execmem: drop unused execmem_update_copy()

Patch series "x86: enable EXECMEM_ROX_CACHE for ftrace and kprobes", v3.

These patches enable use of EXECMEM_ROX_CACHE for ftrace and kprobes
allocations on x86.

They also include some ground work in execmem.

Since the execmem model for caching large ROX pages changed from the
initial assumption that the memory that is allocated from ROX cache is
always ROX to the current state where memory can be temporarily made RW
and then restored to ROX, we can stop using text poking to update it. 
This also saves the hassle of trying lock text_mutex in
execmem_cache_free() when kprobes already hold that mutex.


This patch (of 8):

The execmem_update_copy() that used text poking was required when memory
allocated from ROX cache was always read-only.  Since now its permissions
can be switched to read-write there is no need in a function that updates
memory with text poking.

Remove it.

Link: https://lkml.kernel.org/r/20250713071730.4117334-1-rppt@kernel.org
Link: https://lkml.kernel.org/r/20250713071730.4117334-2-rppt@kernel.org
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Daniel Gomez <da.gomez@samsung.com>
Cc: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Cc: Petr Pavlu <petr.pavlu@suse.com>
Cc: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Author: rppt

include/linux/execmem.h

@@ -185,19 +185,6 @@ DEFINE_FREE(execmem, void *, if (_T) execmem_free(_T));
 struct vm_struct *execmem_vmap(size_t size);
 #endif
 
-/**
- * execmem_update_copy - copy an update to executable memory
- * @dst:  destination address to update
- * @src:  source address containing the data
- * @size: how many bytes of memory shold be copied
- *
- * Copy @size bytes from @src to @dst using text poking if the memory at
- * @dst is read-only.
- *
- * Return: a pointer to @dst or NULL on error
- */
-void *execmem_update_copy(void *dst, const void *src, size_t size);
-
 /**
  * execmem_is_rox - check if execmem is read-only
  * @type - the execmem type to check

mm/execmem.c

@@ -399,11 +399,6 @@ void execmem_free(void *ptr)
 		vfree(ptr);
 }
 
-void *execmem_update_copy(void *dst, const void *src, size_t size)
-{
-	return text_poke_copy(dst, src, size);
-}
-
 bool execmem_is_rox(enum execmem_type type)
 {
 	return !!(execmem_info->ranges[type].flags & EXECMEM_ROX_CACHE);