linux-imx

crypto: s5p-sss - Fix spinlock recursion on LRW(AES)

Running TCRYPT with LRW compiled causes spinlock recursion:

    testing speed of async lrw(aes) (lrw(ecb-aes-s5p)) encryption
    tcrypt: test 0 (256 bit key, 16 byte blocks): 19007 operations in 1 seconds (304112 bytes)
    tcrypt: test 1 (256 bit key, 64 byte blocks): 15753 operations in 1 seconds (1008192 bytes)
    tcrypt: test 2 (256 bit key, 256 byte blocks): 14293 operations in 1 seconds (3659008 bytes)
    tcrypt: test 3 (256 bit key, 1024 byte blocks): 11906 operations in 1 seconds (12191744 bytes)
    tcrypt: test 4 (256 bit key, 8192 byte blocks):
    BUG: spinlock recursion on CPU#1, irq/84-10830000/89
     lock: 0xeea99a68, .magic: dead4ead, .owner: irq/84-10830000/89, .owner_cpu: 1
    CPU: 1 PID: 89 Comm: irq/84-10830000 Not tainted 4.11.0-rc1-00001-g897ca6d0800d #559
    Hardware name: SAMSUNG EXYNOS (Flattened Device Tree)
    [<c010e1ec>] (unwind_backtrace) from [<c010ae1c>] (show_stack+0x10/0x14)
    [<c010ae1c>] (show_stack) from [<c03449c0>] (dump_stack+0x78/0x8c)
    [<c03449c0>] (dump_stack) from [<c015de68>] (do_raw_spin_lock+0x11c/0x120)
    [<c015de68>] (do_raw_spin_lock) from [<c0720110>] (_raw_spin_lock_irqsave+0x20/0x28)
    [<c0720110>] (_raw_spin_lock_irqsave) from [<c0572ca0>] (s5p_aes_crypt+0x2c/0xb4)
    [<c0572ca0>] (s5p_aes_crypt) from [<bf1d8aa4>] (do_encrypt+0x78/0xb0 [lrw])
    [<bf1d8aa4>] (do_encrypt [lrw]) from [<bf1d8b00>] (encrypt_done+0x24/0x54 [lrw])
    [<bf1d8b00>] (encrypt_done [lrw]) from [<c05732a0>] (s5p_aes_complete+0x60/0xcc)
    [<c05732a0>] (s5p_aes_complete) from [<c0573440>] (s5p_aes_interrupt+0x134/0x1a0)
    [<c0573440>] (s5p_aes_interrupt) from [<c01667c4>] (irq_thread_fn+0x1c/0x54)
    [<c01667c4>] (irq_thread_fn) from [<c0166a98>] (irq_thread+0x12c/0x1e0)
    [<c0166a98>] (irq_thread) from [<c0136a28>] (kthread+0x108/0x138)
    [<c0136a28>] (kthread) from [<c0107778>] (ret_from_fork+0x14/0x3c)

Interrupt handling routine was calling req->base.complete() under
spinlock.  In most cases this wasn't fatal but when combined with some
of the cipher modes (like LRW) this caused recursion - starting the new
encryption (s5p_aes_crypt()) while still holding the spinlock from
previous round (s5p_aes_complete()).

Beside that, the s5p_aes_interrupt() error handling path could execute
two completions in case of error for RX and TX blocks.

Rewrite the interrupt handling routine and the completion by:

1. Splitting the operations on scatterlist copies from
   s5p_aes_complete() into separate s5p_sg_done(). This still should be
   done under lock.
   The s5p_aes_complete() now only calls req->base.complete() and it has
   to be called outside of lock.

2. Moving the s5p_aes_complete() out of spinlock critical sections.
   In interrupt service routine s5p_aes_interrupts(), it appeared in few
   places, including error paths inside other functions called from ISR.
   This code was not so obvious to read so simplify it by putting the
   s5p_aes_complete() only within ISR level.

Reported-by: Nathan Royce <nroycea+kernel@gmail.com>
Cc: <stable@vger.kernel.org> # v4.10.x: 07de4bc88c crypto: s5p-sss - Fix completing
Cc: <stable@vger.kernel.org> # v4.10.x
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>