On Tue, Jul 6, 2021 at 1:23 PM Peter Zijlstra [off-list ref] wrote:

On Tue, Jul 06, 2021 at 12:18:05PM +0800, Huacai Chen wrote:

quoted

+
+static inline u32 csr_xchgl(u32 val, u32 mask, u32 reg)
+{
+     return __csrxchg(val, mask, reg);
+}
+
+static inline u64 csr_xchgq(u64 val, u64 mask, u32 reg)
+{
+     return __dcsrxchg(val, mask, reg);
+}

What are these __csrfoo() things, I cannot seem to find a definition of
them anywhere..

It seems that those are provided as compiler intrinsics in <larchintrin.h>,
based on an architecture specific __builtin_loongarch_csrxchg() etc.

The specific registers are documented at
https://loongson.github.io/LoongArch-Documentation/LoongArch-Vol1-EN#control-and-status-registers

    Arnd