diff options
author | Ralf Baechle <ralf@linux-mips.org> | 2015-09-29 10:19:48 (GMT) |
---|---|---|
committer | Ralf Baechle <ralf@linux-mips.org> | 2015-10-26 08:49:43 (GMT) |
commit | 1ee3630a3e57f38f688a6f0a5f9edbd8a0d7201f (patch) | |
tree | 3326b59ffb2650bff622642700981bf5541a1b04 | |
parent | d478b088a2f74fc8f34af7ceed86fa7640ca8610 (diff) | |
download | linux-1ee3630a3e57f38f688a6f0a5f9edbd8a0d7201f.tar.xz |
MIPS: Use ARCH_USE_BUILTIN_BSWAP.
ARCH_USE_BUILTIN_BSWAP will use __builtin_bswap16(), __builtin_bswap32()
and __builtin_bswap64() where available. This allows better instruction
scheduling. On pre-R2 processors it will result in 32 bit and 64 bit
swapping being performed in a call to a __bswapsi2() rsp. __bswapdi2()
functions, so we add these, too.
For a 4.2 kernel with GCC 4.9 this yields the following kernel sizes:
text data bss dec hex filename
3996071 155804 88992 4240867 40b5e3 vmlinux ip22 baseline
3985687 159900 88992 4234579 409d53 vmlinux ip22 + bswap patch
6913157 378552 251024 7542733 7317cd vmlinux ip27 baseline
6878581 378552 251024 7508157 7290bd vmlinux ip27 + bswap patch
5773777 268752 187424 6229953 5f0fc1 vmlinux malta baseline
5773401 268752 187424 6229577 5f0e49 vmlinux malta + bswap patch
Presumably the code size improvments yield better cache hit rate thus
better performance compensating for the extra function call but this
will still need to be benchmarked.
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
-rw-r--r-- | arch/mips/Kconfig | 1 | ||||
-rw-r--r-- | arch/mips/lib/Makefile | 2 | ||||
-rw-r--r-- | arch/mips/lib/bswapdi.c | 15 | ||||
-rw-r--r-- | arch/mips/lib/bswapsi.c | 11 |
4 files changed, 28 insertions, 1 deletions
diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig index e3aa5b0..c08e701 100644 --- a/arch/mips/Kconfig +++ b/arch/mips/Kconfig @@ -5,6 +5,7 @@ config MIPS select ARCH_MIGHT_HAVE_PC_PARPORT select ARCH_MIGHT_HAVE_PC_SERIO select ARCH_USE_CMPXCHG_LOCKREF if 64BIT + select ARCH_USE_BUILTIN_BSWAP select HAVE_CONTEXT_TRACKING select HAVE_GENERIC_DMA_COHERENT select HAVE_IDE diff --git a/arch/mips/lib/Makefile b/arch/mips/lib/Makefile index 1e9e900..0344e57 100644 --- a/arch/mips/lib/Makefile +++ b/arch/mips/lib/Makefile @@ -15,4 +15,4 @@ obj-$(CONFIG_CPU_R3000) += r3k_dump_tlb.o obj-$(CONFIG_CPU_TX39XX) += r3k_dump_tlb.o # libgcc-style stuff needed in the kernel -obj-y += ashldi3.o ashrdi3.o cmpdi2.o lshrdi3.o ucmpdi2.o +obj-y += ashldi3.o ashrdi3.o bswapsi.o bswapdi.o cmpdi2.o lshrdi3.o ucmpdi2.o diff --git a/arch/mips/lib/bswapdi.c b/arch/mips/lib/bswapdi.c new file mode 100644 index 0000000..77e5f9c --- /dev/null +++ b/arch/mips/lib/bswapdi.c @@ -0,0 +1,15 @@ +#include <linux/module.h> + +unsigned long long __bswapdi2(unsigned long long u) +{ + return (((u) & 0xff00000000000000ull) >> 56) | + (((u) & 0x00ff000000000000ull) >> 40) | + (((u) & 0x0000ff0000000000ull) >> 24) | + (((u) & 0x000000ff00000000ull) >> 8) | + (((u) & 0x00000000ff000000ull) << 8) | + (((u) & 0x0000000000ff0000ull) << 24) | + (((u) & 0x000000000000ff00ull) << 40) | + (((u) & 0x00000000000000ffull) << 56); +} + +EXPORT_SYMBOL(__bswapdi2); diff --git a/arch/mips/lib/bswapsi.c b/arch/mips/lib/bswapsi.c new file mode 100644 index 0000000..2b302ff --- /dev/null +++ b/arch/mips/lib/bswapsi.c @@ -0,0 +1,11 @@ +#include <linux/module.h> + +unsigned int __bswapsi2(unsigned int u) +{ + return (((u) & 0xff000000) >> 24) | + (((u) & 0x00ff0000) >> 8) | + (((u) & 0x0000ff00) << 8) | + (((u) & 0x000000ff) << 24); +} + +EXPORT_SYMBOL(__bswapsi2); |