gdbstub: Expose gdb_write_register function to consumers of gdbstub

This patch exposes the gdb_write_register function from
gdbstub/gdbstub.c via the exec/gdbstub.h header file to support use in
plugins to write register contents.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Julian Ganz <neither@nut.email>
Reviewed-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
Signed-off-by: Rowan Hart <rowanbhart@gmail.com>
Message-ID: <20250624175351.440780-2-rowanbhart@gmail.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-ID: <20250627112512.1880708-6-alex.bennee@linaro.org>
diff --git a/gdbstub/gdbstub.c b/gdbstub/gdbstub.c
index def0b7e..dd5fb56 100644
--- a/gdbstub/gdbstub.c
+++ b/gdbstub/gdbstub.c
@@ -535,7 +535,7 @@
     return 0;
 }
 
-static int gdb_write_register(CPUState *cpu, uint8_t *mem_buf, int reg)
+int gdb_write_register(CPUState *cpu, uint8_t *mem_buf, int reg)
 {
     GDBRegisterState *r;
 
diff --git a/include/exec/gdbstub.h b/include/exec/gdbstub.h
index 0675b0b..a16c005 100644
--- a/include/exec/gdbstub.h
+++ b/include/exec/gdbstub.h
@@ -125,6 +125,20 @@
 int gdb_read_register(CPUState *cpu, GByteArray *buf, int reg);
 
 /**
+ * gdb_write_register() - Write a register associated with a CPU.
+ * @cpu: The CPU associated with the register.
+ * @buf: The buffer that the register contents will be set to.
+ * @reg: The register's number returned by gdb_find_feature_register().
+ *
+ * The size of @buf must be at least the size of the register being
+ * written.
+ *
+ * Return: The number of written bytes, or 0 if an error occurred (for
+ * example, an unknown register was provided).
+ */
+int gdb_write_register(CPUState *cpu, uint8_t *mem_buf, int reg);
+
+/**
  * typedef GDBRegDesc - a register description from gdbstub
  */
 typedef struct {