riscv: support trap-based WARN()

The WARN() related function will trigger a debug exception. This can help
developers to analyze the cause of WARN() because if the debugger is
connected, the control flow will be transferred to debugging
environment.

Signed-off-by: Vincent Chen <vincentc@andestech.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>

diff --git a/arch/riscv/include/asm/bug.h b/arch/riscv/include/asm/bug.h
index bfc7f09..4d906d8 100644 (file)
--- a/arch/riscv/include/asm/bug.h
+++ b/arch/riscv/include/asm/bug.h
@@ -38,38 +38,46 @@ typedef u32 bug_insn_t;
 #define __BUG_ENTRY                    \
        __BUG_ENTRY_ADDR "\n\t"         \
        __BUG_ENTRY_FILE "\n\t"         \
-       RISCV_SHORT " %1"
+       RISCV_SHORT " %1\n\t"           \
+       RISCV_SHORT " %2"
 #else
 #define __BUG_ENTRY                    \
-       __BUG_ENTRY_ADDR
+       __BUG_ENTRY_ADDR "\n\t"         \
+       RISCV_SHORT " %2"
 #endif
 
-#define BUG()                                                  \
+#define __BUG_FLAGS(flags)                                     \
 do {                                                           \
        __asm__ __volatile__ (                                  \
                "1:\n\t"                                        \
                        "ebreak\n"                              \
-                       ".pushsection __bug_table,\"a\"\n\t"    \
+                       ".pushsection __bug_table,\"aw\"\n\t"   \
                "2:\n\t"                                        \
                        __BUG_ENTRY "\n\t"                      \
-                       ".org 2b + %2\n\t"                      \
+                       ".org 2b + %3\n\t"                      \
                        ".popsection"                           \
                :                                               \
                : "i" (__FILE__), "i" (__LINE__),               \
-                 "i" (sizeof(struct bug_entry)));              \
-       unreachable();                                          \
+                 "i" (flags),                                  \
+                 "i" (sizeof(struct bug_entry)));              \
 } while (0)
+
 #endif /* !__ASSEMBLY__ */
 #else /* CONFIG_GENERIC_BUG */
 #ifndef __ASSEMBLY__
-#define BUG()                                                  \
-do {                                                           \
+#define __BUG_FLAGS(flags) do {                                        \
        __asm__ __volatile__ ("ebreak\n");                      \
-       unreachable();                                          \
 } while (0)
 #endif /* !__ASSEMBLY__ */
 #endif /* CONFIG_GENERIC_BUG */
 
+#define BUG() do {                                             \
+       __BUG_FLAGS(0);                                         \
+       unreachable();                                          \
+} while (0)
+
+#define __WARN_FLAGS(flags) __BUG_FLAGS(BUGFLAG_WARNING|(flags))
+
 #define HAVE_ARCH_BUG
 
 #include <asm-generic/bug.h>