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mips, uasm: Add workaround for Loongson-2F nop CPU errata
authorJohan Almbladh <johan.almbladh@anyfinetworks.com>
Tue, 5 Oct 2021 16:54:03 +0000 (18:54 +0200)
committerAndrii Nakryiko <andrii@kernel.org>
Wed, 6 Oct 2021 19:28:09 +0000 (12:28 -0700)
commitf7c036c15b5388749bc8de208fb7b19d69c4f6fa
treec055560c6ab84e6fa3dd3dd842c89d6887021987
parente737547eab6af8b57d77f7ba323c8d2d6b1a0008
mips, uasm: Add workaround for Loongson-2F nop CPU errata

This patch implements a workaround for the Loongson-2F nop in generated,
code, if the existing option CONFIG_CPU_NOP_WORKAROUND is set. Before,
the binutils option -mfix-loongson2f-nop was enabled, but no workaround
was done when emitting MIPS code. Now, the nop pseudo instruction is
emitted as "or ax,ax,zero" instead of the default "sll zero,zero,0". This
is consistent with the workaround implemented by binutils.

Signed-off-by: Johan Almbladh <johan.almbladh@anyfinetworks.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Reviewed-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
Link: https://sourceware.org/legacy-ml/binutils/2009-11/msg00387.html
Link: https://lore.kernel.org/bpf/20211005165408.2305108-3-johan.almbladh@anyfinetworks.com
arch/mips/include/asm/uasm.h