From cb0b50b813f6198b7d44ae8e169803440333577a Mon Sep 17 00:00:00 2001 From: Sebastian Andrzej Siewior Date: Tue, 9 May 2023 15:49:02 +0200 Subject: module: Remove preempt_disable() from module reference counting. The preempt_disable() section in module_put() was added in commit e1783a240f491 ("module: Use this_cpu_xx to dynamically allocate counters") while the per-CPU counter were switched to another API. The API requires that during the RMW operation the CPU remained the same. This counting API was later replaced with atomic_t in commit 2f35c41f58a97 ("module: Replace module_ref with atomic_t refcnt") Since this atomic_t replacement there is no need to keep preemption disabled while the reference counter is modified. Remove preempt_disable() from module_put(), __module_get() and try_module_get(). Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Luis Chamberlain --- kernel/module/main.c | 7 ------- 1 file changed, 7 deletions(-) (limited to 'kernel') diff --git a/kernel/module/main.c b/kernel/module/main.c index 044aa2c9e3cb..ea7d0c7f3e60 100644 --- a/kernel/module/main.c +++ b/kernel/module/main.c @@ -820,10 +820,8 @@ static struct module_attribute modinfo_refcnt = void __module_get(struct module *module) { if (module) { - preempt_disable(); atomic_inc(&module->refcnt); trace_module_get(module, _RET_IP_); - preempt_enable(); } } EXPORT_SYMBOL(__module_get); @@ -833,15 +831,12 @@ bool try_module_get(struct module *module) bool ret = true; if (module) { - preempt_disable(); /* Note: here, we can fail to get a reference */ if (likely(module_is_live(module) && atomic_inc_not_zero(&module->refcnt) != 0)) trace_module_get(module, _RET_IP_); else ret = false; - - preempt_enable(); } return ret; } @@ -852,11 +847,9 @@ void module_put(struct module *module) int ret; if (module) { - preempt_disable(); ret = atomic_dec_if_positive(&module->refcnt); WARN_ON(ret < 0); /* Failed to put refcount */ trace_module_put(module, _RET_IP_); - preempt_enable(); } } EXPORT_SYMBOL(module_put); -- cgit v1.2.3-70-g09d2 From 15d5daa0a7006b9bd4dcc49f90e7ac8ddbe102f2 Mon Sep 17 00:00:00 2001 From: Arnd Bergmann Date: Wed, 17 May 2023 15:18:07 +0200 Subject: kallsyms: remove unused arch_get_kallsym() helper The arch_get_kallsym() function was introduced so that x86 could override it, but that override was removed in bf904d2762ee ("x86/pti/64: Remove the SYSCALL64 entry trampoline"), so now this does nothing except causing a warning about a missing prototype: kernel/kallsyms.c:662:12: error: no previous prototype for 'arch_get_kallsym' [-Werror=missing-prototypes] 662 | int __weak arch_get_kallsym(unsigned int symnum, unsigned long *value, Restore the old behavior before d83212d5dd67 ("kallsyms, x86: Export addresses of PTI entry trampolines") to simplify the code and avoid the warning. Signed-off-by: Arnd Bergmann Tested-by: Alan Maguire [mcgrof: fold in bpf selftest fix] Signed-off-by: Luis Chamberlain --- kernel/kallsyms.c | 28 +---------------------- tools/testing/selftests/bpf/progs/bpf_iter_ksym.c | 4 +--- 2 files changed, 2 insertions(+), 30 deletions(-) (limited to 'kernel') diff --git a/kernel/kallsyms.c b/kernel/kallsyms.c index 77747391f49b..290d8cc1943a 100644 --- a/kernel/kallsyms.c +++ b/kernel/kallsyms.c @@ -646,7 +646,6 @@ int sprint_backtrace_build_id(char *buffer, unsigned long address) /* To avoid using get_symbol_offset for every symbol, we carry prefix along. */ struct kallsym_iter { loff_t pos; - loff_t pos_arch_end; loff_t pos_mod_end; loff_t pos_ftrace_mod_end; loff_t pos_bpf_end; @@ -659,29 +658,9 @@ struct kallsym_iter { int show_value; }; -int __weak arch_get_kallsym(unsigned int symnum, unsigned long *value, - char *type, char *name) -{ - return -EINVAL; -} - -static int get_ksymbol_arch(struct kallsym_iter *iter) -{ - int ret = arch_get_kallsym(iter->pos - kallsyms_num_syms, - &iter->value, &iter->type, - iter->name); - - if (ret < 0) { - iter->pos_arch_end = iter->pos; - return 0; - } - - return 1; -} - static int get_ksymbol_mod(struct kallsym_iter *iter) { - int ret = module_get_kallsym(iter->pos - iter->pos_arch_end, + int ret = module_get_kallsym(iter->pos - kallsyms_num_syms, &iter->value, &iter->type, iter->name, iter->module_name, &iter->exported); @@ -764,7 +743,6 @@ static void reset_iter(struct kallsym_iter *iter, loff_t new_pos) iter->nameoff = get_symbol_offset(new_pos); iter->pos = new_pos; if (new_pos == 0) { - iter->pos_arch_end = 0; iter->pos_mod_end = 0; iter->pos_ftrace_mod_end = 0; iter->pos_bpf_end = 0; @@ -780,10 +758,6 @@ static int update_iter_mod(struct kallsym_iter *iter, loff_t pos) { iter->pos = pos; - if ((!iter->pos_arch_end || iter->pos_arch_end > pos) && - get_ksymbol_arch(iter)) - return 1; - if ((!iter->pos_mod_end || iter->pos_mod_end > pos) && get_ksymbol_mod(iter)) return 1; diff --git a/tools/testing/selftests/bpf/progs/bpf_iter_ksym.c b/tools/testing/selftests/bpf/progs/bpf_iter_ksym.c index 5ddcc46fd886..521267818f4d 100644 --- a/tools/testing/selftests/bpf/progs/bpf_iter_ksym.c +++ b/tools/testing/selftests/bpf/progs/bpf_iter_ksym.c @@ -59,9 +59,7 @@ int dump_ksym(struct bpf_iter__ksym *ctx) } else { BPF_SEQ_PRINTF(seq, "0x%llx %c %s ", value, type, iter->name); } - if (!iter->pos_arch_end || iter->pos_arch_end > iter->pos) - BPF_SEQ_PRINTF(seq, "CORE "); - else if (!iter->pos_mod_end || iter->pos_mod_end > iter->pos) + if (!iter->pos_mod_end || iter->pos_mod_end > iter->pos) BPF_SEQ_PRINTF(seq, "MOD "); else if (!iter->pos_ftrace_mod_end || iter->pos_ftrace_mod_end > iter->pos) BPF_SEQ_PRINTF(seq, "FTRACE_MOD "); -- cgit v1.2.3-70-g09d2 From 4f521bab5bfc854ec0dab7ef560dfa75247e615d Mon Sep 17 00:00:00 2001 From: Maninder Singh Date: Fri, 26 May 2023 12:51:23 +0530 Subject: kallsyms: remove unsed API lookup_symbol_attrs with commit '7878c231dae0 ("slab: remove /proc/slab_allocators")' lookup_symbol_attrs usage is removed. Thus removing redundant API. Signed-off-by: Maninder Singh Reviewed-by: Kees Cook Signed-off-by: Luis Chamberlain --- include/linux/kallsyms.h | 6 ------ include/linux/module.h | 9 --------- kernel/kallsyms.c | 28 ---------------------------- kernel/module/kallsyms.c | 28 ---------------------------- 4 files changed, 71 deletions(-) (limited to 'kernel') diff --git a/include/linux/kallsyms.h b/include/linux/kallsyms.h index fe3c9993b5bf..1037f4957caa 100644 --- a/include/linux/kallsyms.h +++ b/include/linux/kallsyms.h @@ -93,7 +93,6 @@ extern int sprint_backtrace(char *buffer, unsigned long address); extern int sprint_backtrace_build_id(char *buffer, unsigned long address); int lookup_symbol_name(unsigned long addr, char *symname); -int lookup_symbol_attrs(unsigned long addr, unsigned long *size, unsigned long *offset, char *modname, char *name); /* How and when do we show kallsyms values? */ extern bool kallsyms_show_value(const struct cred *cred); @@ -155,11 +154,6 @@ static inline int lookup_symbol_name(unsigned long addr, char *symname) return -ERANGE; } -static inline int lookup_symbol_attrs(unsigned long addr, unsigned long *size, unsigned long *offset, char *modname, char *name) -{ - return -ERANGE; -} - static inline bool kallsyms_show_value(const struct cred *cred) { return false; diff --git a/include/linux/module.h b/include/linux/module.h index 9e56763dff81..a98e188cf37b 100644 --- a/include/linux/module.h +++ b/include/linux/module.h @@ -968,15 +968,6 @@ static inline int lookup_module_symbol_name(unsigned long addr, char *symname) return -ERANGE; } -static inline int lookup_module_symbol_attrs(unsigned long addr, - unsigned long *size, - unsigned long *offset, - char *modname, - char *name) -{ - return -ERANGE; -} - static inline int module_get_kallsym(unsigned int symnum, unsigned long *value, char *type, char *name, char *module_name, int *exported) diff --git a/kernel/kallsyms.c b/kernel/kallsyms.c index 290d8cc1943a..8193e947aa10 100644 --- a/kernel/kallsyms.c +++ b/kernel/kallsyms.c @@ -484,34 +484,6 @@ found: return 0; } -int lookup_symbol_attrs(unsigned long addr, unsigned long *size, - unsigned long *offset, char *modname, char *name) -{ - int res; - - name[0] = '\0'; - name[KSYM_NAME_LEN - 1] = '\0'; - - if (is_ksym_addr(addr)) { - unsigned long pos; - - pos = get_symbol_pos(addr, size, offset); - /* Grab name */ - kallsyms_expand_symbol(get_symbol_offset(pos), - name, KSYM_NAME_LEN); - modname[0] = '\0'; - goto found; - } - /* See if it's in a module. */ - res = lookup_module_symbol_attrs(addr, size, offset, modname, name); - if (res) - return res; - -found: - cleanup_symbol_name(name); - return 0; -} - /* Look up a kernel symbol and return it in a text buffer. */ static int __sprint_symbol(char *buffer, unsigned long address, int symbol_offset, int add_offset, int add_buildid) diff --git a/kernel/module/kallsyms.c b/kernel/module/kallsyms.c index c550d7d45f2f..ef73ae7c8909 100644 --- a/kernel/module/kallsyms.c +++ b/kernel/module/kallsyms.c @@ -381,34 +381,6 @@ out: return -ERANGE; } -int lookup_module_symbol_attrs(unsigned long addr, unsigned long *size, - unsigned long *offset, char *modname, char *name) -{ - struct module *mod; - - preempt_disable(); - list_for_each_entry_rcu(mod, &modules, list) { - if (mod->state == MODULE_STATE_UNFORMED) - continue; - if (within_module(addr, mod)) { - const char *sym; - - sym = find_kallsyms_symbol(mod, addr, size, offset); - if (!sym) - goto out; - if (modname) - strscpy(modname, mod->name, MODULE_NAME_LEN); - if (name) - strscpy(name, sym, KSYM_NAME_LEN); - preempt_enable(); - return 0; - } - } -out: - preempt_enable(); - return -ERANGE; -} - int module_get_kallsym(unsigned int symnum, unsigned long *value, char *type, char *name, char *module_name, int *exported) { -- cgit v1.2.3-70-g09d2 From b06e9318bfd03f531b918bd27b63f1eb88c21729 Mon Sep 17 00:00:00 2001 From: Maninder Singh Date: Thu, 8 Jun 2023 09:01:18 +0530 Subject: kallsyms: move kallsyms_show_value() out of kallsyms.c function kallsyms_show_value() is used by other parts like modules_open(), kprobes_read() etc. which can work in case of !KALLSYMS also. e.g. as of now lsmod do not show module address if KALLSYMS is disabled. since kallsyms_show_value() defination is not present, it returns false in !KALLSYMS. / # lsmod test 12288 0 - Live 0x0000000000000000 (O) So kallsyms_show_value() can be made generic without dependency on KALLSYMS. Thus moving out function to a new file ksyms_common.c. With this patch code is just moved to new file and no functional change. Co-developed-by: Onkarnath Signed-off-by: Onkarnath Signed-off-by: Maninder Singh Reviewed-by: Zhen Lei Signed-off-by: Luis Chamberlain --- kernel/Makefile | 2 +- kernel/kallsyms.c | 35 ----------------------------------- kernel/ksyms_common.c | 45 +++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 46 insertions(+), 36 deletions(-) create mode 100644 kernel/ksyms_common.c (limited to 'kernel') diff --git a/kernel/Makefile b/kernel/Makefile index b69c95315480..e7e63bb4b7fe 100644 --- a/kernel/Makefile +++ b/kernel/Makefile @@ -10,7 +10,7 @@ obj-y = fork.o exec_domain.o panic.o \ extable.o params.o \ kthread.o sys_ni.o nsproxy.o \ notifier.o ksysfs.o cred.o reboot.o \ - async.o range.o smpboot.o ucount.o regset.o + async.o range.o smpboot.o ucount.o regset.o ksyms_common.o obj-$(CONFIG_USERMODE_DRIVER) += usermode_driver.o obj-$(CONFIG_MULTIUSER) += groups.o diff --git a/kernel/kallsyms.c b/kernel/kallsyms.c index 8193e947aa10..0f82c3d5a57d 100644 --- a/kernel/kallsyms.c +++ b/kernel/kallsyms.c @@ -907,41 +907,6 @@ late_initcall(bpf_ksym_iter_register); #endif /* CONFIG_BPF_SYSCALL */ -static inline int kallsyms_for_perf(void) -{ -#ifdef CONFIG_PERF_EVENTS - extern int sysctl_perf_event_paranoid; - if (sysctl_perf_event_paranoid <= 1) - return 1; -#endif - return 0; -} - -/* - * We show kallsyms information even to normal users if we've enabled - * kernel profiling and are explicitly not paranoid (so kptr_restrict - * is clear, and sysctl_perf_event_paranoid isn't set). - * - * Otherwise, require CAP_SYSLOG (assuming kptr_restrict isn't set to - * block even that). - */ -bool kallsyms_show_value(const struct cred *cred) -{ - switch (kptr_restrict) { - case 0: - if (kallsyms_for_perf()) - return true; - fallthrough; - case 1: - if (security_capable(cred, &init_user_ns, CAP_SYSLOG, - CAP_OPT_NOAUDIT) == 0) - return true; - fallthrough; - default: - return false; - } -} - static int kallsyms_open(struct inode *inode, struct file *file) { /* diff --git a/kernel/ksyms_common.c b/kernel/ksyms_common.c new file mode 100644 index 000000000000..3840fa1c9c86 --- /dev/null +++ b/kernel/ksyms_common.c @@ -0,0 +1,45 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * ksyms_common.c: A split of kernel/kallsyms.c + * Contains a few generic function definations independent of config KALLSYMS. + */ +#include +#include + +#ifdef CONFIG_KALLSYMS +static inline int kallsyms_for_perf(void) +{ +#ifdef CONFIG_PERF_EVENTS + extern int sysctl_perf_event_paranoid; + + if (sysctl_perf_event_paranoid <= 1) + return 1; +#endif + return 0; +} + +/* + * We show kallsyms information even to normal users if we've enabled + * kernel profiling and are explicitly not paranoid (so kptr_restrict + * is clear, and sysctl_perf_event_paranoid isn't set). + * + * Otherwise, require CAP_SYSLOG (assuming kptr_restrict isn't set to + * block even that). + */ +bool kallsyms_show_value(const struct cred *cred) +{ + switch (kptr_restrict) { + case 0: + if (kallsyms_for_perf()) + return true; + fallthrough; + case 1: + if (security_capable(cred, &init_user_ns, CAP_SYSLOG, + CAP_OPT_NOAUDIT) == 0) + return true; + fallthrough; + default: + return false; + } +} +#endif -- cgit v1.2.3-70-g09d2 From 0eeaf1eb40a34fddd1d568a9b32c3d6669238743 Mon Sep 17 00:00:00 2001 From: Maninder Singh Date: Thu, 8 Jun 2023 09:01:19 +0530 Subject: kallsyms: make kallsyms_show_value() as generic function This change makes function kallsyms_show_value() as generic function without dependency on CONFIG_KALLSYMS. Now module address will be displayed with lsmod and /proc/modules. Earlier: ======= / # insmod test.ko / # lsmod test 12288 0 - Live 0x0000000000000000 (O) // No Module Load address / # With change: ========== / # insmod test.ko / # lsmod test 12288 0 - Live 0xffff800000fc0000 (O) // Module address / # cat /proc/modules test 12288 0 - Live 0xffff800000fc0000 (O) Co-developed-by: Onkarnath Signed-off-by: Onkarnath Signed-off-by: Maninder Singh Reviewed-by: Zhen Lei Signed-off-by: Luis Chamberlain --- include/linux/kallsyms.h | 11 +++-------- kernel/ksyms_common.c | 2 -- 2 files changed, 3 insertions(+), 10 deletions(-) (limited to 'kernel') diff --git a/include/linux/kallsyms.h b/include/linux/kallsyms.h index 1037f4957caa..c3f075e8f60c 100644 --- a/include/linux/kallsyms.h +++ b/include/linux/kallsyms.h @@ -65,6 +65,9 @@ static inline void *dereference_symbol_descriptor(void *ptr) return ptr; } +/* How and when do we show kallsyms values? */ +extern bool kallsyms_show_value(const struct cred *cred); + #ifdef CONFIG_KALLSYMS unsigned long kallsyms_sym_address(int idx); int kallsyms_on_each_symbol(int (*fn)(void *, const char *, unsigned long), @@ -94,9 +97,6 @@ extern int sprint_backtrace_build_id(char *buffer, unsigned long address); int lookup_symbol_name(unsigned long addr, char *symname); -/* How and when do we show kallsyms values? */ -extern bool kallsyms_show_value(const struct cred *cred); - #else /* !CONFIG_KALLSYMS */ static inline unsigned long kallsyms_lookup_name(const char *name) @@ -154,11 +154,6 @@ static inline int lookup_symbol_name(unsigned long addr, char *symname) return -ERANGE; } -static inline bool kallsyms_show_value(const struct cred *cred) -{ - return false; -} - static inline int kallsyms_on_each_symbol(int (*fn)(void *, const char *, unsigned long), void *data) { diff --git a/kernel/ksyms_common.c b/kernel/ksyms_common.c index 3840fa1c9c86..cf1a73cbf2f6 100644 --- a/kernel/ksyms_common.c +++ b/kernel/ksyms_common.c @@ -6,7 +6,6 @@ #include #include -#ifdef CONFIG_KALLSYMS static inline int kallsyms_for_perf(void) { #ifdef CONFIG_PERF_EVENTS @@ -42,4 +41,3 @@ bool kallsyms_show_value(const struct cred *cred) return false; } } -#endif -- cgit v1.2.3-70-g09d2