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* [hnaz-linux-mm:master 90/340] arch/x86/mm/fault.c:1468:34: sparse: sparse: incorrect type in argument 1 (different base types)
@ 2020-03-11  4:30 kbuild test robot
  2020-03-11 14:59 ` Peter Xu
  0 siblings, 1 reply; 2+ messages in thread
From: kbuild test robot @ 2020-03-11  4:30 UTC (permalink / raw)
  To: Peter Xu
  Cc: kbuild-all, Johannes Weiner, Andrew Morton, Linux Memory Management List

tree:   https://github.com/hnaz/linux-mm master
head:   5d9ee416b5701096536c7a63c04dbe25012baa9e
commit: 79181dfcc4b8c2091126a8b3175957a598ae61e1 [90/340] x86/mm: use helper fault_signal_pending()
reproduce:
        # apt-get install sparse
        # sparse version: v0.6.1-174-g094d5a94-dirty
        git checkout 79181dfcc4b8c2091126a8b3175957a598ae61e1
        make ARCH=x86_64 allmodconfig
        make C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__'

If you fix the issue, kindly add following tag
Reported-by: kbuild test robot <lkp@intel.com>


sparse warnings: (new ones prefixed by >>)

>> arch/x86/mm/fault.c:1468:34: sparse: sparse: incorrect type in argument 1 (different base types) @@    expected unsigned int fault_flags @@    got restricted vm_fault_t [assignedunsigned int fault_flags @@
>> arch/x86/mm/fault.c:1468:34: sparse:    expected unsigned int fault_flags
>> arch/x86/mm/fault.c:1468:34: sparse:    got restricted vm_fault_t [assigned] [usertype] fault
>> include/linux/sched/signal.h:381:16: sparse: sparse: restricted vm_fault_t degrades to integer

vim +1468 arch/x86/mm/fault.c

  1392	
  1393		/*
  1394		 * Kernel-mode access to the user address space should only occur
  1395		 * on well-defined single instructions listed in the exception
  1396		 * tables.  But, an erroneous kernel fault occurring outside one of
  1397		 * those areas which also holds mmap_sem might deadlock attempting
  1398		 * to validate the fault against the address space.
  1399		 *
  1400		 * Only do the expensive exception table search when we might be at
  1401		 * risk of a deadlock.  This happens if we
  1402		 * 1. Failed to acquire mmap_sem, and
  1403		 * 2. The access did not originate in userspace.
  1404		 */
  1405		if (unlikely(!down_read_trylock(&mm->mmap_sem))) {
  1406			if (!user_mode(regs) && !search_exception_tables(regs->ip)) {
  1407				/*
  1408				 * Fault from code in kernel from
  1409				 * which we do not expect faults.
  1410				 */
  1411				bad_area_nosemaphore(regs, hw_error_code, address);
  1412				return;
  1413			}
  1414	retry:
  1415			down_read(&mm->mmap_sem);
  1416		} else {
  1417			/*
  1418			 * The above down_read_trylock() might have succeeded in
  1419			 * which case we'll have missed the might_sleep() from
  1420			 * down_read():
  1421			 */
  1422			might_sleep();
  1423		}
  1424	
  1425		vma = find_vma(mm, address);
  1426		if (unlikely(!vma)) {
  1427			bad_area(regs, hw_error_code, address);
  1428			return;
  1429		}
  1430		if (likely(vma->vm_start <= address))
  1431			goto good_area;
  1432		if (unlikely(!(vma->vm_flags & VM_GROWSDOWN))) {
  1433			bad_area(regs, hw_error_code, address);
  1434			return;
  1435		}
  1436		if (unlikely(expand_stack(vma, address))) {
  1437			bad_area(regs, hw_error_code, address);
  1438			return;
  1439		}
  1440	
  1441		/*
  1442		 * Ok, we have a good vm_area for this memory access, so
  1443		 * we can handle it..
  1444		 */
  1445	good_area:
  1446		if (unlikely(access_error(hw_error_code, vma))) {
  1447			bad_area_access_error(regs, hw_error_code, address, vma);
  1448			return;
  1449		}
  1450	
  1451		/*
  1452		 * If for any reason at all we couldn't handle the fault,
  1453		 * make sure we exit gracefully rather than endlessly redo
  1454		 * the fault.  Since we never set FAULT_FLAG_RETRY_NOWAIT, if
  1455		 * we get VM_FAULT_RETRY back, the mmap_sem has been unlocked.
  1456		 *
  1457		 * Note that handle_userfault() may also release and reacquire mmap_sem
  1458		 * (and not return with VM_FAULT_RETRY), when returning to userland to
  1459		 * repeat the page fault later with a VM_FAULT_NOPAGE retval
  1460		 * (potentially after handling any pending signal during the return to
  1461		 * userland). The return to userland is identified whenever
  1462		 * FAULT_FLAG_USER|FAULT_FLAG_KILLABLE are both set in flags.
  1463		 */
  1464		fault = handle_mm_fault(vma, address, flags);
  1465		major |= fault & VM_FAULT_MAJOR;
  1466	
  1467		/* Quick path to respond to signals */
> 1468		if (fault_signal_pending(fault, regs)) {
  1469			if (!user_mode(regs))
  1470				no_context(regs, hw_error_code, address, SIGBUS,
  1471					   BUS_ADRERR);
  1472			return;
  1473		}
  1474	
  1475		/*
  1476		 * If we need to retry the mmap_sem has already been released,
  1477		 * and if there is a fatal signal pending there is no guarantee
  1478		 * that we made any progress. Handle this case first.
  1479		 */
  1480		if (unlikely((fault & VM_FAULT_RETRY) &&
  1481			     (flags & FAULT_FLAG_ALLOW_RETRY))) {
  1482			/* Retry at most once */
  1483			flags &= ~FAULT_FLAG_ALLOW_RETRY;
  1484			flags |= FAULT_FLAG_TRIED;
  1485			goto retry;
  1486		}
  1487	
  1488		up_read(&mm->mmap_sem);
  1489		if (unlikely(fault & VM_FAULT_ERROR)) {
  1490			mm_fault_error(regs, hw_error_code, address, fault);
  1491			return;
  1492		}
  1493	
  1494		/*
  1495		 * Major/minor page fault accounting. If any of the events
  1496		 * returned VM_FAULT_MAJOR, we account it as a major fault.
  1497		 */
  1498		if (major) {
  1499			tsk->maj_flt++;
  1500			perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, regs, address);
  1501		} else {
  1502			tsk->min_flt++;
  1503			perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, regs, address);
  1504		}
  1505	
  1506		check_v8086_mode(regs, address, tsk);
  1507	}
  1508	NOKPROBE_SYMBOL(do_user_addr_fault);
  1509	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org


^ permalink raw reply	[flat|nested] 2+ messages in thread

* Re: [hnaz-linux-mm:master 90/340] arch/x86/mm/fault.c:1468:34: sparse: sparse: incorrect type in argument 1 (different base types)
  2020-03-11  4:30 [hnaz-linux-mm:master 90/340] arch/x86/mm/fault.c:1468:34: sparse: sparse: incorrect type in argument 1 (different base types) kbuild test robot
@ 2020-03-11 14:59 ` Peter Xu
  0 siblings, 0 replies; 2+ messages in thread
From: Peter Xu @ 2020-03-11 14:59 UTC (permalink / raw)
  To: kbuild test robot, Andrew Morton
  Cc: kbuild-all, Johannes Weiner, Andrew Morton, Linux Memory Management List

On Wed, Mar 11, 2020 at 12:30:41PM +0800, kbuild test robot wrote:
> tree:   https://github.com/hnaz/linux-mm master
> head:   5d9ee416b5701096536c7a63c04dbe25012baa9e
> commit: 79181dfcc4b8c2091126a8b3175957a598ae61e1 [90/340] x86/mm: use helper fault_signal_pending()
> reproduce:
>         # apt-get install sparse
>         # sparse version: v0.6.1-174-g094d5a94-dirty
>         git checkout 79181dfcc4b8c2091126a8b3175957a598ae61e1
>         make ARCH=x86_64 allmodconfig
>         make C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__'
> 
> If you fix the issue, kindly add following tag
> Reported-by: kbuild test robot <lkp@intel.com>
> 
> 
> sparse warnings: (new ones prefixed by >>)
> 
> >> arch/x86/mm/fault.c:1468:34: sparse: sparse: incorrect type in argument 1 (different base types) @@    expected unsigned int fault_flags @@    got restricted vm_fault_t [assignedunsigned int fault_flags @@
> >> arch/x86/mm/fault.c:1468:34: sparse:    expected unsigned int fault_flags
> >> arch/x86/mm/fault.c:1468:34: sparse:    got restricted vm_fault_t [assigned] [usertype] fault
> >> include/linux/sched/signal.h:381:16: sparse: sparse: restricted vm_fault_t degrades to integer

Hi, Andrew,

I'm not sure whether this comes from the extra "-fdiagnostic-prefix"
because I didn't encounter that, but if after the previous signal.h
fixup squashed into patch "mm: Introduce fault_signal_pending()", then
we have linux/mm_types.h included already, and it'll be pretty safe to
just use vm_fault_t here.

To be explicit, maybe another squash-in would work to the same patch:

-------------8<-------------
diff --git a/include/linux/sched/signal.h b/include/linux/sched/signal.h
index c8e0e4f801e4..65ea429daaa2 100644
--- a/include/linux/sched/signal.h
+++ b/include/linux/sched/signal.h
@@ -377,7 +377,7 @@ static inline int signal_pending_state(long state, struct task_struct *p)
  * instead, especially with the case where we've got interrupted with
  * a VM_FAULT_RETRY.
  */
-static inline bool fault_signal_pending(unsigned int fault_flags,
+static inline bool fault_signal_pending(vm_fault_t fault_flags,
                                        struct pt_regs *regs)
 {
        return unlikely((fault_flags & VM_FAULT_RETRY) &&
------------->8-------------

So the whole fixup is (against "mm: Introduce fault_signal_pending()"):

-------------8<-------------
diff --git a/arch/mips/mm/fault.c b/arch/mips/mm/fault.c
index fd64b135fd7b..4a0eafe3d932 100644
--- a/arch/mips/mm/fault.c
+++ b/arch/mips/mm/fault.c
@@ -154,7 +154,7 @@ static void __kprobes __do_page_fault(struct pt_regs *regs, unsigned long write,
         */
        fault = handle_mm_fault(vma, address, flags);

-       if (fault_signal_pending(regs))
+       if (fault_signal_pending(fault, regs))
                return;

        perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS, 1, regs, address);
diff --git a/include/linux/sched/signal.h b/include/linux/sched/signal.h
index 09d40ce6a162..65ea429daaa2 100644
--- a/include/linux/sched/signal.h
+++ b/include/linux/sched/signal.h
@@ -10,6 +10,8 @@
 #include <linux/cred.h>
 #include <linux/refcount.h>
 #include <linux/posix-timers.h>
+#include <linux/mm_types.h>
+#include <asm/ptrace.h>

 /*
  * Types defining task->signal and task->sighand and APIs using them:
@@ -375,7 +377,7 @@ static inline int signal_pending_state(long state, struct task_struct *p)
  * instead, especially with the case where we've got interrupted with
  * a VM_FAULT_RETRY.
  */
-static inline bool fault_signal_pending(unsigned int fault_flags,
+static inline bool fault_signal_pending(vm_fault_t fault_flags,
                                        struct pt_regs *regs)
 {
        return unlikely((fault_flags & VM_FAULT_RETRY) &&
------------->8-------------

Thanks,

-- 
Peter Xu



^ permalink raw reply	[flat|nested] 2+ messages in thread

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2020-03-11  4:30 [hnaz-linux-mm:master 90/340] arch/x86/mm/fault.c:1468:34: sparse: sparse: incorrect type in argument 1 (different base types) kbuild test robot
2020-03-11 14:59 ` Peter Xu

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