leandrof/linux
1
0
Fork 0
forked from Minki/linux
Code Issues Pull Requests Packages Projects Releases Wiki Activity
20ffa1caec
linux/arch/s390/mm/fault.c
Greg Kroah-Hartman b24413180f License cleanup: add SPDX GPL-2.0 license identifier to files with no license 
Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.

By default all files without license information are under the default
license of the kernel, which is GPL version 2.

Update the files which contain no license information with the 'GPL-2.0'
SPDX license identifier.  The SPDX identifier is a legally binding
shorthand, which can be used instead of the full boiler plate text.

This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.

How this work was done:

Patches were generated and checked against linux-4.14-rc6 for a subset of
the use cases:
 - file had no licensing information it it.
 - file was a */uapi/* one with no licensing information in it,
 - file was a */uapi/* one with existing licensing information,

Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to license
had to be inferred by heuristics based on keywords.

The analysis to determine which SPDX License Identifier to be applied to
a file was done in a spreadsheet of side by side results from of the
output of two independent scanners (ScanCode & Windriver) producing SPDX
tag:value files created by Philippe Ombredanne.  Philippe prepared the
base worksheet, and did an initial spot review of a few 1000 files.

The 4.13 kernel was the starting point of the analysis with 60,537 files
assessed.  Kate Stewart did a file by file comparison of the scanner
results in the spreadsheet to determine which SPDX license identifier(s)
to be applied to the file. She confirmed any determination that was not
immediately clear with lawyers working with the Linux Foundation.

Criteria used to select files for SPDX license identifier tagging was:
 - Files considered eligible had to be source code files.
 - Make and config files were included as candidates if they contained >5
   lines of source
 - File already had some variant of a license header in it (even if <5
   lines).

All documentation files were explicitly excluded.

The following heuristics were used to determine which SPDX license
identifiers to apply.

 - when both scanners couldn't find any license traces, file was
   considered to have no license information in it, and the top level
   COPYING file license applied.

   For non */uapi/* files that summary was:

   SPDX license identifier                            # files
   ---------------------------------------------------|-------
   GPL-2.0                                              11139

   and resulted in the first patch in this series.

   If that file was a */uapi/* path one, it was "GPL-2.0 WITH
   Linux-syscall-note" otherwise it was "GPL-2.0".  Results of that was:

   SPDX license identifier                            # files
   ---------------------------------------------------|-------
   GPL-2.0 WITH Linux-syscall-note                        930

   and resulted in the second patch in this series.

 - if a file had some form of licensing information in it, and was one
   of the */uapi/* ones, it was denoted with the Linux-syscall-note if
   any GPL family license was found in the file or had no licensing in
   it (per prior point).  Results summary:

   SPDX license identifier                            # files
   ---------------------------------------------------|------
   GPL-2.0 WITH Linux-syscall-note                       270
   GPL-2.0+ WITH Linux-syscall-note                      169
   ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause)    21
   ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause)    17
   LGPL-2.1+ WITH Linux-syscall-note                      15
   GPL-1.0+ WITH Linux-syscall-note                       14
   ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause)    5
   LGPL-2.0+ WITH Linux-syscall-note                       4
   LGPL-2.1 WITH Linux-syscall-note                        3
   ((GPL-2.0 WITH Linux-syscall-note) OR MIT)              3
   ((GPL-2.0 WITH Linux-syscall-note) AND MIT)             1

   and that resulted in the third patch in this series.

 - when the two scanners agreed on the detected license(s), that became
   the concluded license(s).

 - when there was disagreement between the two scanners (one detected a
   license but the other didn't, or they both detected different
   licenses) a manual inspection of the file occurred.

 - In most cases a manual inspection of the information in the file
   resulted in a clear resolution of the license that should apply (and
   which scanner probably needed to revisit its heuristics).

 - When it was not immediately clear, the license identifier was
   confirmed with lawyers working with the Linux Foundation.

 - If there was any question as to the appropriate license identifier,
   the file was flagged for further research and to be revisited later
   in time.

In total, over 70 hours of logged manual review was done on the
spreadsheet to determine the SPDX license identifiers to apply to the
source files by Kate, Philippe, Thomas and, in some cases, confirmation
by lawyers working with the Linux Foundation.

Kate also obtained a third independent scan of the 4.13 code base from
FOSSology, and compared selected files where the other two scanners
disagreed against that SPDX file, to see if there was new insights.  The
Windriver scanner is based on an older version of FOSSology in part, so
they are related.

Thomas did random spot checks in about 500 files from the spreadsheets
for the uapi headers and agreed with SPDX license identifier in the
files he inspected. For the non-uapi files Thomas did random spot checks
in about 15000 files.

In initial set of patches against 4.14-rc6, 3 files were found to have
copy/paste license identifier errors, and have been fixed to reflect the
correct identifier.

Additionally Philippe spent 10 hours this week doing a detailed manual
inspection and review of the 12,461 patched files from the initial patch
version early this week with:
 - a full scancode scan run, collecting the matched texts, detected
   license ids and scores
 - reviewing anything where there was a license detected (about 500+
   files) to ensure that the applied SPDX license was correct
 - reviewing anything where there was no detection but the patch license
   was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied
   SPDX license was correct

This produced a worksheet with 20 files needing minor correction.  This
worksheet was then exported into 3 different .csv files for the
different types of files to be modified.

These .csv files were then reviewed by Greg.  Thomas wrote a script to
parse the csv files and add the proper SPDX tag to the file, in the
format that the file expected.  This script was further refined by Greg
based on the output to detect more types of files automatically and to
distinguish between header and source .c files (which need different
comment types.)  Finally Greg ran the script using the .csv files to
generate the patches.

Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-11-02 11:10:55 +01:00

817 lines
21 KiB
C
Raw Blame History

// 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/pgtable.h>
#include <asm/gmap.h>
#include <asm/irq.h>
#include <asm/mmu_context.h>
#include <asm/facility.h>
#include "../kernel/entry.h"
#define __FAIL_ADDR_MASK -4096L
#define __SUBCODE_MASK 0x0600
#define __PF_RES_FIELD 0x8000000000000000ULL
#define VM_FAULT_BADCONTEXT 0x010000
#define VM_FAULT_BADMAP 0x020000
#define VM_FAULT_BADACCESS 0x040000
#define VM_FAULT_SIGNAL 0x080000
#define VM_FAULT_PFAULT 0x100000
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);
static inline int notify_page_fault(struct pt_regs *regs)
{
int ret = 0;
/* kprobe_running() needs smp_processor_id() */
if (kprobes_built_in() && !user_mode(regs)) {
preempt_disable();
if (kprobe_running() && kprobe_fault_handler(regs, 14))
ret = 1;
preempt_enable();
}
return ret;
}
/*
* Unlock any spinlocks which will prevent us from getting the
* message out.
*/
void bust_spinlocks(int yes)
{
if (yes) {
oops_in_progress = 1;
} else {
int loglevel_save = console_loglevel;
console_unblank();
oops_in_progress = 0;
/*
* OK, the message is on the console. Now we call printk()
* without oops_in_progress set so that printk will give klogd
* a poke. Hold onto your hats...
*/
console_loglevel = 15;
printk(" ");
console_loglevel = loglevel_save;
}
}
/*
* Returns the address space associated with the fault.
* Returns 0 for kernel space and 1 for user space.
*/
static inline int user_space_fault(struct pt_regs *regs)
{
unsigned long trans_exc_code;
/*
* The lowest two bits of the translation exception
* identification indicate which paging table was used.
*/
trans_exc_code = regs->int_parm_long & 3;
if (trans_exc_code == 3) /* home space -> kernel */
return 0;
if (user_mode(regs))
return 1;
if (trans_exc_code == 2) /* secondary space -> set_fs */
return current->thread.mm_segment.ar4;
if (current->flags & PF_VCPU)
return 1;
return 0;
}
static int bad_address(void *p)
{
unsigned long dummy;
return probe_kernel_address((unsigned long *)p, dummy);
}
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 ");
if (!user_space_fault(regs)) {
asce = S390_lowcore.kernel_asce;
pr_cont("kernel ");
}
#ifdef CONFIG_PGSTE
else if ((current->flags & PF_VCPU) && S390_lowcore.gmap) {
struct gmap *gmap = (struct gmap *)S390_lowcore.gmap;
asce = gmap->asce;
pr_cont("gmap ");
}
#endif
else {
asce = S390_lowcore.user_asce;
pr_cont("user ");
}
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)
{
struct siginfo si;
report_user_fault(regs, SIGSEGV, 1);
si.si_signo = SIGSEGV;
si.si_errno = 0;
si.si_code = si_code;
si.si_addr = (void __user *)(regs->int_parm_long & __FAIL_ADDR_MASK);
force_sig_info(SIGSEGV, &si, current);
}
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 = search_exception_tables(regs->psw.addr);
if (fixup) {
regs->psw.addr = extable_fixup(fixup);
return;
}
/*
* Oops. The kernel tried to access some bad page. We'll have to
* terminate things with extreme prejudice.
*/
if (!user_space_fault(regs))
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)
{
struct task_struct *tsk = current;
struct siginfo si;
/*
* Send a sigbus, regardless of whether we were in kernel
* or user mode.
*/
si.si_signo = SIGBUS;
si.si_errno = 0;
si.si_code = BUS_ADRERR;
si.si_addr = (void __user *)(regs->int_parm_long & __FAIL_ADDR_MASK);
force_sig_info(SIGBUS, &si, tsk);
}
static noinline int signal_return(struct pt_regs *regs)
{
u16 instruction;
int rc;
rc = __get_user(instruction, (u16 __user *) regs->psw.addr);
if (rc)
return rc;
if (instruction == 0x0a77) {
set_pt_regs_flag(regs, PIF_SYSCALL);
regs->int_code = 0x00040077;
return 0;
} else if (instruction == 0x0aad) {
set_pt_regs_flag(regs, PIF_SYSCALL);
regs->int_code = 0x000400ad;
return 0;
}
return -EACCES;
}
static noinline void do_fault_error(struct pt_regs *regs, int access, int fault)
{
int si_code;
switch (fault) {
case VM_FAULT_BADACCESS:
if (access == VM_EXEC && signal_return(regs) == 0)
break;
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;
}
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 (suprression)
* 10 Segment translation -> Not present (nullification)
* 11 Page translation -> Not present (nullification)
* 3b Region third trans. -> Not present (nullification)
*/
static inline int do_exception(struct pt_regs *regs, int access)
{
#ifdef CONFIG_PGSTE
struct gmap *gmap;
#endif
struct task_struct *tsk;
struct mm_struct *mm;
struct vm_area_struct *vma;
unsigned long trans_exc_code;
unsigned long address;
unsigned int flags;
int fault;
tsk = current;
/*
* The instruction that caused the program check has
* been nullified. Don't signal single step via SIGTRAP.
*/
clear_pt_regs_flag(regs, PIF_PER_TRAP);
if (notify_page_fault(regs))
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;
if (unlikely(!user_space_fault(regs) || faulthandler_disabled() || !mm))
goto out;
address = trans_exc_code & __FAIL_ADDR_MASK;
perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
if (user_mode(regs))
flags |= FAULT_FLAG_USER;
if (access == VM_WRITE || (trans_exc_code & store_indication) == 0x400)
flags |= FAULT_FLAG_WRITE;
down_read(&mm->mmap_sem);
#ifdef CONFIG_PGSTE
gmap = (current->flags & PF_VCPU) ?
(struct gmap *) S390_lowcore.gmap : NULL;
if (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;
}
#endif
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);
/* No reason to continue if interrupted by SIGKILL. */
if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current)) {
fault = VM_FAULT_SIGNAL;
goto out;
}
if (unlikely(fault & VM_FAULT_ERROR))
goto out_up;
/*
* Major/minor page fault accounting is only done on the
* initial attempt. If we go through a retry, it is extremely
* likely that the page will be found in page cache at that point.
*/
if (flags & FAULT_FLAG_ALLOW_RETRY) {
if (fault & VM_FAULT_MAJOR) {
tsk->maj_flt++;
perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1,
regs, address);
} else {
tsk->min_flt++;
perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1,
regs, address);
}
if (fault & VM_FAULT_RETRY) {
#ifdef CONFIG_PGSTE
if (gmap && (flags & FAULT_FLAG_RETRY_NOWAIT)) {
/* FAULT_FLAG_RETRY_NOWAIT has been set,
* mmap_sem has not been released */
current->thread.gmap_pfault = 1;
fault = VM_FAULT_PFAULT;
goto out_up;
}
#endif
/* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk
* of starvation. */
flags &= ~(FAULT_FLAG_ALLOW_RETRY |
FAULT_FLAG_RETRY_NOWAIT);
flags |= FAULT_FLAG_TRIED;
down_read(&mm->mmap_sem);
goto retry;
}
}
#ifdef CONFIG_PGSTE
if (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;
}
}
#endif
fault = 0;
out_up:
up_read(&mm->mmap_sem);
out:
return fault;
}
void do_protection_exception(struct pt_regs *regs)
{
unsigned long trans_exc_code;
int access, 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, fault;
access = VM_READ | VM_EXEC | VM_WRITE;
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)));
int pfault_init(void)
{
struct pfault_refbk refbk = {
.refdiagc = 0x258,
.reffcode = 0,
.refdwlen = 5,
.refversn = 2,
.refgaddr = __LC_LPP,
.refselmk = 1ULL << 48,
.refcmpmk = 1ULL << 48,
.reserved = __PF_RES_FIELD };
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" (&refbk), "m" (refbk) : "cc");
return rc;
}
void pfault_fini(void)
{
struct pfault_refbk refbk = {
.refdiagc = 0x258,
.reffcode = 1,
.refdwlen = 5,
.refversn = 2,
};
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" (&refbk), "m" (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_PFAULT_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 (tsk->state == TASK_RUNNING)
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 */
Reference in New Issue View Git Blame Copy Permalink