diff mbox series

[v3,13/16] x86/alternative: Add debug prints to apply_retpolines()

Message ID 20211026120310.422273830@infradead.org (mailing list archive)
State Superseded
Delegated to: BPF
Headers show
Series x86: Rewrite the retpoline rewrite logic | expand

Checks

Context Check Description
netdev/tree_selection success Not a local patch
bpf/vmtest-bpf-next-PR fail merge-conflict
bpf/vmtest-bpf-PR fail merge-conflict
bpf/vmtest-bpf-next pending VM_Test

Commit Message

Peter Zijlstra Oct. 26, 2021, 12:01 p.m. UTC
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>
---
 arch/x86/kernel/alternative.c |   10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)
diff mbox series

Patch

--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -492,9 +492,15 @@  void __init_or_module noinline apply_ret
 			continue;
 		}
 
+		DPRINTK("retpoline at: %pS (%px) len: %d to: %pS",
+			addr, addr, insn.length,
+			addr + insn.length + insn.immediate.value);
+
 		len = patch_retpoline(addr, &insn, bytes);
 		if (len == insn.length) {
 			optimize_nops(bytes, len);
+			DUMP_BYTES(((u8*)addr),  len, "%px: orig: ", addr);
+			DUMP_BYTES(((u8*)bytes), len, "%px: repl: ", addr);
 			text_poke_early(addr, bytes, len);
 		}
 	}