| Message ID | 20200117164318.21941-1-ardb@kernel.org (mailing list archive) |
|---|---|
| State | Mainlined |
| Commit | 0bc81767c5bd9d005fae1099fb39eb3688370cb1 |
| Headers | show |
| Series | crypto: arm/chacha - fix build failured when kernel mode NEON is disabled | expand |
On Fri, Jan 17, 2020 at 05:43:18PM +0100, Ard Biesheuvel wrote: > When the ARM accelerated ChaCha driver is built as part of a configuration > that has kernel mode NEON disabled, we expect the compiler to propagate > the build time constant expression IS_ENABLED(CONFIG_KERNEL_MODE_NEON) in > a way that eliminates all the cross-object references to the actual NEON > routines, which allows the chacha-neon-core.o object to be omitted from > the build entirely. > > Unfortunately, this fails to work as expected in some cases, and we may > end up with a build error such as > > chacha-glue.c:(.text+0xc0): undefined reference to `chacha_4block_xor_neon' > > caused by the fact that chacha_doneon() has not been eliminated from the > object code, even though it will never be called in practice. > > Let's fix this by adding some IS_ENABLED(CONFIG_KERNEL_MODE_NEON) tests > that are not strictly needed from a logical point of view, but should > help the compiler infer that the NEON code paths are unreachable in > those cases. > > Fixes: b36d8c09e710c71f ("crypto: arm/chacha - remove dependency on generic ...") > Reported-by: Russell King <linux@armlinux.org.uk> > Cc: Arnd Bergmann <arnd@arndb.de> > Signed-off-by: Ard Biesheuvel <ardb@kernel.org> > --- > arch/arm/crypto/chacha-glue.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) Patch applied. Thanks.
diff --git a/arch/arm/crypto/chacha-glue.c b/arch/arm/crypto/chacha-glue.c index 6ebbb2b241d2..6fdb0ac62b3d 100644 --- a/arch/arm/crypto/chacha-glue.c +++ b/arch/arm/crypto/chacha-glue.c @@ -115,7 +115,7 @@ static int chacha_stream_xor(struct skcipher_request *req, if (nbytes < walk.total) nbytes = round_down(nbytes, walk.stride); - if (!neon) { + if (!IS_ENABLED(CONFIG_KERNEL_MODE_NEON) || !neon) { chacha_doarm(walk.dst.virt.addr, walk.src.virt.addr, nbytes, state, ctx->nrounds); state[12] += DIV_ROUND_UP(nbytes, CHACHA_BLOCK_SIZE); @@ -159,7 +159,7 @@ static int do_xchacha(struct skcipher_request *req, bool neon) chacha_init_generic(state, ctx->key, req->iv); - if (!neon) { + if (!IS_ENABLED(CONFIG_KERNEL_MODE_NEON) || !neon) { hchacha_block_arm(state, subctx.key, ctx->nrounds); } else { kernel_neon_begin();
When the ARM accelerated ChaCha driver is built as part of a configuration that has kernel mode NEON disabled, we expect the compiler to propagate the build time constant expression IS_ENABLED(CONFIG_KERNEL_MODE_NEON) in a way that eliminates all the cross-object references to the actual NEON routines, which allows the chacha-neon-core.o object to be omitted from the build entirely. Unfortunately, this fails to work as expected in some cases, and we may end up with a build error such as chacha-glue.c:(.text+0xc0): undefined reference to `chacha_4block_xor_neon' caused by the fact that chacha_doneon() has not been eliminated from the object code, even though it will never be called in practice. Let's fix this by adding some IS_ENABLED(CONFIG_KERNEL_MODE_NEON) tests that are not strictly needed from a logical point of view, but should help the compiler infer that the NEON code paths are unreachable in those cases. Fixes: b36d8c09e710c71f ("crypto: arm/chacha - remove dependency on generic ...") Reported-by: Russell King <linux@armlinux.org.uk> Cc: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Ard Biesheuvel <ardb@kernel.org> --- arch/arm/crypto/chacha-glue.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)