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Message-ID: <20241123-extended-modversions-v9-3-bc0403f054bf@google.com>
Date: Sat, 23 Nov 2024 00:19:00 +0000
From: Matthew Maurer <mmaurer@...gle.com>
To: Michael Ellerman <mpe@...erman.id.au>, Nicholas Piggin <npiggin@...il.com>,
Christophe Leroy <christophe.leroy@...roup.eu>, Naveen N Rao <naveen@...nel.org>,
Madhavan Srinivasan <maddy@...ux.ibm.com>, Luis Chamberlain <mcgrof@...nel.org>,
Petr Pavlu <petr.pavlu@...e.com>, Sami Tolvanen <samitolvanen@...gle.com>,
Daniel Gomez <da.gomez@...sung.com>, Masahiro Yamada <masahiroy@...nel.org>,
Nathan Chancellor <nathan@...nel.org>, Nicolas Schier <nicolas@...sle.eu>, Miguel Ojeda <ojeda@...nel.org>,
Alex Gaynor <alex.gaynor@...il.com>, Boqun Feng <boqun.feng@...il.com>,
Gary Guo <gary@...yguo.net>,
"Björn Roy Baron" <bjorn3_gh@...tonmail.com>, Benno Lossin <benno.lossin@...ton.me>,
Andreas Hindborg <a.hindborg@...nel.org>, Alice Ryhl <aliceryhl@...gle.com>,
Trevor Gross <tmgross@...ch.edu>, Jonathan Corbet <corbet@....net>
Cc: linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
linux-modules@...r.kernel.org, linux-kbuild@...r.kernel.org,
rust-for-linux@...r.kernel.org, linux-doc@...r.kernel.org,
Matthew Maurer <mmaurer@...gle.com>
Subject: [PATCH v9 3/5] modules: Allow extended modversions without basic MODVERSIONS
If you know that your kernel modules will only ever be loaded by a newer
kernel, you can disable BASIC_MODVERSIONS to save space. This also
allows easy creation of test modules to seee how tooling will respond to
modules that only have the new format.
Signed-off-by: Matthew Maurer <mmaurer@...gle.com>
---
kernel/module/Kconfig | 15 +++++++++++++++
scripts/Makefile.modpost | 1 +
scripts/mod/modpost.c | 19 +++++++++++--------
3 files changed, 27 insertions(+), 8 deletions(-)
diff --git a/kernel/module/Kconfig b/kernel/module/Kconfig
index a31c617cd67d3d66b24d2fba34cbd5cc9c53ab78..f28b361494c4b4cc2446d683589f9452a0043b2b 100644
--- a/kernel/module/Kconfig
+++ b/kernel/module/Kconfig
@@ -161,6 +161,7 @@ config MODULE_UNLOAD_TAINT_TRACKING
config MODVERSIONS
bool "Module versioning support"
depends on !COMPILE_TEST
+ selects BASIC_MODVERSIONS
help
Usually, you have to use modules compiled with your kernel.
Saying Y here makes it sometimes possible to use modules
@@ -218,6 +219,20 @@ config EXTENDED_MODVERSIONS
The most likely reason you would enable this is to enable Rust
support. If unsure, say N.
+config BASIC_MODVERSIONS
+ bool "Basic Module Versioning Support"
+ depends on MODVERSIONS
+ help
+ This enables basic MODVERSIONS support, allowing older tools or
+ kernels to potentially load modules.
+
+ Disabling this may cause older `modprobe` or `kmod` to be unable
+ to read MODVERSIONS information from built modules. With this
+ disabled, older kernels may treat this module as unversioned.
+
+ This is enabled by default when MODVERSIONS are enabled.
+ If unsure, say Y.
+
config MODULE_SRCVERSION_ALL
bool "Source checksum for all modules"
help
diff --git a/scripts/Makefile.modpost b/scripts/Makefile.modpost
index 40426fc6350985780c0092beb49c6cc29b9eff62..d7d45067d08b94a82451d66a64eae29b6826e139 100644
--- a/scripts/Makefile.modpost
+++ b/scripts/Makefile.modpost
@@ -43,6 +43,7 @@ MODPOST = $(objtree)/scripts/mod/modpost
modpost-args = \
$(if $(CONFIG_MODULES),-M) \
$(if $(CONFIG_MODVERSIONS),-m) \
+ $(if $(CONFIG_BASIC_MODVERSIONS),-b) \
$(if $(CONFIG_EXTENDED_MODVERSIONS),-x) \
$(if $(CONFIG_MODULE_SRCVERSION_ALL),-a) \
$(if $(CONFIG_SECTION_MISMATCH_WARN_ONLY),,-E) \
diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index bd38f33fd41fbd98bce34f8924b2fb0ac04297ee..ed52f9aa45a490bba706ffb2caa3e238e4697814 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -32,6 +32,8 @@ static bool module_enabled;
static bool modversions;
/* Is CONFIG_MODULE_SRCVERSION_ALL set? */
static bool all_versions;
+/* Is CONFIG_BASIC_MODVERSIONS set? */
+static bool basic_modversions;
/* Is CONFIG_EXTENDED_MODVERSIONS set? */
static bool extended_modversions;
/* If we are modposting external module set to 1 */
@@ -1836,10 +1838,8 @@ static void add_extended_versions(struct buffer *b, struct module *mod)
if (!s->module)
continue;
if (!s->crc_valid) {
- /*
- * We already warned on this when producing the legacy
- * modversions table.
- */
+ warn("\"%s\" [%s.ko] has no CRC!\n",
+ s->name, mod->name);
continue;
}
buf_printf(b, "\t%#8x,\n", s->crc);
@@ -1853,8 +1853,8 @@ static void add_extended_versions(struct buffer *b, struct module *mod)
continue;
if (!s->crc_valid) {
/*
- * We already warned on this when producing the legacy
- * modversions table.
+ * We already warned on this when producing the crc
+ * table.
* We need to skip its name too, as the indexes in
* both tables need to align.
*/
@@ -1872,7 +1872,7 @@ static void add_versions(struct buffer *b, struct module *mod)
{
struct symbol *s;
- if (!modversions)
+ if (!basic_modversions)
return;
buf_printf(b, "\n");
@@ -2184,7 +2184,7 @@ int main(int argc, char **argv)
LIST_HEAD(dump_lists);
struct dump_list *dl, *dl2;
- while ((opt = getopt(argc, argv, "ei:MmnT:to:au:WwENd:x")) != -1) {
+ while ((opt = getopt(argc, argv, "ei:MmnT:to:au:WwENd:xb")) != -1) {
switch (opt) {
case 'e':
external_module = true;
@@ -2233,6 +2233,9 @@ int main(int argc, char **argv)
case 'd':
missing_namespace_deps = optarg;
break;
+ case 'b':
+ basic_modversions = true;
+ break;
case 'x':
extended_modversions = true;
break;
--
2.47.0.371.ga323438b13-goog
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