[PATCH 2/2] Loongarch: KGDB: fix build when CPU_HAS_LBT not set

[Randy Dunlap]

Fix build errors when CONFIG_CPU_HAS_LBT is not set:

loongarch64-linux-ld: arch/loongarch/kernel/kgdb.o: in function `dbg_get_reg':
arch/loongarch/kernel/kgdb.c:154:(.text+0xc7c): undefined reference to `_save_lbt'
loongarch64-linux-ld: arch/loongarch/kernel/kgdb.o: in function `dbg_set_reg':
arch/loongarch/kernel/kgdb.c:229:(.text+0x13a4): undefined reference to `_restore_lbt'

Fixes: 8968eb010689 ("LoongArch: Add basic KGDB & KDB support")
Signed-off-by: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
Cc: Qing Zhang <zhangqing@xxxxxxxxxxx>
Cc: Hui Li <lihui@xxxxxxxxxxx>
Cc: Binbin Zhou <zhoubinbin@xxxxxxxxxxx>
Cc: Huacai Chen <chenhuacai@xxxxxxxxxx>
Cc: WANG Xuerui <kernel@xxxxxxxxxx>
Cc: loongarch@xxxxxxxxxxxxxxx
---
 arch/loongarch/kernel/kgdb.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff -- a/arch/loongarch/kernel/kgdb.c b/arch/loongarch/kernel/kgdb.c
--- a/arch/loongarch/kernel/kgdb.c
+++ b/arch/loongarch/kernel/kgdb.c
@@ -150,7 +150,8 @@ char *dbg_get_reg(int regno, void *mem,
 	}
 
 	/* Handle LBT registers */
-	if ((regs->csr_euen & CSR_EUEN_LBTEN)) {
+	if (IS_ENABLED(CONFIG_CPU_HAS_LBT) &&
+	    (regs->csr_euen & CSR_EUEN_LBTEN)) {
 		_save_lbt(&current->thread.lbt);
 
 		switch (regno) {
@@ -211,7 +212,8 @@ int dbg_set_reg(int regno, void *mem, st
 	}
 
 	/* Handle LBT registers */
-	if ((regs->csr_euen & CSR_EUEN_LBTEN)) {
+	if (IS_ENABLED(CONFIG_CPU_HAS_LBT) &&
+	    (regs->csr_euen & CSR_EUEN_LBTEN)) {
 		switch (regno) {
 		case DBG_FTOP:				/* Process the ftop */
 			memcpy((char *)&current->thread.fpu.ftop, mem, reg_size);