[PATCH v2] riscv: KGDB: Do not inline arch_kgdb_breakpoint()

[WangYuli]

The arch_kgdb_breakpoint() function defines the kgdb_compiled_break
symbol using inline assembly.

There's a potential issue where the compiler might inline
arch_kgdb_breakpoint(), which would then define the kgdb_breakinst
symbol multiple times, leading to fail to link vmlinux.o.

This isn't merely a potential compilation problem. The intent here
is to determine the global symbol address of kgdb_compiled_break,
and if this function is inlined multiple times, it would logically
be a grave error.

Link: https://lore.kernel.org/all/4b4187c1-77e5-44b7-885f-d6826723dd9a@sifive.com/
Fixes: fe89bd2be866 ("riscv: Add KGDB support")
Co-developed-by: Huacai Chen <chenhuacai at loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai at loongson.cn>
Signed-off-by: WangYuli <wangyuli at uniontech.com>
---
Changelog:
 *v1->v2: Add the missing __ASSEMBLY__ check and substitute
".option rvc/norvc" with ".option push/pop".
---
 arch/riscv/include/asm/kgdb.h | 9 +--------
 arch/riscv/kernel/kgdb.c      | 8 ++++++++
 2 files changed, 9 insertions(+), 8 deletions(-)

diff --git a/arch/riscv/include/asm/kgdb.h b/arch/riscv/include/asm/kgdb.h
index 46677daf708b..d9f6a8fc387f 100644
--- a/arch/riscv/include/asm/kgdb.h
+++ b/arch/riscv/include/asm/kgdb.h
@@ -19,16 +19,9 @@
 
 #ifndef	__ASSEMBLY__
 
+extern void arch_kgdb_breakpoint(void);
 extern unsigned long kgdb_compiled_break;
 
-static inline void arch_kgdb_breakpoint(void)
-{
-	asm(".global kgdb_compiled_break\n"
-	    ".option norvc\n"
-	    "kgdb_compiled_break: ebreak\n"
-	    ".option rvc\n");
-}
-
 #endif /* !__ASSEMBLY__ */
 
 #define DBG_REG_ZERO "zero"
diff --git a/arch/riscv/kernel/kgdb.c b/arch/riscv/kernel/kgdb.c
index 2e0266ae6bd7..5873d3970360 100644
--- a/arch/riscv/kernel/kgdb.c
+++ b/arch/riscv/kernel/kgdb.c
@@ -254,6 +254,14 @@ void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long pc)
 	regs->epc = pc;
 }
 
+noinline void arch_kgdb_breakpoint(void)
+{
+	asm(".global kgdb_compiled_break\n"
+	    ".option push\n"
+	    "kgdb_compiled_break: ebreak\n"
+	    ".option pop\n");
+}
+
 void kgdb_arch_handle_qxfer_pkt(char *remcom_in_buffer,
 				char *remcom_out_buffer)
 {
-- 
2.49.0