Merge branch 'Implement formatted output helpers with bstr_printf'

Florent Revest says:

====================

BPF's formatted output helpers are currently implemented with
snprintf-like functions which use variadic arguments. The types of all
arguments need to be known at compilation time. BPF_CAST_FMT_ARG casts
all arguments to the size they should be (known at runtime), but the C
type promotion rules cast them back to u64s. On 32 bit architectures,
this can cause misaligned va_lists and generate mangled output.

This series refactors these helpers to avoid variadic arguments. It uses
a "binary printf" instead, where arguments are passed in a buffer
constructed at runtime.
---
Changes in v2:
- Reworded the second patch's description to better describe how
  arguments get mangled on 32 bit architectures
====================

Signed-off-by: Alexei Starovoitov <ast@kernel.org>

2 files changed, 7 insertions, 19 deletions

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index ad4bcf1cadbb..b33f199c4cc2 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -2081,24 +2081,8 @@ int bpf_arch_text_poke(void *ip, enum bpf_text_poke_type t,
 struct btf_id_set;
 bool btf_id_set_contains(const struct btf_id_set *set, u32 id);
 
-enum bpf_printf_mod_type {
-	BPF_PRINTF_INT,
-	BPF_PRINTF_LONG,
-	BPF_PRINTF_LONG_LONG,
-};
-
-/* Workaround for getting va_list handling working with different argument type
- * combinations generically for 32 and 64 bit archs.
- */
-#define BPF_CAST_FMT_ARG(arg_nb, args, mod)				\
-	(mod[arg_nb] == BPF_PRINTF_LONG_LONG ||				\
-	 (mod[arg_nb] == BPF_PRINTF_LONG && __BITS_PER_LONG == 64)	\
-	  ? (u64)args[arg_nb]						\
-	  : (u32)args[arg_nb])
-
-int bpf_printf_prepare(char *fmt, u32 fmt_size, const u64 *raw_args,
-		       u64 *final_args, enum bpf_printf_mod_type *mod,
-		       u32 num_args);
-void bpf_printf_cleanup(void);
+int bpf_bprintf_prepare(char *fmt, u32 fmt_size, const u64 *raw_args,
+			u32 **bin_buf, u32 num_args);
+void bpf_bprintf_cleanup(void);
 
 #endif /* _LINUX_BPF_H */
diff --git a/include/linux/seq_file.h b/include/linux/seq_file.h
index b83b3ae3c877..723b1fa1177e 100644
--- a/include/linux/seq_file.h
+++ b/include/linux/seq_file.h
@@ -146,6 +146,10 @@ void *__seq_open_private(struct file *, const struct seq_operations *, int);
 int seq_open_private(struct file *, const struct seq_operations *, int);
 int seq_release_private(struct inode *, struct file *);
 
+#ifdef CONFIG_BINARY_PRINTF
+void seq_bprintf(struct seq_file *m, const char *f, const u32 *binary);
+#endif
+
 #define DEFINE_SEQ_ATTRIBUTE(__name)					\
 static int __name ## _open(struct inode *inode, struct file *file)	\
 {									\