linux-stable.git/arch/parisc, branch v5.8

parisc: Add atomic64_set_release() define to avoid CPU soft lockups

2020-07-21T15:16:37+00:00

Stalls are quite frequent with recent kernels. I enabled
CONFIG_SOFTLOCKUP_DETECTOR and I caught the following stall:

watchdog: BUG: soft lockup - CPU#0 stuck for 22s! [cc1:22803]
CPU: 0 PID: 22803 Comm: cc1 Not tainted 5.6.17+ #3
Hardware name: 9000/800/rp3440
 IAOQ[0]: d_alloc_parallel+0x384/0x688
 IAOQ[1]: d_alloc_parallel+0x388/0x688
 RP(r2): d_alloc_parallel+0x134/0x688
Backtrace:
 [<000000004036974c>] __lookup_slow+0xa4/0x200
 [<0000000040369fc8>] walk_component+0x288/0x458
 [<000000004036a9a0>] path_lookupat+0x88/0x198
 [<000000004036e748>] filename_lookup+0xa0/0x168
 [<000000004036e95c>] user_path_at_empty+0x64/0x80
 [<000000004035d93c>] vfs_statx+0x104/0x158
 [<000000004035dfcc>] __do_sys_lstat64+0x44/0x80
 [<000000004035e5a0>] sys_lstat64+0x20/0x38
 [<0000000040180054>] syscall_exit+0x0/0x14

The code was stuck in this loop in d_alloc_parallel:

    4037d414:   0e 00 10 dc     ldd 0(r16),ret0
    4037d418:   c7 fc 5f ed     bb,< ret0,1f,4037d414 
    4037d41c:   08 00 02 40     nop

This is the inner loop of bit_spin_lock which is called by hlist_bl_unlock in
d_alloc_parallel:

static inline void bit_spin_lock(int bitnum, unsigned long *addr)
{
        /*
         * Assuming the lock is uncontended, this never enters
         * the body of the outer loop. If it is contended, then
         * within the inner loop a non-atomic test is used to
         * busywait with less bus contention for a good time to
         * attempt to acquire the lock bit.
         */
        preempt_disable();
#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
        while (unlikely(test_and_set_bit_lock(bitnum, addr))) {
                preempt_enable();
                do {
                        cpu_relax();
                } while (test_bit(bitnum, addr));
                preempt_disable();
        }
#endif
        __acquire(bitlock);
}

After consideration, I realized that we must be losing bit unlocks.
Then, I noticed that we missed defining atomic64_set_release().
Adding this define fixes the stalls in bit operations.

Signed-off-by: Dave Anglin 
Cc: stable@vger.kernel.org
Signed-off-by: Helge Deller

parisc: add support for cmpxchg on u8 pointers

2020-07-21T06:11:12+00:00

The kernel test bot reported[1] that using set_mask_bits on a u8 causes
the following issue on parisc:

	hppa-linux-ld: drivers/phy/ti/phy-tusb1210.o: in function `tusb1210_probe':
	>> (.text+0x2f4): undefined reference to `__cmpxchg_called_with_bad_pointer'
	>> hppa-linux-ld: (.text+0x324): undefined reference to `__cmpxchg_called_with_bad_pointer'
	hppa-linux-ld: (.text+0x354): undefined reference to `__cmpxchg_called_with_bad_pointer'

Add support for cmpxchg on u8 pointers.

[1] https://lore.kernel.org/patchwork/patch/1272617/#1468946

Reported-by: kernel test robot 
Signed-off-by: Liam Beguin 
Tested-by: Dave Anglin 
Signed-off-by: Helge Deller

maccess: make get_kernel_nofault() check for minimal type compatibility

2020-06-18T19:10:37+00:00

Now that we've renamed probe_kernel_address() to get_kernel_nofault()
and made it look and behave more in line with get_user(), some of the
subtle type behavior differences end up being more obvious and possibly
dangerous.

When you do

        get_user(val, user_ptr);

the type of the access comes from the "user_ptr" part, and the above
basically acts as

        val = *user_ptr;

by design (except, of course, for the fact that the actual dereference
is done with a user access).

Note how in the above case, the type of the end result comes from the
pointer argument, and then the value is cast to the type of 'val' as
part of the assignment.

So the type of the pointer is ultimately the more important type both
for the access itself.

But 'get_kernel_nofault()' may now _look_ similar, but it behaves very
differently.  When you do

        get_kernel_nofault(val, kernel_ptr);

it behaves like

        val = *(typeof(val) *)kernel_ptr;

except, of course, for the fact that the actual dereference is done with
exception handling so that a faulting access is suppressed and returned
as the error code.

But note how different the casting behavior of the two superficially
similar accesses are: one does the actual access in the size of the type
the pointer points to, while the other does the access in the size of
the target, and ignores the pointer type entirely.

Actually changing get_kernel_nofault() to act like get_user() is almost
certainly the right thing to do eventually, but in the meantime this
patch adds logit to at least verify that the pointer type is compatible
with the type of the result.

In many cases, this involves just casting the pointer to 'void *' to
make it obvious that the type of the pointer is not the important part.
It's not how 'get_user()' acts, but at least the behavioral difference
is now obvious and explicit.

Cc: Christoph Hellwig 
Signed-off-by: Linus Torvalds

maccess: rename probe_kernel_address to get_kernel_nofault

2020-06-18T18:14:40+00:00

Better describe what this helper does, and match the naming of
copy_from_kernel_nofault.

Also switch the argument order around, so that it acts and looks
like get_user().

Signed-off-by: Christoph Hellwig 
Signed-off-by: Linus Torvalds

maccess: rename probe_kernel_{read,write} to copy_{from,to}_kernel_nofault

2020-06-17T17:57:41+00:00

Better describe what these functions do.

Suggested-by: Linus Torvalds 
Signed-off-by: Christoph Hellwig 
Signed-off-by: Linus Torvalds

treewide: replace '---help---' in Kconfig files with 'help'

2020-06-13T16:57:21+00:00

Since commit 84af7a6194e4 ("checkpatch: kconfig: prefer 'help' over
'---help---'"), the number of '---help---' has been gradually
decreasing, but there are still more than 2400 instances.

This commit finishes the conversion. While I touched the lines,
I also fixed the indentation.

There are a variety of indentation styles found.

  a) 4 spaces + '---help---'
  b) 7 spaces + '---help---'
  c) 8 spaces + '---help---'
  d) 1 space + 1 tab + '---help---'
  e) 1 tab + '---help---'    (correct indentation)
  f) 1 tab + 1 space + '---help---'
  g) 1 tab + 2 spaces + '---help---'

In order to convert all of them to 1 tab + 'help', I ran the
following commend:

  $ find . -name 'Kconfig*' | xargs sed -i 's/^[[:space:]]*---help---/\thelp/'

Signed-off-by: Masahiro Yamada

kbuild: fix broken builds because of GZIP,BZIP2,LZOP variables

2020-06-11T11:14:41+00:00

Redefine GZIP, BZIP2, LZOP variables as KGZIP, KBZIP2, KLZOP resp.
GZIP, BZIP2, LZOP env variables are reserved by the tools. The original
attempt to redefine them internally doesn't work in makefiles/scripts
intercall scenarios, e.g., "make GZIP=gzip bindeb-pkg" and results in
broken builds. There can be other broken build commands because of this,
so the universal solution is to use non-reserved env variables for the
compression tools.

Fixes: 8dfb61dcbace ("kbuild: add variables for compression tools")
Signed-off-by: Denis Efremov 
Tested-by: Guenter Roeck 
Signed-off-by: Masahiro Yamada

maccess: always use strict semantics for probe_kernel_read

2020-06-09T16:39:15+00:00

Except for historical confusion in the kprobes/uprobes and bpf tracers,
which has been fixed now, there is no good reason to ever allow user
memory accesses from probe_kernel_read.  Switch probe_kernel_read to only
read from kernel memory.

[akpm@linux-foundation.org: update it for "mm, dump_page(): do not crash with invalid mapping pointer"]

Signed-off-by: Christoph Hellwig 
Signed-off-by: Andrew Morton 
Cc: Alexei Starovoitov 
Cc: Daniel Borkmann 
Cc: "H. Peter Anvin" 
Cc: Ingo Molnar 
Cc: Masami Hiramatsu 
Cc: Thomas Gleixner 
Link: http://lkml.kernel.org/r/20200521152301.2587579-17-hch@lst.de
Signed-off-by: Linus Torvalds

maccess: unify the probe kernel arch hooks

2020-06-09T16:39:15+00:00

Currently architectures have to override every routine that probes
kernel memory, which includes a pure read and strcpy, both in strict
and not strict variants.  Just provide a single arch hooks instead to
make sure all architectures cover all the cases.

[akpm@linux-foundation.org: fix !CONFIG_X86_64 build]

Signed-off-by: Christoph Hellwig 
Signed-off-by: Andrew Morton 
Cc: Alexei Starovoitov 
Cc: Daniel Borkmann 
Cc: "H. Peter Anvin" 
Cc: Ingo Molnar 
Cc: Masami Hiramatsu 
Cc: Thomas Gleixner 
Link: http://lkml.kernel.org/r/20200521152301.2587579-11-hch@lst.de
Signed-off-by: Linus Torvalds

mmap locking API: convert mmap_sem API comments

2020-06-09T16:39:14+00:00

Convert comments that reference old mmap_sem APIs to reference
corresponding new mmap locking APIs instead.

Signed-off-by: Michel Lespinasse 
Signed-off-by: Andrew Morton 
Reviewed-by: Vlastimil Babka 
Reviewed-by: Davidlohr Bueso 
Reviewed-by: Daniel Jordan 
Cc: David Rientjes 
Cc: Hugh Dickins 
Cc: Jason Gunthorpe 
Cc: Jerome Glisse 
Cc: John Hubbard 
Cc: Laurent Dufour 
Cc: Liam Howlett 
Cc: Matthew Wilcox 
Cc: Peter Zijlstra 
Cc: Ying Han 
Link: http://lkml.kernel.org/r/20200520052908.204642-12-walken@google.com
Signed-off-by: Linus Torvalds