bpf: Remove arch_unprotect_bpf_trampoline()

Last user of arch_unprotect_bpf_trampoline() was removed by
commit 187e2af ("bpf: struct_ops supports more than one page for
trampolines.")

Remove arch_unprotect_bpf_trampoline()

Reported-by: Daniel Borkmann <daniel@iogearbox.net>
Fixes: 187e2af ("bpf: struct_ops supports more than one page for trampolines.")
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Link: https://lore.kernel.org/r/42c635bb54d3af91db0f9b85d724c7c290069f67.1710574353.git.christophe.leroy@csgroup.eu
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>

arch/arm64/net/bpf_jit_comp.c

@@ -2180,10 +2180,6 @@ void arch_protect_bpf_trampoline(void *image, unsigned int size)
 {
 }
 
-void arch_unprotect_bpf_trampoline(void *image, unsigned int size)
-{
-}
-
 int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *ro_image,
 				void *ro_image_end, const struct btf_func_model *m,
 				u32 flags, struct bpf_tramp_links *tlinks,

arch/x86/net/bpf_jit_comp.c

@@ -3008,10 +3008,6 @@ void arch_protect_bpf_trampoline(void *image, unsigned int size)
 {
 }
 
-void arch_unprotect_bpf_trampoline(void *image, unsigned int size)
-{
-}
-
 int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, void *image_end,
 				const struct btf_func_model *m, u32 flags,
 				struct bpf_tramp_links *tlinks,

include/linux/bpf.h

@@ -1117,7 +1117,6 @@ int arch_prepare_bpf_trampoline(struct bpf_tramp_image *im, void *image, void *i
 void *arch_alloc_bpf_trampoline(unsigned int size);
 void arch_free_bpf_trampoline(void *image, unsigned int size);
 void arch_protect_bpf_trampoline(void *image, unsigned int size);
-void arch_unprotect_bpf_trampoline(void *image, unsigned int size);
 int arch_bpf_trampoline_size(const struct btf_func_model *m, u32 flags,
 			     struct bpf_tramp_links *tlinks, void *func_addr);
 

kernel/bpf/trampoline.c

@@ -1078,13 +1078,6 @@ void __weak arch_protect_bpf_trampoline(void *image, unsigned int size)
 	set_memory_rox((long)image, 1);
 }
 
-void __weak arch_unprotect_bpf_trampoline(void *image, unsigned int size)
-{
-	WARN_ON_ONCE(size > PAGE_SIZE);
-	set_memory_nx((long)image, 1);
-	set_memory_rw((long)image, 1);
-}
-
 int __weak arch_bpf_trampoline_size(const struct btf_func_model *m, u32 flags,
 				    struct bpf_tramp_links *tlinks, void *func_addr)
 {