[PATCH -next] riscv: Enable ARCH_HAVE_NMI_SAFE_CMPXCHG

[Pu Lehui]

From: Pu Lehui <pulehui at huawei.com>

The implement of cmpxchg() in riscv is based on atomic primitives and
has NMI-safe features, so it can be used safely in the in_nmi context.
ftrace's ringbuffer relies on NMI-safe cmpxchg() in the NMI context.
Currently, in_nmi() is true when riscv kprobe is in trap-based mode, so
this config needs to be selected, otherwise kprobetrace will not be
available.

Signed-off-by: Pu Lehui <pulehui at huawei.com>
---
 arch/riscv/Kconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 36061f4732b7..0e2dfa98338a 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -23,6 +23,7 @@ config RISCV
 	select ARCH_ENABLE_MEMORY_HOTREMOVE if MEMORY_HOTPLUG
 	select ARCH_ENABLE_SPLIT_PMD_PTLOCK if PGTABLE_LEVELS > 2
 	select ARCH_ENABLE_THP_MIGRATION if TRANSPARENT_HUGEPAGE
+	select ARCH_HAVE_NMI_SAFE_CMPXCHG
 	select ARCH_HAS_BINFMT_FLAT
 	select ARCH_HAS_CRC32 if RISCV_ISA_ZBC
 	select ARCH_HAS_CRC64 if 64BIT && RISCV_ISA_ZBC
-- 
2.34.1