[PATCH v2 bpf-next 3/4] bpf: allow %pB in bpf_seq_printf() and bpf_trace_printk()

[Song Liu]

This makes it easy to dump stack trace in text.

Signed-off-by: Song Liu <songliubrav...@fb.com>
---
 kernel/trace/bpf_trace.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 65fa62723e2f8..1cb90b0868817 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -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]) &&
@@ -479,7 +484,7 @@ BPF_CALL_5(bpf_trace_printk, char *, fmt, u32, fmt_size, 
u64, arg1,
 #define __BPF_TP_EMIT()        __BPF_ARG3_TP()
 #define __BPF_TP(...)                                                  \
        __trace_printk(0 /* Fake ip */,                                 \
-                      fmt, ##__VA_ARGS__)
+                      fmt, ##__VA_ARGS__)\
 
 #define __BPF_ARG1_TP(...)                                             \
        ((mod[0] == 2 || (mod[0] == 1 && __BITS_PER_LONG == 64))        \
@@ -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++;
-- 
2.24.1