mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-09-12 05:48:40 +00:00
![Christophe Leroy](/assets/img/avatar_default.png)
Running vdsotest leaves many times the following log: [ 79.629901] vdsotest[396]: User access of kernel address (ffffffff) - exploit attempt? (uid: 0) A pointer set to (-1) is likely a programming error similar to a NULL pointer and is not worth logging as an exploit attempt. Don't log user accesses to 0xffffffff. Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/0728849e826ba16f1fbd6fa7f5c6cc87bd64e097.1577087627.git.christophe.leroy@c-s.fr
687 lines
20 KiB
C
687 lines
20 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
|
|
/*
|
|
* 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)
|
|
*/
|
|
|
|
#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>
|
|
#include <asm/kup.h>
|
|
|
|
/*
|
|
* 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);
|
|
return 0;
|
|
}
|
|
|
|
#endif
|
|
force_sig_fault(SIGBUS, BUS_ADRERR, (void __user *)address);
|
|
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(struct pt_regs *regs, unsigned long error_code,
|
|
unsigned long address, bool is_write)
|
|
{
|
|
int is_exec = TRAP(regs) == 0x400;
|
|
|
|
/* NX faults set DSISR_PROTFAULT on the 8xx, DSISR_NOEXEC_OR_G on others */
|
|
if (is_exec && (error_code & (DSISR_NOEXEC_OR_G | DSISR_KEYFAULT |
|
|
DSISR_PROTFAULT))) {
|
|
pr_crit_ratelimited("kernel tried to execute %s page (%lx) - exploit attempt? (uid: %d)\n",
|
|
address >= TASK_SIZE ? "exec-protected" : "user",
|
|
address,
|
|
from_kuid(&init_user_ns, current_uid()));
|
|
|
|
// Kernel exec fault is always bad
|
|
return true;
|
|
}
|
|
|
|
if (!is_exec && address < TASK_SIZE && (error_code & DSISR_PROTFAULT) &&
|
|
!search_exception_tables(regs->nip)) {
|
|
pr_crit_ratelimited("Kernel attempted to access user page (%lx) - exploit attempt? (uid: %d)\n",
|
|
address,
|
|
from_kuid(&init_user_ns, current_uid()));
|
|
}
|
|
|
|
// Kernel fault on kernel address is bad
|
|
if (address >= TASK_SIZE)
|
|
return true;
|
|
|
|
// Fault on user outside of certain regions (eg. copy_tofrom_user()) is bad
|
|
if (!search_exception_tables(regs->nip))
|
|
return true;
|
|
|
|
// Read/write fault in a valid region (the exception table search passed
|
|
// above), but blocked by KUAP is bad, it can never succeed.
|
|
if (bad_kuap_fault(regs, is_write))
|
|
return true;
|
|
|
|
// What's left? Kernel fault on user in well defined regions (extable
|
|
// matched), and allowed by KUAP in the faulting context.
|
|
return false;
|
|
}
|
|
|
|
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 < vma->vm_end) {
|
|
unsigned int __user *nip = (unsigned int __user *)regs->nip;
|
|
/* get user regs even if this fault is in kernel mode */
|
|
struct pt_regs *uregs = current->thread.regs;
|
|
if (uregs == NULL)
|
|
return true;
|
|
|
|
/*
|
|
* A user-mode access to an address a long way below
|
|
* the stack pointer is only valid if the instruction
|
|
* is one which would update the stack pointer to the
|
|
* address accessed if the instruction completed,
|
|
* i.e. either stwu rs,n(r1) or stwux rs,r1,rb
|
|
* (or the byte, halfword, float or double forms).
|
|
*
|
|
* If we don't check this then any write to the area
|
|
* between the last mapped region and the stack will
|
|
* expand the stack rather than segfaulting.
|
|
*/
|
|
if (address + 2048 >= uregs->gpr[1])
|
|
return false;
|
|
|
|
if ((flags & FAULT_FLAG_WRITE) && (flags & FAULT_FLAG_USER) &&
|
|
access_ok(nip, sizeof(*nip))) {
|
|
unsigned int inst;
|
|
|
|
if (!probe_user_read(&inst, nip, sizeof(inst)))
|
|
return !store_updates_sp(inst);
|
|
*must_retry = true;
|
|
}
|
|
return true;
|
|
}
|
|
return false;
|
|
}
|
|
|
|
static bool access_error(bool is_write, bool is_exec,
|
|
struct vm_area_struct *vma)
|
|
{
|
|
/*
|
|
* Allow execution from readable areas if the MMU does not
|
|
* provide separate controls over reading and executing.
|
|
*
|
|
* Note: That code used to not be enabled for 4xx/BookE.
|
|
* It is now as I/D cache coherency for these is done at
|
|
* set_pte_at() time and I see no reason why the test
|
|
* below wouldn't be valid on those processors. This -may-
|
|
* break programs compiled with a really old ABI though.
|
|
*/
|
|
if (is_exec) {
|
|
return !(vma->vm_flags & VM_EXEC) &&
|
|
(cpu_has_feature(CPU_FTR_NOEXECUTE) ||
|
|
!(vma->vm_flags & (VM_READ | VM_WRITE)));
|
|
}
|
|
|
|
if (is_write) {
|
|
if (unlikely(!(vma->vm_flags & VM_WRITE)))
|
|
return true;
|
|
return false;
|
|
}
|
|
|
|
if (unlikely(!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE))))
|
|
return true;
|
|
/*
|
|
* We should ideally do the vma pkey access check here. But in the
|
|
* fault path, handle_mm_fault() also does the same check. To avoid
|
|
* these multiple checks, we skip it here and handle access error due
|
|
* to pkeys later.
|
|
*/
|
|
return false;
|
|
}
|
|
|
|
#ifdef CONFIG_PPC_SMLPAR
|
|
static inline void cmo_account_page_fault(void)
|
|
{
|
|
if (firmware_has_feature(FW_FEATURE_CMO)) {
|
|
u32 page_ins;
|
|
|
|
preempt_disable();
|
|
page_ins = be32_to_cpu(get_lppaca()->page_ins);
|
|
page_ins += 1 << PAGE_FACTOR;
|
|
get_lppaca()->page_ins = cpu_to_be32(page_ins);
|
|
preempt_enable();
|
|
}
|
|
}
|
|
#else
|
|
static inline void cmo_account_page_fault(void) { }
|
|
#endif /* CONFIG_PPC_SMLPAR */
|
|
|
|
#ifdef CONFIG_PPC_BOOK3S
|
|
static void sanity_check_fault(bool is_write, bool is_user,
|
|
unsigned long error_code, unsigned long address)
|
|
{
|
|
/*
|
|
* Userspace trying to access kernel address, we get PROTFAULT for that.
|
|
*/
|
|
if (is_user && address >= TASK_SIZE) {
|
|
if ((long)address == -1)
|
|
return;
|
|
|
|
pr_crit_ratelimited("%s[%d]: User access of kernel address (%lx) - exploit attempt? (uid: %d)\n",
|
|
current->comm, current->pid, address,
|
|
from_kuid(&init_user_ns, current_uid()));
|
|
return;
|
|
}
|
|
|
|
/*
|
|
* For hash translation mode, we should never get a
|
|
* PROTFAULT. Any update to pte to reduce access will result in us
|
|
* removing the hash page table entry, thus resulting in a DSISR_NOHPTE
|
|
* fault instead of DSISR_PROTFAULT.
|
|
*
|
|
* A pte update to relax the access will not result in a hash page table
|
|
* entry invalidate and hence can result in DSISR_PROTFAULT.
|
|
* ptep_set_access_flags() doesn't do a hpte flush. This is why we have
|
|
* the special !is_write in the below conditional.
|
|
*
|
|
* For platforms that doesn't supports coherent icache and do support
|
|
* per page noexec bit, we do setup things such that we do the
|
|
* sync between D/I cache via fault. But that is handled via low level
|
|
* hash fault code (hash_page_do_lazy_icache()) and we should not reach
|
|
* here in such case.
|
|
*
|
|
* For wrong access that can result in PROTFAULT, the above vma->vm_flags
|
|
* check should handle those and hence we should fall to the bad_area
|
|
* handling correctly.
|
|
*
|
|
* For embedded with per page exec support that doesn't support coherent
|
|
* icache we do get PROTFAULT and we handle that D/I cache sync in
|
|
* set_pte_at while taking the noexec/prot fault. Hence this is WARN_ON
|
|
* is conditional for server MMU.
|
|
*
|
|
* For radix, we can get prot fault for autonuma case, because radix
|
|
* page table will have them marked noaccess for user.
|
|
*/
|
|
if (radix_enabled() || is_write)
|
|
return;
|
|
|
|
WARN_ON_ONCE(error_code & DSISR_PROTFAULT);
|
|
}
|
|
#else
|
|
static void sanity_check_fault(bool is_write, bool is_user,
|
|
unsigned long error_code, unsigned long address) { }
|
|
#endif /* CONFIG_PPC_BOOK3S */
|
|
|
|
/*
|
|
* Define the correct "is_write" bit in error_code based
|
|
* on the processor family
|
|
*/
|
|
#if (defined(CONFIG_4xx) || defined(CONFIG_BOOKE))
|
|
#define page_fault_is_write(__err) ((__err) & ESR_DST)
|
|
#define page_fault_is_bad(__err) (0)
|
|
#else
|
|
#define page_fault_is_write(__err) ((__err) & DSISR_ISSTORE)
|
|
#if defined(CONFIG_PPC_8xx)
|
|
#define page_fault_is_bad(__err) ((__err) & DSISR_NOEXEC_OR_G)
|
|
#elif defined(CONFIG_PPC64)
|
|
#define page_fault_is_bad(__err) ((__err) & DSISR_BAD_FAULT_64S)
|
|
#else
|
|
#define page_fault_is_bad(__err) ((__err) & DSISR_BAD_FAULT_32S)
|
|
#endif
|
|
#endif
|
|
|
|
/*
|
|
* For 600- and 800-family processors, the error_code parameter is DSISR
|
|
* for a data fault, SRR1 for an instruction fault. For 400-family processors
|
|
* the error_code parameter is ESR for a data fault, 0 for an instruction
|
|
* fault.
|
|
* For 64-bit processors, the error_code parameter is
|
|
* - DSISR for a non-SLB data access fault,
|
|
* - SRR1 & 0x08000000 for a non-SLB instruction access fault
|
|
* - 0 any SLB fault.
|
|
*
|
|
* The return value is 0 if the fault was handled, or the signal
|
|
* number if this is a kernel fault that can't be handled here.
|
|
*/
|
|
static int __do_page_fault(struct pt_regs *regs, unsigned long address,
|
|
unsigned long error_code)
|
|
{
|
|
struct vm_area_struct * vma;
|
|
struct mm_struct *mm = current->mm;
|
|
unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
|
|
int is_exec = TRAP(regs) == 0x400;
|
|
int is_user = user_mode(regs);
|
|
int is_write = page_fault_is_write(error_code);
|
|
vm_fault_t fault, major = 0;
|
|
bool must_retry = false;
|
|
bool kprobe_fault = kprobe_page_fault(regs, 11);
|
|
|
|
if (unlikely(debugger_fault_handler(regs) || kprobe_fault))
|
|
return 0;
|
|
|
|
if (unlikely(page_fault_is_bad(error_code))) {
|
|
if (is_user) {
|
|
_exception(SIGBUS, regs, BUS_OBJERR, address);
|
|
return 0;
|
|
}
|
|
return SIGBUS;
|
|
}
|
|
|
|
/* Additional sanity check(s) */
|
|
sanity_check_fault(is_write, is_user, error_code, address);
|
|
|
|
/*
|
|
* The kernel should never take an execute fault nor should it
|
|
* take a page fault to a kernel address or a page fault to a user
|
|
* address outside of dedicated places
|
|
*/
|
|
if (unlikely(!is_user && bad_kernel_fault(regs, error_code, address, is_write)))
|
|
return SIGSEGV;
|
|
|
|
/*
|
|
* If we're in an interrupt, have no user context or are running
|
|
* in a region with pagefaults disabled then we must not take the fault
|
|
*/
|
|
if (unlikely(faulthandler_disabled() || !mm)) {
|
|
if (is_user)
|
|
printk_ratelimited(KERN_ERR "Page fault in user mode"
|
|
" with faulthandler_disabled()=%d"
|
|
" mm=%p\n",
|
|
faulthandler_disabled(), mm);
|
|
return bad_area_nosemaphore(regs, address);
|
|
}
|
|
|
|
/* We restore the interrupt state now */
|
|
if (!arch_irq_disabled_regs(regs))
|
|
local_irq_enable();
|
|
|
|
perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
|
|
|
|
if (error_code & DSISR_KEYFAULT)
|
|
return bad_key_fault_exception(regs, address,
|
|
get_mm_addr_key(mm, address));
|
|
|
|
/*
|
|
* We want to do this outside mmap_sem, because reading code around nip
|
|
* can result in fault, which will cause a deadlock when called with
|
|
* mmap_sem held
|
|
*/
|
|
if (is_user)
|
|
flags |= FAULT_FLAG_USER;
|
|
if (is_write)
|
|
flags |= FAULT_FLAG_WRITE;
|
|
if (is_exec)
|
|
flags |= FAULT_FLAG_INSTRUCTION;
|
|
|
|
/* When running in the kernel we expect faults to occur only to
|
|
* addresses in user space. All other faults represent errors in the
|
|
* kernel and should generate an OOPS. Unfortunately, in the case of an
|
|
* erroneous fault occurring in a code path which already holds mmap_sem
|
|
* we will deadlock attempting to validate the fault against the
|
|
* address space. Luckily the kernel only validly references user
|
|
* space from well defined areas of code, which are listed in the
|
|
* exceptions table.
|
|
*
|
|
* As the vast majority of faults will be valid we will only perform
|
|
* the source reference check when there is a possibility of a deadlock.
|
|
* Attempt to lock the address space, if we cannot we then validate the
|
|
* source. If this is invalid we can skip the address space check,
|
|
* thus avoiding the deadlock.
|
|
*/
|
|
if (unlikely(!down_read_trylock(&mm->mmap_sem))) {
|
|
if (!is_user && !search_exception_tables(regs->nip))
|
|
return bad_area_nosemaphore(regs, address);
|
|
|
|
retry:
|
|
down_read(&mm->mmap_sem);
|
|
} else {
|
|
/*
|
|
* The above down_read_trylock() might have succeeded in
|
|
* which case we'll have missed the might_sleep() from
|
|
* down_read():
|
|
*/
|
|
might_sleep();
|
|
}
|
|
|
|
vma = find_vma(mm, address);
|
|
if (unlikely(!vma))
|
|
return bad_area(regs, address);
|
|
if (likely(vma->vm_start <= address))
|
|
goto good_area;
|
|
if (unlikely(!(vma->vm_flags & VM_GROWSDOWN)))
|
|
return bad_area(regs, address);
|
|
|
|
/* The stack is being expanded, check if it's valid */
|
|
if (unlikely(bad_stack_expansion(regs, address, vma, flags,
|
|
&must_retry))) {
|
|
if (!must_retry)
|
|
return bad_area(regs, address);
|
|
|
|
up_read(&mm->mmap_sem);
|
|
if (fault_in_pages_readable((const char __user *)regs->nip,
|
|
sizeof(unsigned int)))
|
|
return bad_area_nosemaphore(regs, address);
|
|
goto retry;
|
|
}
|
|
|
|
/* Try to expand it */
|
|
if (unlikely(expand_stack(vma, address)))
|
|
return bad_area(regs, address);
|
|
|
|
good_area:
|
|
if (unlikely(access_error(is_write, is_exec, vma)))
|
|
return bad_access(regs, address);
|
|
|
|
/*
|
|
* 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);
|
|
|
|
#ifdef CONFIG_PPC_MEM_KEYS
|
|
/*
|
|
* we skipped checking for access error due to key earlier.
|
|
* Check that using handle_mm_fault error return.
|
|
*/
|
|
if (unlikely(fault & VM_FAULT_SIGSEGV) &&
|
|
!arch_vma_access_permitted(vma, is_write, is_exec, 0)) {
|
|
|
|
int pkey = vma_pkey(vma);
|
|
|
|
up_read(&mm->mmap_sem);
|
|
return bad_key_fault_exception(regs, address, pkey);
|
|
}
|
|
#endif /* CONFIG_PPC_MEM_KEYS */
|
|
|
|
major |= fault & VM_FAULT_MAJOR;
|
|
|
|
/*
|
|
* Handle the retry right now, the mmap_sem has been released in that
|
|
* case.
|
|
*/
|
|
if (unlikely(fault & VM_FAULT_RETRY)) {
|
|
/* We retry only once */
|
|
if (flags & FAULT_FLAG_ALLOW_RETRY) {
|
|
/*
|
|
* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk
|
|
* of starvation.
|
|
*/
|
|
flags &= ~FAULT_FLAG_ALLOW_RETRY;
|
|
flags |= FAULT_FLAG_TRIED;
|
|
if (!fatal_signal_pending(current))
|
|
goto retry;
|
|
}
|
|
|
|
/*
|
|
* User mode? Just return to handle the fatal exception otherwise
|
|
* return to bad_page_fault
|
|
*/
|
|
return is_user ? 0 : SIGBUS;
|
|
}
|
|
|
|
up_read(¤t->mm->mmap_sem);
|
|
|
|
if (unlikely(fault & VM_FAULT_ERROR))
|
|
return mm_fault_error(regs, address, fault);
|
|
|
|
/*
|
|
* Major/minor page fault accounting.
|
|
*/
|
|
if (major) {
|
|
current->maj_flt++;
|
|
perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, regs, address);
|
|
cmo_account_page_fault();
|
|
} else {
|
|
current->min_flt++;
|
|
perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, regs, address);
|
|
}
|
|
return 0;
|
|
}
|
|
NOKPROBE_SYMBOL(__do_page_fault);
|
|
|
|
int do_page_fault(struct pt_regs *regs, unsigned long address,
|
|
unsigned long error_code)
|
|
{
|
|
enum ctx_state prev_state = exception_enter();
|
|
int rc = __do_page_fault(regs, address, error_code);
|
|
exception_exit(prev_state);
|
|
return rc;
|
|
}
|
|
NOKPROBE_SYMBOL(do_page_fault);
|
|
|
|
/*
|
|
* bad_page_fault is called when we have a bad access from the kernel.
|
|
* It is called from the DSI and ISI handlers in head.S and from some
|
|
* of the procedures in traps.c.
|
|
*/
|
|
void bad_page_fault(struct pt_regs *regs, unsigned long address, int sig)
|
|
{
|
|
const struct exception_table_entry *entry;
|
|
int is_write = page_fault_is_write(regs->dsisr);
|
|
|
|
/* Are we prepared to handle this fault? */
|
|
if ((entry = search_exception_tables(regs->nip)) != NULL) {
|
|
regs->nip = extable_fixup(entry);
|
|
return;
|
|
}
|
|
|
|
/* kernel has accessed a bad area */
|
|
|
|
switch (TRAP(regs)) {
|
|
case 0x300:
|
|
case 0x380:
|
|
case 0xe00:
|
|
pr_alert("BUG: %s on %s at 0x%08lx\n",
|
|
regs->dar < PAGE_SIZE ? "Kernel NULL pointer dereference" :
|
|
"Unable to handle kernel data access",
|
|
is_write ? "write" : "read", regs->dar);
|
|
break;
|
|
case 0x400:
|
|
case 0x480:
|
|
pr_alert("BUG: Unable to handle kernel instruction fetch%s",
|
|
regs->nip < PAGE_SIZE ? " (NULL pointer?)\n" : "\n");
|
|
break;
|
|
case 0x600:
|
|
pr_alert("BUG: Unable to handle kernel unaligned access at 0x%08lx\n",
|
|
regs->dar);
|
|
break;
|
|
default:
|
|
pr_alert("BUG: Unable to handle unknown paging fault at 0x%08lx\n",
|
|
regs->dar);
|
|
break;
|
|
}
|
|
printk(KERN_ALERT "Faulting instruction address: 0x%08lx\n",
|
|
regs->nip);
|
|
|
|
if (task_stack_end_corrupted(current))
|
|
printk(KERN_ALERT "Thread overran stack, or stack corrupted\n");
|
|
|
|
die("Kernel access of bad area", regs, sig);
|
|
}
|