[PATCH] RISC-V: selftests: fix cbo.c compilation error

[Yunhui Cui <cuiyunhui@xxxxxxxxxxxxx>]

When compiling with -O0, the following error will occur:
cbo.c: In function 'cbo_insn':
cbo.c:43:9: warning: 'asm' operand 1 probably does not match constraints
   43 |         asm volatile(
      |         ^~~
cbo.c:43:9: warning: 'asm' operand 2 probably does not match constraints
cbo.c:43:9: error: impossible constraint in 'asm'

Add __attribute__((optimize("O"))) to fix.

Fixes: a29e2a48afe3 ("RISC-V: selftests: Add CBO tests")
Signed-off-by: Yunhui Cui <cuiyunhui@xxxxxxxxxxxxx>
Suggested-by: Zhipeng Xu <xuzhipeng.1973@xxxxxxxxxxxxx>
---
 tools/testing/selftests/riscv/hwprobe/cbo.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/tools/testing/selftests/riscv/hwprobe/cbo.c b/tools/testing/selftests/riscv/hwprobe/cbo.c
index 50a2cc8aef38..ff1d8e843d70 100644
--- a/tools/testing/selftests/riscv/hwprobe/cbo.c
+++ b/tools/testing/selftests/riscv/hwprobe/cbo.c
@@ -36,7 +36,7 @@ static void sigill_handler(int sig, siginfo_t *info, void *context)
 	regs[0] += 4;
 }
 
-static void cbo_insn(char *base, int fn)
+static __always_inline void cbo_insn(char *base, int fn)
 {
 	uint32_t insn = MK_CBO(fn);
 
@@ -47,10 +47,11 @@ static void cbo_insn(char *base, int fn)
 	: : "r" (base), "i" (fn), "i" (insn) : "a0", "a1", "memory");
 }
 
-static void cbo_inval(char *base) { cbo_insn(base, 0); }
-static void cbo_clean(char *base) { cbo_insn(base, 1); }
-static void cbo_flush(char *base) { cbo_insn(base, 2); }
-static void cbo_zero(char *base)  { cbo_insn(base, 4); }
+#define OPTIMIZE __attribute__((optimize("O")))
+OPTIMIZE static void cbo_inval(char *base) { cbo_insn(base, 0); }
+OPTIMIZE static void cbo_clean(char *base) { cbo_insn(base, 1); }
+OPTIMIZE static void cbo_flush(char *base) { cbo_insn(base, 2); }
+OPTIMIZE static void cbo_zero(char *base)  { cbo_insn(base, 4); }
 
 static void test_no_zicbom(void *arg)
 {
-- 
2.20.1