x86/bpf: Fix IP after emitting call depth accounting

Adjust the IP passed to `emit_patch` so it calculates the correct offset
for the CALL instruction if `x86_call_depth_emit_accounting` emits code.
Otherwise we will skip some instructions and most likely crash.

Fixes: b2e9dfe ("x86/bpf: Emit call depth accounting if required")
Link: https://lore.kernel.org/lkml/[email protected]/
Co-developed-by: Joan Bruguera Micó <[email protected]>
Signed-off-by: Joan Bruguera Micó <[email protected]>
Signed-off-by: Uros Bizjak <[email protected]>
Cc: Alexei Starovoitov <[email protected]>
Cc: Daniel Borkmann <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Alexei Starovoitov <[email protected]>

Author: ubizjak

arch/x86/net/bpf_jit_comp.c

@@ -480,7 +480,7 @@ static int emit_call(u8 **pprog, void *func, void *ip)
 static int emit_rsb_call(u8 **pprog, void *func, void *ip)
 {
 	OPTIMIZER_HIDE_VAR(func);
-	x86_call_depth_emit_accounting(pprog, func);
+	ip += x86_call_depth_emit_accounting(pprog, func);
 	return emit_patch(pprog, func, ip, 0xE8);
 }