From b74d7bb7ca2412ab37bab782591573b5f265872b Mon Sep 17 00:00:00 2001 From: Luis Chamberlain Date: Wed, 14 Dec 2022 15:17:18 -0800 Subject: [PATCH 1/7] kbuild: Modify default INSTALL_MOD_DIR from extra to updates The default INSTALL_MOD_DIR of using the /lib/modules/$(uname -r)/extra directory for external modules assumes distributions will have something like /etc/depmod.d/dist.conf with: search updates extra built-in However, only some Red Hat releases have and use the "extra" stuff for years now. Meanwhile, the depmod.c tool in kmod has *forever* used the "updates" directory as part of the search path by default *if* your distribution does not have any depmod.d configuration. If you compile and install an external module today, even upstream kernel mock drivers (tools/testing/cxl) the modules_install target will pick up the new drivers but will not allow override of drivers from updates to override built-in ones. Since module-init-tools was deprecated over 11 years ago and now kmod has since its inception used the "updates" directory as part of its default search path to allow overrides, and since the "extra" stuff was in practice only used by Red Hat stuff, use the more distro agnostic override path "updates" to allow external modules to also override proper production kernel modules. This would allow mocking drivers tools to not have to muck with depmod.d config files or assume that your distro will have extra on a configuration file over built-in. With today's default you end up actually *crashing* Linux when trying to load cxl_test with the default "extra" [0] directory being used. This fixes that and allows other mocking drivers to do less work. [0] https://lkml.kernel.org/r/20221209062919.1096779-1-mcgrof@kernel.org Signed-off-by: Luis Chamberlain Acked-by: Dan Williams Acked-by: Masahiro Yamada Reviewed-by: Nicolas Schier --- scripts/Makefile.modinst | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/scripts/Makefile.modinst b/scripts/Makefile.modinst index 836391e5d209..f598eb83f776 100644 --- a/scripts/Makefile.modinst +++ b/scripts/Makefile.modinst @@ -14,7 +14,7 @@ modules := $(call read-file, $(MODORDER)) ifeq ($(KBUILD_EXTMOD),) dst := $(MODLIB)/kernel else -INSTALL_MOD_DIR ?= extra +INSTALL_MOD_DIR ?= updates dst := $(MODLIB)/$(INSTALL_MOD_DIR) endif From c093a74dac1c008daee92d6d613e9e3fe20b6585 Mon Sep 17 00:00:00 2001 From: Randy Dunlap Date: Mon, 2 Jan 2023 13:16:05 -0800 Subject: [PATCH 2/7] test_kmod: stop kernel-doc warnings Use kernel-doc notation to prevent warnings: lib/test_kmod.c:58: warning: contents before sections lib/test_kmod.c:94: warning: cannot understand function prototype: 'struct kmod_test_device_info ' lib/test_kmod.c:119: warning: cannot understand function prototype: 'struct kmod_test_device ' Signed-off-by: Randy Dunlap Cc: Luis Chamberlain Cc: linux-modules@vger.kernel.org Signed-off-by: Luis Chamberlain --- lib/test_kmod.c | 11 +++++------ 1 file changed, 5 insertions(+), 6 deletions(-) diff --git a/lib/test_kmod.c b/lib/test_kmod.c index 6423df9fa8dd..43d9dfd57ab7 100644 --- a/lib/test_kmod.c +++ b/lib/test_kmod.c @@ -51,12 +51,11 @@ static int num_test_devs; /** * enum kmod_test_case - linker table test case - * - * If you add a test case, please be sure to review if you need to se - * @need_mod_put for your tests case. - * * @TEST_KMOD_DRIVER: stress tests request_module() * @TEST_KMOD_FS_TYPE: stress tests get_fs_type() + * + * If you add a test case, please be sure to review if you need to set + * @need_mod_put for your tests case. */ enum kmod_test_case { __TEST_KMOD_INVALID = 0, @@ -78,7 +77,7 @@ struct test_config { struct kmod_test_device; /** - * kmod_test_device_info - thread info + * struct kmod_test_device_info - thread info * * @ret_sync: return value if request_module() is used, sync request for * @TEST_KMOD_DRIVER @@ -101,7 +100,7 @@ struct kmod_test_device_info { }; /** - * kmod_test_device - test device to help test kmod + * struct kmod_test_device - test device to help test kmod * * @dev_idx: unique ID for test device * @config: configuration for the test From def7b92efd868a6c78da86770704c1a03506016e Mon Sep 17 00:00:00 2001 From: Christophe JAILLET Date: Sat, 14 Jan 2023 10:08:13 +0100 Subject: [PATCH 3/7] kernel/params.c: Use kstrtobool() instead of strtobool() strtobool() is the same as kstrtobool(). However, the latter is more used within the kernel. In order to remove strtobool() and slightly simplify kstrtox.h, switch to the other function name. While at it, include the corresponding header file () Signed-off-by: Christophe JAILLET Reviewed-by: Miroslav Benes Signed-off-by: Luis Chamberlain --- kernel/params.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/kernel/params.c b/kernel/params.c index 14d66070757b..6e34ca89ebae 100644 --- a/kernel/params.c +++ b/kernel/params.c @@ -4,6 +4,7 @@ */ #include +#include #include #include #include @@ -310,7 +311,7 @@ int param_set_bool(const char *val, const struct kernel_param *kp) if (!val) val = "1"; /* One of =[yYnN01] */ - return strtobool(val, kp->arg); + return kstrtobool(val, kp->arg); } EXPORT_SYMBOL(param_set_bool); From fbed4fea6422a237382bf317db88a37993955f3b Mon Sep 17 00:00:00 2001 From: Christophe JAILLET Date: Tue, 1 Nov 2022 22:14:06 +0100 Subject: [PATCH 4/7] module: Use kstrtobool() instead of strtobool() strtobool() is the same as kstrtobool(). However, the latter is more used within the kernel. In order to remove strtobool() and slightly simplify kstrtox.h, switch to the other function name. While at it, include the corresponding header file () Signed-off-by: Christophe JAILLET Reviewed-by: Luis Chamberlain Reviewed-by: Aaron Tomlin Signed-off-by: Luis Chamberlain --- kernel/module/main.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/kernel/module/main.c b/kernel/module/main.c index 4ac3fe43e6c8..d3be89de706d 100644 --- a/kernel/module/main.c +++ b/kernel/module/main.c @@ -17,6 +17,7 @@ #include #include #include +#include #include #include #include @@ -2675,7 +2676,7 @@ static int unknown_module_param_cb(char *param, char *val, const char *modname, int ret; if (strcmp(param, "async_probe") == 0) { - if (strtobool(val, &mod->async_probe_requested)) + if (kstrtobool(val, &mod->async_probe_requested)) mod->async_probe_requested = true; return 0; } From eca0edaf6caa66b6eb26277a7dce5d7296cedfca Mon Sep 17 00:00:00 2001 From: Marcos Paulo de Souza Date: Fri, 3 Feb 2023 09:22:21 -0300 Subject: [PATCH 5/7] module.h: Document klp_modinfo struct using kdoc Previously the documentation existed only in Documentation/livepatch directory. Signed-off-by: Marcos Paulo de Souza Signed-off-by: Luis Chamberlain --- include/linux/module.h | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/include/linux/module.h b/include/linux/module.h index 8c5909c0076c..6449ea59c074 100644 --- a/include/linux/module.h +++ b/include/linux/module.h @@ -352,6 +352,14 @@ struct mod_kallsyms { }; #ifdef CONFIG_LIVEPATCH +/** + * struct klp_modinfo - Elf information preserved from the livepatch module + * + * @hdr: Elf header + * @sechdrs: Section header table + * @secstrings: String table for the section headers + * @symndx: The symbol table section index + */ struct klp_modinfo { Elf_Ehdr hdr; Elf_Shdr *sechdrs; From f412eef03938d3a40d4f6f5a79d0f98ed89b596d Mon Sep 17 00:00:00 2001 From: Marcos Paulo de Souza Date: Fri, 3 Feb 2023 09:22:22 -0300 Subject: [PATCH 6/7] Documentation: livepatch: module-elf-format: Remove local klp_modinfo definition Refer to klp_modinfo declaration using kdoc. Signed-off-by: Marcos Paulo de Souza Signed-off-by: Luis Chamberlain --- Documentation/livepatch/module-elf-format.rst | 11 ++--------- 1 file changed, 2 insertions(+), 9 deletions(-) diff --git a/Documentation/livepatch/module-elf-format.rst b/Documentation/livepatch/module-elf-format.rst index 7347638895a0..d48f530c0881 100644 --- a/Documentation/livepatch/module-elf-format.rst +++ b/Documentation/livepatch/module-elf-format.rst @@ -298,12 +298,5 @@ A livepatch module's symbol table is accessible through module->symtab. Since apply_relocate_add() requires access to a module's section headers, symbol table, and relocation section indices, Elf information is preserved for livepatch modules and is made accessible by the module loader through -module->klp_info, which is a klp_modinfo struct. When a livepatch module loads, -this struct is filled in by the module loader. Its fields are documented below:: - - struct klp_modinfo { - Elf_Ehdr hdr; /* Elf header */ - Elf_Shdr *sechdrs; /* Section header table */ - char *secstrings; /* String table for the section headers */ - unsigned int symndx; /* The symbol table section index */ - }; +module->klp_info, which is a :c:type:`klp_modinfo` struct. When a livepatch module +loads, this struct is filled in by the module loader. From 6486a57f05d3d40aa8698908de16feebe52e9f13 Mon Sep 17 00:00:00 2001 From: Alexey Dobriyan Date: Tue, 28 Feb 2023 15:11:06 +0300 Subject: [PATCH 7/7] livepatch: fix ELF typos ELF is acronym. Signed-off-by: Alexey Dobriyan Reviewed-by: Petr Mladek Signed-off-by: Petr Mladek Link: https://lore.kernel.org/r/Y/3vWjQ/SBA5a0i5@p183 --- Documentation/livepatch/module-elf-format.rst | 20 +++++++++---------- include/linux/module.h | 6 +++--- kernel/module/livepatch.c | 10 +++++----- 3 files changed, 18 insertions(+), 18 deletions(-) diff --git a/Documentation/livepatch/module-elf-format.rst b/Documentation/livepatch/module-elf-format.rst index d48f530c0881..a03ed02ec57e 100644 --- a/Documentation/livepatch/module-elf-format.rst +++ b/Documentation/livepatch/module-elf-format.rst @@ -1,8 +1,8 @@ =========================== -Livepatch module Elf format +Livepatch module ELF format =========================== -This document outlines the Elf format requirements that livepatch modules must follow. +This document outlines the ELF format requirements that livepatch modules must follow. .. Table of Contents @@ -20,17 +20,17 @@ code. So, instead of duplicating code and re-implementing what the module loader can already do, livepatch leverages existing code in the module loader to perform the all the arch-specific relocation work. Specifically, livepatch reuses the apply_relocate_add() function in the module loader to -write relocations. The patch module Elf format described in this document +write relocations. The patch module ELF format described in this document enables livepatch to be able to do this. The hope is that this will make livepatch more easily portable to other architectures and reduce the amount of arch-specific code required to port livepatch to a particular architecture. Since apply_relocate_add() requires access to a module's section header -table, symbol table, and relocation section indices, Elf information is +table, symbol table, and relocation section indices, ELF information is preserved for livepatch modules (see section 5). Livepatch manages its own relocation sections and symbols, which are described in this document. The -Elf constants used to mark livepatch symbols and relocation sections were +ELF constants used to mark livepatch symbols and relocation sections were selected from OS-specific ranges according to the definitions from glibc. Why does livepatch need to write its own relocations? @@ -43,7 +43,7 @@ reject the livepatch module. Furthermore, we cannot apply relocations that affect modules not yet loaded at patch module load time (e.g. a patch to a driver that is not loaded). Formerly, livepatch solved this problem by embedding special "dynrela" (dynamic rela) sections in the resulting patch -module Elf output. Using these dynrela sections, livepatch could resolve +module ELF output. Using these dynrela sections, livepatch could resolve symbols while taking into account its scope and what module the symbol belongs to, and then manually apply the dynamic relocations. However this approach required livepatch to supply arch-specific code in order to write @@ -80,7 +80,7 @@ Example: 3. Livepatch relocation sections ================================ -A livepatch module manages its own Elf relocation sections to apply +A livepatch module manages its own ELF relocation sections to apply relocations to modules as well as to the kernel (vmlinux) at the appropriate time. For example, if a patch module patches a driver that is not currently loaded, livepatch will apply the corresponding livepatch @@ -95,7 +95,7 @@ also possible for a livepatch module to have no livepatch relocation sections, as in the case of the sample livepatch module (see samples/livepatch). -Since Elf information is preserved for livepatch modules (see Section 5), a +Since ELF information is preserved for livepatch modules (see Section 5), a livepatch relocation section can be applied simply by passing in the appropriate section index to apply_relocate_add(), which then uses it to access the relocation section and apply the relocations. @@ -291,12 +291,12 @@ Examples: Note that the 'Ndx' (Section index) for these symbols is SHN_LIVEPATCH (0xff20). "OS" means OS-specific. -5. Symbol table and Elf section access +5. Symbol table and ELF section access ====================================== A livepatch module's symbol table is accessible through module->symtab. Since apply_relocate_add() requires access to a module's section headers, -symbol table, and relocation section indices, Elf information is preserved for +symbol table, and relocation section indices, ELF information is preserved for livepatch modules and is made accessible by the module loader through module->klp_info, which is a :c:type:`klp_modinfo` struct. When a livepatch module loads, this struct is filled in by the module loader. diff --git a/include/linux/module.h b/include/linux/module.h index 4435ad9439ab..e65a71b04490 100644 --- a/include/linux/module.h +++ b/include/linux/module.h @@ -353,9 +353,9 @@ struct mod_kallsyms { #ifdef CONFIG_LIVEPATCH /** - * struct klp_modinfo - Elf information preserved from the livepatch module + * struct klp_modinfo - ELF information preserved from the livepatch module * - * @hdr: Elf header + * @hdr: ELF header * @sechdrs: Section header table * @secstrings: String table for the section headers * @symndx: The symbol table section index @@ -523,7 +523,7 @@ struct module { bool klp; /* Is this a livepatch module? */ bool klp_alive; - /* Elf information */ + /* ELF information */ struct klp_modinfo *klp_info; #endif diff --git a/kernel/module/livepatch.c b/kernel/module/livepatch.c index 486d4ff92719..a89f01e1d6b7 100644 --- a/kernel/module/livepatch.c +++ b/kernel/module/livepatch.c @@ -11,7 +11,7 @@ #include "internal.h" /* - * Persist Elf information about a module. Copy the Elf header, + * Persist ELF information about a module. Copy the ELF header, * section header table, section string table, and symtab section * index from info to mod->klp_info. */ @@ -25,11 +25,11 @@ int copy_module_elf(struct module *mod, struct load_info *info) if (!mod->klp_info) return -ENOMEM; - /* Elf header */ + /* ELF header */ size = sizeof(mod->klp_info->hdr); memcpy(&mod->klp_info->hdr, info->hdr, size); - /* Elf section header table */ + /* ELF section header table */ size = sizeof(*info->sechdrs) * info->hdr->e_shnum; mod->klp_info->sechdrs = kmemdup(info->sechdrs, size, GFP_KERNEL); if (!mod->klp_info->sechdrs) { @@ -37,7 +37,7 @@ int copy_module_elf(struct module *mod, struct load_info *info) goto free_info; } - /* Elf section name string table */ + /* ELF section name string table */ size = info->sechdrs[info->hdr->e_shstrndx].sh_size; mod->klp_info->secstrings = kmemdup(info->secstrings, size, GFP_KERNEL); if (!mod->klp_info->secstrings) { @@ -45,7 +45,7 @@ int copy_module_elf(struct module *mod, struct load_info *info) goto free_sechdrs; } - /* Elf symbol section index */ + /* ELF symbol section index */ symndx = info->index.sym; mod->klp_info->symndx = symndx;