From 1cd9502ee9275c6176a7312863f939cca9506114 Mon Sep 17 00:00:00 2001 From: Masahiro Yamada Date: Sun, 29 Dec 2024 00:45:28 +0900 Subject: module: get symbol CRC back to unsigned Commit 71810db27c1c ("modversions: treat symbol CRCs as 32 bit quantities") changed the CRC fields to s32 because the __kcrctab and __kcrctab_gpl sections contained relative references to the actual CRC values stored in the .rodata section when CONFIG_MODULE_REL_CRCS=y. Commit 7b4537199a4a ("kbuild: link symbol CRCs at final link, removing CONFIG_MODULE_REL_CRCS") removed this complexity. Now, the __kcrctab and __kcrctab_gpl sections directly contain the CRC values in all cases. The genksyms tool outputs unsigned 32-bit CRC values, so u32 is preferred over s32. No functional changes are intended. Regardless of this change, the CRC value is assigned to the u32 variable 'crcval' before the comparison, as seen in kernel/module/version.c: crcval = *crc; It was previously mandatory (but now optional) in order to avoid sign extension because the following line previously compared 'unsigned long' and 's32': if (versions[i].crc == crcval) return 1; versions[i].crc is still 'unsigned long' for backward compatibility. Signed-off-by: Masahiro Yamada Reviewed-by: Petr Pavlu --- include/linux/module.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'include/linux/module.h') diff --git a/include/linux/module.h b/include/linux/module.h index 94acbacdcdf1..903ef8fe4c04 100644 --- a/include/linux/module.h +++ b/include/linux/module.h @@ -430,7 +430,7 @@ struct module { /* Exported symbols */ const struct kernel_symbol *syms; - const s32 *crcs; + const u32 *crcs; unsigned int num_syms; #ifdef CONFIG_ARCH_USES_CFI_TRAPS @@ -448,7 +448,7 @@ struct module { /* GPL-only exported symbols. */ unsigned int num_gpl_syms; const struct kernel_symbol *gpl_syms; - const s32 *gpl_crcs; + const u32 *gpl_crcs; bool using_gplonly_symbols; #ifdef CONFIG_MODULE_SIG -- cgit v1.2.3 From 4bcf29741145e73440323e3e9af8b1a6f4961183 Mon Sep 17 00:00:00 2001 From: Petr Pavlu Date: Tue, 7 Jan 2025 16:34:57 +0100 Subject: module: fix writing of livepatch relocations in ROX text A livepatch module can contain a special relocation section .klp.rela.. to apply its relocations at the appropriate time and to additionally access local and unexported symbols. When points to another module, such relocations are processed separately from the regular module relocation process. For instance, only when the target actually becomes loaded. With CONFIG_STRICT_MODULE_RWX, when the livepatch core decides to apply these relocations, their processing results in the following bug: [ 25.827238] BUG: unable to handle page fault for address: 00000000000012ba [ 25.827819] #PF: supervisor read access in kernel mode [ 25.828153] #PF: error_code(0x0000) - not-present page [ 25.828588] PGD 0 P4D 0 [ 25.829063] Oops: Oops: 0000 [#1] PREEMPT SMP NOPTI [ 25.829742] CPU: 2 UID: 0 PID: 452 Comm: insmod Tainted: G O K 6.13.0-rc4-00078-g059dd502b263 #7820 [ 25.830417] Tainted: [O]=OOT_MODULE, [K]=LIVEPATCH [ 25.830768] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.0-20220807_005459-localhost 04/01/2014 [ 25.831651] RIP: 0010:memcmp+0x24/0x60 [ 25.832190] Code: [...] [ 25.833378] RSP: 0018:ffffa40b403a3ae8 EFLAGS: 00000246 [ 25.833637] RAX: 0000000000000000 RBX: ffff93bc81d8e700 RCX: ffffffffc0202000 [ 25.834072] RDX: 0000000000000000 RSI: 0000000000000004 RDI: 00000000000012ba [ 25.834548] RBP: ffffa40b403a3b68 R08: ffffa40b403a3b30 R09: 0000004a00000002 [ 25.835088] R10: ffffffffffffd222 R11: f000000000000000 R12: 0000000000000000 [ 25.835666] R13: ffffffffc02032ba R14: ffffffffc007d1e0 R15: 0000000000000004 [ 25.836139] FS: 00007fecef8c3080(0000) GS:ffff93bc8f900000(0000) knlGS:0000000000000000 [ 25.836519] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 25.836977] CR2: 00000000000012ba CR3: 0000000002f24000 CR4: 00000000000006f0 [ 25.837442] Call Trace: [ 25.838297] [ 25.841083] __write_relocate_add.constprop.0+0xc7/0x2b0 [ 25.841701] apply_relocate_add+0x75/0xa0 [ 25.841973] klp_write_section_relocs+0x10e/0x140 [ 25.842304] klp_write_object_relocs+0x70/0xa0 [ 25.842682] klp_init_object_loaded+0x21/0xf0 [ 25.842972] klp_enable_patch+0x43d/0x900 [ 25.843572] do_one_initcall+0x4c/0x220 [ 25.844186] do_init_module+0x6a/0x260 [ 25.844423] init_module_from_file+0x9c/0xe0 [ 25.844702] idempotent_init_module+0x172/0x270 [ 25.845008] __x64_sys_finit_module+0x69/0xc0 [ 25.845253] do_syscall_64+0x9e/0x1a0 [ 25.845498] entry_SYSCALL_64_after_hwframe+0x77/0x7f [ 25.846056] RIP: 0033:0x7fecef9eb25d [ 25.846444] Code: [...] [ 25.847563] RSP: 002b:00007ffd0c5d6de8 EFLAGS: 00000246 ORIG_RAX: 0000000000000139 [ 25.848082] RAX: ffffffffffffffda RBX: 000055b03f05e470 RCX: 00007fecef9eb25d [ 25.848456] RDX: 0000000000000000 RSI: 000055b001e74e52 RDI: 0000000000000003 [ 25.848969] RBP: 00007ffd0c5d6ea0 R08: 0000000000000040 R09: 0000000000004100 [ 25.849411] R10: 00007fecefac7b20 R11: 0000000000000246 R12: 000055b001e74e52 [ 25.849905] R13: 0000000000000000 R14: 000055b03f05e440 R15: 0000000000000000 [ 25.850336] [ 25.850553] Modules linked in: deku(OK+) uinput [ 25.851408] CR2: 00000000000012ba [ 25.852085] ---[ end trace 0000000000000000 ]--- The problem is that the .klp.rela.. relocations are processed after the module was already formed and mod->rw_copy was reset. However, the code in __write_relocate_add() calls module_writable_address() which translates the target address 'loc' still to 'loc + (mem->rw_copy - mem->base)', with mem->rw_copy now being 0. Fix the problem by returning directly 'loc' in module_writable_address() when the module is already formed. Function __write_relocate_add() knows to use text_poke() in such a case. Link: https://lkml.kernel.org/r/20250107153507.14733-1-petr.pavlu@suse.com Fixes: 0c133b1e78cd ("module: prepare to handle ROX allocations for text") Signed-off-by: Petr Pavlu Reported-by: Marek Maslanka Closes: https://lore.kernel.org/linux-modules/CAGcaFA2hdThQV6mjD_1_U+GNHThv84+MQvMWLgEuX+LVbAyDxg@mail.gmail.com/ Reviewed-by: Petr Mladek Tested-by: Petr Mladek Cc: Joe Lawrence Cc: Josh Poimboeuf Cc: Luis Chamberlain Cc: Mike Rapoport (Microsoft) Cc: Petr Mladek Signed-off-by: Andrew Morton --- include/linux/module.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'include/linux/module.h') diff --git a/include/linux/module.h b/include/linux/module.h index 94acbacdcdf1..b3a643435357 100644 --- a/include/linux/module.h +++ b/include/linux/module.h @@ -773,7 +773,8 @@ void *__module_writable_address(struct module *mod, void *loc); static inline void *module_writable_address(struct module *mod, void *loc) { - if (!IS_ENABLED(CONFIG_ARCH_HAS_EXECMEM_ROX) || !mod) + if (!IS_ENABLED(CONFIG_ARCH_HAS_EXECMEM_ROX) || !mod || + mod->state != MODULE_STATE_UNFORMED) return loc; return __module_writable_address(mod, loc); } -- cgit v1.2.3 From 38e3fe6595e1fa806c0450b2db666bc46325025e Mon Sep 17 00:00:00 2001 From: Thomas Weißschuh Date: Mon, 16 Dec 2024 18:25:09 +0100 Subject: module: Handle 'struct module_version_attribute' as const MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The structure is always read-only due to its placement in the read-only section __modver. Reflect this at its usage sites. Also prepare for the const handling of 'struct module_attribute' itself. Signed-off-by: Thomas Weißschuh Reviewed-by: Petr Pavlu Link: https://lore.kernel.org/r/20241216-sysfs-const-attr-module-v1-2-3790b53e0abf@weissschuh.net Signed-off-by: Petr Pavlu --- include/linux/module.h | 2 +- kernel/params.c | 4 ++-- 2 files changed, 3 insertions(+), 3 deletions(-) (limited to 'include/linux/module.h') diff --git a/include/linux/module.h b/include/linux/module.h index b3a643435357..5001c166c74f 100644 --- a/include/linux/module.h +++ b/include/linux/module.h @@ -275,7 +275,7 @@ extern typeof(name) __mod_device_table__##type##__##name \ #else #define MODULE_VERSION(_version) \ MODULE_INFO(version, _version); \ - static struct module_version_attribute __modver_attr \ + static const struct module_version_attribute __modver_attr \ __used __section("__modver") \ __aligned(__alignof__(struct module_version_attribute)) \ = { \ diff --git a/kernel/params.c b/kernel/params.c index e90733824528..763261a7fef9 100644 --- a/kernel/params.c +++ b/kernel/params.c @@ -860,8 +860,8 @@ static void __init param_sysfs_builtin(void) ssize_t __modver_version_show(struct module_attribute *mattr, struct module_kobject *mk, char *buf) { - struct module_version_attribute *vattr = - container_of(mattr, struct module_version_attribute, mattr); + const struct module_version_attribute *vattr = + container_of_const(mattr, struct module_version_attribute, mattr); return scnprintf(buf, PAGE_SIZE, "%s\n", vattr->version); } -- cgit v1.2.3 From f3227ffda07470848abe3cfa2039b21816ce3090 Mon Sep 17 00:00:00 2001 From: Thomas Weißschuh Date: Mon, 16 Dec 2024 18:25:10 +0100 Subject: module: Constify 'struct module_attribute' MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit These structs are never modified, move them to read-only memory. This makes the API clearer and also prepares for the constification of 'struct attribute' itself. While at it, also constify 'modinfo_attrs_count'. Signed-off-by: Thomas Weißschuh Reviewed-by: Petr Pavlu Link: https://lore.kernel.org/r/20241216-sysfs-const-attr-module-v1-3-3790b53e0abf@weissschuh.net Signed-off-by: Petr Pavlu --- include/linux/module.h | 8 ++++---- kernel/module/internal.h | 4 ++-- kernel/module/main.c | 40 ++++++++++++++++++++-------------------- kernel/module/sysfs.c | 4 ++-- kernel/params.c | 12 ++++++------ 5 files changed, 34 insertions(+), 34 deletions(-) (limited to 'include/linux/module.h') diff --git a/include/linux/module.h b/include/linux/module.h index 5001c166c74f..37eb5d88f6eb 100644 --- a/include/linux/module.h +++ b/include/linux/module.h @@ -52,9 +52,9 @@ struct module_kobject { struct module_attribute { struct attribute attr; - ssize_t (*show)(struct module_attribute *, struct module_kobject *, + ssize_t (*show)(const struct module_attribute *, struct module_kobject *, char *); - ssize_t (*store)(struct module_attribute *, struct module_kobject *, + ssize_t (*store)(const struct module_attribute *, struct module_kobject *, const char *, size_t count); void (*setup)(struct module *, const char *); int (*test)(struct module *); @@ -67,10 +67,10 @@ struct module_version_attribute { const char *version; }; -extern ssize_t __modver_version_show(struct module_attribute *, +extern ssize_t __modver_version_show(const struct module_attribute *, struct module_kobject *, char *); -extern struct module_attribute module_uevent; +extern const struct module_attribute module_uevent; /* These are either module local, or the kernel's dummy ones. */ extern int init_module(void); diff --git a/kernel/module/internal.h b/kernel/module/internal.h index daef2be83902..ac73da5f15bc 100644 --- a/kernel/module/internal.h +++ b/kernel/module/internal.h @@ -47,8 +47,8 @@ struct kernel_symbol { extern struct mutex module_mutex; extern struct list_head modules; -extern struct module_attribute *modinfo_attrs[]; -extern size_t modinfo_attrs_count; +extern const struct module_attribute *const modinfo_attrs[]; +extern const size_t modinfo_attrs_count; /* Provided by the linker */ extern const struct kernel_symbol __start___ksymtab[]; diff --git a/kernel/module/main.c b/kernel/module/main.c index fd483d436e43..8154e1665cdb 100644 --- a/kernel/module/main.c +++ b/kernel/module/main.c @@ -538,7 +538,7 @@ static void setup_modinfo_##field(struct module *mod, const char *s) \ { \ mod->field = kstrdup(s, GFP_KERNEL); \ } \ -static ssize_t show_modinfo_##field(struct module_attribute *mattr, \ +static ssize_t show_modinfo_##field(const struct module_attribute *mattr, \ struct module_kobject *mk, char *buffer) \ { \ return scnprintf(buffer, PAGE_SIZE, "%s\n", mk->mod->field); \ @@ -552,7 +552,7 @@ static void free_modinfo_##field(struct module *mod) \ kfree(mod->field); \ mod->field = NULL; \ } \ -static struct module_attribute modinfo_##field = { \ +static const struct module_attribute modinfo_##field = { \ .attr = { .name = __stringify(field), .mode = 0444 }, \ .show = show_modinfo_##field, \ .setup = setup_modinfo_##field, \ @@ -842,13 +842,13 @@ void symbol_put_addr(void *addr) } EXPORT_SYMBOL_GPL(symbol_put_addr); -static ssize_t show_refcnt(struct module_attribute *mattr, +static ssize_t show_refcnt(const struct module_attribute *mattr, struct module_kobject *mk, char *buffer) { return sprintf(buffer, "%i\n", module_refcount(mk->mod)); } -static struct module_attribute modinfo_refcnt = +static const struct module_attribute modinfo_refcnt = __ATTR(refcnt, 0444, show_refcnt, NULL); void __module_get(struct module *module) @@ -917,7 +917,7 @@ size_t module_flags_taint(unsigned long taints, char *buf) return l; } -static ssize_t show_initstate(struct module_attribute *mattr, +static ssize_t show_initstate(const struct module_attribute *mattr, struct module_kobject *mk, char *buffer) { const char *state = "unknown"; @@ -938,10 +938,10 @@ static ssize_t show_initstate(struct module_attribute *mattr, return sprintf(buffer, "%s\n", state); } -static struct module_attribute modinfo_initstate = +static const struct module_attribute modinfo_initstate = __ATTR(initstate, 0444, show_initstate, NULL); -static ssize_t store_uevent(struct module_attribute *mattr, +static ssize_t store_uevent(const struct module_attribute *mattr, struct module_kobject *mk, const char *buffer, size_t count) { @@ -951,10 +951,10 @@ static ssize_t store_uevent(struct module_attribute *mattr, return rc ? rc : count; } -struct module_attribute module_uevent = +const struct module_attribute module_uevent = __ATTR(uevent, 0200, NULL, store_uevent); -static ssize_t show_coresize(struct module_attribute *mattr, +static ssize_t show_coresize(const struct module_attribute *mattr, struct module_kobject *mk, char *buffer) { unsigned int size = mk->mod->mem[MOD_TEXT].size; @@ -966,11 +966,11 @@ static ssize_t show_coresize(struct module_attribute *mattr, return sprintf(buffer, "%u\n", size); } -static struct module_attribute modinfo_coresize = +static const struct module_attribute modinfo_coresize = __ATTR(coresize, 0444, show_coresize, NULL); #ifdef CONFIG_ARCH_WANTS_MODULES_DATA_IN_VMALLOC -static ssize_t show_datasize(struct module_attribute *mattr, +static ssize_t show_datasize(const struct module_attribute *mattr, struct module_kobject *mk, char *buffer) { unsigned int size = 0; @@ -980,11 +980,11 @@ static ssize_t show_datasize(struct module_attribute *mattr, return sprintf(buffer, "%u\n", size); } -static struct module_attribute modinfo_datasize = +static const struct module_attribute modinfo_datasize = __ATTR(datasize, 0444, show_datasize, NULL); #endif -static ssize_t show_initsize(struct module_attribute *mattr, +static ssize_t show_initsize(const struct module_attribute *mattr, struct module_kobject *mk, char *buffer) { unsigned int size = 0; @@ -994,10 +994,10 @@ static ssize_t show_initsize(struct module_attribute *mattr, return sprintf(buffer, "%u\n", size); } -static struct module_attribute modinfo_initsize = +static const struct module_attribute modinfo_initsize = __ATTR(initsize, 0444, show_initsize, NULL); -static ssize_t show_taint(struct module_attribute *mattr, +static ssize_t show_taint(const struct module_attribute *mattr, struct module_kobject *mk, char *buffer) { size_t l; @@ -1007,10 +1007,10 @@ static ssize_t show_taint(struct module_attribute *mattr, return l; } -static struct module_attribute modinfo_taint = +static const struct module_attribute modinfo_taint = __ATTR(taint, 0444, show_taint, NULL); -struct module_attribute *modinfo_attrs[] = { +const struct module_attribute *const modinfo_attrs[] = { &module_uevent, &modinfo_version, &modinfo_srcversion, @@ -1027,7 +1027,7 @@ struct module_attribute *modinfo_attrs[] = { NULL, }; -size_t modinfo_attrs_count = ARRAY_SIZE(modinfo_attrs); +const size_t modinfo_attrs_count = ARRAY_SIZE(modinfo_attrs); static const char vermagic[] = VERMAGIC_STRING; @@ -1681,7 +1681,7 @@ static void module_license_taint_check(struct module *mod, const char *license) static void setup_modinfo(struct module *mod, struct load_info *info) { - struct module_attribute *attr; + const struct module_attribute *attr; int i; for (i = 0; (attr = modinfo_attrs[i]); i++) { @@ -1692,7 +1692,7 @@ static void setup_modinfo(struct module *mod, struct load_info *info) static void free_modinfo(struct module *mod) { - struct module_attribute *attr; + const struct module_attribute *attr; int i; for (i = 0; (attr = modinfo_attrs[i]); i++) { diff --git a/kernel/module/sysfs.c b/kernel/module/sysfs.c index 456358e1fdc4..31e7f3055407 100644 --- a/kernel/module/sysfs.c +++ b/kernel/module/sysfs.c @@ -275,7 +275,7 @@ static int add_usage_links(struct module *mod) static void module_remove_modinfo_attrs(struct module *mod, int end) { - struct module_attribute *attr; + const struct module_attribute *attr; int i; for (i = 0; (attr = &mod->modinfo_attrs[i]); i++) { @@ -293,7 +293,7 @@ static void module_remove_modinfo_attrs(struct module *mod, int end) static int module_add_modinfo_attrs(struct module *mod) { - struct module_attribute *attr; + const struct module_attribute *attr; struct module_attribute *temp_attr; int error = 0; int i; diff --git a/kernel/params.c b/kernel/params.c index 763261a7fef9..0074d29c9b80 100644 --- a/kernel/params.c +++ b/kernel/params.c @@ -538,7 +538,7 @@ const struct kernel_param_ops param_ops_string = { EXPORT_SYMBOL(param_ops_string); /* sysfs output in /sys/modules/XYZ/parameters/ */ -#define to_module_attr(n) container_of(n, struct module_attribute, attr) +#define to_module_attr(n) container_of_const(n, struct module_attribute, attr) #define to_module_kobject(n) container_of(n, struct module_kobject, kobj) struct param_attribute @@ -557,7 +557,7 @@ struct module_param_attrs #ifdef CONFIG_SYSFS #define to_param_attr(n) container_of_const(n, struct param_attribute, mattr) -static ssize_t param_attr_show(struct module_attribute *mattr, +static ssize_t param_attr_show(const struct module_attribute *mattr, struct module_kobject *mk, char *buf) { int count; @@ -573,7 +573,7 @@ static ssize_t param_attr_show(struct module_attribute *mattr, } /* sysfs always hands a nul-terminated string in buf. We rely on that. */ -static ssize_t param_attr_store(struct module_attribute *mattr, +static ssize_t param_attr_store(const struct module_attribute *mattr, struct module_kobject *mk, const char *buf, size_t len) { @@ -857,7 +857,7 @@ static void __init param_sysfs_builtin(void) } } -ssize_t __modver_version_show(struct module_attribute *mattr, +ssize_t __modver_version_show(const struct module_attribute *mattr, struct module_kobject *mk, char *buf) { const struct module_version_attribute *vattr = @@ -892,7 +892,7 @@ static ssize_t module_attr_show(struct kobject *kobj, struct attribute *attr, char *buf) { - struct module_attribute *attribute; + const struct module_attribute *attribute; struct module_kobject *mk; int ret; @@ -911,7 +911,7 @@ static ssize_t module_attr_store(struct kobject *kobj, struct attribute *attr, const char *buf, size_t len) { - struct module_attribute *attribute; + const struct module_attribute *attribute; struct module_kobject *mk; int ret; -- cgit v1.2.3 From 4c56eb33e603c3b9eb4bd24efbfdd0283c1c37e4 Mon Sep 17 00:00:00 2001 From: Masahiro Yamada Date: Sun, 2 Feb 2025 03:51:41 +0900 Subject: kbuild: keep symbols for symbol_get() even with CONFIG_TRIM_UNUSED_KSYMS Linus observed that the symbol_request(utf8_data_table) call fails when CONFIG_UNICODE=y and CONFIG_TRIM_UNUSED_KSYMS=y. symbol_get() relies on the symbol data being present in the ksymtab for symbol lookups. However, EXPORT_SYMBOL_GPL(utf8_data_table) is dropped due to CONFIG_TRIM_UNUSED_KSYMS, as no module references it in this case. Probably, this has been broken since commit dbacb0ef670d ("kconfig option for TRIM_UNUSED_KSYMS"). This commit addresses the issue by leveraging modpost. Symbol names passed to symbol_get() are recorded in the special .no_trim_symbol section, which is then parsed by modpost to forcibly keep such symbols. The .no_trim_symbol section is discarded by the linker scripts, so there is no impact on the size of the final vmlinux or modules. This commit cannot resolve the issue for direct calls to __symbol_get() because the symbol name is not known at compile-time. Although symbol_get() may eventually be deprecated, this workaround should be good enough meanwhile. Reported-by: Linus Torvalds Suggested-by: Linus Torvalds Signed-off-by: Masahiro Yamada --- include/asm-generic/vmlinux.lds.h | 1 + include/linux/module.h | 5 ++++- scripts/mod/modpost.c | 35 +++++++++++++++++++++++++++++++++++ scripts/mod/modpost.h | 6 ++++++ scripts/module.lds.S | 1 + 5 files changed, 47 insertions(+), 1 deletion(-) (limited to 'include/linux/module.h') diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h index 54504013c749..02a4adb4a999 100644 --- a/include/asm-generic/vmlinux.lds.h +++ b/include/asm-generic/vmlinux.lds.h @@ -1038,6 +1038,7 @@ defined(CONFIG_AUTOFDO_CLANG) || defined(CONFIG_PROPELLER_CLANG) *(.discard) \ *(.discard.*) \ *(.export_symbol) \ + *(.no_trim_symbol) \ *(.modinfo) \ /* ld.bfd warns about .gnu.version* even when not emitted */ \ *(.gnu.version*) \ diff --git a/include/linux/module.h b/include/linux/module.h index 23792d5d7b74..30e5b19bafa9 100644 --- a/include/linux/module.h +++ b/include/linux/module.h @@ -306,7 +306,10 @@ extern int modules_disabled; /* for sysctl */ /* Get/put a kernel symbol (calls must be symmetric) */ void *__symbol_get(const char *symbol); void *__symbol_get_gpl(const char *symbol); -#define symbol_get(x) ((typeof(&x))(__symbol_get(__stringify(x)))) +#define symbol_get(x) ({ \ + static const char __notrim[] \ + __used __section(".no_trim_symbol") = __stringify(x); \ + (typeof(&x))(__symbol_get(__stringify(x))); }) /* modules using other modules: kdb wants to see this. */ struct module_use { diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c index e18ae7dc8140..36b28987a2f0 100644 --- a/scripts/mod/modpost.c +++ b/scripts/mod/modpost.c @@ -507,6 +507,9 @@ static int parse_elf(struct elf_info *info, const char *filename) info->modinfo_len = sechdrs[i].sh_size; } else if (!strcmp(secname, ".export_symbol")) { info->export_symbol_secndx = i; + } else if (!strcmp(secname, ".no_trim_symbol")) { + info->no_trim_symbol = (void *)hdr + sechdrs[i].sh_offset; + info->no_trim_symbol_len = sechdrs[i].sh_size; } if (sechdrs[i].sh_type == SHT_SYMTAB) { @@ -1566,6 +1569,14 @@ static void read_symbols(const char *modname) /* strip trailing .o */ mod = new_module(modname, strlen(modname) - strlen(".o")); + /* save .no_trim_symbol section for later use */ + if (info.no_trim_symbol_len) { + mod->no_trim_symbol = xmalloc(info.no_trim_symbol_len); + memcpy(mod->no_trim_symbol, info.no_trim_symbol, + info.no_trim_symbol_len); + mod->no_trim_symbol_len = info.no_trim_symbol_len; + } + if (!mod->is_vmlinux) { license = get_modinfo(&info, "license"); if (!license) @@ -1728,6 +1739,28 @@ static void handle_white_list_exports(const char *white_list) free(buf); } +/* + * Keep symbols recorded in the .no_trim_symbol section. This is necessary to + * prevent CONFIG_TRIM_UNUSED_KSYMS from dropping EXPORT_SYMBOL because + * symbol_get() relies on the symbol being present in the ksymtab for lookups. + */ +static void keep_no_trim_symbols(struct module *mod) +{ + unsigned long size = mod->no_trim_symbol_len; + + for (char *s = mod->no_trim_symbol; s; s = next_string(s , &size)) { + struct symbol *sym; + + /* + * If find_symbol() returns NULL, this symbol is not provided + * by any module, and symbol_get() will fail. + */ + sym = find_symbol(s); + if (sym) + sym->used = true; + } +} + static void check_modname_len(struct module *mod) { const char *mod_name; @@ -2254,6 +2287,8 @@ int main(int argc, char **argv) read_symbols_from_files(files_source); list_for_each_entry(mod, &modules, list) { + keep_no_trim_symbols(mod); + if (mod->dump_file || mod->is_vmlinux) continue; diff --git a/scripts/mod/modpost.h b/scripts/mod/modpost.h index ffd0a52a606e..59366f456b76 100644 --- a/scripts/mod/modpost.h +++ b/scripts/mod/modpost.h @@ -111,6 +111,8 @@ struct module_alias { * * @dump_file: path to the .symvers file if loaded from a file * @aliases: list head for module_aliases + * @no_trim_symbol: .no_trim_symbol section data + * @no_trim_symbol_len: length of the .no_trim_symbol section */ struct module { struct list_head list; @@ -128,6 +130,8 @@ struct module { // Actual imported namespaces struct list_head imported_namespaces; struct list_head aliases; + char *no_trim_symbol; + unsigned int no_trim_symbol_len; char name[]; }; @@ -141,6 +145,8 @@ struct elf_info { char *strtab; char *modinfo; unsigned int modinfo_len; + char *no_trim_symbol; + unsigned int no_trim_symbol_len; /* support for 32bit section numbers */ diff --git a/scripts/module.lds.S b/scripts/module.lds.S index c2f80f9141d4..450f1088d5fd 100644 --- a/scripts/module.lds.S +++ b/scripts/module.lds.S @@ -16,6 +16,7 @@ SECTIONS { *(.discard) *(.discard.*) *(.export_symbol) + *(.no_trim_symbol) } __ksymtab 0 : ALIGN(8) { *(SORT(___ksymtab+*)) } -- cgit v1.2.3