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-rw-r--r--arch/loongarch/mm/fault.c270
1 files changed, 270 insertions, 0 deletions
diff --git a/arch/loongarch/mm/fault.c b/arch/loongarch/mm/fault.c
new file mode 100644
index 0000000000..1fc2f6813e
--- /dev/null
+++ b/arch/loongarch/mm/fault.c
@@ -0,0 +1,270 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
+ *
+ * Derived from MIPS:
+ * Copyright (C) 1995 - 2000 by Ralf Baechle
+ */
+#include <linux/context_tracking.h>
+#include <linux/signal.h>
+#include <linux/sched.h>
+#include <linux/interrupt.h>
+#include <linux/kernel.h>
+#include <linux/entry-common.h>
+#include <linux/errno.h>
+#include <linux/string.h>
+#include <linux/types.h>
+#include <linux/ptrace.h>
+#include <linux/ratelimit.h>
+#include <linux/mman.h>
+#include <linux/mm.h>
+#include <linux/smp.h>
+#include <linux/kdebug.h>
+#include <linux/perf_event.h>
+#include <linux/uaccess.h>
+#include <linux/kfence.h>
+
+#include <asm/branch.h>
+#include <asm/exception.h>
+#include <asm/mmu_context.h>
+#include <asm/ptrace.h>
+
+int show_unhandled_signals = 1;
+
+static void __kprobes no_context(struct pt_regs *regs,
+ unsigned long write, unsigned long address)
+{
+ const int field = sizeof(unsigned long) * 2;
+
+ /* Are we prepared to handle this kernel fault? */
+ if (fixup_exception(regs))
+ return;
+
+ if (kfence_handle_page_fault(address, write, 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("CPU %d Unable to handle kernel paging request at "
+ "virtual address %0*lx, era == %0*lx, ra == %0*lx\n",
+ raw_smp_processor_id(), field, address, field, regs->csr_era,
+ field, regs->regs[1]);
+ die("Oops", regs);
+}
+
+static void __kprobes do_out_of_memory(struct pt_regs *regs,
+ unsigned long write, unsigned long address)
+{
+ /*
+ * 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, write, address);
+ return;
+ }
+ pagefault_out_of_memory();
+}
+
+static void __kprobes do_sigbus(struct pt_regs *regs,
+ unsigned long write, unsigned long address, int si_code)
+{
+ /* Kernel mode? Handle exceptions or die */
+ if (!user_mode(regs)) {
+ no_context(regs, write, address);
+ return;
+ }
+
+ /*
+ * Send a sigbus, regardless of whether we were in kernel
+ * or user mode.
+ */
+ current->thread.csr_badvaddr = address;
+ current->thread.trap_nr = read_csr_excode();
+ force_sig_fault(SIGBUS, BUS_ADRERR, (void __user *)address);
+}
+
+static void __kprobes do_sigsegv(struct pt_regs *regs,
+ unsigned long write, unsigned long address, int si_code)
+{
+ const int field = sizeof(unsigned long) * 2;
+ static DEFINE_RATELIMIT_STATE(ratelimit_state, 5 * HZ, 10);
+
+ /* Kernel mode? Handle exceptions or die */
+ if (!user_mode(regs)) {
+ no_context(regs, write, address);
+ return;
+ }
+
+ /* User mode accesses just cause a SIGSEGV */
+ current->thread.csr_badvaddr = address;
+ if (!write)
+ current->thread.error_code = 1;
+ else
+ current->thread.error_code = 2;
+ current->thread.trap_nr = read_csr_excode();
+
+ if (show_unhandled_signals &&
+ unhandled_signal(current, SIGSEGV) && __ratelimit(&ratelimit_state)) {
+ pr_info("do_page_fault(): sending SIGSEGV to %s for invalid %s %0*lx\n",
+ current->comm,
+ write ? "write access to" : "read access from",
+ field, address);
+ pr_info("era = %0*lx in", field,
+ (unsigned long) regs->csr_era);
+ print_vma_addr(KERN_CONT " ", regs->csr_era);
+ pr_cont("\n");
+ pr_info("ra = %0*lx in", field,
+ (unsigned long) regs->regs[1]);
+ print_vma_addr(KERN_CONT " ", regs->regs[1]);
+ pr_cont("\n");
+ }
+ force_sig_fault(SIGSEGV, si_code, (void __user *)address);
+}
+
+/*
+ * This routine handles page faults. It determines the address,
+ * and the problem, and then passes it off to one of the appropriate
+ * routines.
+ */
+static void __kprobes __do_page_fault(struct pt_regs *regs,
+ unsigned long write, unsigned long address)
+{
+ int si_code = SEGV_MAPERR;
+ unsigned int flags = FAULT_FLAG_DEFAULT;
+ struct task_struct *tsk = current;
+ struct mm_struct *mm = tsk->mm;
+ struct vm_area_struct *vma = NULL;
+ vm_fault_t fault;
+
+ if (kprobe_page_fault(regs, current->thread.trap_nr))
+ return;
+
+ /*
+ * 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 (address & __UA_LIMIT) {
+ if (!user_mode(regs))
+ no_context(regs, write, address);
+ else
+ do_sigsegv(regs, write, address, si_code);
+ return;
+ }
+
+ /*
+ * If we're in an interrupt or have no user
+ * context, we must not take the fault..
+ */
+ if (faulthandler_disabled() || !mm) {
+ do_sigsegv(regs, write, address, si_code);
+ return;
+ }
+
+ if (user_mode(regs))
+ flags |= FAULT_FLAG_USER;
+
+ perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
+retry:
+ vma = lock_mm_and_find_vma(mm, address, regs);
+ if (unlikely(!vma))
+ goto bad_area_nosemaphore;
+ goto good_area;
+
+/*
+ * 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:
+ mmap_read_unlock(mm);
+bad_area_nosemaphore:
+ do_sigsegv(regs, write, address, si_code);
+ return;
+
+/*
+ * Ok, we have a good vm_area for this memory access, so
+ * we can handle it..
+ */
+good_area:
+ si_code = SEGV_ACCERR;
+
+ if (write) {
+ flags |= FAULT_FLAG_WRITE;
+ if (!(vma->vm_flags & VM_WRITE))
+ goto bad_area;
+ } else {
+ if (!(vma->vm_flags & VM_READ) && address != exception_era(regs))
+ goto bad_area;
+ if (!(vma->vm_flags & VM_EXEC) && address == exception_era(regs))
+ 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(vma, address, flags, regs);
+
+ if (fault_signal_pending(fault, regs)) {
+ if (!user_mode(regs))
+ no_context(regs, write, address);
+ 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_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;
+ }
+ if (unlikely(fault & VM_FAULT_ERROR)) {
+ mmap_read_unlock(mm);
+ if (fault & VM_FAULT_OOM) {
+ do_out_of_memory(regs, write, address);
+ return;
+ } else if (fault & VM_FAULT_SIGSEGV) {
+ do_sigsegv(regs, write, address, si_code);
+ return;
+ } else if (fault & (VM_FAULT_SIGBUS|VM_FAULT_HWPOISON|VM_FAULT_HWPOISON_LARGE)) {
+ do_sigbus(regs, write, address, si_code);
+ return;
+ }
+ BUG();
+ }
+
+ mmap_read_unlock(mm);
+}
+
+asmlinkage void __kprobes do_page_fault(struct pt_regs *regs,
+ unsigned long write, unsigned long address)
+{
+ irqentry_state_t state = irqentry_enter(regs);
+
+ /* Enable interrupt if enabled in parent context */
+ if (likely(regs->csr_prmd & CSR_PRMD_PIE))
+ local_irq_enable();
+
+ __do_page_fault(regs, write, address);
+
+ local_irq_disable();
+
+ irqentry_exit(regs, state);
+}