[PATCH dwarves] btf: Add --btf_gen_all flag

* [PATCH dwarves] btf: Add --btf_gen_all flag
@ 2021-03-12  0:08 Ilya Leoshkevich
  2021-03-12 13:39 ` Arnaldo Carvalho de Melo
  0 siblings, 1 reply; 6+ messages in thread
From: Ilya Leoshkevich @ 2021-03-12  0:08 UTC (permalink / raw)
  To: Arnaldo Carvalho de Melo, Andrii Nakryiko
  Cc: dwarves, bpf, Alexei Starovoitov, Daniel Borkmann, Yonghong Song,
	Heiko Carstens, Vasily Gorbik, Ilya Leoshkevich

By default, pahole makes use only of BTF features introduced with
kernel v5.2. Features that are added later need to be turned on with
explicit feature flags, such as --btf_gen_floats. According to [1],
this will hinder the people who generate BTF for kernels externally
(e.g. for old kernels to support BPF CO-RE).

Introduce --btf_gen_all that allows using all BTF features supported
by pahole.

[1] https://lore.kernel.org/dwarves/CAEf4Bzbyugfb2RkBkRuxNGKwSk40Tbq4zAvhQT8W=fVMYWuaxA@mail.gmail.com/

Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
---
 man-pages/pahole.1 | 4 ++++
 pahole.c           | 8 ++++++++
 2 files changed, 12 insertions(+)

diff --git a/man-pages/pahole.1 b/man-pages/pahole.1
index e292b2c..cbbefbf 100644
--- a/man-pages/pahole.1
+++ b/man-pages/pahole.1
@@ -204,6 +204,10 @@ to "/sys/kernel/btf/vmlinux".
 Allow producing BTF_KIND_FLOAT entries in systems where the vmlinux DWARF
 information has float types.
 
+.TP
+.B \-\-btf_gen_all
+Allow using all the BTF features supported by pahole.
+
 .TP
 .B \-l, \-\-show_first_biggest_size_base_type_member
 Show first biggest size base_type member.
diff --git a/pahole.c b/pahole.c
index c8d38f5..df6aa83 100644
--- a/pahole.c
+++ b/pahole.c
@@ -826,6 +826,7 @@ ARGP_PROGRAM_VERSION_HOOK_DEF = dwarves_print_version;
 #define ARGP_numeric_version       320
 #define ARGP_btf_base		   321
 #define ARGP_btf_gen_floats	   322
+#define ARGP_btf_gen_all	   323
 
 static const struct argp_option pahole__options[] = {
 	{
@@ -1125,6 +1126,11 @@ static const struct argp_option pahole__options[] = {
 		.key  = ARGP_btf_gen_floats,
 		.doc  = "Allow producing BTF_KIND_FLOAT entries."
 	},
+	{
+		.name = "btf_gen_all",
+		.key  = ARGP_btf_gen_all,
+		.doc  = "Allow using all the BTF features supported by pahole."
+	},
 	{
 		.name = "structs",
 		.key  = ARGP_just_structs,
@@ -1262,6 +1268,8 @@ static error_t pahole__options_parser(int key, char *arg,
 		print_numeric_version = true;		break;
 	case ARGP_btf_gen_floats:
 		btf_gen_floats = true;			break;
+	case ARGP_btf_gen_all:
+		btf_gen_floats = true;			break;
 	default:
 		return ARGP_ERR_UNKNOWN;
 	}
-- 
2.29.2


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