arm64/debug: Simplify BRK insn opcode declarations

The way the KGDB_DYN_BRK_INS_BYTEx macros are declared is more
complex than it needs to be.  Also, the macros are only used in one
place, which is arch-specific anyway.

This patch refactors the macros to simplify them, and exposes an
argument so that we can have a single macro instead of 4.

As a side effect, this patch also fixes some anomalous spellings of
"KGDB".

These changes alter the compile types of some integer constants
that are harmless but trigger truncation warnings in gcc when
assigning to 32-bit variables.  This patch adds an explicit cast
for the affected cases.

Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

arch/arm64/include/asm/debug-monitors.h

@@ -66,25 +66,10 @@
  */
 #define AARCH64_BREAK_FAULT	(AARCH64_BREAK_MON | (FAULT_BRK_IMM << 5))
 
-/*
- * Extract byte from BRK instruction
- */
-#define KGDB_DYN_DBG_BRK_INS_BYTE(x) \
-	((((AARCH64_BREAK_MON) & 0xffe0001f) >> (x * 8)) & 0xff)
-
-/*
- * Extract byte from BRK #imm16
- */
-#define KGBD_DYN_DBG_BRK_IMM_BYTE(x) \
-	(((((KGDB_DYN_DBG_BRK_IMM) & 0xffff) << 5) >> (x * 8)) & 0xff)
-
-#define KGDB_DYN_DBG_BRK_BYTE(x) \
-	(KGDB_DYN_DBG_BRK_INS_BYTE(x) | KGBD_DYN_DBG_BRK_IMM_BYTE(x))
-
-#define  KGDB_DYN_BRK_INS_BYTE0  KGDB_DYN_DBG_BRK_BYTE(0)
-#define  KGDB_DYN_BRK_INS_BYTE1  KGDB_DYN_DBG_BRK_BYTE(1)
-#define  KGDB_DYN_BRK_INS_BYTE2  KGDB_DYN_DBG_BRK_BYTE(2)
-#define  KGDB_DYN_BRK_INS_BYTE3  KGDB_DYN_DBG_BRK_BYTE(3)
+#define AARCH64_BREAK_KGDB_DYN_DBG	\
+	(AARCH64_BREAK_MON | (KGDB_DYN_DBG_BRK_IMM << 5))
+#define KGDB_DYN_BRK_INS_BYTE(x)	\
+	((AARCH64_BREAK_KGDB_DYN_DBG >> (8 * (x))) & 0xff)
 
 #define CACHE_FLUSH_IS_SAFE		1
 

arch/arm64/kernel/kgdb.c

@@ -235,13 +235,13 @@ static int kgdb_step_brk_fn(struct pt_regs *regs, unsigned int esr)
 
 static struct break_hook kgdb_brkpt_hook = {
 	.esr_mask	= 0xffffffff,
-	.esr_val	= ESR_ELx_VAL_BRK64(KGDB_DYN_DBG_BRK_IMM),
+	.esr_val	= (u32)ESR_ELx_VAL_BRK64(KGDB_DYN_DBG_BRK_IMM),
 	.fn		= kgdb_brk_fn
 };
 
 static struct break_hook kgdb_compiled_brkpt_hook = {
 	.esr_mask	= 0xffffffff,
-	.esr_val	= ESR_ELx_VAL_BRK64(KGDB_COMPILED_DBG_BRK_IMM),
+	.esr_val	= (u32)ESR_ELx_VAL_BRK64(KGDB_COMPILED_DBG_BRK_IMM),
 	.fn		= kgdb_compiled_brk_fn
 };
 
@@ -328,9 +328,9 @@ void kgdb_arch_exit(void)
  */
 struct kgdb_arch arch_kgdb_ops = {
 	.gdb_bpt_instr = {
-		KGDB_DYN_BRK_INS_BYTE0,
-		KGDB_DYN_BRK_INS_BYTE1,
-		KGDB_DYN_BRK_INS_BYTE2,
-		KGDB_DYN_BRK_INS_BYTE3,
+		KGDB_DYN_BRK_INS_BYTE(0),
+		KGDB_DYN_BRK_INS_BYTE(1),
+		KGDB_DYN_BRK_INS_BYTE(2),
+		KGDB_DYN_BRK_INS_BYTE(3),
 	}
 };