netdev - [PATCH net-next 5/7] bpf: extend bpf_trace

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Date:   Sun,  2 Jul 2017 02:13:29 +0200
From:   Daniel Borkmann <daniel@...earbox.net>
To:     davem@...emloft.net
Cc:     ast@...com, john.fastabend@...il.com, netdev@...r.kernel.org
Subject: [PATCH net-next 5/7] bpf: extend bpf_trace_printk to support %i

From: John Fastabend <john.fastabend@...il.com>

Currently, bpf_trace_printk does not support common formatting
symbol '%i' however vsprintf does and is what eventually gets
called by bpf helper. If users are used to '%i' and currently
make use of it, then bpf_trace_printk will just return with
error without dumping anything to the trace pipe, so just add
support for '%i' to the helper.

Signed-off-by: John Fastabend <john.fastabend@...il.com>
Acked-by: Daniel Borkmann <daniel@...earbox.net>
Acked-by: Alexei Starovoitov <ast@...nel.org>
---
 kernel/trace/bpf_trace.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 5c6d538..3738519 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -122,8 +122,8 @@ static const struct bpf_func_proto *bpf_get_probe_write_proto(void)
 }
 
 /*
- * limited trace_printk()
- * only %d %u %x %ld %lu %lx %lld %llu %llx %p %s conversion specifiers allowed
+ * Only limited trace_printk() conversion specifiers allowed:
+ * %d %i %u %x %ld %li %lu %lx %lld %lli %llu %llx %p %s
  */
 BPF_CALL_5(bpf_trace_printk, char *, fmt, u32, fmt_size, u64, arg1,
 	   u64, arg2, u64, arg3)
@@ -198,7 +198,8 @@ static const struct bpf_func_proto *bpf_get_probe_write_proto(void)
 			i++;
 		}
 
-		if (fmt[i] != 'd' && fmt[i] != 'u' && fmt[i] != 'x')
+		if (fmt[i] != 'i' && fmt[i] != 'd' &&
+		    fmt[i] != 'u' && fmt[i] != 'x')
 			return -EINVAL;
 		fmt_cnt++;
 	}
-- 
1.9.3