From e1180c8cee4aa8013279767db3acffe5979f2594 Mon Sep 17 00:00:00 2001
From: Daniel Leung <daniel.leung@intel.com>
Date: Thu, 14 Oct 2021 10:56:36 -0700
Subject: [PATCH] x86: gdbstub: add arch-specific funcs to read/write registers

This adds some architecture-specific functions to read/write
registers for the GDB stub. This is in preparation for the actual
introduction of these functions in the core GDB stub code to
avoid breaking the build in between commits.

Signed-off-by: Daniel Leung <daniel.leung@intel.com>
---
 arch/x86/core/ia32/gdbstub.c    | 85 +++++++++++++++++++++++++++++++++
 include/arch/x86/ia32/gdbstub.h |  7 ++-
 2 files changed, 90 insertions(+), 2 deletions(-)

diff --git a/arch/x86/core/ia32/gdbstub.c b/arch/x86/core/ia32/gdbstub.c
index bf1f08a4d8e..f40797a3bcb 100644
--- a/arch/x86/core/ia32/gdbstub.c
+++ b/arch/x86/core/ia32/gdbstub.c
@@ -133,6 +133,91 @@ void arch_gdb_step(void)
 	ctx.registers[GDB_EFLAGS] |= BIT(8);
 }
 
+size_t arch_gdb_reg_readall(struct gdb_ctx *ctx, uint8_t *buf, size_t buflen)
+{
+	size_t ret;
+
+	if (buflen < (sizeof(ctx->registers) * 2)) {
+		ret = 0;
+	} else {
+		ret = bin2hex((const uint8_t *)&(ctx->registers),
+			      sizeof(ctx->registers), buf, buflen);
+	}
+
+	return ret;
+}
+
+size_t arch_gdb_reg_writeall(struct gdb_ctx *ctx, uint8_t *hex, size_t hexlen)
+{
+	size_t ret;
+
+	if (hexlen != (sizeof(ctx->registers) * 2)) {
+		ret = 0;
+	} else {
+		ret = hex2bin(hex, hexlen,
+			      (uint8_t *)&(ctx->registers),
+			      sizeof(ctx->registers));
+	}
+
+	return ret;
+}
+
+size_t arch_gdb_reg_readone(struct gdb_ctx *ctx, uint8_t *buf, size_t buflen,
+			    uint32_t regno)
+{
+	size_t ret;
+
+	if (buflen < (sizeof(unsigned int) * 2)) {
+		/* Make sure there is enough space to write hex string */
+		ret = 0;
+	} else if (regno >= GDB_STUB_NUM_REGISTERS) {
+		/* Return hex string "xx" to tell GDB that this register
+		 * is not available. So GDB will continue probing other
+		 * registers instead of stopping in the middle of
+		 * "info registers all".
+		 */
+		if (buflen >= 2) {
+			strncpy(buf, "xx", 2);
+			ret = 2;
+		} else {
+			ret = 0;
+		}
+	} else {
+		ret = bin2hex((const uint8_t *)&(ctx->registers[regno]),
+			      sizeof(ctx->registers[regno]),
+			      buf, buflen);
+	}
+
+	return ret;
+}
+
+size_t arch_gdb_reg_writeone(struct gdb_ctx *ctx, uint8_t *hex, size_t hexlen,
+			     uint32_t regno)
+{
+	size_t ret;
+
+	if (regno == GDB_ORIG_EAX) {
+		/* GDB requires orig_eax that seems to be
+		 * Linux specific. Unfortunely if we just
+		 * return error, GDB will stop working.
+		 * So just fake an OK response by saying
+		 * that we have processed the hex string.
+		 */
+		ret = hexlen;
+	} else if (regno >= GDB_STUB_NUM_REGISTERS) {
+		ret = 0;
+	} else if (hexlen != (sizeof(unsigned int) * 2)) {
+		/* Make sure the input hex string matches register size */
+		ret = 0;
+	} else {
+		ret = hex2bin(hex, hexlen,
+			      (uint8_t *)&(ctx->registers[regno]),
+			      sizeof(ctx->registers[regno]));
+	}
+
+	return ret;
+}
+
 static __used void z_gdb_debug_isr(z_arch_esf_t *esf)
 {
 	z_gdb_interrupt(IV_DEBUG, esf);
diff --git a/include/arch/x86/ia32/gdbstub.h b/include/arch/x86/ia32/gdbstub.h
index 450928216f6..1a7a3068d3e 100644
--- a/include/arch/x86/ia32/gdbstub.h
+++ b/include/arch/x86/ia32/gdbstub.h
@@ -22,6 +22,8 @@
  */
 #define ARCH_GDB_NUM_REGISTERS 16
 
+#define GDB_STUB_NUM_REGISTERS 16
+
 /**
  * @brief GDB interruption context
  *
@@ -71,12 +73,13 @@ enum GDB_REGISTER {
 	GDB_DS,
 	GDB_ES,
 	GDB_FS,
-	GDB_GS
+	GDB_GS,
+	GDB_ORIG_EAX = 41,
 };
 
 struct gdb_ctx {
 	unsigned int exception;
-	unsigned int registers[ARCH_GDB_NUM_REGISTERS];
+	unsigned int registers[GDB_STUB_NUM_REGISTERS];
 };
 
 #endif /* _ASMLANGUAGE */