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/*
* PowerPC version
* Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
*
* Derived from "arch/i386/mm/fault.c"
* Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
*
* Modified by Cort Dougan and Paul Mackerras.
*
* Modified for PPC64 by Dave Engebretsen (engebret@ibm.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#include <linux/signal.h>
#include <linux/sched.h>
#include <linux/sched/task_stack.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/types.h>
#include <linux/pagemap.h>
#include <linux/ptrace.h>
#include <linux/mman.h>
#include <linux/mm.h>
#include <linux/interrupt.h>
#include <linux/highmem.h>
#include <linux/extable.h>
#include <linux/kprobes.h>
#include <linux/kdebug.h>
#include <linux/perf_event.h>
#include <linux/ratelimit.h>
#include <linux/context_tracking.h>
#include <linux/hugetlb.h>
#include <linux/uaccess.h>
#include <asm/firmware.h>
#include <asm/page.h>
#include <asm/pgtable.h>
#include <asm/mmu.h>
#include <asm/mmu_context.h>
#include <asm/siginfo.h>
#include <asm/debug.h>
static inline bool notify_page_fault(struct pt_regs *regs)
{
bool ret = false;
#ifdef CONFIG_KPROBES
/* kprobe_running() needs smp_processor_id() */
if (!user_mode(regs)) {
preempt_disable();
if (kprobe_running() && kprobe_fault_handler(regs, 11))
ret = true;
preempt_enable();
}
#endif /* CONFIG_KPROBES */
if (unlikely(debugger_fault_handler(regs)))
ret = true;
return ret;
}
/*
* Check whether the instruction inst is a store using
* an update addressing form which will update r1.
*/
static bool store_updates_sp(unsigned int inst)
{
/* check for 1 in the rA field */
if (((inst >> 16) & 0x1f) != 1)
return false;
/* check major opcode */
switch (inst >> 26) {
case OP_STWU:
case OP_STBU:
case OP_STHU:
case OP_STFSU:
case OP_STFDU:
return true;
case OP_STD: /* std or stdu */
return (inst & 3) == 1;
case OP_31:
/* check minor opcode */
switch ((inst >> 1) & 0x3ff) {
case OP_31_XOP_STDUX:
case OP_31_XOP_STWUX:
case OP_31_XOP_STBUX:
case OP_31_XOP_STHUX:
case OP_31_XOP_STFSUX:
case OP_31_XOP_STFDUX:
return true;
}
}
return false;
}
/*
* do_page_fault error handling helpers
*/
static int
__bad_area_nosemaphore(struct pt_regs *regs, unsigned long address, int si_code)
{
/*
* If we are in kernel mode, bail out with a SEGV, this will
* be caught by the assembly which will restore the non-volatile
* registers before calling bad_page_fault()
*/
if (!user_mode(regs))
return SIGSEGV;
_exception(SIGSEGV, regs, si_code, address);
return 0;
}
static noinline int bad_area_nosemaphore(struct pt_regs *regs, unsigned long address)
{
return __bad_area_nosemaphore(regs, address, SEGV_MAPERR);
}
static int __bad_area(struct pt_regs *regs, unsigned long address, int si_code)
{
struct mm_struct *mm = current->mm;
/*
* Something tried to access memory that isn't in our memory map..
* Fix it, but check if it's kernel or user first..
*/
up_read(&mm->mmap_sem);
return __bad_area_nosemaphore(regs, address, si_code);
}
static noinline int bad_area(struct pt_regs *regs, unsigned long address)
{
return __bad_area(regs, address, SEGV_MAPERR);
}
static int bad_key_fault_exception(struct pt_regs *regs, unsigned long address,
int pkey)
{
/*
* If we are in kernel mode, bail out with a SEGV, this will
* be caught by the assembly which will restore the non-volatile
* registers before calling bad_page_fault()
*/
if (!user_mode(regs))
return SIGSEGV;
_exception_pkey(regs, address, pkey);
return 0;
}
static noinline int bad_access(struct pt_regs *regs, unsigned long address)
{
return __bad_area(regs, address, SEGV_ACCERR);
}
static int do_sigbus(struct pt_regs *regs, unsigned long address,
vm_fault_t fault)
{
if (!user_mode(regs))
return SIGBUS;
current->thread.trap_nr = BUS_ADRERR;
#ifdef CONFIG_MEMORY_FAILURE
if (fault & (VM_FAULT_HWPOISON|VM_FAULT_HWPOISON_LARGE)) {
unsigned int lsb = 0; /* shutup gcc */
pr_err("MCE: Killing %s:%d due to hardware memory corruption fault at %lx\n",
current->comm, current->pid, address);
if (fault & VM_FAULT_HWPOISON_LARGE)
lsb = hstate_index_to_shift(VM_FAULT_GET_HINDEX(fault));
if (fault & VM_FAULT_HWPOISON)
lsb = PAGE_SHIFT;
force_sig_mceerr(BUS_MCEERR_AR, (void __user *)address, lsb,
current);
return 0;
}
#endif
force_sig_fault(SIGBUS, BUS_ADRERR, (void __user *)address, current);
return 0;
}
static int mm_fault_error(struct pt_regs *regs, unsigned long addr,
vm_fault_t fault)
{
/*
* Kernel page fault interrupted by SIGKILL. We have no reason to
* continue processing.
*/
if (fatal_signal_pending(current) && !user_mode(regs))
return SIGKILL;
/* Out of memory */
if (fault & VM_FAULT_OOM) {
/*
* We ran out of memory, or some other thing happened to us that
* made us unable to handle the page fault gracefully.
*/
if (!user_mode(regs))
return SIGSEGV;
pagefault_out_of_memory();
} else {
if (fault & (VM_FAULT_SIGBUS|VM_FAULT_HWPOISON|
VM_FAULT_HWPOISON_LARGE))
return do_sigbus(regs, addr, fault);
else if (fault & VM_FAULT_SIGSEGV)
return bad_area_nosemaphore(regs, addr);
else
BUG();
}
return 0;
}
/* Is this a bad kernel fault ? */
static bool bad_kernel_fault(bool is_exec, unsigned long error_code,
unsigned long address)
{
if (is_exec && (error_code & (DSISR_NOEXEC_OR_G | DSISR_KEYFAULT))) {
printk_ratelimited(KERN_CRIT "kernel tried to execute"
" exec-protected page (%lx) -"
"exploit attempt? (uid: %d)\n",
address, from_kuid(&init_user_ns,
current_uid()));
}
return is_exec || (address >= TASK_SIZE);
}
static bool bad_stack_expansion(struct pt_regs *regs, unsigned long address,
struct vm_area_struct *vma, unsigned int flags,
bool *must_retry)
{
/*
* N.B. The POWER/Open ABI allows programs to access up to
* 288 bytes below the stack pointer.
* The kernel signal delivery code writes up to about 1.5kB
* below the stack pointer (r1) before decrementing it.
* The exec code can write slightly over 640kB to the stack
* before setting the user r1. Thus we allow the stack to
* expand to 1MB without further checks.
*/
if (address + 0x100000 <
|