On 4/9/20 8:26 PM, Alexei Starovoitov wrote:
On Wed, Apr 08, 2020 at 04:25:31PM -0700, Yonghong Song wrote:
+BPF_CALL_5(bpf_seq_printf, struct seq_file *, m, char *, fmt, u32, fmt_size, u64, arg1,
+ u64, arg2)
+{
+ bool buf_used = false;
+ int i, copy_size;
+ int mod[2] = {};
+ int fmt_cnt = 0;
+ u64 unsafe_addr;
+ char buf[64];
+
+ /*
+ * bpf_check()->check_func_arg()->check_stack_boundary()
+ * guarantees that fmt points to bpf program stack,
+ * fmt_size bytes of it were initialized and fmt_size > 0
+ */
+ if (fmt[--fmt_size] != 0)
+ return -EINVAL;
...
+/* Horrid workaround for getting va_list handling working with different
+ * argument type combinations generically for 32 and 64 bit archs.
+ */
+#define __BPF_SP_EMIT() __BPF_ARG2_SP()
+#define __BPF_SP(...) \
+ seq_printf(m, fmt, ##__VA_ARGS__)
+
+#define __BPF_ARG1_SP(...) \
+ ((mod[0] == 2 || (mod[0] == 1 && __BITS_PER_LONG == 64)) \
+ ? __BPF_SP(arg1, ##__VA_ARGS__) \
+ : ((mod[0] == 1 || (mod[0] == 0 && __BITS_PER_LONG == 32)) \
+ ? __BPF_SP((long)arg1, ##__VA_ARGS__) \
+ : __BPF_SP((u32)arg1, ##__VA_ARGS__)))
+
+#define __BPF_ARG2_SP(...) \
+ ((mod[1] == 2 || (mod[1] == 1 && __BITS_PER_LONG == 64)) \
+ ? __BPF_ARG1_SP(arg2, ##__VA_ARGS__) \
+ : ((mod[1] == 1 || (mod[1] == 0 && __BITS_PER_LONG == 32)) \
+ ? __BPF_ARG1_SP((long)arg2, ##__VA_ARGS__) \
+ : __BPF_ARG1_SP((u32)arg2, ##__VA_ARGS__)))
+
+ __BPF_SP_EMIT();
+ return seq_has_overflowed(m);
+}
This function is mostly a copy-paste of bpf_trace_printk() with difference
of printing via seq_printf vs __trace_printk.
Please find a way to share the code.
Will do.
