[v2,12/12] kprobes: remove dependcy on CONFIG_MODULES
Commit Message
From: "Mike Rapoport (IBM)" <rppt@kernel.org>
kprobes depended on CONFIG_MODULES because it has to allocate memory for
code.
Since code allocations are now implemented with execmem, kprobes can be
enabled in non-modular kernels.
Add #ifdef CONFIG_MODULE guards for the code dealing with kprobes inside
modules, make CONFIG_KPROBES select CONFIG_EXECMEM and drop the
dependency of CONFIG_KPROBES on CONFIG_MODULES.
Signed-off-by: Mike Rapoport (IBM) <rppt@kernel.org>
---
arch/Kconfig | 2 +-
kernel/kprobes.c | 43 +++++++++++++++++++++----------------
kernel/trace/trace_kprobe.c | 11 ++++++++++
3 files changed, 37 insertions(+), 19 deletions(-)
Comments
Mike Rapoport <rppt@kernel.org> writes:
> From: "Mike Rapoport (IBM)" <rppt@kernel.org>
>
> kprobes depended on CONFIG_MODULES because it has to allocate memory for
> code.
I think you can remove the MODULES dependency from BPF_JIT as well:
--8<--
diff --git a/kernel/bpf/Kconfig b/kernel/bpf/Kconfig
index 2dfe1079f772..fa4587027f8b 100644
--- a/kernel/bpf/Kconfig
+++ b/kernel/bpf/Kconfig
@@ -41,7 +41,6 @@ config BPF_JIT
bool "Enable BPF Just In Time compiler"
depends on BPF
depends on HAVE_CBPF_JIT || HAVE_EBPF_JIT
- depends on MODULES
help
BPF programs are normally handled by a BPF interpreter. This option
allows the kernel to generate native code when a program is loaded
--8<--
Björn
On Fri, Jun 16, 2023 at 01:44:55PM +0200, Björn Töpel wrote:
> Mike Rapoport <rppt@kernel.org> writes:
>
> > From: "Mike Rapoport (IBM)" <rppt@kernel.org>
> >
> > kprobes depended on CONFIG_MODULES because it has to allocate memory for
> > code.
>
> I think you can remove the MODULES dependency from BPF_JIT as well:
Yeah, I think so. Thanks!
> --8<--
> diff --git a/kernel/bpf/Kconfig b/kernel/bpf/Kconfig
> index 2dfe1079f772..fa4587027f8b 100644
> --- a/kernel/bpf/Kconfig
> +++ b/kernel/bpf/Kconfig
> @@ -41,7 +41,6 @@ config BPF_JIT
> bool "Enable BPF Just In Time compiler"
> depends on BPF
> depends on HAVE_CBPF_JIT || HAVE_EBPF_JIT
> - depends on MODULES
> help
> BPF programs are normally handled by a BPF interpreter. This option
> allows the kernel to generate native code when a program is loaded
> --8<--
>
>
> Björn
@@ -39,9 +39,9 @@ config GENERIC_ENTRY
config KPROBES
bool "Kprobes"
- depends on MODULES
depends on HAVE_KPROBES
select KALLSYMS
+ select EXECMEM
select TASKS_RCU if PREEMPTION
help
Kprobes allows you to trap at almost any kernel address and
@@ -1568,6 +1568,7 @@ static int check_kprobe_address_safe(struct kprobe *p,
goto out;
}
+#ifdef CONFIG_MODULES
/* Check if 'p' is probing a module. */
*probed_mod = __module_text_address((unsigned long) p->addr);
if (*probed_mod) {
@@ -1591,6 +1592,8 @@ static int check_kprobe_address_safe(struct kprobe *p,
ret = -ENOENT;
}
}
+#endif
+
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;
@@ -2667,6 +2671,7 @@ static struct notifier_block kprobe_module_nb = {
.notifier_call = kprobes_module_callback,
.priority = 0
};
+#endif
void kprobe_free_init_mem(void)
{
@@ -2726,8 +2731,10 @@ static int __init init_kprobes(void)
err = arch_init_kprobes();
if (!err)
err = register_die_notifier(&kprobe_exceptions_nb);
+#ifdef CONFIG_MODULES
if (!err)
err = register_module_notifier(&kprobe_module_nb);
+#endif
kprobes_initialized = (err == 0);
kprobe_sysctls_init();
@@ -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 +130,12 @@ static nokprobe_inline bool trace_kprobe_module_exist(struct trace_kprobe *tk)
return ret;
}
+#else
+static inline bool trace_kprobe_module_exist(struct trace_kprobe *tk)
+{
+ return false;
+}
+#endif
static bool trace_kprobe_is_busy(struct dyn_event *ev)
{
@@ -670,6 +677,7 @@ 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)
@@ -704,6 +712,7 @@ static struct notifier_block trace_kprobe_module_nb = {
.notifier_call = trace_kprobe_module_callback,
.priority = 1 /* Invoked after kprobe module callback */
};
+#endif
static int __trace_kprobe_create(int argc, const char *argv[])
{
@@ -1797,8 +1806,10 @@ static __init int init_kprobe_trace_early(void)
if (ret)
return ret;
+#ifdef CONFIG_MODULES
if (register_module_notifier(&trace_kprobe_module_nb))
return -EINVAL;
+#endif
return 0;
}