x86/alternative: Add debug prints to apply_retpolines()

stable inclusion
from stable-v5.10.133
commit 38a80a3ca2cb069dd5608703b015a206a672aae5
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I5YVKO

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=38a80a3ca2cb069dd5608703b015a206a672aae5



--------------------------------

commit d4b5a5c9 upstream.

Make sure we can see the text changes when booting with
'debug-alternative'.

Example output:

 [ ] SMP alternatives: retpoline at: __traceiter_initcall_level+0x1f/0x30 (ffffffff8100066f) len: 5 to: __x86_indirect_thunk_rax+0x0/0x20
 [ ] SMP alternatives: ffffffff82603e58: [2:5) optimized NOPs: ff d0 0f 1f 00
 [ ] SMP alternatives: ffffffff8100066f: orig: e8 cc 30 00 01
 [ ] SMP alternatives: ffffffff8100066f: repl: ff d0 0f 1f 00

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Borislav Petkov <bp@suse.de>
Acked-by: Josh Poimboeuf <jpoimboe@redhat.com>
Tested-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/r/20211026120310.422273830@infradead.org


Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>
Acked-by: Xie XiuQi <xiexiuqi@huawei.com>