Messages in this thread | | | Date | Wed, 03 Apr 2024 19:41:20 +0300 | Subject | Re: [PATCH v2 4/4] kprobes: Remove core dependency on modules | From | "Jarkko Sakkinen" <> |
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On Wed Apr 3, 2024 at 6:01 PM EEST, Mark Rutland wrote: > 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; > }
I'll test the patch set asap.
BR, Jarkko
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