MIPS: lib: Mark intrinsics notrace

2016-06-08T01:14:32+00:00

commit aedcfbe06558a9f53002e82d5be64c6c94687726 upstream. On certain MIPS32 devices, the ftrace tracer "function_graph" uses __lshrdi3() during the capturing of trace data. ftrace then attempts to trace __lshrdi3() which leads to infinite recursion and a stack overflow. Fix this by marking __lshrdi3() as notrace. Mark the other compiler intrinsics as notrace in case the compiler decides to use them in the ftrace path. Signed-off-by: Harvey Hunt Cc: Cc: Patchwork: https://patchwork.linux-mips.org/patch/13354/ Signed-off-by: Ralf Baechle Signed-off-by: Greg Kroah-Hartman

MIPS: Use ARCH_USE_BUILTIN_BSWAP.

2015-10-26T08:49:43+00:00

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

kernel/linux.git/arch/mips/lib/bswapsi.c, branch linux-4.4.y

MIPS: lib: Mark intrinsics notrace

MIPS: Use ARCH_USE_BUILTIN_BSWAP.