// SPDX-License-Identifier: GPL-2.0-only /* * Memory fault handling for Hexagon * * Copyright (c) 2010-2011, The Linux Foundation. All rights reserved. */ /* * Page fault handling for the Hexagon Virtual Machine. * Can also be called by a native port emulating the HVM * execptions. */ #include <asm/traps.h> #include <linux/uaccess.h> #include <linux/mm.h> #include <linux/sched/signal.h> #include <linux/signal.h> #include <linux/extable.h> #include <linux/hardirq.h> #include <linux/perf_event.h> /* * Decode of hardware exception sends us to one of several * entry points. At each, we generate canonical arguments * for handling by the abstract memory management code. */ #define FLT_IFETCH -1 #define FLT_LOAD 0 #define FLT_STORE 1 /* * Canonical page fault handler */ void do_page_fault(unsigned long address, long cause, struct pt_regs *regs) { struct vm_area_struct *vma; struct mm_struct *mm = current->mm; int si_signo; int si_code = SEGV_MAPERR; vm_fault_t fault; const struct exception_table_entry *fixup; unsigned int flags = FAULT_FLAG_DEFAULT; /* * If we're in an interrupt or have no user context, * then must not take the fault. */ if (unlikely(in_interrupt() || !mm)) goto no_context; local_irq_enable(); if (user_mode(regs)) flags |= FAULT_FLAG_USER; perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address); retry: mmap_read_lock(mm); 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: /* Address space is OK. Now check access rights. */ si_code = SEGV_ACCERR; switch (cause) { case FLT_IFETCH: if (!(vma->vm_flags & VM_EXEC)) goto bad_area; break; case FLT_LOAD: if (!(vma->vm_flags & VM_READ)) goto bad_area; break; case FLT_STORE: if (!(vma->vm_flags & VM_WRITE)) goto bad_area; flags |= FAULT_FLAG_WRITE; break; } fault = handle_mm_fault(vma, address, flags, regs); if (fault_signal_pending(fault, regs)) return; /* The fault is fully completed (including releasing mmap lock) */ if (fault & VM_FAULT_COMPLETED) return; /* The most common case -- we are done. */ if (likely(!(fault & VM_FAULT_ERROR))) { if (fault & VM_FAULT_RETRY) { flags |= FAULT_FLAG_TRIED; goto retry; } mmap_read_unlock(mm); return; } mmap_read_unlock(mm); /* Handle copyin/out exception cases */ if (!user_mode(regs)) goto no_context; if (fault & VM_FAULT_OOM) { pagefault_out_of_memory(); return; } /* User-mode address is in the memory map, but we are * unable to fix up the page fault. */ if (fault & VM_FAULT_SIGBUS) { si_signo = SIGBUS; si_code = BUS_ADRERR; } /* Address is not in the memory map */ else { si_signo = SIGSEGV; si_code = SEGV_ACCERR; } force_sig_fault(si_signo, si_code, (void __user *)address); return; bad_area: mmap_read_unlock(mm); if (user_mode(regs)) { force_sig_fault(SIGSEGV, si_code, (void __user *)address); return; } /* Kernel-mode fault falls through */ no_context: fixup = search_exception_tables(pt_elr(regs)); if (fixup) { pt_set_elr(regs, fixup->fixup); return; } /* Things are looking very, very bad now */ bust_spinlocks(1); printk(KERN_EMERG "Unable to handle kernel paging request at " "virtual address 0x%08lx, regs %p\n", address, regs); die("Bad Kernel VA", regs, SIGKILL); } void read_protection_fault(struct pt_regs *regs) { unsigned long badvadr = pt_badva(regs); do_page_fault(badvadr, FLT_LOAD, regs); } void write_protection_fault(struct pt_regs *regs) { unsigned long badvadr = pt_badva(regs); do_page_fault(badvadr, FLT_STORE, regs); } void execute_protection_fault(struct pt_regs *regs) { unsigned long badvadr = pt_badva(regs); do_page_fault(badvadr, FLT_IFETCH, regs); }