Messages in this thread Patch in this message | | | From | Mark Rutland <> | Subject | [PATCH v2 4/4] kprobes: Remove core dependency on modules | Date | Wed, 3 Apr 2024 16:01:54 +0100 |
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From: Jarkko Sakkinen <jarkko@kernel.org>
Tracing with kprobes while running a monolithic kernel is currently impossible because KPROBES depends on MODULES. While this dependency is necessary when HAVE_KPROBES_ALLOC=n and the core kprobes code allocates memory using module_alloc(), all the other module-specific code only exist to handle the case when MODULES=y, and can be hidden behind ifdeffery.
Add the necessary ifdeffery, and remove the dependency on MODULES=y when HAVE_KPROBES_ALLOC=y.
As of this patch kprobes can be used when MODULES=n on arm64 and riscv. All other architectures still depend on MODULES, either by virtue of the core dependency on MODULES when HAVE_KPROBES_ALLOC=n, or by virtue of an explciit dependency on MODULES in arch code.
Other architectures can enable support by implementing their own kprobes_alloc_insn_page() and kprobes_free_insn_page() which do not depend on MODULES.
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org> Link: https://lore.kernel.org/lkml/20240326134616.7691-1-jarkko@kernel.org/ [Mark: Remove execmem changes, depend on HAVE_KPROBES_ALLOC] Signed-off-by: Mark Rutland <mark.rutland@arm.com> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: David S. Miller <davem@davemloft.net> Cc: Jarkko Sakkinen <jarkko@kernel.org> Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Naveen N. Rao <naveen.n.rao@linux.ibm.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Will Deacon <will@kernel.org> --- arch/Kconfig | 2 +- kernel/kprobes.c | 46 ++++++++++++++++++++++--------------- kernel/trace/trace_kprobe.c | 15 ++++++++++-- 3 files changed, 41 insertions(+), 22 deletions(-)
diff --git a/arch/Kconfig b/arch/Kconfig index 85bb59f7b8c07..0df2c88547b3c 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -52,7 +52,7 @@ config GENERIC_ENTRY config KPROBES bool "Kprobes" - depends on MODULES + depends on MODULES || HAVE_KPROBES_ALLOC depends on HAVE_KPROBES select KALLSYMS select TASKS_RCU if PREEMPTION diff --git a/kernel/kprobes.c b/kernel/kprobes.c index fa2ee4e59eca2..ec4493a41b505 100644 --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -1594,6 +1594,7 @@ static int check_kprobe_address_safe(struct kprobe *p, goto out; } +#ifdef CONFIG_MODULES /* * If the module freed '.init.text', we couldn't insert * kprobes in there. @@ -1604,7 +1605,9 @@ static int check_kprobe_address_safe(struct kprobe *p, *probed_mod = NULL; ret = -ENOENT; } +#endif /* CONFIG_MODULES */ } + out: preempt_enable(); jump_label_unlock(); @@ -2484,24 +2487,6 @@ int kprobe_add_area_blacklist(unsigned long start, unsigned long end) return 0; } -/* Remove all symbols in given area from kprobe blacklist */ -static void kprobe_remove_area_blacklist(unsigned long start, unsigned long end) -{ - struct kprobe_blacklist_entry *ent, *n; - - list_for_each_entry_safe(ent, n, &kprobe_blacklist, list) { - if (ent->start_addr < start || ent->start_addr >= end) - continue; - list_del(&ent->list); - kfree(ent); - } -} - -static void kprobe_remove_ksym_blacklist(unsigned long entry) -{ - kprobe_remove_area_blacklist(entry, entry + 1); -} - int __weak arch_kprobe_get_kallsym(unsigned int *symnum, unsigned long *value, char *type, char *sym) { @@ -2566,6 +2551,25 @@ static int __init populate_kprobe_blacklist(unsigned long *start, return ret ? : arch_populate_kprobe_blacklist(); } +#ifdef CONFIG_MODULES +/* Remove all symbols in given area from kprobe blacklist */ +static void kprobe_remove_area_blacklist(unsigned long start, unsigned long end) +{ + struct kprobe_blacklist_entry *ent, *n; + + list_for_each_entry_safe(ent, n, &kprobe_blacklist, list) { + if (ent->start_addr < start || ent->start_addr >= end) + continue; + list_del(&ent->list); + kfree(ent); + } +} + +static void kprobe_remove_ksym_blacklist(unsigned long entry) +{ + kprobe_remove_area_blacklist(entry, entry + 1); +} + static void add_module_kprobe_blacklist(struct module *mod) { unsigned long start, end; @@ -2662,6 +2666,9 @@ static int kprobes_module_callback(struct notifier_block *nb, mutex_unlock(&kprobe_mutex); return NOTIFY_DONE; } +#else +#define kprobes_module_callback (NULL) +#endif /* CONFIG_MODULES */ static struct notifier_block kprobe_module_nb = { .notifier_call = kprobes_module_callback, @@ -2726,7 +2733,8 @@ static int __init init_kprobes(void) err = arch_init_kprobes(); if (!err) err = register_die_notifier(&kprobe_exceptions_nb); - if (!err) + + if (!err && IS_ENABLED(CONFIG_MODULES)) err = register_module_notifier(&kprobe_module_nb); kprobes_initialized = (err == 0); diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c index 14099cc17fc9e..c509ba776e679 100644 --- a/kernel/trace/trace_kprobe.c +++ b/kernel/trace/trace_kprobe.c @@ -111,6 +111,7 @@ static nokprobe_inline bool trace_kprobe_within_module(struct trace_kprobe *tk, return strncmp(module_name(mod), name, len) == 0 && name[len] == ':'; } +#ifdef CONFIG_MODULES static nokprobe_inline bool trace_kprobe_module_exist(struct trace_kprobe *tk) { char *p; @@ -129,6 +130,9 @@ static nokprobe_inline bool trace_kprobe_module_exist(struct trace_kprobe *tk) return ret; } +#else +#define trace_kprobe_module_exist(tk) false /* aka a module never exists */ +#endif /* CONFIG_MODULES */ static bool trace_kprobe_is_busy(struct dyn_event *ev) { @@ -670,6 +674,7 @@ static int register_trace_kprobe(struct trace_kprobe *tk) return ret; } +#ifdef CONFIG_MODULES /* Module notifier call back, checking event on the module */ static int trace_kprobe_module_callback(struct notifier_block *nb, unsigned long val, void *data) @@ -699,6 +704,9 @@ static int trace_kprobe_module_callback(struct notifier_block *nb, return NOTIFY_DONE; } +#else +#define trace_kprobe_module_callback (NULL) +#endif /* CONFIG_MODULES */ static struct notifier_block trace_kprobe_module_nb = { .notifier_call = trace_kprobe_module_callback, @@ -1933,8 +1941,11 @@ static __init int init_kprobe_trace_early(void) if (ret) return ret; - if (register_module_notifier(&trace_kprobe_module_nb)) - return -EINVAL; + if (IS_ENABLED(CONFIG_MODULES)) { + ret = register_module_notifier(&trace_kprobe_module_nb); + if (ret) + return -EINVAL; + } return 0; } -- 2.30.2
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