From 0801a0073f86e020987acbbd96b50f9c85d79de8 Mon Sep 17 00:00:00 2001 From: Johan Hovold Date: Mon, 23 Nov 2020 11:23:14 +0100 Subject: module: drop version-attribute alignment Commit 98562ad8cb03 ("module: explicitly align module_version_attribute structure") added an alignment attribute to the struct module_version_attribute type in order to fix an alignment issue on m68k where the structure is 2-byte aligned while MODULE_VERSION() forced the __modver section entries to be 4-byte aligned (sizeof(void *)). This was essentially an alternative fix to the problem addressed by b4bc842802db ("module: deal with alignment issues in built-in module versions") which used the array-of-pointer trick to prevent gcc from increasing alignment of the version attribute entries. And with the pointer indirection in place there's no need to increase the alignment of the type. Link: https://lore.kernel.org/lkml/20201103175711.10731-1-johan@kernel.org Signed-off-by: Johan Hovold Signed-off-by: Jessica Yu --- include/linux/module.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include/linux') diff --git a/include/linux/module.h b/include/linux/module.h index 7ccdf87f376f..293250958512 100644 --- a/include/linux/module.h +++ b/include/linux/module.h @@ -66,7 +66,7 @@ struct module_version_attribute { struct module_attribute mattr; const char *module_name; const char *version; -} __attribute__ ((__aligned__(sizeof(void *)))); +}; extern ssize_t __modver_version_show(struct module_attribute *, struct module_kobject *, char *); -- cgit v1.2.3-71-gd317 From b112082c8930e7aa72422484b2d31d3aa06f58bc Mon Sep 17 00:00:00 2001 From: Johan Hovold Date: Mon, 23 Nov 2020 11:23:15 +0100 Subject: module: simplify version-attribute handling Instead of using the array-of-pointers trick to avoid having gcc mess up the built-in module-version array stride, specify type alignment when declaring entries to prevent gcc from increasing alignment. This is essentially an alternative (one-line) fix to the problem addressed by commit b4bc842802db ("module: deal with alignment issues in built-in module versions"). gcc can increase the alignment of larger objects with static extent as an optimisation, but this can be suppressed by using the aligned attribute when declaring variables. Note that we have been relying on this behaviour for kernel parameters for 16 years and it indeed hasn't changed since the introduction of the aligned attribute in gcc-3.1. Link: https://lore.kernel.org/lkml/20201103175711.10731-1-johan@kernel.org Signed-off-by: Johan Hovold Signed-off-by: Jessica Yu --- include/linux/module.h | 26 +++++++++++++------------- kernel/params.c | 10 ++++------ 2 files changed, 17 insertions(+), 19 deletions(-) (limited to 'include/linux') diff --git a/include/linux/module.h b/include/linux/module.h index 293250958512..5958075ea3f4 100644 --- a/include/linux/module.h +++ b/include/linux/module.h @@ -266,20 +266,20 @@ extern typeof(name) __mod_##type##__##name##_device_table \ #else #define MODULE_VERSION(_version) \ MODULE_INFO(version, _version); \ - static struct module_version_attribute ___modver_attr = { \ - .mattr = { \ - .attr = { \ - .name = "version", \ - .mode = S_IRUGO, \ + static struct module_version_attribute __modver_attr \ + __used __section("__modver") \ + __aligned(__alignof__(struct module_version_attribute)) \ + = { \ + .mattr = { \ + .attr = { \ + .name = "version", \ + .mode = S_IRUGO, \ + }, \ + .show = __modver_version_show, \ }, \ - .show = __modver_version_show, \ - }, \ - .module_name = KBUILD_MODNAME, \ - .version = _version, \ - }; \ - static const struct module_version_attribute \ - __used __section("__modver") \ - * __moduleparam_const __modver_attr = &___modver_attr + .module_name = KBUILD_MODNAME, \ + .version = _version, \ + }; #endif /* Optional firmware file (or files) needed by the module diff --git a/kernel/params.c b/kernel/params.c index 3835fb82c64b..aa7d6f2213f1 100644 --- a/kernel/params.c +++ b/kernel/params.c @@ -843,18 +843,16 @@ ssize_t __modver_version_show(struct module_attribute *mattr, return scnprintf(buf, PAGE_SIZE, "%s\n", vattr->version); } -extern const struct module_version_attribute *__start___modver[]; -extern const struct module_version_attribute *__stop___modver[]; +extern const struct module_version_attribute __start___modver[]; +extern const struct module_version_attribute __stop___modver[]; static void __init version_sysfs_builtin(void) { - const struct module_version_attribute **p; + const struct module_version_attribute *vattr; struct module_kobject *mk; int err; - for (p = __start___modver; p < __stop___modver; p++) { - const struct module_version_attribute *vattr = *p; - + for (vattr = __start___modver; vattr < __stop___modver; vattr++) { mk = locate_module_kobject(vattr->module_name); if (mk) { err = sysfs_create_file(&mk->kobj, &vattr->mattr.attr); -- cgit v1.2.3-71-gd317 From 8d6615f1fccc4f39d7d3dcf286b33e8a1e833d2b Mon Sep 17 00:00:00 2001 From: Johan Hovold Date: Mon, 23 Nov 2020 11:23:17 +0100 Subject: params: drop redundant "unused" attributes Drop the redundant "unused" attributes from module-parameter structures already marked "used". Link: https://lore.kernel.org/lkml/20201103175711.10731-1-johan@kernel.org Signed-off-by: Johan Hovold Signed-off-by: Jessica Yu --- include/linux/moduleparam.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'include/linux') diff --git a/include/linux/moduleparam.h b/include/linux/moduleparam.h index 6388eb9734a5..742074ad9f6e 100644 --- a/include/linux/moduleparam.h +++ b/include/linux/moduleparam.h @@ -22,7 +22,7 @@ #define __MODULE_INFO(tag, name, info) \ static const char __UNIQUE_ID(name)[] \ - __used __section(".modinfo") __attribute__((unused, aligned(1))) \ + __used __section(".modinfo") __attribute__((aligned(1))) \ = __MODULE_INFO_PREFIX __stringify(tag) "=" info #define __MODULE_PARM_TYPE(name, _type) \ @@ -289,7 +289,7 @@ struct kparam_array static const char __param_str_##name[] = prefix #name; \ static struct kernel_param __moduleparam_const __param_##name \ __used \ - __section("__param") __attribute__ ((unused, aligned(sizeof(void *)))) \ + __section("__param") __attribute__ ((aligned(sizeof(void *)))) \ = { __param_str_##name, THIS_MODULE, ops, \ VERIFY_OCTAL_PERMISSIONS(perm), level, flags, { arg } } -- cgit v1.2.3-71-gd317 From fe2f4fe139b321a38daafc715aeb7d21d9e8e5ad Mon Sep 17 00:00:00 2001 From: Johan Hovold Date: Mon, 23 Nov 2020 11:23:18 +0100 Subject: params: use type alignment for kernel parameters Specify type alignment for kernel parameters instead of sizeof(void *). The alignment attribute is used to prevent gcc from increasing the alignment of objects with static extent as an optimisation, something which would mess up the __param array stride. Using __alignof__(struct kernel_param) rather than sizeof(void *) is preferred since it better indicates why it is there and doesn't break should the type size or alignment change. Note that on m68k the alignment of struct kernel_param is actually two and that adding a 1- or 2-byte field to the 20-byte struct would cause a breakage with the current 4-byte alignment. Link: https://lore.kernel.org/lkml/20201103175711.10731-1-johan@kernel.org Signed-off-by: Johan Hovold Signed-off-by: Jessica Yu --- include/linux/moduleparam.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'include/linux') diff --git a/include/linux/moduleparam.h b/include/linux/moduleparam.h index 742074ad9f6e..15ecc6cc3a3b 100644 --- a/include/linux/moduleparam.h +++ b/include/linux/moduleparam.h @@ -288,8 +288,8 @@ struct kparam_array /* Default value instead of permissions? */ \ static const char __param_str_##name[] = prefix #name; \ static struct kernel_param __moduleparam_const __param_##name \ - __used \ - __section("__param") __attribute__ ((aligned(sizeof(void *)))) \ + __used __section("__param") \ + __aligned(__alignof__(struct kernel_param)) \ = { __param_str_##name, THIS_MODULE, ops, \ VERIFY_OCTAL_PERMISSIONS(perm), level, flags, { arg } } -- cgit v1.2.3-71-gd317 From 2aec389e19150ed3bf67ab708f2435563f76050f Mon Sep 17 00:00:00 2001 From: Johan Hovold Date: Mon, 23 Nov 2020 11:23:19 +0100 Subject: params: clean up module-param macros Clean up the module-param macros by adding some indentation and using the __aligned() macro to improve readability. Link: https://lore.kernel.org/lkml/20201103175711.10731-1-johan@kernel.org Signed-off-by: Johan Hovold Signed-off-by: Jessica Yu --- include/linux/moduleparam.h | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) (limited to 'include/linux') diff --git a/include/linux/moduleparam.h b/include/linux/moduleparam.h index 15ecc6cc3a3b..eed280fae433 100644 --- a/include/linux/moduleparam.h +++ b/include/linux/moduleparam.h @@ -21,12 +21,12 @@ #define MAX_PARAM_PREFIX_LEN (64 - sizeof(unsigned long)) #define __MODULE_INFO(tag, name, info) \ -static const char __UNIQUE_ID(name)[] \ - __used __section(".modinfo") __attribute__((aligned(1))) \ - = __MODULE_INFO_PREFIX __stringify(tag) "=" info + static const char __UNIQUE_ID(name)[] \ + __used __section(".modinfo") __aligned(1) \ + = __MODULE_INFO_PREFIX __stringify(tag) "=" info #define __MODULE_PARM_TYPE(name, _type) \ - __MODULE_INFO(parmtype, name##type, #name ":" _type) + __MODULE_INFO(parmtype, name##type, #name ":" _type) /* One for each parameter, describing how to use it. Some files do multiple of these per line, so can't just use MODULE_INFO. */ -- cgit v1.2.3-71-gd317 From 147ad605dc12c515c97136899ccb5c70e6c674e1 Mon Sep 17 00:00:00 2001 From: Johan Hovold Date: Mon, 23 Nov 2020 11:23:16 +0100 Subject: init: use type alignment for kernel parameters Specify type alignment for kernel parameters instead of sizeof(long). The alignment attribute is used to prevent gcc from increasing the alignment of objects with static extent as an optimisation, something which would mess up the __setup array stride. Using __alignof__(struct obs_kernel_param) rather than sizeof(long) is preferred since it better indicates why it is there and doesn't break should the type size or alignment change. Note that on m68k the alignment of struct obs_kernel_param is actually two and that adding a 1- or 2-byte field to the 12-byte struct would cause a breakage with the current 4-byte alignment. Link: https://lore.kernel.org/lkml/20201103175711.10731-1-johan@kernel.org Signed-off-by: Johan Hovold Signed-off-by: Jessica Yu --- include/linux/init.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include/linux') diff --git a/include/linux/init.h b/include/linux/init.h index 7b53cb3092ee..e668832ef66a 100644 --- a/include/linux/init.h +++ b/include/linux/init.h @@ -255,7 +255,7 @@ struct obs_kernel_param { __aligned(1) = str; \ static struct obs_kernel_param __setup_##unique_id \ __used __section(".init.setup") \ - __attribute__((aligned((sizeof(long))))) \ + __aligned(__alignof__(struct obs_kernel_param)) \ = { __setup_str_##unique_id, fn, early } #define __setup(str, fn) \ -- cgit v1.2.3-71-gd317 From 2d26c716fc49f41a63e1efe8f1f772b0adeaacef Mon Sep 17 00:00:00 2001 From: Johan Hovold Date: Mon, 7 Dec 2020 10:13:08 +0100 Subject: module: drop semicolon from version macro Drop the trailing semicolon from the MODULE_VERSION() macro definition which was left when removing the array-of-pointer indirection. Signed-off-by: Johan Hovold Signed-off-by: Jessica Yu --- include/linux/module.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include/linux') diff --git a/include/linux/module.h b/include/linux/module.h index 5958075ea3f4..e7a619c2457e 100644 --- a/include/linux/module.h +++ b/include/linux/module.h @@ -279,7 +279,7 @@ extern typeof(name) __mod_##type##__##name##_device_table \ }, \ .module_name = KBUILD_MODNAME, \ .version = _version, \ - }; + } #endif /* Optional firmware file (or files) needed by the module -- cgit v1.2.3-71-gd317