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    Subject[PATCH AUTOSEL 5.2 183/249] crypto: serpent - mark __serpent_setkey_sbox noinline
    Date
    From: Arnd Bergmann <arnd@arndb.de>

    [ Upstream commit 473971187d6727609951858c63bf12b0307ef015 ]

    The same bug that gcc hit in the past is apparently now showing
    up with clang, which decides to inline __serpent_setkey_sbox:

    crypto/serpent_generic.c:268:5: error: stack frame size of 2112 bytes in function '__serpent_setkey' [-Werror,-Wframe-larger-than=]

    Marking it 'noinline' reduces the stack usage from 2112 bytes to
    192 and 96 bytes, respectively, and seems to generate more
    useful object code.

    Fixes: c871c10e4ea7 ("crypto: serpent - improve __serpent_setkey with UBSAN")
    Signed-off-by: Arnd Bergmann <arnd@arndb.de>
    Reviewed-by: Eric Biggers <ebiggers@kernel.org>
    Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    crypto/serpent_generic.c | 8 +++++++-
    1 file changed, 7 insertions(+), 1 deletion(-)

    diff --git a/crypto/serpent_generic.c b/crypto/serpent_generic.c
    index 16f612b6dbca..a9cc0b2aa0d6 100644
    --- a/crypto/serpent_generic.c
    +++ b/crypto/serpent_generic.c
    @@ -225,7 +225,13 @@
    x4 ^= x2; \
    })

    -static void __serpent_setkey_sbox(u32 r0, u32 r1, u32 r2, u32 r3, u32 r4, u32 *k)
    +/*
    + * both gcc and clang have misoptimized this function in the past,
    + * producing horrible object code from spilling temporary variables
    + * on the stack. Forcing this part out of line avoids that.
    + */
    +static noinline void __serpent_setkey_sbox(u32 r0, u32 r1, u32 r2,
    + u32 r3, u32 r4, u32 *k)
    {
    k += 100;
    S3(r3, r4, r0, r1, r2); store_and_load_keys(r1, r2, r4, r3, 28, 24);
    --
    2.20.1
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