mirror of
https://github.com/torvalds/linux.git
synced 2024-12-05 18:41:23 +00:00
9857a17f20
try_get_page() is very similar to try_get_compound_head(), and in fact try_get_page() has fallen a little behind in terms of maintenance: try_get_compound_head() handles speculative page references more thoroughly. There are only two try_get_page() callsites, so just call try_get_compound_head() directly from those, and remove try_get_page() entirely. Also, seeing as how this changes try_get_compound_head() into a non-static function, provide some kerneldoc documentation for it. Link: https://lkml.kernel.org/r/20210813044133.1536842-4-jhubbard@nvidia.com Signed-off-by: John Hubbard <jhubbard@nvidia.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Cc: Matthew Wilcox <willy@infradead.org> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Heiko Carstens <hca@linux.ibm.com> Cc: Vasily Gorbik <gor@linux.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
867 lines
22 KiB
C
867 lines
22 KiB
C
// SPDX-License-Identifier: GPL-2.0
|
|
/*
|
|
* S390 version
|
|
* Copyright IBM Corp. 1999
|
|
* Author(s): Hartmut Penner (hp@de.ibm.com)
|
|
* Ulrich Weigand (uweigand@de.ibm.com)
|
|
*
|
|
* Derived from "arch/i386/mm/fault.c"
|
|
* Copyright (C) 1995 Linus Torvalds
|
|
*/
|
|
|
|
#include <linux/kernel_stat.h>
|
|
#include <linux/perf_event.h>
|
|
#include <linux/signal.h>
|
|
#include <linux/sched.h>
|
|
#include <linux/sched/debug.h>
|
|
#include <linux/kernel.h>
|
|
#include <linux/errno.h>
|
|
#include <linux/string.h>
|
|
#include <linux/types.h>
|
|
#include <linux/ptrace.h>
|
|
#include <linux/mman.h>
|
|
#include <linux/mm.h>
|
|
#include <linux/compat.h>
|
|
#include <linux/smp.h>
|
|
#include <linux/kdebug.h>
|
|
#include <linux/init.h>
|
|
#include <linux/console.h>
|
|
#include <linux/extable.h>
|
|
#include <linux/hardirq.h>
|
|
#include <linux/kprobes.h>
|
|
#include <linux/uaccess.h>
|
|
#include <linux/hugetlb.h>
|
|
#include <asm/asm-offsets.h>
|
|
#include <asm/diag.h>
|
|
#include <asm/gmap.h>
|
|
#include <asm/irq.h>
|
|
#include <asm/mmu_context.h>
|
|
#include <asm/facility.h>
|
|
#include <asm/uv.h>
|
|
#include "../kernel/entry.h"
|
|
|
|
#define __FAIL_ADDR_MASK -4096L
|
|
#define __SUBCODE_MASK 0x0600
|
|
#define __PF_RES_FIELD 0x8000000000000000ULL
|
|
|
|
#define VM_FAULT_BADCONTEXT ((__force vm_fault_t) 0x010000)
|
|
#define VM_FAULT_BADMAP ((__force vm_fault_t) 0x020000)
|
|
#define VM_FAULT_BADACCESS ((__force vm_fault_t) 0x040000)
|
|
#define VM_FAULT_SIGNAL ((__force vm_fault_t) 0x080000)
|
|
#define VM_FAULT_PFAULT ((__force vm_fault_t) 0x100000)
|
|
|
|
enum fault_type {
|
|
KERNEL_FAULT,
|
|
USER_FAULT,
|
|
GMAP_FAULT,
|
|
};
|
|
|
|
static unsigned long store_indication __read_mostly;
|
|
|
|
static int __init fault_init(void)
|
|
{
|
|
if (test_facility(75))
|
|
store_indication = 0xc00;
|
|
return 0;
|
|
}
|
|
early_initcall(fault_init);
|
|
|
|
/*
|
|
* Find out which address space caused the exception.
|
|
*/
|
|
static enum fault_type get_fault_type(struct pt_regs *regs)
|
|
{
|
|
unsigned long trans_exc_code;
|
|
|
|
trans_exc_code = regs->int_parm_long & 3;
|
|
if (likely(trans_exc_code == 0)) {
|
|
/* primary space exception */
|
|
if (user_mode(regs))
|
|
return USER_FAULT;
|
|
if (!IS_ENABLED(CONFIG_PGSTE))
|
|
return KERNEL_FAULT;
|
|
if (test_pt_regs_flag(regs, PIF_GUEST_FAULT))
|
|
return GMAP_FAULT;
|
|
return KERNEL_FAULT;
|
|
}
|
|
if (trans_exc_code == 2)
|
|
return USER_FAULT;
|
|
if (trans_exc_code == 1) {
|
|
/* access register mode, not used in the kernel */
|
|
return USER_FAULT;
|
|
}
|
|
/* home space exception -> access via kernel ASCE */
|
|
return KERNEL_FAULT;
|
|
}
|
|
|
|
static int bad_address(void *p)
|
|
{
|
|
unsigned long dummy;
|
|
|
|
return get_kernel_nofault(dummy, (unsigned long *)p);
|
|
}
|
|
|
|
static void dump_pagetable(unsigned long asce, unsigned long address)
|
|
{
|
|
unsigned long *table = __va(asce & _ASCE_ORIGIN);
|
|
|
|
pr_alert("AS:%016lx ", asce);
|
|
switch (asce & _ASCE_TYPE_MASK) {
|
|
case _ASCE_TYPE_REGION1:
|
|
table += (address & _REGION1_INDEX) >> _REGION1_SHIFT;
|
|
if (bad_address(table))
|
|
goto bad;
|
|
pr_cont("R1:%016lx ", *table);
|
|
if (*table & _REGION_ENTRY_INVALID)
|
|
goto out;
|
|
table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN);
|
|
fallthrough;
|
|
case _ASCE_TYPE_REGION2:
|
|
table += (address & _REGION2_INDEX) >> _REGION2_SHIFT;
|
|
if (bad_address(table))
|
|
goto bad;
|
|
pr_cont("R2:%016lx ", *table);
|
|
if (*table & _REGION_ENTRY_INVALID)
|
|
goto out;
|
|
table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN);
|
|
fallthrough;
|
|
case _ASCE_TYPE_REGION3:
|
|
table += (address & _REGION3_INDEX) >> _REGION3_SHIFT;
|
|
if (bad_address(table))
|
|
goto bad;
|
|
pr_cont("R3:%016lx ", *table);
|
|
if (*table & (_REGION_ENTRY_INVALID | _REGION3_ENTRY_LARGE))
|
|
goto out;
|
|
table = (unsigned long *)(*table & _REGION_ENTRY_ORIGIN);
|
|
fallthrough;
|
|
case _ASCE_TYPE_SEGMENT:
|
|
table += (address & _SEGMENT_INDEX) >> _SEGMENT_SHIFT;
|
|
if (bad_address(table))
|
|
goto bad;
|
|
pr_cont("S:%016lx ", *table);
|
|
if (*table & (_SEGMENT_ENTRY_INVALID | _SEGMENT_ENTRY_LARGE))
|
|
goto out;
|
|
table = (unsigned long *)(*table & _SEGMENT_ENTRY_ORIGIN);
|
|
}
|
|
table += (address & _PAGE_INDEX) >> _PAGE_SHIFT;
|
|
if (bad_address(table))
|
|
goto bad;
|
|
pr_cont("P:%016lx ", *table);
|
|
out:
|
|
pr_cont("\n");
|
|
return;
|
|
bad:
|
|
pr_cont("BAD\n");
|
|
}
|
|
|
|
static void dump_fault_info(struct pt_regs *regs)
|
|
{
|
|
unsigned long asce;
|
|
|
|
pr_alert("Failing address: %016lx TEID: %016lx\n",
|
|
regs->int_parm_long & __FAIL_ADDR_MASK, regs->int_parm_long);
|
|
pr_alert("Fault in ");
|
|
switch (regs->int_parm_long & 3) {
|
|
case 3:
|
|
pr_cont("home space ");
|
|
break;
|
|
case 2:
|
|
pr_cont("secondary space ");
|
|
break;
|
|
case 1:
|
|
pr_cont("access register ");
|
|
break;
|
|
case 0:
|
|
pr_cont("primary space ");
|
|
break;
|
|
}
|
|
pr_cont("mode while using ");
|
|
switch (get_fault_type(regs)) {
|
|
case USER_FAULT:
|
|
asce = S390_lowcore.user_asce;
|
|
pr_cont("user ");
|
|
break;
|
|
case GMAP_FAULT:
|
|
asce = ((struct gmap *) S390_lowcore.gmap)->asce;
|
|
pr_cont("gmap ");
|
|
break;
|
|
case KERNEL_FAULT:
|
|
asce = S390_lowcore.kernel_asce;
|
|
pr_cont("kernel ");
|
|
break;
|
|
default:
|
|
unreachable();
|
|
}
|
|
pr_cont("ASCE.\n");
|
|
dump_pagetable(asce, regs->int_parm_long & __FAIL_ADDR_MASK);
|
|
}
|
|
|
|
int show_unhandled_signals = 1;
|
|
|
|
void report_user_fault(struct pt_regs *regs, long signr, int is_mm_fault)
|
|
{
|
|
if ((task_pid_nr(current) > 1) && !show_unhandled_signals)
|
|
return;
|
|
if (!unhandled_signal(current, signr))
|
|
return;
|
|
if (!printk_ratelimit())
|
|
return;
|
|
printk(KERN_ALERT "User process fault: interruption code %04x ilc:%d ",
|
|
regs->int_code & 0xffff, regs->int_code >> 17);
|
|
print_vma_addr(KERN_CONT "in ", regs->psw.addr);
|
|
printk(KERN_CONT "\n");
|
|
if (is_mm_fault)
|
|
dump_fault_info(regs);
|
|
show_regs(regs);
|
|
}
|
|
|
|
/*
|
|
* Send SIGSEGV to task. This is an external routine
|
|
* to keep the stack usage of do_page_fault small.
|
|
*/
|
|
static noinline void do_sigsegv(struct pt_regs *regs, int si_code)
|
|
{
|
|
report_user_fault(regs, SIGSEGV, 1);
|
|
force_sig_fault(SIGSEGV, si_code,
|
|
(void __user *)(regs->int_parm_long & __FAIL_ADDR_MASK));
|
|
}
|
|
|
|
const struct exception_table_entry *s390_search_extables(unsigned long addr)
|
|
{
|
|
const struct exception_table_entry *fixup;
|
|
|
|
fixup = search_extable(__start_dma_ex_table,
|
|
__stop_dma_ex_table - __start_dma_ex_table,
|
|
addr);
|
|
if (!fixup)
|
|
fixup = search_exception_tables(addr);
|
|
return fixup;
|
|
}
|
|
|
|
static noinline void do_no_context(struct pt_regs *regs)
|
|
{
|
|
const struct exception_table_entry *fixup;
|
|
|
|
/* Are we prepared to handle this kernel fault? */
|
|
fixup = s390_search_extables(regs->psw.addr);
|
|
if (fixup && ex_handle(fixup, regs))
|
|
return;
|
|
|
|
/*
|
|
* Oops. The kernel tried to access some bad page. We'll have to
|
|
* terminate things with extreme prejudice.
|
|
*/
|
|
if (get_fault_type(regs) == KERNEL_FAULT)
|
|
printk(KERN_ALERT "Unable to handle kernel pointer dereference"
|
|
" in virtual kernel address space\n");
|
|
else
|
|
printk(KERN_ALERT "Unable to handle kernel paging request"
|
|
" in virtual user address space\n");
|
|
dump_fault_info(regs);
|
|
die(regs, "Oops");
|
|
do_exit(SIGKILL);
|
|
}
|
|
|
|
static noinline void do_low_address(struct pt_regs *regs)
|
|
{
|
|
/* Low-address protection hit in kernel mode means
|
|
NULL pointer write access in kernel mode. */
|
|
if (regs->psw.mask & PSW_MASK_PSTATE) {
|
|
/* Low-address protection hit in user mode 'cannot happen'. */
|
|
die (regs, "Low-address protection");
|
|
do_exit(SIGKILL);
|
|
}
|
|
|
|
do_no_context(regs);
|
|
}
|
|
|
|
static noinline void do_sigbus(struct pt_regs *regs)
|
|
{
|
|
/*
|
|
* Send a sigbus, regardless of whether we were in kernel
|
|
* or user mode.
|
|
*/
|
|
force_sig_fault(SIGBUS, BUS_ADRERR,
|
|
(void __user *)(regs->int_parm_long & __FAIL_ADDR_MASK));
|
|
}
|
|
|
|
static noinline void do_fault_error(struct pt_regs *regs, int access,
|
|
vm_fault_t fault)
|
|
{
|
|
int si_code;
|
|
|
|
switch (fault) {
|
|
case VM_FAULT_BADACCESS:
|
|
case VM_FAULT_BADMAP:
|
|
/* Bad memory access. Check if it is kernel or user space. */
|
|
if (user_mode(regs)) {
|
|
/* User mode accesses just cause a SIGSEGV */
|
|
si_code = (fault == VM_FAULT_BADMAP) ?
|
|
SEGV_MAPERR : SEGV_ACCERR;
|
|
do_sigsegv(regs, si_code);
|
|
break;
|
|
}
|
|
fallthrough;
|
|
case VM_FAULT_BADCONTEXT:
|
|
case VM_FAULT_PFAULT:
|
|
do_no_context(regs);
|
|
break;
|
|
case VM_FAULT_SIGNAL:
|
|
if (!user_mode(regs))
|
|
do_no_context(regs);
|
|
break;
|
|
default: /* fault & VM_FAULT_ERROR */
|
|
if (fault & VM_FAULT_OOM) {
|
|
if (!user_mode(regs))
|
|
do_no_context(regs);
|
|
else
|
|
pagefault_out_of_memory();
|
|
} else if (fault & VM_FAULT_SIGSEGV) {
|
|
/* Kernel mode? Handle exceptions or die */
|
|
if (!user_mode(regs))
|
|
do_no_context(regs);
|
|
else
|
|
do_sigsegv(regs, SEGV_MAPERR);
|
|
} else if (fault & VM_FAULT_SIGBUS) {
|
|
/* Kernel mode? Handle exceptions or die */
|
|
if (!user_mode(regs))
|
|
do_no_context(regs);
|
|
else
|
|
do_sigbus(regs);
|
|
} else
|
|
BUG();
|
|
break;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* This routine handles page faults. It determines the address,
|
|
* and the problem, and then passes it off to one of the appropriate
|
|
* routines.
|
|
*
|
|
* interruption code (int_code):
|
|
* 04 Protection -> Write-Protection (suppression)
|
|
* 10 Segment translation -> Not present (nullification)
|
|
* 11 Page translation -> Not present (nullification)
|
|
* 3b Region third trans. -> Not present (nullification)
|
|
*/
|
|
static inline vm_fault_t do_exception(struct pt_regs *regs, int access)
|
|
{
|
|
struct gmap *gmap;
|
|
struct task_struct *tsk;
|
|
struct mm_struct *mm;
|
|
struct vm_area_struct *vma;
|
|
enum fault_type type;
|
|
unsigned long trans_exc_code;
|
|
unsigned long address;
|
|
unsigned int flags;
|
|
vm_fault_t fault;
|
|
|
|
tsk = current;
|
|
/*
|
|
* The instruction that caused the program check has
|
|
* been nullified. Don't signal single step via SIGTRAP.
|
|
*/
|
|
clear_thread_flag(TIF_PER_TRAP);
|
|
|
|
if (kprobe_page_fault(regs, 14))
|
|
return 0;
|
|
|
|
mm = tsk->mm;
|
|
trans_exc_code = regs->int_parm_long;
|
|
|
|
/*
|
|
* Verify that the fault happened in user space, that
|
|
* we are not in an interrupt and that there is a
|
|
* user context.
|
|
*/
|
|
fault = VM_FAULT_BADCONTEXT;
|
|
type = get_fault_type(regs);
|
|
switch (type) {
|
|
case KERNEL_FAULT:
|
|
goto out;
|
|
case USER_FAULT:
|
|
case GMAP_FAULT:
|
|
if (faulthandler_disabled() || !mm)
|
|
goto out;
|
|
break;
|
|
}
|
|
|
|
address = trans_exc_code & __FAIL_ADDR_MASK;
|
|
perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
|
|
flags = FAULT_FLAG_DEFAULT;
|
|
if (user_mode(regs))
|
|
flags |= FAULT_FLAG_USER;
|
|
if (access == VM_WRITE || (trans_exc_code & store_indication) == 0x400)
|
|
flags |= FAULT_FLAG_WRITE;
|
|
mmap_read_lock(mm);
|
|
|
|
gmap = NULL;
|
|
if (IS_ENABLED(CONFIG_PGSTE) && type == GMAP_FAULT) {
|
|
gmap = (struct gmap *) S390_lowcore.gmap;
|
|
current->thread.gmap_addr = address;
|
|
current->thread.gmap_write_flag = !!(flags & FAULT_FLAG_WRITE);
|
|
current->thread.gmap_int_code = regs->int_code & 0xffff;
|
|
address = __gmap_translate(gmap, address);
|
|
if (address == -EFAULT) {
|
|
fault = VM_FAULT_BADMAP;
|
|
goto out_up;
|
|
}
|
|
if (gmap->pfault_enabled)
|
|
flags |= FAULT_FLAG_RETRY_NOWAIT;
|
|
}
|
|
|
|
retry:
|
|
fault = VM_FAULT_BADMAP;
|
|
vma = find_vma(mm, address);
|
|
if (!vma)
|
|
goto out_up;
|
|
|
|
if (unlikely(vma->vm_start > address)) {
|
|
if (!(vma->vm_flags & VM_GROWSDOWN))
|
|
goto out_up;
|
|
if (expand_stack(vma, address))
|
|
goto out_up;
|
|
}
|
|
|
|
/*
|
|
* Ok, we have a good vm_area for this memory access, so
|
|
* we can handle it..
|
|
*/
|
|
fault = VM_FAULT_BADACCESS;
|
|
if (unlikely(!(vma->vm_flags & access)))
|
|
goto out_up;
|
|
|
|
if (is_vm_hugetlb_page(vma))
|
|
address &= HPAGE_MASK;
|
|
/*
|
|
* 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)) {
|
|
fault = VM_FAULT_SIGNAL;
|
|
if (flags & FAULT_FLAG_RETRY_NOWAIT)
|
|
goto out_up;
|
|
goto out;
|
|
}
|
|
if (unlikely(fault & VM_FAULT_ERROR))
|
|
goto out_up;
|
|
|
|
if (flags & FAULT_FLAG_ALLOW_RETRY) {
|
|
if (fault & VM_FAULT_RETRY) {
|
|
if (IS_ENABLED(CONFIG_PGSTE) && gmap &&
|
|
(flags & FAULT_FLAG_RETRY_NOWAIT)) {
|
|
/* FAULT_FLAG_RETRY_NOWAIT has been set,
|
|
* mmap_lock has not been released */
|
|
current->thread.gmap_pfault = 1;
|
|
fault = VM_FAULT_PFAULT;
|
|
goto out_up;
|
|
}
|
|
flags &= ~FAULT_FLAG_RETRY_NOWAIT;
|
|
flags |= FAULT_FLAG_TRIED;
|
|
mmap_read_lock(mm);
|
|
goto retry;
|
|
}
|
|
}
|
|
if (IS_ENABLED(CONFIG_PGSTE) && gmap) {
|
|
address = __gmap_link(gmap, current->thread.gmap_addr,
|
|
address);
|
|
if (address == -EFAULT) {
|
|
fault = VM_FAULT_BADMAP;
|
|
goto out_up;
|
|
}
|
|
if (address == -ENOMEM) {
|
|
fault = VM_FAULT_OOM;
|
|
goto out_up;
|
|
}
|
|
}
|
|
fault = 0;
|
|
out_up:
|
|
mmap_read_unlock(mm);
|
|
out:
|
|
return fault;
|
|
}
|
|
|
|
void do_protection_exception(struct pt_regs *regs)
|
|
{
|
|
unsigned long trans_exc_code;
|
|
int access;
|
|
vm_fault_t fault;
|
|
|
|
trans_exc_code = regs->int_parm_long;
|
|
/*
|
|
* Protection exceptions are suppressing, decrement psw address.
|
|
* The exception to this rule are aborted transactions, for these
|
|
* the PSW already points to the correct location.
|
|
*/
|
|
if (!(regs->int_code & 0x200))
|
|
regs->psw.addr = __rewind_psw(regs->psw, regs->int_code >> 16);
|
|
/*
|
|
* Check for low-address protection. This needs to be treated
|
|
* as a special case because the translation exception code
|
|
* field is not guaranteed to contain valid data in this case.
|
|
*/
|
|
if (unlikely(!(trans_exc_code & 4))) {
|
|
do_low_address(regs);
|
|
return;
|
|
}
|
|
if (unlikely(MACHINE_HAS_NX && (trans_exc_code & 0x80))) {
|
|
regs->int_parm_long = (trans_exc_code & ~PAGE_MASK) |
|
|
(regs->psw.addr & PAGE_MASK);
|
|
access = VM_EXEC;
|
|
fault = VM_FAULT_BADACCESS;
|
|
} else {
|
|
access = VM_WRITE;
|
|
fault = do_exception(regs, access);
|
|
}
|
|
if (unlikely(fault))
|
|
do_fault_error(regs, access, fault);
|
|
}
|
|
NOKPROBE_SYMBOL(do_protection_exception);
|
|
|
|
void do_dat_exception(struct pt_regs *regs)
|
|
{
|
|
int access;
|
|
vm_fault_t fault;
|
|
|
|
access = VM_ACCESS_FLAGS;
|
|
fault = do_exception(regs, access);
|
|
if (unlikely(fault))
|
|
do_fault_error(regs, access, fault);
|
|
}
|
|
NOKPROBE_SYMBOL(do_dat_exception);
|
|
|
|
#ifdef CONFIG_PFAULT
|
|
/*
|
|
* 'pfault' pseudo page faults routines.
|
|
*/
|
|
static int pfault_disable;
|
|
|
|
static int __init nopfault(char *str)
|
|
{
|
|
pfault_disable = 1;
|
|
return 1;
|
|
}
|
|
|
|
__setup("nopfault", nopfault);
|
|
|
|
struct pfault_refbk {
|
|
u16 refdiagc;
|
|
u16 reffcode;
|
|
u16 refdwlen;
|
|
u16 refversn;
|
|
u64 refgaddr;
|
|
u64 refselmk;
|
|
u64 refcmpmk;
|
|
u64 reserved;
|
|
} __attribute__ ((packed, aligned(8)));
|
|
|
|
static struct pfault_refbk pfault_init_refbk = {
|
|
.refdiagc = 0x258,
|
|
.reffcode = 0,
|
|
.refdwlen = 5,
|
|
.refversn = 2,
|
|
.refgaddr = __LC_LPP,
|
|
.refselmk = 1ULL << 48,
|
|
.refcmpmk = 1ULL << 48,
|
|
.reserved = __PF_RES_FIELD
|
|
};
|
|
|
|
int pfault_init(void)
|
|
{
|
|
int rc;
|
|
|
|
if (pfault_disable)
|
|
return -1;
|
|
diag_stat_inc(DIAG_STAT_X258);
|
|
asm volatile(
|
|
" diag %1,%0,0x258\n"
|
|
"0: j 2f\n"
|
|
"1: la %0,8\n"
|
|
"2:\n"
|
|
EX_TABLE(0b,1b)
|
|
: "=d" (rc)
|
|
: "a" (&pfault_init_refbk), "m" (pfault_init_refbk) : "cc");
|
|
return rc;
|
|
}
|
|
|
|
static struct pfault_refbk pfault_fini_refbk = {
|
|
.refdiagc = 0x258,
|
|
.reffcode = 1,
|
|
.refdwlen = 5,
|
|
.refversn = 2,
|
|
};
|
|
|
|
void pfault_fini(void)
|
|
{
|
|
|
|
if (pfault_disable)
|
|
return;
|
|
diag_stat_inc(DIAG_STAT_X258);
|
|
asm volatile(
|
|
" diag %0,0,0x258\n"
|
|
"0: nopr %%r7\n"
|
|
EX_TABLE(0b,0b)
|
|
: : "a" (&pfault_fini_refbk), "m" (pfault_fini_refbk) : "cc");
|
|
}
|
|
|
|
static DEFINE_SPINLOCK(pfault_lock);
|
|
static LIST_HEAD(pfault_list);
|
|
|
|
#define PF_COMPLETE 0x0080
|
|
|
|
/*
|
|
* The mechanism of our pfault code: if Linux is running as guest, runs a user
|
|
* space process and the user space process accesses a page that the host has
|
|
* paged out we get a pfault interrupt.
|
|
*
|
|
* This allows us, within the guest, to schedule a different process. Without
|
|
* this mechanism the host would have to suspend the whole virtual cpu until
|
|
* the page has been paged in.
|
|
*
|
|
* So when we get such an interrupt then we set the state of the current task
|
|
* to uninterruptible and also set the need_resched flag. Both happens within
|
|
* interrupt context(!). If we later on want to return to user space we
|
|
* recognize the need_resched flag and then call schedule(). It's not very
|
|
* obvious how this works...
|
|
*
|
|
* Of course we have a lot of additional fun with the completion interrupt (->
|
|
* host signals that a page of a process has been paged in and the process can
|
|
* continue to run). This interrupt can arrive on any cpu and, since we have
|
|
* virtual cpus, actually appear before the interrupt that signals that a page
|
|
* is missing.
|
|
*/
|
|
static void pfault_interrupt(struct ext_code ext_code,
|
|
unsigned int param32, unsigned long param64)
|
|
{
|
|
struct task_struct *tsk;
|
|
__u16 subcode;
|
|
pid_t pid;
|
|
|
|
/*
|
|
* Get the external interruption subcode & pfault initial/completion
|
|
* signal bit. VM stores this in the 'cpu address' field associated
|
|
* with the external interrupt.
|
|
*/
|
|
subcode = ext_code.subcode;
|
|
if ((subcode & 0xff00) != __SUBCODE_MASK)
|
|
return;
|
|
inc_irq_stat(IRQEXT_PFL);
|
|
/* Get the token (= pid of the affected task). */
|
|
pid = param64 & LPP_PID_MASK;
|
|
rcu_read_lock();
|
|
tsk = find_task_by_pid_ns(pid, &init_pid_ns);
|
|
if (tsk)
|
|
get_task_struct(tsk);
|
|
rcu_read_unlock();
|
|
if (!tsk)
|
|
return;
|
|
spin_lock(&pfault_lock);
|
|
if (subcode & PF_COMPLETE) {
|
|
/* signal bit is set -> a page has been swapped in by VM */
|
|
if (tsk->thread.pfault_wait == 1) {
|
|
/* Initial interrupt was faster than the completion
|
|
* interrupt. pfault_wait is valid. Set pfault_wait
|
|
* back to zero and wake up the process. This can
|
|
* safely be done because the task is still sleeping
|
|
* and can't produce new pfaults. */
|
|
tsk->thread.pfault_wait = 0;
|
|
list_del(&tsk->thread.list);
|
|
wake_up_process(tsk);
|
|
put_task_struct(tsk);
|
|
} else {
|
|
/* Completion interrupt was faster than initial
|
|
* interrupt. Set pfault_wait to -1 so the initial
|
|
* interrupt doesn't put the task to sleep.
|
|
* If the task is not running, ignore the completion
|
|
* interrupt since it must be a leftover of a PFAULT
|
|
* CANCEL operation which didn't remove all pending
|
|
* completion interrupts. */
|
|
if (task_is_running(tsk))
|
|
tsk->thread.pfault_wait = -1;
|
|
}
|
|
} else {
|
|
/* signal bit not set -> a real page is missing. */
|
|
if (WARN_ON_ONCE(tsk != current))
|
|
goto out;
|
|
if (tsk->thread.pfault_wait == 1) {
|
|
/* Already on the list with a reference: put to sleep */
|
|
goto block;
|
|
} else if (tsk->thread.pfault_wait == -1) {
|
|
/* Completion interrupt was faster than the initial
|
|
* interrupt (pfault_wait == -1). Set pfault_wait
|
|
* back to zero and exit. */
|
|
tsk->thread.pfault_wait = 0;
|
|
} else {
|
|
/* Initial interrupt arrived before completion
|
|
* interrupt. Let the task sleep.
|
|
* An extra task reference is needed since a different
|
|
* cpu may set the task state to TASK_RUNNING again
|
|
* before the scheduler is reached. */
|
|
get_task_struct(tsk);
|
|
tsk->thread.pfault_wait = 1;
|
|
list_add(&tsk->thread.list, &pfault_list);
|
|
block:
|
|
/* Since this must be a userspace fault, there
|
|
* is no kernel task state to trample. Rely on the
|
|
* return to userspace schedule() to block. */
|
|
__set_current_state(TASK_UNINTERRUPTIBLE);
|
|
set_tsk_need_resched(tsk);
|
|
set_preempt_need_resched();
|
|
}
|
|
}
|
|
out:
|
|
spin_unlock(&pfault_lock);
|
|
put_task_struct(tsk);
|
|
}
|
|
|
|
static int pfault_cpu_dead(unsigned int cpu)
|
|
{
|
|
struct thread_struct *thread, *next;
|
|
struct task_struct *tsk;
|
|
|
|
spin_lock_irq(&pfault_lock);
|
|
list_for_each_entry_safe(thread, next, &pfault_list, list) {
|
|
thread->pfault_wait = 0;
|
|
list_del(&thread->list);
|
|
tsk = container_of(thread, struct task_struct, thread);
|
|
wake_up_process(tsk);
|
|
put_task_struct(tsk);
|
|
}
|
|
spin_unlock_irq(&pfault_lock);
|
|
return 0;
|
|
}
|
|
|
|
static int __init pfault_irq_init(void)
|
|
{
|
|
int rc;
|
|
|
|
rc = register_external_irq(EXT_IRQ_CP_SERVICE, pfault_interrupt);
|
|
if (rc)
|
|
goto out_extint;
|
|
rc = pfault_init() == 0 ? 0 : -EOPNOTSUPP;
|
|
if (rc)
|
|
goto out_pfault;
|
|
irq_subclass_register(IRQ_SUBCLASS_SERVICE_SIGNAL);
|
|
cpuhp_setup_state_nocalls(CPUHP_S390_PFAULT_DEAD, "s390/pfault:dead",
|
|
NULL, pfault_cpu_dead);
|
|
return 0;
|
|
|
|
out_pfault:
|
|
unregister_external_irq(EXT_IRQ_CP_SERVICE, pfault_interrupt);
|
|
out_extint:
|
|
pfault_disable = 1;
|
|
return rc;
|
|
}
|
|
early_initcall(pfault_irq_init);
|
|
|
|
#endif /* CONFIG_PFAULT */
|
|
|
|
#if IS_ENABLED(CONFIG_PGSTE)
|
|
|
|
void do_secure_storage_access(struct pt_regs *regs)
|
|
{
|
|
unsigned long addr = regs->int_parm_long & __FAIL_ADDR_MASK;
|
|
struct vm_area_struct *vma;
|
|
struct mm_struct *mm;
|
|
struct page *page;
|
|
int rc;
|
|
|
|
/*
|
|
* bit 61 tells us if the address is valid, if it's not we
|
|
* have a major problem and should stop the kernel or send a
|
|
* SIGSEGV to the process. Unfortunately bit 61 is not
|
|
* reliable without the misc UV feature so we need to check
|
|
* for that as well.
|
|
*/
|
|
if (test_bit_inv(BIT_UV_FEAT_MISC, &uv_info.uv_feature_indications) &&
|
|
!test_bit_inv(61, ®s->int_parm_long)) {
|
|
/*
|
|
* When this happens, userspace did something that it
|
|
* was not supposed to do, e.g. branching into secure
|
|
* memory. Trigger a segmentation fault.
|
|
*/
|
|
if (user_mode(regs)) {
|
|
send_sig(SIGSEGV, current, 0);
|
|
return;
|
|
}
|
|
|
|
/*
|
|
* The kernel should never run into this case and we
|
|
* have no way out of this situation.
|
|
*/
|
|
panic("Unexpected PGM 0x3d with TEID bit 61=0");
|
|
}
|
|
|
|
switch (get_fault_type(regs)) {
|
|
case USER_FAULT:
|
|
mm = current->mm;
|
|
mmap_read_lock(mm);
|
|
vma = find_vma(mm, addr);
|
|
if (!vma) {
|
|
mmap_read_unlock(mm);
|
|
do_fault_error(regs, VM_READ | VM_WRITE, VM_FAULT_BADMAP);
|
|
break;
|
|
}
|
|
page = follow_page(vma, addr, FOLL_WRITE | FOLL_GET);
|
|
if (IS_ERR_OR_NULL(page)) {
|
|
mmap_read_unlock(mm);
|
|
break;
|
|
}
|
|
if (arch_make_page_accessible(page))
|
|
send_sig(SIGSEGV, current, 0);
|
|
put_page(page);
|
|
mmap_read_unlock(mm);
|
|
break;
|
|
case KERNEL_FAULT:
|
|
page = phys_to_page(addr);
|
|
if (unlikely(!try_get_compound_head(page, 1)))
|
|
break;
|
|
rc = arch_make_page_accessible(page);
|
|
put_page(page);
|
|
if (rc)
|
|
BUG();
|
|
break;
|
|
case GMAP_FAULT:
|
|
default:
|
|
do_fault_error(regs, VM_READ | VM_WRITE, VM_FAULT_BADMAP);
|
|
WARN_ON_ONCE(1);
|
|
}
|
|
}
|
|
NOKPROBE_SYMBOL(do_secure_storage_access);
|
|
|
|
void do_non_secure_storage_access(struct pt_regs *regs)
|
|
{
|
|
unsigned long gaddr = regs->int_parm_long & __FAIL_ADDR_MASK;
|
|
struct gmap *gmap = (struct gmap *)S390_lowcore.gmap;
|
|
|
|
if (get_fault_type(regs) != GMAP_FAULT) {
|
|
do_fault_error(regs, VM_READ | VM_WRITE, VM_FAULT_BADMAP);
|
|
WARN_ON_ONCE(1);
|
|
return;
|
|
}
|
|
|
|
if (gmap_convert_to_secure(gmap, gaddr) == -EINVAL)
|
|
send_sig(SIGSEGV, current, 0);
|
|
}
|
|
NOKPROBE_SYMBOL(do_non_secure_storage_access);
|
|
|
|
void do_secure_storage_violation(struct pt_regs *regs)
|
|
{
|
|
/*
|
|
* Either KVM messed up the secure guest mapping or the same
|
|
* page is mapped into multiple secure guests.
|
|
*
|
|
* This exception is only triggered when a guest 2 is running
|
|
* and can therefore never occur in kernel context.
|
|
*/
|
|
printk_ratelimited(KERN_WARNING
|
|
"Secure storage violation in task: %s, pid %d\n",
|
|
current->comm, current->pid);
|
|
send_sig(SIGSEGV, current, 0);
|
|
}
|
|
|
|
#endif /* CONFIG_PGSTE */
|