cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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vm_fault.c (3789B)

      1// SPDX-License-Identifier: GPL-2.0-only
      2/*
      3 * Memory fault handling for Hexagon
      4 *
      5 * Copyright (c) 2010-2011, The Linux Foundation. All rights reserved.
      6 */
      7
      8/*
      9 * Page fault handling for the Hexagon Virtual Machine.
     10 * Can also be called by a native port emulating the HVM
     11 * execptions.
     12 */
     13
     14#include <asm/traps.h>
     15#include <linux/uaccess.h>
     16#include <linux/mm.h>
     17#include <linux/sched/signal.h>
     18#include <linux/signal.h>
     19#include <linux/extable.h>
     20#include <linux/hardirq.h>
     21#include <linux/perf_event.h>
     22
     23/*
     24 * Decode of hardware exception sends us to one of several
     25 * entry points.  At each, we generate canonical arguments
     26 * for handling by the abstract memory management code.
     27 */
     28#define FLT_IFETCH     -1
     29#define FLT_LOAD        0
     30#define FLT_STORE       1
     31
     32
     33/*
     34 * Canonical page fault handler
     35 */
     36void do_page_fault(unsigned long address, long cause, struct pt_regs *regs)
     37{
     38	struct vm_area_struct *vma;
     39	struct mm_struct *mm = current->mm;
     40	int si_signo;
     41	int si_code = SEGV_MAPERR;
     42	vm_fault_t fault;
     43	const struct exception_table_entry *fixup;
     44	unsigned int flags = FAULT_FLAG_DEFAULT;
     45
     46	/*
     47	 * If we're in an interrupt or have no user context,
     48	 * then must not take the fault.
     49	 */
     50	if (unlikely(in_interrupt() || !mm))
     51		goto no_context;
     52
     53	local_irq_enable();
     54
     55	if (user_mode(regs))
     56		flags |= FAULT_FLAG_USER;
     57
     58	perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
     59retry:
     60	mmap_read_lock(mm);
     61	vma = find_vma(mm, address);
     62	if (!vma)
     63		goto bad_area;
     64
     65	if (vma->vm_start <= address)
     66		goto good_area;
     67
     68	if (!(vma->vm_flags & VM_GROWSDOWN))
     69		goto bad_area;
     70
     71	if (expand_stack(vma, address))
     72		goto bad_area;
     73
     74good_area:
     75	/* Address space is OK.  Now check access rights. */
     76	si_code = SEGV_ACCERR;
     77
     78	switch (cause) {
     79	case FLT_IFETCH:
     80		if (!(vma->vm_flags & VM_EXEC))
     81			goto bad_area;
     82		break;
     83	case FLT_LOAD:
     84		if (!(vma->vm_flags & VM_READ))
     85			goto bad_area;
     86		break;
     87	case FLT_STORE:
     88		if (!(vma->vm_flags & VM_WRITE))
     89			goto bad_area;
     90		flags |= FAULT_FLAG_WRITE;
     91		break;
     92	}
     93
     94	fault = handle_mm_fault(vma, address, flags, regs);
     95
     96	if (fault_signal_pending(fault, regs))
     97		return;
     98
     99	/* The most common case -- we are done. */
    100	if (likely(!(fault & VM_FAULT_ERROR))) {
    101		if (fault & VM_FAULT_RETRY) {
    102			flags |= FAULT_FLAG_TRIED;
    103			goto retry;
    104		}
    105
    106		mmap_read_unlock(mm);
    107		return;
    108	}
    109
    110	mmap_read_unlock(mm);
    111
    112	/* Handle copyin/out exception cases */
    113	if (!user_mode(regs))
    114		goto no_context;
    115
    116	if (fault & VM_FAULT_OOM) {
    117		pagefault_out_of_memory();
    118		return;
    119	}
    120
    121	/* User-mode address is in the memory map, but we are
    122	 * unable to fix up the page fault.
    123	 */
    124	if (fault & VM_FAULT_SIGBUS) {
    125		si_signo = SIGBUS;
    126		si_code = BUS_ADRERR;
    127	}
    128	/* Address is not in the memory map */
    129	else {
    130		si_signo = SIGSEGV;
    131		si_code  = SEGV_ACCERR;
    132	}
    133	force_sig_fault(si_signo, si_code, (void __user *)address);
    134	return;
    135
    136bad_area:
    137	mmap_read_unlock(mm);
    138
    139	if (user_mode(regs)) {
    140		force_sig_fault(SIGSEGV, si_code, (void __user *)address);
    141		return;
    142	}
    143	/* Kernel-mode fault falls through */
    144
    145no_context:
    146	fixup = search_exception_tables(pt_elr(regs));
    147	if (fixup) {
    148		pt_set_elr(regs, fixup->fixup);
    149		return;
    150	}
    151
    152	/* Things are looking very, very bad now */
    153	bust_spinlocks(1);
    154	printk(KERN_EMERG "Unable to handle kernel paging request at "
    155		"virtual address 0x%08lx, regs %p\n", address, regs);
    156	die("Bad Kernel VA", regs, SIGKILL);
    157}
    158
    159
    160void read_protection_fault(struct pt_regs *regs)
    161{
    162	unsigned long badvadr = pt_badva(regs);
    163
    164	do_page_fault(badvadr, FLT_LOAD, regs);
    165}
    166
    167void write_protection_fault(struct pt_regs *regs)
    168{
    169	unsigned long badvadr = pt_badva(regs);
    170
    171	do_page_fault(badvadr, FLT_STORE, regs);
    172}
    173
    174void execute_protection_fault(struct pt_regs *regs)
    175{
    176	unsigned long badvadr = pt_badva(regs);
    177
    178	do_page_fault(badvadr, FLT_IFETCH, regs);
    179}