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-rw-r--r--arch/csky/mm/fault.c298
1 files changed, 298 insertions, 0 deletions
diff --git a/arch/csky/mm/fault.c b/arch/csky/mm/fault.c
new file mode 100644
index 0000000000..a885518ce1
--- /dev/null
+++ b/arch/csky/mm/fault.c
@@ -0,0 +1,298 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2018 Hangzhou C-SKY Microsystems co.,ltd.
+
+#include <linux/extable.h>
+#include <linux/kprobes.h>
+#include <linux/mmu_context.h>
+#include <linux/perf_event.h>
+
+int fixup_exception(struct pt_regs *regs)
+{
+ const struct exception_table_entry *fixup;
+
+ fixup = search_exception_tables(instruction_pointer(regs));
+ if (fixup) {
+ regs->pc = fixup->fixup;
+
+ return 1;
+ }
+
+ return 0;
+}
+
+static inline bool is_write(struct pt_regs *regs)
+{
+ switch (trap_no(regs)) {
+ case VEC_TLBINVALIDS:
+ return true;
+ case VEC_TLBMODIFIED:
+ return true;
+ }
+
+ return false;
+}
+
+#ifdef CONFIG_CPU_HAS_LDSTEX
+static inline void csky_cmpxchg_fixup(struct pt_regs *regs)
+{
+ return;
+}
+#else
+extern unsigned long csky_cmpxchg_ldw;
+extern unsigned long csky_cmpxchg_stw;
+static inline void csky_cmpxchg_fixup(struct pt_regs *regs)
+{
+ if (trap_no(regs) != VEC_TLBMODIFIED)
+ return;
+
+ if (instruction_pointer(regs) == csky_cmpxchg_stw)
+ instruction_pointer_set(regs, csky_cmpxchg_ldw);
+ return;
+}
+#endif
+
+static inline void no_context(struct pt_regs *regs, unsigned long addr)
+{
+ current->thread.trap_no = trap_no(regs);
+
+ /* Are we prepared to handle this kernel fault? */
+ if (fixup_exception(regs))
+ return;
+
+ /*
+ * Oops. The kernel tried to access some bad page. We'll have to
+ * terminate things with extreme prejudice.
+ */
+ bust_spinlocks(1);
+ pr_alert("Unable to handle kernel paging request at virtual "
+ "addr 0x%08lx, pc: 0x%08lx\n", addr, regs->pc);
+ die(regs, "Oops");
+ make_task_dead(SIGKILL);
+}
+
+static inline void mm_fault_error(struct pt_regs *regs, unsigned long addr, vm_fault_t fault)
+{
+ current->thread.trap_no = trap_no(regs);
+
+ if (fault & VM_FAULT_OOM) {
+ /*
+ * We ran out of memory, call the OOM killer, and return the userspace
+ * (which will retry the fault, or kill us if we got oom-killed).
+ */
+ if (!user_mode(regs)) {
+ no_context(regs, addr);
+ return;
+ }
+ pagefault_out_of_memory();
+ return;
+ } else if (fault & VM_FAULT_SIGBUS) {
+ /* Kernel mode? Handle exceptions or die */
+ if (!user_mode(regs)) {
+ no_context(regs, addr);
+ return;
+ }
+ do_trap(regs, SIGBUS, BUS_ADRERR, addr);
+ return;
+ }
+ BUG();
+}
+
+static inline void bad_area_nosemaphore(struct pt_regs *regs, struct mm_struct *mm, int code, unsigned long addr)
+{
+ /*
+ * Something tried to access memory that isn't in our memory map.
+ * Fix it, but check if it's kernel or user first.
+ */
+ /* User mode accesses just cause a SIGSEGV */
+ if (user_mode(regs)) {
+ do_trap(regs, SIGSEGV, code, addr);
+ return;
+ }
+
+ no_context(regs, addr);
+}
+
+static inline void vmalloc_fault(struct pt_regs *regs, int code, unsigned long addr)
+{
+ pgd_t *pgd, *pgd_k;
+ pud_t *pud, *pud_k;
+ pmd_t *pmd, *pmd_k;
+ pte_t *pte_k;
+ int offset;
+
+ /* User mode accesses just cause a SIGSEGV */
+ if (user_mode(regs)) {
+ do_trap(regs, SIGSEGV, code, addr);
+ return;
+ }
+
+ /*
+ * Synchronize this task's top level page-table
+ * with the 'reference' page table.
+ *
+ * Do _not_ use "tsk" here. We might be inside
+ * an interrupt in the middle of a task switch..
+ */
+ offset = pgd_index(addr);
+
+ pgd = get_pgd() + offset;
+ pgd_k = init_mm.pgd + offset;
+
+ if (!pgd_present(*pgd_k)) {
+ no_context(regs, addr);
+ return;
+ }
+ set_pgd(pgd, *pgd_k);
+
+ pud = (pud_t *)pgd;
+ pud_k = (pud_t *)pgd_k;
+ if (!pud_present(*pud_k)) {
+ no_context(regs, addr);
+ return;
+ }
+
+ pmd = pmd_offset(pud, addr);
+ pmd_k = pmd_offset(pud_k, addr);
+ if (!pmd_present(*pmd_k)) {
+ no_context(regs, addr);
+ return;
+ }
+ set_pmd(pmd, *pmd_k);
+
+ pte_k = pte_offset_kernel(pmd_k, addr);
+ if (!pte_present(*pte_k)) {
+ no_context(regs, addr);
+ return;
+ }
+
+ flush_tlb_one(addr);
+}
+
+static inline bool access_error(struct pt_regs *regs, struct vm_area_struct *vma)
+{
+ if (is_write(regs)) {
+ if (!(vma->vm_flags & VM_WRITE))
+ return true;
+ } else {
+ if (unlikely(!vma_is_accessible(vma)))
+ return true;
+ }
+ return false;
+}
+
+/*
+ * This routine handles page faults. It determines the address and the
+ * problem, and then passes it off to one of the appropriate routines.
+ */
+asmlinkage void do_page_fault(struct pt_regs *regs)
+{
+ struct task_struct *tsk;
+ struct vm_area_struct *vma;
+ struct mm_struct *mm;
+ unsigned long addr = read_mmu_entryhi() & PAGE_MASK;
+ unsigned int flags = FAULT_FLAG_DEFAULT;
+ int code = SEGV_MAPERR;
+ vm_fault_t fault;
+
+ tsk = current;
+ mm = tsk->mm;
+
+ csky_cmpxchg_fixup(regs);
+
+ if (kprobe_page_fault(regs, tsk->thread.trap_no))
+ return;
+
+ /*
+ * 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 (unlikely((addr >= VMALLOC_START) && (addr <= VMALLOC_END))) {
+ vmalloc_fault(regs, code, addr);
+ return;
+ }
+
+ /* Enable interrupts if they were enabled in the parent context. */
+ if (likely(regs->sr & BIT(6)))
+ local_irq_enable();
+
+ /*
+ * If we're in an interrupt, have no user context, or are running
+ * in an atomic region, then we must not take the fault.
+ */
+ if (unlikely(faulthandler_disabled() || !mm)) {
+ no_context(regs, addr);
+ return;
+ }
+
+ if (user_mode(regs))
+ flags |= FAULT_FLAG_USER;
+
+ perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, addr);
+
+ if (is_write(regs))
+ flags |= FAULT_FLAG_WRITE;
+retry:
+ vma = lock_mm_and_find_vma(mm, addr, regs);
+ if (unlikely(!vma)) {
+ bad_area_nosemaphore(regs, mm, code, addr);
+ return;
+ }
+
+ /*
+ * Ok, we have a good vm_area for this memory access, so
+ * we can handle it.
+ */
+ code = SEGV_ACCERR;
+
+ if (unlikely(access_error(regs, vma))) {
+ mmap_read_unlock(mm);
+ bad_area_nosemaphore(regs, mm, code, addr);
+ return;
+ }
+
+ /*
+ * If for any reason at all we could not handle the fault,
+ * make sure we exit gracefully rather than endlessly redo
+ * the fault.
+ */
+ fault = handle_mm_fault(vma, addr, flags, regs);
+
+ /*
+ * If we need to retry but a fatal signal is pending, handle the
+ * signal first. We do not need to release the mmap_lock because it
+ * would already be released in __lock_page_or_retry in mm/filemap.c.
+ */
+ if (fault_signal_pending(fault, regs)) {
+ if (!user_mode(regs))
+ no_context(regs, addr);
+ return;
+ }
+
+ /* The fault is fully completed (including releasing mmap lock) */
+ if (fault & VM_FAULT_COMPLETED)
+ return;
+
+ if (unlikely((fault & VM_FAULT_RETRY) && (flags & FAULT_FLAG_ALLOW_RETRY))) {
+ flags |= FAULT_FLAG_TRIED;
+
+ /*
+ * No need to mmap_read_unlock(mm) as we would
+ * have already released it in __lock_page_or_retry
+ * in mm/filemap.c.
+ */
+ goto retry;
+ }
+
+ mmap_read_unlock(mm);
+
+ if (unlikely(fault & VM_FAULT_ERROR)) {
+ mm_fault_error(regs, addr, fault);
+ return;
+ }
+ return;
+}