LinuxLists.cc - [PATCH v2 1/2] modpost: rework and consolidate logging interface

2020-02-26 14:26:42

Subject: [PATCH v2 1/2] modpost: rework and consolidate logging interface

Rework modpost's logging interface by consolidating merror(), warn(),
and fatal() to use a single function, modpost_log(). Introduce different
logging levels (WARN, ERROR, FATAL) as well as a conditional warn
(warn_unless()). The conditional warn is useful in determining whether
to use merror() or warn() based on a condition. This reduces code
duplication overall.

Signed-off-by: Jessica Yu <[email protected]>
---
v2:
- modpost_log: initialize level to ""
- remove parens () from case labels

scripts/mod/modpost.c | 69 +++++++++++++++++++++++----------------------------
scripts/mod/modpost.h | 22 +++++++++++++---
2 files changed, 50 insertions(+), 41 deletions(-)

diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index 7edfdb2f4497..3201a2ac5cc4 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -51,41 +51,37 @@ enum export {

#define MODULE_NAME_LEN (64 - sizeof(Elf_Addr))

-#define PRINTF __attribute__ ((format (printf, 1, 2)))
+#define PRINTF __attribute__ ((format (printf, 2, 3)))

-PRINTF void fatal(const char *fmt, ...)
+PRINTF void modpost_log(enum loglevel loglevel, const char *fmt, ...)
{
+ char *level = "";
va_list arglist;

- fprintf(stderr, "FATAL: ");
-
- va_start(arglist, fmt);
- vfprintf(stderr, fmt, arglist);
- va_end(arglist);
-
- exit(1);
-}
-
-PRINTF void warn(const char *fmt, ...)
-{
- va_list arglist;
+ switch(loglevel) {
+ case LOG_WARN:
+ level = "WARNING: ";
+ break;
+ case LOG_ERROR:
+ level = "ERROR: ";
+ break;
+ case LOG_FATAL:
+ level = "FATAL: ";
+ break;
+ default: /* invalid loglevel, ignore */
+ break;
+ }

- fprintf(stderr, "WARNING: ");
+ fprintf(stderr, level);
+ fprintf(stderr, "modpost: ");

va_start(arglist, fmt);
vfprintf(stderr, fmt, arglist);
va_end(arglist);
-}

-PRINTF void merror(const char *fmt, ...)
-{
- va_list arglist;
-
- fprintf(stderr, "ERROR: ");
+ if (loglevel == LOG_FATAL)
+ exit(1);

- va_start(arglist, fmt);
- vfprintf(stderr, fmt, arglist);
- va_end(arglist);
}

static inline bool strends(const char *str, const char *postfix)
@@ -113,7 +109,7 @@ static int is_vmlinux(const char *modname)
void *do_nofail(void *ptr, const char *expr)
{
if (!ptr)
- fatal("modpost: Memory allocation failure: %s.\n", expr);
+ fatal("Memory allocation failure: %s.\n", expr);

return ptr;
}
@@ -2021,7 +2017,7 @@ static void read_symbols(const char *modname)

license = get_modinfo(&info, "license");
if (!license && !is_vmlinux(modname))
- warn("modpost: missing MODULE_LICENSE() in %s\n"
+ warn("missing MODULE_LICENSE() in %s\n"
"see include/linux/module.h for "
"more information\n", modname);
while (license) {
@@ -2152,15 +2148,15 @@ static void check_for_gpl_usage(enum export exp, const char *m, const char *s)

switch (exp) {
case export_gpl:
- fatal("modpost: GPL-incompatible module %s%s "
+ fatal("GPL-incompatible module %s%s "
"uses GPL-only symbol '%s'\n", m, e, s);
break;
case export_unused_gpl:
- fatal("modpost: GPL-incompatible module %s%s "
+ fatal("GPL-incompatible module %s%s "
"uses GPL-only symbol marked UNUSED '%s'\n", m, e, s);
break;
case export_gpl_future:
- warn("modpost: GPL-incompatible module %s%s "
+ warn("GPL-incompatible module %s%s "
"uses future GPL-only symbol '%s'\n", m, e, s);
break;
case export_plain:
@@ -2178,7 +2174,7 @@ static void check_for_unused(enum export exp, const char *m, const char *s)
switch (exp) {
case export_unused:
case export_unused_gpl:
- warn("modpost: module %s%s "
+ warn("module %s%s "
"uses symbol '%s' marked UNUSED\n", m, e, s);
break;
default:
@@ -2197,14 +2193,11 @@ static int check_exports(struct module *mod)
exp = find_symbol(s->name);
if (!exp || exp->module == mod) {
if (have_vmlinux && !s->weak) {
- if (warn_unresolved) {
- warn("\"%s\" [%s.ko] undefined!\n",
- s->name, mod->name);
- } else {
- merror("\"%s\" [%s.ko] undefined!\n",
- s->name, mod->name);
+ warn_unless(!warn_unresolved,
+ "\"%s\" [%s.ko] undefined!\n",
+ s->name, mod->name);
+ if (!warn_unresolved)
err = 1;
- }
}
continue;
}
@@ -2653,7 +2646,7 @@ int main(int argc, char **argv)
if (dump_write)
write_dump(dump_write);
if (sec_mismatch_count && sec_mismatch_fatal)
- fatal("modpost: Section mismatches detected.\n"
+ fatal("Section mismatches detected.\n"
"Set CONFIG_SECTION_MISMATCH_WARN_ONLY=y to allow them.\n");
for (n = 0; n < SYMBOL_HASH_SIZE; n++) {
struct symbol *s;
diff --git a/scripts/mod/modpost.h b/scripts/mod/modpost.h
index 64a82d2d85f6..631d07714f7a 100644
--- a/scripts/mod/modpost.h
+++ b/scripts/mod/modpost.h
@@ -198,6 +198,22 @@ void *grab_file(const char *filename, unsigned long *size);
char* get_next_line(unsigned long *pos, void *file, unsigned long size);
void release_file(void *file, unsigned long size);

-void fatal(const char *fmt, ...);
-void warn(const char *fmt, ...);
-void merror(const char *fmt, ...);
+enum loglevel {
+ LOG_WARN,
+ LOG_ERROR,
+ LOG_FATAL
+};
+
+void modpost_log(enum loglevel loglevel, const char *fmt, ...);
+
+#define warn(fmt, args...) modpost_log(LOG_WARN, fmt, ##args)
+#define merror(fmt, args...) modpost_log(LOG_ERROR, fmt, ##args)
+#define fatal(fmt, args...) modpost_log(LOG_FATAL, fmt, ##args)
+/* Warn unless condition is true, then use merror() */
+#define warn_unless(condition, fmt, args...) \
+do { \
+ if (condition) \
+ merror(fmt, ##args); \
+ else \
+ warn(fmt, ##args); \
+} while (0)
--
2.16.4

2020-02-26 14:27:33

by Jessica Yu

[permalink] [raw]

Subject: [PATCH v2 2/2] modpost: return error if module is missing ns imports and MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS=n

Currently when CONFIG_MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS=n, modpost only warns
when a module is missing namespace imports. Under this configuration, such a module
cannot be loaded into the kernel anyway, as the module loader would reject it.
We might as well return a build error when a module is missing namespace imports
under CONFIG_MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS=n, so that the build
warning does not go ignored/unnoticed.

Signed-off-by: Jessica Yu <[email protected]>
---
scripts/Makefile.modpost | 15 ++++++++-------
scripts/mod/modpost.c | 14 +++++++++++---
2 files changed, 19 insertions(+), 10 deletions(-)

diff --git a/scripts/Makefile.modpost b/scripts/Makefile.modpost
index b4d3f2d122ac..957eed6a17a5 100644
--- a/scripts/Makefile.modpost
+++ b/scripts/Makefile.modpost
@@ -46,13 +46,14 @@ include scripts/Kbuild.include
kernelsymfile := $(objtree)/Module.symvers
modulesymfile := $(firstword $(KBUILD_EXTMOD))/Module.symvers

-MODPOST = scripts/mod/modpost \
- $(if $(CONFIG_MODVERSIONS),-m) \
- $(if $(CONFIG_MODULE_SRCVERSION_ALL),-a) \
- $(if $(KBUILD_EXTMOD),-i,-o) $(kernelsymfile) \
- $(if $(KBUILD_EXTMOD),$(addprefix -e ,$(KBUILD_EXTRA_SYMBOLS))) \
- $(if $(KBUILD_EXTMOD),-o $(modulesymfile)) \
- $(if $(CONFIG_SECTION_MISMATCH_WARN_ONLY),,-E) \
+MODPOST = scripts/mod/modpost \
+ $(if $(CONFIG_MODVERSIONS),-m) \
+ $(if $(CONFIG_MODULE_SRCVERSION_ALL),-a) \
+ $(if $(KBUILD_EXTMOD),-i,-o) $(kernelsymfile) \
+ $(if $(KBUILD_EXTMOD),$(addprefix -e ,$(KBUILD_EXTRA_SYMBOLS))) \
+ $(if $(KBUILD_EXTMOD),-o $(modulesymfile)) \
+ $(if $(CONFIG_SECTION_MISMATCH_WARN_ONLY),,-E) \
+ $(if $(CONFIG_MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS)$(KBUILD_NSDEPS),-N) \
$(if $(KBUILD_MODPOST_WARN),-w)

ifdef MODPOST_VMLINUX
diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index 3201a2ac5cc4..d164be63c2e3 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -39,6 +39,8 @@ static int sec_mismatch_count = 0;
static int sec_mismatch_fatal = 0;
/* ignore missing files */
static int ignore_missing_files;
+/* If set to 1, only warn (instead of error) about missing ns imports */
+static int allow_missing_ns_imports = 0;

enum export {
export_plain, export_unused, export_gpl,
@@ -2209,8 +2211,11 @@ static int check_exports(struct module *mod)

if (exp->namespace &&
!module_imports_namespace(mod, exp->namespace)) {
- warn("module %s uses symbol %s from namespace %s, but does not import it.\n",
- basename, exp->name, exp->namespace);
+ warn_unless(!allow_missing_ns_imports,
+ "module %s uses symbol %s from namespace %s, but does not import it.\n",
+ basename, exp->name, exp->namespace);
+ if (!allow_missing_ns_imports)
+ err = 1;
add_namespace(&mod->missing_namespaces, exp->namespace);
}

@@ -2553,7 +2558,7 @@ int main(int argc, char **argv)
struct ext_sym_list *extsym_iter;
struct ext_sym_list *extsym_start = NULL;

- while ((opt = getopt(argc, argv, "i:e:mnsT:o:awEd:")) != -1) {
+ while ((opt = getopt(argc, argv, "i:e:mnsT:o:awENd:")) != -1) {
switch (opt) {
case 'i':
kernel_read = optarg;
@@ -2591,6 +2596,9 @@ int main(int argc, char **argv)
case 'E':
sec_mismatch_fatal = 1;
break;
+ case 'N':
+ allow_missing_ns_imports = 1;
+ break;
case 'd':
missing_namespace_deps = optarg;
break;
--
2.16.4

2020-03-03 14:44:31

by Masahiro Yamada

[permalink] [raw]

Subject: Re: [PATCH v2 1/2] modpost: rework and consolidate logging interface

On Wed, Feb 26, 2020 at 11:26 PM Jessica Yu <[email protected]> wrote:
>
> Rework modpost's logging interface by consolidating merror(), warn(),
> and fatal() to use a single function, modpost_log(). Introduce different
> logging levels (WARN, ERROR, FATAL) as well as a conditional warn
> (warn_unless()). The conditional warn is useful in determining whether
> to use merror() or warn() based on a condition. This reduces code
> duplication overall.
>
> Signed-off-by: Jessica Yu <[email protected]>
> ---
> v2:
> - modpost_log: initialize level to ""
> - remove parens () from case labels
>
> scripts/mod/modpost.c | 69 +++++++++++++++++++++++----------------------------
> scripts/mod/modpost.h | 22 +++++++++++++---
> 2 files changed, 50 insertions(+), 41 deletions(-)
>
> diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
> index 7edfdb2f4497..3201a2ac5cc4 100644
> --- a/scripts/mod/modpost.c
> +++ b/scripts/mod/modpost.c
> @@ -51,41 +51,37 @@ enum export {
>
> #define MODULE_NAME_LEN (64 - sizeof(Elf_Addr))
>
> -#define PRINTF __attribute__ ((format (printf, 1, 2)))
> +#define PRINTF __attribute__ ((format (printf, 2, 3)))
>
> -PRINTF void fatal(const char *fmt, ...)
> +PRINTF void modpost_log(enum loglevel loglevel, const char *fmt, ...)
> {
> + char *level = "";

You can add 'const'.

const char *level = "";

> va_list arglist;
>
> - fprintf(stderr, "FATAL: ");
> -
> - va_start(arglist, fmt);
> - vfprintf(stderr, fmt, arglist);
> - va_end(arglist);
> -
> - exit(1);
> -}
> -
> -PRINTF void warn(const char *fmt, ...)
> -{
> - va_list arglist;
> + switch(loglevel) {
> + case LOG_WARN:
> + level = "WARNING: ";
> + break;
> + case LOG_ERROR:
> + level = "ERROR: ";
> + break;
> + case LOG_FATAL:
> + level = "FATAL: ";
> + break;
> + default: /* invalid loglevel, ignore */
> + break;
> + }
>
> - fprintf(stderr, "WARNING: ");
> + fprintf(stderr, level);

If I apply this patch, I see this warning:

scripts/mod/modpost.c: In function ‘modpost_log’:
scripts/mod/modpost.c:77:2: warning: format not a string literal and
no format arguments [-Wformat-security]
fprintf(stderr, level);
^~~~~~~

Please write like this:

fprintf(stderr, "%s", level);

Or, you can delete 'level', then write
string literals directly in fprintf().

switch(loglevel) {
case LOG_WARN:
fprintf(stderr, "WARNING: ");
break;
case LOG_ERROR:
fprintf(stderr, "ERROR: ");
break;
case LOG_FATAL:
fprintf(stderr, "FATAL: ");
break;
}

> + fprintf(stderr, "modpost: ");
>
> va_start(arglist, fmt);
> vfprintf(stderr, fmt, arglist);
> va_end(arglist);
> -}
>

<snip>

> diff --git a/scripts/mod/modpost.h b/scripts/mod/modpost.h
> index 64a82d2d85f6..631d07714f7a 100644
> --- a/scripts/mod/modpost.h
> +++ b/scripts/mod/modpost.h
> @@ -198,6 +198,22 @@ void *grab_file(const char *filename, unsigned long *size);
> char* get_next_line(unsigned long *pos, void *file, unsigned long size);
> void release_file(void *file, unsigned long size);
>
> -void fatal(const char *fmt, ...);
> -void warn(const char *fmt, ...);
> -void merror(const char *fmt, ...);
> +enum loglevel {
> + LOG_WARN,
> + LOG_ERROR,
> + LOG_FATAL
> +};
> +
> +void modpost_log(enum loglevel loglevel, const char *fmt, ...);
> +
> +#define warn(fmt, args...) modpost_log(LOG_WARN, fmt, ##args)
> +#define merror(fmt, args...) modpost_log(LOG_ERROR, fmt, ##args)
> +#define fatal(fmt, args...) modpost_log(LOG_FATAL, fmt, ##args)
> +/* Warn unless condition is true, then use merror() */
> +#define warn_unless(condition, fmt, args...) \
> +do { \
> + if (condition) \
> + merror(fmt, ##args); \
> + else \
> + warn(fmt, ##args); \
> +} while (0)

Hmm, warn_unless() is not intuitive naming...

You could use modpost_log() directly in C code,
what do you think?

modpost_log(allow_missing_ns_imports ? LOG_WARN : LOG_ERROR,
"module %s uses symbol %s from namespace %s,
but does not import it.\n",
basename, exp->name, exp->namespace);

--
Best Regards
Masahiro Yamada

2020-03-03 15:40:18

by Jessica Yu

[permalink] [raw]

Subject: Re: [PATCH v2 1/2] modpost: rework and consolidate logging interface

+++ Masahiro Yamada [03/03/20 23:42 +0900]:
>On Wed, Feb 26, 2020 at 11:26 PM Jessica Yu <[email protected]> wrote:
>>
>> Rework modpost's logging interface by consolidating merror(), warn(),
>> and fatal() to use a single function, modpost_log(). Introduce different
>> logging levels (WARN, ERROR, FATAL) as well as a conditional warn
>> (warn_unless()). The conditional warn is useful in determining whether
>> to use merror() or warn() based on a condition. This reduces code
>> duplication overall.
>>
>> Signed-off-by: Jessica Yu <[email protected]>
>> ---
>> v2:
>> - modpost_log: initialize level to ""
>> - remove parens () from case labels
>>
>> scripts/mod/modpost.c | 69 +++++++++++++++++++++++----------------------------
>> scripts/mod/modpost.h | 22 +++++++++++++---
>> 2 files changed, 50 insertions(+), 41 deletions(-)
>>
>> diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
>> index 7edfdb2f4497..3201a2ac5cc4 100644
>> --- a/scripts/mod/modpost.c
>> +++ b/scripts/mod/modpost.c
>> @@ -51,41 +51,37 @@ enum export {
>>
>> #define MODULE_NAME_LEN (64 - sizeof(Elf_Addr))
>>
>> -#define PRINTF __attribute__ ((format (printf, 1, 2)))
>> +#define PRINTF __attribute__ ((format (printf, 2, 3)))
>>
>> -PRINTF void fatal(const char *fmt, ...)
>> +PRINTF void modpost_log(enum loglevel loglevel, const char *fmt, ...)
>> {
>> + char *level = "";
>
>
>You can add 'const'.
>
>
> const char *level = "";
>
>
>
>> va_list arglist;
>>
>> - fprintf(stderr, "FATAL: ");
>> -
>> - va_start(arglist, fmt);
>> - vfprintf(stderr, fmt, arglist);
>> - va_end(arglist);
>> -
>> - exit(1);
>> -}
>> -
>> -PRINTF void warn(const char *fmt, ...)
>> -{
>> - va_list arglist;
>> + switch(loglevel) {
>> + case LOG_WARN:
>> + level = "WARNING: ";
>> + break;
>> + case LOG_ERROR:
>> + level = "ERROR: ";
>> + break;
>> + case LOG_FATAL:
>> + level = "FATAL: ";
>> + break;
>> + default: /* invalid loglevel, ignore */
>> + break;
>> + }
>>
>> - fprintf(stderr, "WARNING: ");
>> + fprintf(stderr, level);
>
>
>
>If I apply this patch, I see this warning:
>
>scripts/mod/modpost.c: In function ‘modpost_log’:
>scripts/mod/modpost.c:77:2: warning: format not a string literal and
>no format arguments [-Wformat-security]
> fprintf(stderr, level);
> ^~~~~~~
>
>
>Please write like this:
>
>
> fprintf(stderr, "%s", level);
>
>
>
>
>Or, you can delete 'level', then write
>string literals directly in fprintf().
>
>
>switch(loglevel) {
>case LOG_WARN:
> fprintf(stderr, "WARNING: ");
> break;
>case LOG_ERROR:
> fprintf(stderr, "ERROR: ");
> break;
>case LOG_FATAL:
> fprintf(stderr, "FATAL: ");
> break;
>}
>
>
>
>
>> + fprintf(stderr, "modpost: ");
>>
>> va_start(arglist, fmt);
>> vfprintf(stderr, fmt, arglist);
>> va_end(arglist);
>> -}
>>
>
><snip>
>
>> diff --git a/scripts/mod/modpost.h b/scripts/mod/modpost.h
>> index 64a82d2d85f6..631d07714f7a 100644
>> --- a/scripts/mod/modpost.h
>> +++ b/scripts/mod/modpost.h
>> @@ -198,6 +198,22 @@ void *grab_file(const char *filename, unsigned long *size);
>> char* get_next_line(unsigned long *pos, void *file, unsigned long size);
>> void release_file(void *file, unsigned long size);
>>
>> -void fatal(const char *fmt, ...);
>> -void warn(const char *fmt, ...);
>> -void merror(const char *fmt, ...);
>> +enum loglevel {
>> + LOG_WARN,
>> + LOG_ERROR,
>> + LOG_FATAL
>> +};
>> +
>> +void modpost_log(enum loglevel loglevel, const char *fmt, ...);
>> +
>> +#define warn(fmt, args...) modpost_log(LOG_WARN, fmt, ##args)
>> +#define merror(fmt, args...) modpost_log(LOG_ERROR, fmt, ##args)
>> +#define fatal(fmt, args...) modpost_log(LOG_FATAL, fmt, ##args)
>> +/* Warn unless condition is true, then use merror() */
>> +#define warn_unless(condition, fmt, args...) \
>> +do { \
>> + if (condition) \
>> + merror(fmt, ##args); \
>> + else \
>> + warn(fmt, ##args); \
>> +} while (0)
>
>
>Hmm, warn_unless() is not intuitive naming...
>
>You could use modpost_log() directly in C code,
>what do you think?
>
>
> modpost_log(allow_missing_ns_imports ? LOG_WARN : LOG_ERROR,
> "module %s uses symbol %s from namespace %s,
>but does not import it.\n",
> basename, exp->name, exp->namespace);

Yeah, I wasn't sure if I should expose modpost_log() and call it
directly, so I wrapped it in warn_unless(). But I think it's not a big
deal, so I'll just change it to a direct call. Thank you for the review!

Jessica

2020-03-03 15:50:16

by Masahiro Yamada

[permalink] [raw]

Subject: Re: [PATCH v2 2/2] modpost: return error if module is missing ns imports and MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS=n

On Wed, Feb 26, 2020 at 11:26 PM Jessica Yu <[email protected]> wrote:
>
> Currently when CONFIG_MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS=n, modpost only warns
> when a module is missing namespace imports. Under this configuration, such a module
> cannot be loaded into the kernel anyway, as the module loader would reject it.
> We might as well return a build error when a module is missing namespace imports
> under CONFIG_MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS=n, so that the build
> warning does not go ignored/unnoticed.
>
> Signed-off-by: Jessica Yu <[email protected]>
> ---

When you send v3, could you please fix the
following checkpatch warning and error?

WARNING: Possible unwrapped commit description (prefer a maximum 75
chars per line)
#59:
Currently when CONFIG_MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS=n,
modpost only warns

ERROR: do not initialise statics to 0
#107: FILE: scripts/mod/modpost.c:43:
+static int allow_missing_ns_imports = 0;

> scripts/Makefile.modpost | 15 ++++++++-------
> scripts/mod/modpost.c | 14 +++++++++++---
> 2 files changed, 19 insertions(+), 10 deletions(-)
>
> diff --git a/scripts/Makefile.modpost b/scripts/Makefile.modpost
> index b4d3f2d122ac..957eed6a17a5 100644
> --- a/scripts/Makefile.modpost
> +++ b/scripts/Makefile.modpost
> @@ -46,13 +46,14 @@ include scripts/Kbuild.include
> kernelsymfile := $(objtree)/Module.symvers
> modulesymfile := $(firstword $(KBUILD_EXTMOD))/Module.symvers
>
> -MODPOST = scripts/mod/modpost \
> - $(if $(CONFIG_MODVERSIONS),-m) \
> - $(if $(CONFIG_MODULE_SRCVERSION_ALL),-a) \
> - $(if $(KBUILD_EXTMOD),-i,-o) $(kernelsymfile) \
> - $(if $(KBUILD_EXTMOD),$(addprefix -e ,$(KBUILD_EXTRA_SYMBOLS))) \
> - $(if $(KBUILD_EXTMOD),-o $(modulesymfile)) \
> - $(if $(CONFIG_SECTION_MISMATCH_WARN_ONLY),,-E) \
> +MODPOST = scripts/mod/modpost \
> + $(if $(CONFIG_MODVERSIONS),-m) \
> + $(if $(CONFIG_MODULE_SRCVERSION_ALL),-a) \
> + $(if $(KBUILD_EXTMOD),-i,-o) $(kernelsymfile) \
> + $(if $(KBUILD_EXTMOD),$(addprefix -e ,$(KBUILD_EXTRA_SYMBOLS))) \
> + $(if $(KBUILD_EXTMOD),-o $(modulesymfile)) \
> + $(if $(CONFIG_SECTION_MISMATCH_WARN_ONLY),,-E) \
> + $(if $(CONFIG_MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS)$(KBUILD_NSDEPS),-N) \
> $(if $(KBUILD_MODPOST_WARN),-w)
>
> ifdef MODPOST_VMLINUX
> diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
> index 3201a2ac5cc4..d164be63c2e3 100644
> --- a/scripts/mod/modpost.c
> +++ b/scripts/mod/modpost.c
> @@ -39,6 +39,8 @@ static int sec_mismatch_count = 0;
> static int sec_mismatch_fatal = 0;
> /* ignore missing files */
> static int ignore_missing_files;
> +/* If set to 1, only warn (instead of error) about missing ns imports */
> +static int allow_missing_ns_imports = 0;
>
> enum export {
> export_plain, export_unused, export_gpl,
> @@ -2209,8 +2211,11 @@ static int check_exports(struct module *mod)
>
> if (exp->namespace &&
> !module_imports_namespace(mod, exp->namespace)) {
> - warn("module %s uses symbol %s from namespace %s, but does not import it.\n",
> - basename, exp->name, exp->namespace);
> + warn_unless(!allow_missing_ns_imports,
> + "module %s uses symbol %s from namespace %s, but does not import it.\n",
> + basename, exp->name, exp->namespace);
> + if (!allow_missing_ns_imports)
> + err = 1;
> add_namespace(&mod->missing_namespaces, exp->namespace);
> }
>
> @@ -2553,7 +2558,7 @@ int main(int argc, char **argv)
> struct ext_sym_list *extsym_iter;
> struct ext_sym_list *extsym_start = NULL;
>
> - while ((opt = getopt(argc, argv, "i:e:mnsT:o:awEd:")) != -1) {
> + while ((opt = getopt(argc, argv, "i:e:mnsT:o:awENd:")) != -1) {
> switch (opt) {
> case 'i':
> kernel_read = optarg;
> @@ -2591,6 +2596,9 @@ int main(int argc, char **argv)
> case 'E':
> sec_mismatch_fatal = 1;
> break;
> + case 'N':
> + allow_missing_ns_imports = 1;
> + break;
> case 'd':
> missing_namespace_deps = optarg;
> break;
> --
> 2.16.4
>

--
Best Regards
Masahiro Yamada

2020-03-03 15:51:04

by Masahiro Yamada

[permalink] [raw]

Subject: Re: [PATCH v2 1/2] modpost: rework and consolidate logging interface

2020-03-04 11:14:41

by Matthias Maennich

[permalink] [raw]

Subject: Re: [PATCH v2 1/2] modpost: rework and consolidate logging interface

On Tue, Mar 03, 2020 at 03:57:36PM +0100, Jessica Yu wrote:
>+++ Masahiro Yamada [03/03/20 23:42 +0900]:
>>On Wed, Feb 26, 2020 at 11:26 PM Jessica Yu <[email protected]> wrote:
>>>
>>>Rework modpost's logging interface by consolidating merror(), warn(),
>>>and fatal() to use a single function, modpost_log(). Introduce different
>>>logging levels (WARN, ERROR, FATAL) as well as a conditional warn
>>>(warn_unless()). The conditional warn is useful in determining whether
>>>to use merror() or warn() based on a condition. This reduces code
>>>duplication overall.
>>>
>>>Signed-off-by: Jessica Yu <[email protected]>
>>>---
>>>v2:
>>> - modpost_log: initialize level to ""
>>> - remove parens () from case labels
>>>
>>> scripts/mod/modpost.c | 69 +++++++++++++++++++++++----------------------------
>>> scripts/mod/modpost.h | 22 +++++++++++++---
>>> 2 files changed, 50 insertions(+), 41 deletions(-)
>>>
>>>diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
>>>index 7edfdb2f4497..3201a2ac5cc4 100644
>>>--- a/scripts/mod/modpost.c
>>>+++ b/scripts/mod/modpost.c
>>>@@ -51,41 +51,37 @@ enum export {
>>>
>>> #define MODULE_NAME_LEN (64 - sizeof(Elf_Addr))
>>>
>>>-#define PRINTF __attribute__ ((format (printf, 1, 2)))
>>>+#define PRINTF __attribute__ ((format (printf, 2, 3)))
>>>
>>>-PRINTF void fatal(const char *fmt, ...)
>>>+PRINTF void modpost_log(enum loglevel loglevel, const char *fmt, ...)
>>> {
>>>+ char *level = "";
>>
>>
>>You can add 'const'.
>>
>>
>> const char *level = "";
>>
>>
>>
>>> va_list arglist;
>>>
>>>- fprintf(stderr, "FATAL: ");
>>>-
>>>- va_start(arglist, fmt);
>>>- vfprintf(stderr, fmt, arglist);
>>>- va_end(arglist);
>>>-
>>>- exit(1);
>>>-}
>>>-
>>>-PRINTF void warn(const char *fmt, ...)
>>>-{
>>>- va_list arglist;
>>>+ switch(loglevel) {
>>>+ case LOG_WARN:
>>>+ level = "WARNING: ";
>>>+ break;
>>>+ case LOG_ERROR:
>>>+ level = "ERROR: ";
>>>+ break;
>>>+ case LOG_FATAL:
>>>+ level = "FATAL: ";
>>>+ break;
>>>+ default: /* invalid loglevel, ignore */
>>>+ break;
>>>+ }
>>>
>>>- fprintf(stderr, "WARNING: ");
>>>+ fprintf(stderr, level);
>>
>>
>>
>>If I apply this patch, I see this warning:
>>
>>scripts/mod/modpost.c: In function ‘modpost_log’:
>>scripts/mod/modpost.c:77:2: warning: format not a string literal and
>>no format arguments [-Wformat-security]
>> fprintf(stderr, level);
>> ^~~~~~~
>>
>>
>>Please write like this:
>>
>>
>> fprintf(stderr, "%s", level);
>>
>>
>>
>>
>>Or, you can delete 'level', then write
>>string literals directly in fprintf().
>>
>>
>>switch(loglevel) {
>>case LOG_WARN:
>> fprintf(stderr, "WARNING: ");
>> break;
>>case LOG_ERROR:
>> fprintf(stderr, "ERROR: ");
>> break;
>>case LOG_FATAL:
>> fprintf(stderr, "FATAL: ");
>> break;
>>}
>>
>>
>>
>>
>>>+ fprintf(stderr, "modpost: ");
>>>
>>> va_start(arglist, fmt);
>>> vfprintf(stderr, fmt, arglist);
>>> va_end(arglist);
>>>-}
>>>
>>
>><snip>
>>
>>>diff --git a/scripts/mod/modpost.h b/scripts/mod/modpost.h
>>>index 64a82d2d85f6..631d07714f7a 100644
>>>--- a/scripts/mod/modpost.h
>>>+++ b/scripts/mod/modpost.h
>>>@@ -198,6 +198,22 @@ void *grab_file(const char *filename, unsigned long *size);
>>> char* get_next_line(unsigned long *pos, void *file, unsigned long size);
>>> void release_file(void *file, unsigned long size);
>>>
>>>-void fatal(const char *fmt, ...);
>>>-void warn(const char *fmt, ...);
>>>-void merror(const char *fmt, ...);
>>>+enum loglevel {
>>>+ LOG_WARN,
>>>+ LOG_ERROR,
>>>+ LOG_FATAL
>>>+};
>>>+
>>>+void modpost_log(enum loglevel loglevel, const char *fmt, ...);
>>>+
>>>+#define warn(fmt, args...) modpost_log(LOG_WARN, fmt, ##args)
>>>+#define merror(fmt, args...) modpost_log(LOG_ERROR, fmt, ##args)

The only thing that bothered me a bit was the inconsistent naming with
'merror'. I know `error` is reserved, but refactoring this whole code
(thanks for that!) seems like a code opportunity to clean this up. (Or
is it just me?)

Cheers,
Matthias

>>>+#define fatal(fmt, args...) modpost_log(LOG_FATAL, fmt, ##args)
>>>+/* Warn unless condition is true, then use merror() */
>>>+#define warn_unless(condition, fmt, args...) \
>>>+do { \
>>>+ if (condition) \
>>>+ merror(fmt, ##args); \
>>>+ else \
>>>+ warn(fmt, ##args); \
>>>+} while (0)
>>
>>
>>Hmm, warn_unless() is not intuitive naming...
>>
>>You could use modpost_log() directly in C code,
>>what do you think?
>>
>>
>> modpost_log(allow_missing_ns_imports ? LOG_WARN : LOG_ERROR,
>> "module %s uses symbol %s from namespace %s,
>>but does not import it.\n",
>> basename, exp->name, exp->namespace);
>
>Yeah, I wasn't sure if I should expose modpost_log() and call it
>directly, so I wrapped it in warn_unless(). But I think it's not a big
>deal, so I'll just change it to a direct call. Thank you for the review!
>
>Jessica