[nrf noup] soc: riscv: Add end of relocation address to start of the code

In order to allow extract relocation code size from the binary
add dummy instruction at the beginning which will write address of
the end of the relocation part to the register. It is decoded by the
host core which copies riscv code.

Signed-off-by: Krzysztof Chruściński <[email protected]>

Author: nordic-krch

include/zephyr/arch/riscv/common/linker.ld

@@ -343,6 +343,10 @@ SECTIONS
  * zephyr_linker_sources() Cmake function.
  */
 #include <snippets-data-sections.ld>
+/* Tag end location of code+data that shall be copied in non-XIP execution.
+ * It must not include noinit section.
+ */
+    __relocation_region_end = .;
 
 #include <zephyr/linker/common-noinit.ld>
 

soc/common/riscv-privileged/vector.S

@@ -21,6 +21,8 @@ SECTION_FUNC(vectors, __start)
 	/* Initialize global pointer */
 	.option push
 	.option norelax
+	/* Include end address of code+data that shall be copied in non-XIP execution. */
+	la gp, __relocation_region_end
 	la gp, __global_pointer$
 	.option pop
 #endif