1. 08 9月, 2016 5 次提交
    • S
      f2fs: set encryption name flag in add inline entry path · 167451ef
      Shuoran Liu 提交于
      This patch sets encryption name flag in the add inline entry path
      if filename is encrypted.
      Signed-off-by: NShuoran Liu <liushuoran@huawei.com>
      Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>
      167451ef
    • C
      f2fs crypto: avoid unneeded memory allocation in ->readdir · e06f86e6
      Chao Yu 提交于
      When decrypting dirents in ->readdir, fscrypt_fname_disk_to_usr won't
      change content of original encrypted dirent, we don't need to allocate
      additional buffer for storing mirror of it, so get rid of it.
      Signed-off-by: NChao Yu <yuchao0@huawei.com>
      Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>
      e06f86e6
    • C
      f2fs: fix to do security initialization of encrypted inode with original filename · 9421d570
      Chao Yu 提交于
      When creating new inode, security_inode_init_security will be called for
      initializing security info related to the inode, and filename is passed to
      security module, it helps security module such as SElinux to know which
      rule or label could be applied for the inode with specified name.
      
      Previously, if new inode is created as an encrypted one, f2fs will transfer
      encrypted filename to security module which may fail the check of security
      policy belong to the inode. So in order to this issue, alter to transfer
      original unencrypted filename instead.
      Signed-off-by: NChao Yu <yuchao0@huawei.com>
      Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>
      9421d570
    • C
      f2fs: do in batch synchronously readahead during GC · 7ea984b0
      Chao Yu 提交于
      In order to enhance performance, we try to readahead node page during
      GC, but before loading node page we should get block address of node page
      which is stored in NAT table, so synchronously read of single NAT page
      block our readahead flow.
      
      f2fs_submit_page_bio: dev = (251,0), ino = 2, page_index = 0xa1e, oldaddr = 0xa1e, newaddr = 0xa1e, rw = READ_SYNC(MP), type = META
      f2fs_submit_page_bio: dev = (251,0), ino = 1, page_index = 0x35e9, oldaddr = 0x72d7a, newaddr = 0x72d7a, rw = READAHEAD ^H, type = NODE
      f2fs_submit_page_bio: dev = (251,0), ino = 2, page_index = 0xc1f, oldaddr = 0xc1f, newaddr = 0xc1f, rw = READ_SYNC(MP), type = META
      f2fs_submit_page_bio: dev = (251,0), ino = 1, page_index = 0x389d, oldaddr = 0x72d7d, newaddr = 0x72d7d, rw = READAHEAD ^H, type = NODE
      f2fs_submit_page_bio: dev = (251,0), ino = 1, page_index = 0x3a82, oldaddr = 0x72d7f, newaddr = 0x72d7f, rw = READAHEAD ^H, type = NODE
      f2fs_submit_page_bio: dev = (251,0), ino = 1, page_index = 0x3bfa, oldaddr = 0x72d86, newaddr = 0x72d86, rw = READAHEAD ^H, type = NODE
      
      This patch adds one phase that do readahead NAT pages in batch before
      readahead node page for more effeciently.
      
      f2fs_submit_page_bio: dev = (251,0), ino = 2, page_index = 0x1952, oldaddr = 0x1952, newaddr = 0x1952, rw = READ_SYNC(MP), type = META
      f2fs_submit_page_mbio: dev = (251,0), ino = 2, page_index = 0xc34, oldaddr = 0xc34, newaddr = 0xc34, rw = READ_SYNC(MP), type = META
      f2fs_submit_page_mbio: dev = (251,0), ino = 2, page_index = 0xa33, oldaddr = 0xa33, newaddr = 0xa33, rw = READ_SYNC(MP), type = META
      f2fs_submit_page_mbio: dev = (251,0), ino = 2, page_index = 0xc30, oldaddr = 0xc30, newaddr = 0xc30, rw = READ_SYNC(MP), type = META
      f2fs_submit_page_mbio: dev = (251,0), ino = 2, page_index = 0xc32, oldaddr = 0xc32, newaddr = 0xc32, rw = READ_SYNC(MP), type = META
      f2fs_submit_page_mbio: dev = (251,0), ino = 2, page_index = 0xc26, oldaddr = 0xc26, newaddr = 0xc26, rw = READ_SYNC(MP), type = META
      f2fs_submit_page_mbio: dev = (251,0), ino = 2, page_index = 0xa2b, oldaddr = 0xa2b, newaddr = 0xa2b, rw = READ_SYNC(MP), type = META
      f2fs_submit_page_mbio: dev = (251,0), ino = 2, page_index = 0xc23, oldaddr = 0xc23, newaddr = 0xc23, rw = READ_SYNC(MP), type = META
      f2fs_submit_page_mbio: dev = (251,0), ino = 2, page_index = 0xc24, oldaddr = 0xc24, newaddr = 0xc24, rw = READ_SYNC(MP), type = META
      f2fs_submit_page_mbio: dev = (251,0), ino = 2, page_index = 0xa10, oldaddr = 0xa10, newaddr = 0xa10, rw = READ_SYNC(MP), type = META
      f2fs_submit_page_mbio: dev = (251,0), ino = 2, page_index = 0xc2c, oldaddr = 0xc2c, newaddr = 0xc2c, rw = READ_SYNC(MP), type = META
      f2fs_submit_page_bio: dev = (251,0), ino = 1, page_index = 0x5db7, oldaddr = 0x6be00, newaddr = 0x6be00, rw = READAHEAD ^H, type = NODE
      f2fs_submit_page_bio: dev = (251,0), ino = 1, page_index = 0x5db9, oldaddr = 0x6be17, newaddr = 0x6be17, rw = READAHEAD ^H, type = NODE
      f2fs_submit_page_bio: dev = (251,0), ino = 1, page_index = 0x5dbc, oldaddr = 0x6be1a, newaddr = 0x6be1a, rw = READAHEAD ^H, type = NODE
      f2fs_submit_page_bio: dev = (251,0), ino = 1, page_index = 0x5dc3, oldaddr = 0x6be20, newaddr = 0x6be20, rw = READAHEAD ^H, type = NODE
      f2fs_submit_page_bio: dev = (251,0), ino = 1, page_index = 0x5dc7, oldaddr = 0x6be24, newaddr = 0x6be24, rw = READAHEAD ^H, type = NODE
      f2fs_submit_page_bio: dev = (251,0), ino = 1, page_index = 0x5dc9, oldaddr = 0x6be25, newaddr = 0x6be25, rw = READAHEAD ^H, type = NODE
      Signed-off-by: NChao Yu <yuchao0@huawei.com>
      Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>
      7ea984b0
    • C
      f2fs: schedule in between two continous batch discards · 74fa5f3d
      Chao Yu 提交于
      In batch discard approach of fstrim will grab/release gc_mutex lock
      repeatly, it makes contention of the lock becoming more intensive.
      
      So after one batch discards were issued in checkpoint and the lock
      was released, it's better to do schedule() to increase opportunity
      of grabbing gc_mutex lock for other competitors.
      Signed-off-by: NChao Yu <yuchao0@huawei.com>
      Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>
      74fa5f3d
  2. 30 8月, 2016 14 次提交
  3. 25 8月, 2016 3 次提交
    • C
      f2fs: clean up bio cache trace · 44819a76
      Chao Yu 提交于
      Trace info related to bio cache operation is out of format, clean up it.
      
      Before:
             <...>-28308 [002] ....  4781.052703: f2fs_submit_write_bio: dev = (251,1), WRITEWRITE_SYNC ^H, DATA, sector = 271424, size = 126976
             <...>-28308 [002] ....  4781.052820: f2fs_submit_page_mbio: dev = (251,1), ino = 103, page_index = 0x1f, oldaddr = 0xffffffff, newaddr = 0x84a7 rw = WRITEWRITE_SYNCi ^H, type = DATA
      kworker/u8:2-29988 [001] ....  5549.293877: f2fs_submit_page_mbio: dev = (251,1), ino = 91, page_index = 0xd, oldaddr = 0xffffffff, newaddr = 0x782f rw = WRITE0x0i ^H type = DATA
      
      After:
      kworker/u8:2-8678  [000] ....  7945.124459: f2fs_submit_write_bio: dev = (251,1), rw = WRITE_SYNC, DATA, sector = 74080, size = 53248
      kworker/u8:2-8678  [000] ....  7945.124551: f2fs_submit_page_mbio: dev = (251,1), ino = 11, page_index = 0xec, oldaddr = 0xffffffff, newaddr = 0x243a, rw = WRITE, type = DATA
      Signed-off-by: NChao Yu <yuchao0@huawei.com>
      Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>
      44819a76
    • J
      f2fs: do not use discard_map for hard disks · 3e025740
      Jaegeuk Kim 提交于
      We don't need to keep discard_map, if disk does not support discard command.
      Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>
      3e025740
    • Y
      f2fs: not allow to write illegal blkaddr · bb413d6a
      Yunlei He 提交于
      we came across an error as below:
      
      [build_nat_area_bitmap:1710] nid[0x    1718] addr[0x         1c18ddc] ino[0x    1718]
      [build_nat_area_bitmap:1710] nid[0x    1719] addr[0x         1c193d5] ino[0x    1719]
      [build_nat_area_bitmap:1710] nid[0x    171a] addr[0x         1c1736e] ino[0x    171a]
      [build_nat_area_bitmap:1710] nid[0x    171b] addr[0x        58b3ee8f] ino[0x815f92ed]
      [build_nat_area_bitmap:1710] nid[0x    171c] addr[0x         fcdc94b] ino[0x49366377]
      [build_nat_area_bitmap:1710] nid[0x    171d] addr[0x        7cd2facf] ino[0xb3c55300]
      [build_nat_area_bitmap:1710] nid[0x    171e] addr[0x        bd4e25d0] ino[0x77c34c09]
      
      ... ...
      
      [build_nat_area_bitmap:1710] nid[0x    1718] addr[0x         1c18ddc] ino[0x    1718]
      [build_nat_area_bitmap:1710] nid[0x    1719] addr[0x         1c193d5] ino[0x    1719]
      [build_nat_area_bitmap:1710] nid[0x    171a] addr[0x         1c1736e] ino[0x    171a]
      [build_nat_area_bitmap:1710] nid[0x    171b] addr[0x        58b3ee8f] ino[0x815f92ed]
      [build_nat_area_bitmap:1710] nid[0x    171c] addr[0x         fcdc94b] ino[0x49366377]
      [build_nat_area_bitmap:1710] nid[0x    171d] addr[0x        7cd2facf] ino[0xb3c55300]
      [build_nat_area_bitmap:1710] nid[0x    171e] addr[0x        bd4e25d0] ino[0x77c34c09]
      
      One nat block may be stepped by a data block, so this patch forbid to
      write if the blkaddr is illegal
      Signed-off-by: NYunlei He <heyunlei@huawei.com>
      Signed-off-by: NJaegeuk Kim <jaegeuk@kernel.org>
      bb413d6a
  4. 24 8月, 2016 4 次提交
  5. 23 8月, 2016 5 次提交
    • B
      vhost/scsi: fix reuse of &vq->iov[out] in response · a77ec83a
      Benjamin Coddington 提交于
      The address of the iovec &vq->iov[out] is not guaranteed to contain the scsi
      command's response iovec throughout the lifetime of the command.  Rather, it
      is more likely to contain an iovec from an immediately following command
      after looping back around to vhost_get_vq_desc().  Pass along the iovec
      entirely instead.
      
      Fixes: 79c14141 ("vhost/scsi: Convert completion path to use copy_to_iter")
      Cc: stable@vger.kernel.org
      Signed-off-by: NBenjamin Coddington <bcodding@redhat.com>
      Signed-off-by: NMichael S. Tsirkin <mst@redhat.com>
      a77ec83a
    • J
      usercopy: fix overlap check for kernel text · 94cd97af
      Josh Poimboeuf 提交于
      When running with a local patch which moves the '_stext' symbol to the
      very beginning of the kernel text area, I got the following panic with
      CONFIG_HARDENED_USERCOPY:
      
        usercopy: kernel memory exposure attempt detected from ffff88103dfff000 (<linear kernel text>) (4096 bytes)
        ------------[ cut here ]------------
        kernel BUG at mm/usercopy.c:79!
        invalid opcode: 0000 [#1] SMP
        ...
        CPU: 0 PID: 4800 Comm: cp Not tainted 4.8.0-rc3.after+ #1
        Hardware name: Dell Inc. PowerEdge R720/0X3D66, BIOS 2.5.4 01/22/2016
        task: ffff880817444140 task.stack: ffff880816274000
        RIP: 0010:[<ffffffff8121c796>] __check_object_size+0x76/0x413
        RSP: 0018:ffff880816277c40 EFLAGS: 00010246
        RAX: 000000000000006b RBX: ffff88103dfff000 RCX: 0000000000000000
        RDX: 0000000000000000 RSI: ffff88081f80dfa8 RDI: ffff88081f80dfa8
        RBP: ffff880816277c90 R08: 000000000000054c R09: 0000000000000000
        R10: 0000000000000005 R11: 0000000000000006 R12: 0000000000001000
        R13: ffff88103e000000 R14: ffff88103dffffff R15: 0000000000000001
        FS:  00007fb9d1750800(0000) GS:ffff88081f800000(0000) knlGS:0000000000000000
        CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
        CR2: 00000000021d2000 CR3: 000000081a08f000 CR4: 00000000001406f0
        Stack:
         ffff880816277cc8 0000000000010000 000000043de07000 0000000000000000
         0000000000001000 ffff880816277e60 0000000000001000 ffff880816277e28
         000000000000c000 0000000000001000 ffff880816277ce8 ffffffff8136c3a6
        Call Trace:
         [<ffffffff8136c3a6>] copy_page_to_iter_iovec+0xa6/0x1c0
         [<ffffffff8136e766>] copy_page_to_iter+0x16/0x90
         [<ffffffff811970e3>] generic_file_read_iter+0x3e3/0x7c0
         [<ffffffffa06a738d>] ? xfs_file_buffered_aio_write+0xad/0x260 [xfs]
         [<ffffffff816e6262>] ? down_read+0x12/0x40
         [<ffffffffa06a61b1>] xfs_file_buffered_aio_read+0x51/0xc0 [xfs]
         [<ffffffffa06a6692>] xfs_file_read_iter+0x62/0xb0 [xfs]
         [<ffffffff812224cf>] __vfs_read+0xdf/0x130
         [<ffffffff81222c9e>] vfs_read+0x8e/0x140
         [<ffffffff81224195>] SyS_read+0x55/0xc0
         [<ffffffff81003a47>] do_syscall_64+0x67/0x160
         [<ffffffff816e8421>] entry_SYSCALL64_slow_path+0x25/0x25
        RIP: 0033:[<00007fb9d0c33c00>] 0x7fb9d0c33c00
        RSP: 002b:00007ffc9c262f28 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
        RAX: ffffffffffffffda RBX: fffffffffff8ffff RCX: 00007fb9d0c33c00
        RDX: 0000000000010000 RSI: 00000000021c3000 RDI: 0000000000000004
        RBP: 00000000021c3000 R08: 0000000000000000 R09: 00007ffc9c264d6c
        R10: 00007ffc9c262c50 R11: 0000000000000246 R12: 0000000000010000
        R13: 00007ffc9c2630b0 R14: 0000000000000004 R15: 0000000000010000
        Code: 81 48 0f 44 d0 48 c7 c6 90 4d a3 81 48 c7 c0 bb b3 a2 81 48 0f 44 f0 4d 89 e1 48 89 d9 48 c7 c7 68 16 a3 81 31 c0 e8 f4 57 f7 ff <0f> 0b 48 8d 90 00 40 00 00 48 39 d3 0f 83 22 01 00 00 48 39 c3
        RIP  [<ffffffff8121c796>] __check_object_size+0x76/0x413
         RSP <ffff880816277c40>
      
      The checked object's range [ffff88103dfff000, ffff88103e000000) is
      valid, so there shouldn't have been a BUG.  The hardened usercopy code
      got confused because the range's ending address is the same as the
      kernel's text starting address at 0xffff88103e000000.  The overlap check
      is slightly off.
      
      Fixes: f5509cc1 ("mm: Hardened usercopy")
      Signed-off-by: NJosh Poimboeuf <jpoimboe@redhat.com>
      Signed-off-by: NKees Cook <keescook@chromium.org>
      94cd97af
    • E
      usercopy: avoid potentially undefined behavior in pointer math · 7329a655
      Eric Biggers 提交于
      check_bogus_address() checked for pointer overflow using this expression,
      where 'ptr' has type 'const void *':
      
      	ptr + n < ptr
      
      Since pointer wraparound is undefined behavior, gcc at -O2 by default
      treats it like the following, which would not behave as intended:
      
      	(long)n < 0
      
      Fortunately, this doesn't currently happen for kernel code because kernel
      code is compiled with -fno-strict-overflow.  But the expression should be
      fixed anyway to use well-defined integer arithmetic, since it could be
      treated differently by different compilers in the future or could be
      reported by tools checking for undefined behavior.
      Signed-off-by: NEric Biggers <ebiggers@google.com>
      Signed-off-by: NKees Cook <keescook@chromium.org>
      7329a655
    • L
      Merge tag 'arc-4.8-rc4-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/vgupta/arc · ef0e1ea8
      Linus Torvalds 提交于
      Pull ARC fixes from Vineet Gupta:
      
       - support for Syscall ABI v4 with upstream gcc 6.x
      
       - lockdep fix (Daniel Mentz)
      
       - gdb register clobber (Liav Rehana)
      
       - couple of missing exports for modules
      
       - other fixes here and there
      
      * tag 'arc-4.8-rc4-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/vgupta/arc:
        ARC: export __udivdi3 for modules
        ARC: mm: fix build breakage with STRICT_MM_TYPECHECKS
        ARC: export kmap
        ARC: Support syscall ABI v4
        ARC: use correct offset in pt_regs for saving/restoring user mode r25
        ARC: Elide redundant setup of DMA callbacks
        ARC: Call trace_hardirqs_on() before enabling irqs
      ef0e1ea8
    • L
      Merge tag 'gpio-v4.8-2' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-gpio · 37c669b2
      Linus Torvalds 提交于
      Pull GPIO fixes from Linus Walleij:
       "Here are a few GPIO fixes for v4.8.
      
        I was expecting some fallout from the new chardev rework but nothing
        like that turned up att all.  Instead a Kconfig confusion that I think
        I have finally nailed, then some ordinary driver noise and trivia.
      
        This fixes a Kconfig issue with UM: when I made GPIOLIB available to
        all archs, that included UM, but the OF part of GPIOLIB requires
        HAS_IOMEM, so we add HAS_IOMEM as a dependency to OF_GPIO.
      
        This in turn exposed the fact that a few GPIO drivers were implicitly
        assuming OF_GPIO as their dependency but instead depended on OF alone
        (the typical problem being a pointer inside gpio_chip not existing
        unless OF_GPIO is selected) and then UM would fail to compile with
        these drivers instead.  Then I lost patience and made any GPIO driver
        depending on just OF depend on OF_GPIO instead, that is certainly what
        they meant and the only thing that makes sense anyway.  GPIO with just
        OF but !OF_GPIO does not make sense.
      
        Also a fix for the max730x driver data pointer, and a minor comment
        fix for the GPIO tools"
      
      * tag 'gpio-v4.8-2' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-gpio:
        gpio: make any OF dependent driver depend on OF_GPIO
        gpio: Fix OF build problem on UM
        gpio: max730x: set gpiochip data pointer before using it
        tools/gpio: fix gpio-event-mon header comment
      37c669b2
  6. 22 8月, 2016 3 次提交
  7. 20 8月, 2016 6 次提交
    • H
      parisc: Fix order of EREFUSED define in errno.h · 3eb53b20
      Helge Deller 提交于
      When building gccgo in userspace, errno.h gets parsed and the go include file
      sysinfo.go is generated.
      
      Since EREFUSED is defined to the same value as ECONNREFUSED, and ECONNREFUSED
      is defined later on in errno.h, this leads to go complaining that EREFUSED
      isn't defined yet.
      
      Fix this trivial problem by moving the define of EREFUSED down after
      ECONNREFUSED in errno.h (and clean up the indenting while touching this line).
      Signed-off-by: NHelge Deller <deller@gmx.de>
      Cc: stable@vger.kernel.org
      3eb53b20
    • H
      parisc: Fix automatic selection of cr16 clocksource · ae141830
      Helge Deller 提交于
      Commit 54b66800 (parisc: Add native high-resolution sched_clock()
      implementation) added support to use the CPU-internal cr16 counters as reliable
      clocksource with the help of HAVE_UNSTABLE_SCHED_CLOCK.
      
      Sadly the commit missed to remove the hack which prevented cr16 to become the
      default clocksource even on SMP systems.
      Signed-off-by: NHelge Deller <deller@gmx.de>
      Cc: stable@vger.kernel.org # 4.7+
      ae141830
    • V
      ARC: export __udivdi3 for modules · c57653dc
      Vineet Gupta 提交于
      Some module using div_u64() was failing to link because the libgcc 64-bit
      divide assist routine was not being exported for modules
      
      Reported-by: avinashp@quantenna.com
      Cc: stable@vger.kernel.org
      Signed-off-by: NVineet Gupta <vgupta@synopsys.com>
      c57653dc
    • L
      Make the hardened user-copy code depend on having a hardened allocator · 6040e576
      Linus Torvalds 提交于
      The kernel test robot reported a usercopy failure in the new hardened
      sanity checks, due to a page-crossing copy of the FPU state into the
      task structure.
      
      This happened because the kernel test robot was testing with SLOB, which
      doesn't actually do the required book-keeping for slab allocations, and
      as a result the hardening code didn't realize that the task struct
      allocation was one single allocation - and the sanity checks fail.
      
      Since SLOB doesn't even claim to support hardening (and you really
      shouldn't use it), the straightforward solution is to just make the
      usercopy hardening code depend on the allocator supporting it.
      Reported-by: Nkernel test robot <xiaolong.ye@intel.com>
      Cc: Kees Cook <keescook@chromium.org>
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      6040e576
    • L
      Merge branch 'i2c/for-current' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux · 8cc9dddd
      Linus Torvalds 提交于
      Pull i2c fixes from Wolfram Sang:
       "I2C has some pretty standard driver bugfixes and one minor cleanup"
      
      * 'i2c/for-current' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux:
        i2c: meson: Use complete() instead of complete_all()
        i2c: brcmstb: Use complete() instead of complete_all()
        i2c: bcm-kona: Use complete() instead of complete_all()
        i2c: bcm-iproc: Use complete() instead of complete_all()
        i2c: at91: fix support of the "alternative command" feature
        i2c: ocores: add missed clk_disable_unprepare() on failure paths
        i2c: cros-ec-tunnel: Fix usage of cros_ec_cmd_xfer()
        i2c: mux: demux-pinctrl: properly roll back when adding adapter fails
      8cc9dddd
    • V
      ARC: mm: fix build breakage with STRICT_MM_TYPECHECKS · 1c3c9093
      Vineet Gupta 提交于
      |  CC      mm/memory.o
      | In file included from ../mm/memory.c:53:0:
      | ../include/linux/pfn_t.h: In function ‘pfn_t_pte’:
      | ../include/linux/pfn_t.h:78:2: error: conversion to non-scalar type requested
      |  return pfn_pte(pfn_t_to_pfn(pfn), pgprot);
      
      With STRICT_MM_TYPECHECKS pte_t is a struct and the offending code
      forces a cast which ends up shifting a struct and hence the gcc warning.
      
      Note that in recent past some of the arches (aarch64, s390) made
      STRICT_MM_TYPECHECKS default, but we don't for ARC as this leads to slightly
      worse generated code, given ARC ABI definition of returning structs
      (which pte_t would become)
      
      Quoting from ARC ABI...
      
        "Results of type struct are returned in a caller-supplied temporary
        variable whose address is passed in r0.
        For such functions, the arguments are shifted so that they are
        passed in r1 and up."
      
      So
       - struct to be returned would be allocated on stack requiring extra
         code at call sites
       - callee updates stack memory to facilitate the return (vs. simple
         MOV into return reg r0)
      
      Hence STRICT_MM_TYPECHECKS is not enabled by default for ARC
      
      Cc: <stable@vger.kernel.org>   #4.4+
      Signed-off-by: NVineet Gupta <vgupta@synopsys.com>
      1c3c9093