Commit 2df6bb54 authored by Song Liu's avatar Song Liu Committed by Alexei Starovoitov
Browse files

bpf: Allow %pB in bpf_seq_printf() and bpf_trace_printk() 



This makes it easy to dump stack trace in text.

Signed-off-by: default avatarSong Liu <songliubraving@fb.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Acked-by: default avatarYonghong Song <yhs@fb.com>
Acked-by: default avatarAndrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200630062846.664389-4-songliubraving@fb.com
parent fa28dcb8

kernel/trace/bpf_trace.c

+8 −2
Original line number Diff line number Diff line
@@ -376,7 +376,7 @@ static void bpf_trace_copy_string(char *buf, void *unsafe_ptr, char fmt_ptype, 


/*

 * Only limited trace_printk() conversion specifiers allowed:

 * %d %i %u %x %ld %li %lu %lx %lld %lli %llu %llx %p %pks %pus %s

 * %d %i %u %x %ld %li %lu %lx %lld %lli %llu %llx %p %pB %pks %pus %s

 */

BPF_CALL_5(bpf_trace_printk, char *, fmt, u32, fmt_size, u64, arg1,

	   u64, arg2, u64, arg3)
@@ -420,6 +420,11 @@ BPF_CALL_5(bpf_trace_printk, char *, fmt, u32, fmt_size, u64, arg1, 
				goto fmt_str;

			}



			if (fmt[i + 1] == 'B') {

				i++;

				goto fmt_next;

			}



			/* disallow any further format extensions */

			if (fmt[i + 1] != 0 &&

			    !isspace(fmt[i + 1]) &&
@@ -636,7 +641,8 @@ BPF_CALL_5(bpf_seq_printf, struct seq_file *, m, char *, fmt, u32, fmt_size, 
		if (fmt[i] == 'p') {

			if (fmt[i + 1] == 0 ||

			    fmt[i + 1] == 'K' ||

			    fmt[i + 1] == 'x') {

			    fmt[i + 1] == 'x' ||

			    fmt[i + 1] == 'B') {

				/* just kernel pointers */

				params[fmt_cnt] = args[fmt_cnt];

				fmt_cnt++;