bpf, x64: remove bpf_flush_icache

Unlike other archs flush_icache_range() is a noop on x64, therefore
remove the JIT's bpf_flush_icache() altogether since not needed.

Reported-by: Linus Torvalds <[e-mail]>
Signed-off-by: Daniel Borkmann <[e-mail]>
Cc: Eric Dumazet <[e-mail]>
Acked-by: Alexei Starovoitov <[e-mail]>
Signed-off-by: Alexei Starovoitov <[e-mail]>

arch/x86/net/bpf_jit_comp.c

···
 #include <linux/netdevice.h>
 #include <linux/filter.h>
 #include <linux/if_vlan.h>
-#include <asm/cacheflush.h>
+#include <linux/bpf.h>
+
 #include <asm/set_memory.h>
 #include <asm/nospec-branch.h>
-#include <linux/bpf.h>
 
 /*
  * assembly code in arch/x86/net/bpf_jit.S
···
 #define X86_JGE 0x7D
 #define X86_JLE 0x7E
 #define X86_JG  0x7F
-
-static void bpf_flush_icache(void *start, void *end)
-{
-	mm_segment_t old_fs = get_fs();
-
-	set_fs(KERNEL_DS);
-	smp_wmb();
-	flush_icache_range((unsigned long)start, (unsigned long)end);
-	set_fs(old_fs);
-}
 
 #define CHOOSE_LOAD_FUNC(K, func) \
 	((int)K < 0 ? ((int)K >= SKF_LL_OFF ? func##_negative_offset : func) : func##_positive_offset)
···
 		bpf_jit_dump(prog->len, proglen, pass + 1, image);
 
 	if (image) {
-		bpf_flush_icache(header, image + proglen);
 		if (!prog->is_func || extra_pass) {
 			bpf_jit_binary_lock_ro(header);
 		} else {