
+ return vma->vm_flags & mask ? false : true;
+}
+
+static int __do_pf(struct mm_struct *mm, unsigned long addr, unsigned int fsr,
+ unsigned int flags, struct task_struct *tsk)
+{
+ struct vm_area_struct *vma;
+ int fault;
+
+ vma = find_vma(mm, addr);
+ fault = VM_FAULT_BADMAP;
+ if (unlikely(!vma))
+ goto out;
+ if (unlikely(vma->vm_start > addr))
+ goto check_stack;
+
+ /*
+ * Ok, we have a good vm_area for this
+ * memory access, so we can handle it.
+ */
+good_area:
+ if (access_error(fsr, vma)) {
+ fault = VM_FAULT_BADACCESS;
+ goto out;
+ }
+
+ /*
+ * 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, addr & PAGE_MASK, flags);
+ return fault;
+
+check_stack:
+ if (vma->vm_flags & VM_GROWSDOWN && !expand_stack(vma, addr))
+ goto good_area;
+out:
+ return fault;
+}
+
+static int do_pf(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
+{
+ struct task_struct *tsk;
+ struct mm_struct *mm;
+ int fault, sig, code;
+ unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
+
+ tsk = current;
+ mm = tsk->mm;
+
+ /*
+ * If we're in an interrupt or have no user
+ * context, we must not take the fault..
+ */
+ if (in_atomic() || !mm)
+ goto no_context;
+
+ if (user_mode(regs))
+ flags |= FAULT_FLAG_USER;
+ if (!(fsr ^ 0x12))
+ flags |= FAULT_FLAG_WRITE;
+
+ /*
+ * As per x86, we may deadlock here. However, since the kernel only
+ * validly references user space from well defined areas of the code,
+ * we can bug out early if this is from code which shouldn't.
+ */
+ if (!down_read_trylock(&mm->mmap_sem)) {
+ if (!user_mode(regs)
+ && !search_exception_tables(regs->UCreg_pc))
+ goto no_context;
+retry:
+ down_read(&mm->mmap_sem);
+ } else {
+ /*
+ * The above down_read_trylock() might have succeeded in
+ * which case, we'll have missed the might_sleep() from
+ * down_read()
+ */
+ might_sleep();
+#ifdef CONFIG_DEBUG_VM
+ if (!user_mode(regs) &&
+ !search_exception_tables(regs->UCreg_pc))
+ goto no_context;
+#endif
+ }
+
+ fault = __do_pf(mm, addr, fsr, flags, tsk);
+
+ /* If we need to retry but a fatal signal is pending, handle the
+ * signal first. We do not need to release the mmap_sem because
+ * it would already be released in __lock_page_or_retry in
+ * mm/filemap.c. */
+ if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
+ return 0;
+
+ if (!(fault & VM_FAULT_ERROR) && (flags & FAULT_FLAG_ALLOW_RETRY)) {
+ if (fault & VM_FAULT_MAJOR)
+ tsk->maj_flt++;
+ else
+ tsk->min_flt++;
+ if (fault & VM_FAULT_RETRY) {
+ /* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk
+ * of starvation. */
+ flags &= ~FAULT_FLAG_ALLOW_RETRY;
+ goto retry;
+ }
+ }
+
+ up_read(&mm->mmap_sem);
+
+ /*
+ * Handle the "normal" case first - VM_FAULT_MAJOR / VM_FAULT_MINOR
+ */
+ if (likely(!(fault &
+ (VM_FAULT_ERROR | VM_FAULT_BADMAP | VM_FAULT_BADACCESS))))
+ return 0;
+
+ /*
+ * If we are in kernel mode at this point, we
+ * have no context to handle this fault with.
+ */
+ if (!user_mode(regs))
+ goto no_context;
+
+ if (fault & VM_FAULT_OOM) {
+ /*
+ * We ran out of memory, call the OOM killer, and return to
+ * userspace (which will retry the fault, or kill us if we
+ * got oom-killed)
+ */
+ pagefault_out_of_memory();
+ return 0;
+ }
+
+ if (fault & VM_FAULT_SIGBUS) {
+ /*
+ * We had some memory, but were unable to
+ * successfully fix up this page fault.
+ */
+ sig = SIGBUS;
+ code = BUS_ADRERR;
+ } else {
+ /*
+ * Something tried to access memory that
+ * isn't in our memory map..
+ */
+ sig = SIGSEGV;
+ code = fault == VM_FAULT_BADACCESS ? SEGV_ACCERR : SEGV_MAPERR;
+ }
+
+ __do_user_fault(tsk, addr, fsr, sig, code, regs);
+ return 0;
+
+no_context:
+ __do_kernel_fault(mm, addr, fsr, regs);
+ return 0;
+}
+
+/*
+ * First Level Translation Fault Handler
+ *
+ * We enter here because the first level page table doesn't contain
+ * a valid entry for the address.
+ *
+ * If the address is in kernel space (>= TASK_SIZE), then we are
+ * probably faulting in the vmalloc() area.
+ *
+ * If the init_task's first level page tables contains the relevant
+ * entry, we copy the it to this task. If not, we send the process
+ * a signal, fixup the exception, or oops the kernel.
+ *
+ * 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.
+ */
+static int do_ifault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
+{
+ unsigned int index;
+ pgd_t *pgd, *pgd_k;
+ pmd_t *pmd, *pmd_k;
+
+ if (addr < TASK_SIZE)
+ return do_pf(addr, fsr, regs);
+
+ if (user_mode(regs))
+ goto bad_area;
+
+ index = pgd_index(addr);
+
+ pgd = cpu_get_pgd() + index;
+ pgd_k = init_mm.pgd + index;
+
+ if (pgd_none(*pgd_k))
+ goto bad_area;
+
+ pmd_k = pmd_offset((pud_t *) pgd_k, addr);
+ pmd = pmd_offset((pud_t *) pgd, addr);
+
+ if (pmd_none(*pmd_k))
+ goto bad_area;
+
+ set_pmd(pmd, *pmd_k);
+ flush_pmd_entry(pmd);
+ return 0;
+
+bad_area:
+ do_bad_area(addr, fsr, regs);
+ return 0;
+}
+
+/*
+ * This abort handler always returns "fault".
+ */
+static int do_bad(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
+{
+ return 1;
+}
+
+static int do_good(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
+{
+ unsigned int res1, res2;
+
+ printk("dabt exception but no error!\n");
+
+ __asm__ __volatile__(
+ "mff %0,f0\n"
+ "mff %1,f1\n"
+ : "=r"(res1), "=r"(res2)
+ :
+ : "memory");
+
+ printk(KERN_EMERG "r0 :%08x r1 :%08x\n", res1, res2);
+ panic("shut up\n");
+ return 0;
+}
+
+static struct fsr_info {
+ int (*fn) (unsigned long addr, unsigned int fsr, struct pt_regs *regs);
+ int sig;
+ int code;
+ const char *name;
+} fsr_info[] = {
+ /*
+ * The following are the standard Unicore-I and UniCore-II aborts.
+ */
+ { do_good, SIGBUS, 0, "no error" },
+ { do_bad, SIGBUS, BUS_ADRALN, "alignment exception" },
+ { do_bad, SIGBUS, BUS_OBJERR, "external exception" },
+ { do_bad, SIGBUS, 0, "burst operation" },
+ { do_bad, SIGBUS, 0, "unknown 00100" },
+ { do_ifault, SIGSEGV, SEGV_MAPERR, "2nd level pt non-exist"},
+ { do_bad, SIGBUS, 0, "2nd lvl large pt non-exist" },
+ { do_bad, SIGBUS, 0, "invalid pte" },
+ { do_pf, SIGSEGV, SEGV_MAPERR, "page miss" },
+ { do_bad, SIGBUS, 0, "middle page miss" },
+ { do_bad, SIGBUS, 0, "large page miss" },
+ { do_pf, SIGSEGV, SEGV_MAPERR, "super page (section) miss" },
+ { do_bad, SIGBUS, 0, "unknown 01100" },
+ { do_bad, SIGBUS, 0, "unknown 01101" },
+ { do_bad, SIGBUS, 0, "unknown 01110" },
+ { do_bad, SIGBUS, 0, "unknown 01111" },
+ { do_bad, SIGBUS, 0, "addr: up 3G or IO" },
+ { do_pf, SIGSEGV, SEGV_ACCERR, "read unreadable addr" },
+ { do_pf, SIGSEGV, SEGV_ACCERR, "write unwriteable addr"},
+ { do_pf, SIGSEGV, SEGV_ACCERR, "exec unexecutable addr"},
+ { do_bad, SIGBUS, 0, "unknown 10100" },
+ { do_bad, SIGBUS, 0, "unknown 10101" },
+ { do_bad, SIGBUS, 0, "unknown 10110" },
+ { do_bad, SIGBUS, 0, "unknown 10111" },
+ { do_bad, SIGBUS, 0, "unknown 11000" },
+ { do_bad, SIGBUS, 0, "unknown 11001" },
+ { do_bad, SIGBUS, 0, "unknown 11010" },
+ { do_bad, SIGBUS, 0, "unknown 11011" },
+ { do_bad, SIGBUS, 0, "unknown 11100" },
+ { do_bad, SIGBUS, 0, "unknown 11101" },
+ { do_bad, SIGBUS, 0, "unknown 11110" },
+ { do_bad, SIGBUS, 0, "unknown 11111" }
+};
+
+void __init hook_fault_code(int nr,
+ int (*fn) (unsigned long, unsigned int, struct pt_regs *),
+ int sig, int code, const char *name)
+{
+ if (nr < 0 || nr >= ARRAY_SIZE(fsr_info))
+ BUG();
+
+ fsr_info[nr].fn = fn;
+ fsr_info[nr].sig = sig;
+ fsr_info[nr].code = code;
+ fsr_info[nr].name = name;
+}
+
+/*
+ * Dispatch a data abort to the relevant handler.
+ */
+asmlinkage void do_DataAbort(unsigned long addr, unsigned int fsr,
+ struct pt_regs *regs)
+{
+ const struct fsr_info *inf = fsr_info + fsr_fs(fsr);
+ struct siginfo info;
+
+ if (!inf->fn(addr, fsr & ~FSR_LNX_PF, regs))
+ return;
+
+ printk(KERN_ALERT "Unhandled fault: %s (0x%03x) at 0x%08lx\n",
+ inf->name, fsr, addr);
+
+ info.si_signo = inf->sig;
+ info.si_errno = 0;
+ info.si_code = inf->code;
+ info.si_addr = (void __user *)addr;
+ uc32_notify_die("", regs, &info, fsr, 0);
+}
+
+asmlinkage void do_PrefetchAbort(unsigned long addr,
+ unsigned int ifsr, struct pt_regs *regs)
+{
+ const struct fsr_info *inf = fsr_info + fsr_fs(ifsr);
+ struct siginfo info;
+
+ if (!inf->fn(addr, ifsr | FSR_LNX_PF, regs))
+ return;
+
+ printk(KERN_ALERT "Unhandled prefetch abort: %s (0x%03x) at 0x%08lx\n",
+ inf->name, ifsr, addr);
+
+ info.si_signo = inf->sig;
+ info.si_errno = 0;
+ info.si_code = inf->code;
+ info.si_addr = (void __user *)addr;
+ uc32_notify_die("", regs, &info, ifsr, 0);
+}
generated by cgit v1.2.3-70-g09d2 (git 2.46.0) at 2025-11-04 13:25:29 +0000