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Date: Wed, 12 Jun 2024 11:02:32 +0800
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From: Li Zetao <lizetao1@huawei.com>
Subject: riscv: link error when supporting KCSAN
To: <linux-riscv@lists.infradead.org>
CC: <dvyukov@google.com>, Kefeng Wang <wangkefeng.wang@huawei.com>,
	<linux-kernel@vger.kernel.org>
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Hi all,

I'm developing support for KCSAN on riscv but getting the following link 
error:

riscv64-linux-gnu-ld: kernel/kcsan/core.o: in function `.L996':
core.c:(.text+0x2b62): undefined reference to `__atomic_exchange_1'
riscv64-linux-gnu-ld: kernel/kcsan/core.o: in function `.L1015':
core.c:(.text+0x2c40): undefined reference to `__atomic_fetch_add_1'
riscv64-linux-gnu-ld: kernel/kcsan/core.o: in function `.L1034':
core.c:(.text+0x2d1e): undefined reference to `__atomic_fetch_sub_1'
riscv64-linux-gnu-ld: kernel/kcsan/core.o: in function `.L1053':
core.c:(.text+0x2dfc): undefined reference to `__atomic_fetch_and_1'
riscv64-linux-gnu-ld: kernel/kcsan/core.o: in function `.L1071':
core.c:(.text+0x2eda): undefined reference to `__atomic_fetch_or_1'
riscv64-linux-gnu-ld: kernel/kcsan/core.o: in function `.L1090':
core.c:(.text+0x2fb8): undefined reference to `__atomic_fetch_xor_1'
riscv64-linux-gnu-ld: kernel/kcsan/core.o: in function `.L1109':
core.c:(.text+0x3096): undefined reference to `__atomic_fetch_nand_1'
riscv64-linux-gnu-ld: kernel/kcsan/core.o: in function `.L1128':
core.c:(.text+0x3182): undefined reference to `__atomic_compare_exchange_1'
riscv64-linux-gnu-ld: kernel/kcsan/core.o: in function `.L1147':
core.c:(.text+0x3274): undefined reference to `__atomic_compare_exchange_1'
riscv64-linux-gnu-ld: kernel/kcsan/core.o: in function `.L1166':
core.c:(.text+0x3366): undefined reference to `__atomic_compare_exchange_1'
riscv64-linux-gnu-ld: kernel/kcsan/core.o: in function `.L1220':
core.c:(.text+0x35ec): undefined reference to `__atomic_exchange_2'
riscv64-linux-gnu-ld: kernel/kcsan/core.o: in function `.L1239':
core.c:(.text+0x36ce): undefined reference to `__atomic_fetch_add_2'
riscv64-linux-gnu-ld: kernel/kcsan/core.o: in function `.L1258':
core.c:(.text+0x37b0): undefined reference to `__atomic_fetch_sub_2'
riscv64-linux-gnu-ld: kernel/kcsan/core.o: in function `.L1277':
core.c:(.text+0x3892): undefined reference to `__atomic_fetch_and_2'
riscv64-linux-gnu-ld: kernel/kcsan/core.o: in function `.L1296':
core.c:(.text+0x3974): undefined reference to `__atomic_fetch_or_2'
riscv64-linux-gnu-ld: kernel/kcsan/core.o: in function `.L1315':
core.c:(.text+0x3a56): undefined reference to `__atomic_fetch_xor_2'
riscv64-linux-gnu-ld: kernel/kcsan/core.o: in function `.L1334':
core.c:(.text+0x3b38): undefined reference to `__atomic_fetch_nand_2'
riscv64-linux-gnu-ld: kernel/kcsan/core.o: in function `.L1353':
core.c:(.text+0x3c28): undefined reference to `__atomic_compare_exchange_2'
riscv64-linux-gnu-ld: kernel/kcsan/core.o: in function `.L1372':
core.c:(.text+0x3d1e): undefined reference to `__atomic_compare_exchange_2'
riscv64-linux-gnu-ld: kernel/kcsan/core.o: in function `.L1391':
core.c:(.text+0x3e14): undefined reference to `__atomic_compare_exchange_2'
make[2]: *** [scripts/Makefile.vmlinux:34: vmlinux] Error 1
make[1]: *** [/home/l00517538/PrIntFuzz/third_party/linux/Makefile:1171: 
vmlinux] Error 2

The reason for the error is that riscv only supports 32-bit or 64-bit 
atomic operations.As far as I know, this error is solved through the 
no-outline-atomics option on arm64. How can I solve this problem on riscv?

Best regards,
Li Zetao