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Date: Tue, 26 Mar 2024 16:36:24 +0000
From: Mark Rutland <mark.rutland@....com>
To: linux-kernel@...r.kernel.org
Cc: agordeev@...ux.ibm.com,
anil.s.keshavamurthy@...el.com,
aou@...s.berkeley.edu,
bp@...en8.de,
catalin.marinas@....com,
dave.hansen@...ux.intel.com,
davem@...emloft.net,
gor@...ux.ibm.com,
hca@...ux.ibm.com,
jarkko@...nel.org,
jcalvinowens@...il.com,
linux-arm-kernel@...ts.infradead.org,
mark.rutland@....com,
mhiramat@...nel.org,
mingo@...hat.com,
mpe@...erman.id.au,
naveen.n.rao@...ux.ibm.com,
palmer@...belt.com,
paul.walmsley@...ive.com,
tglx@...utronix.de,
will@...nel.org
Subject: [PATCH 4/4] kprobes: Remove core dependency on modules
From: Jarkko Sakkinen <jarkko@...nel.org>
Tracing with kprobes while running a monolithic kernel is currently
impossible because KPROBES depends on MODULES. While this dependency is
necessary when KPROBES_USE_MODULE_ALLOC=y, 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=N when
KPROBES_USE_MODULE_ALLOC=n.
Currently this allows kprobes to be used when CONFIG_MODULES=n on arm64
and riscv, and 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@...nel.org>
Link: https://lore.kernel.org/all/20240326012102.27438-1-jarkko@kernel.org/
[Mark: Remove execmem changes, depend on !KPROBES_USE_MODULE_ALLOC]
Signed-off-by: Mark Rutland <mark.rutland@....com>
Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@...el.com>
Cc: David S. Miller <davem@...emloft.net>
Cc: Jarkko Sakkinen <jarkko@...nel.org>
Cc: Masami Hiramatsu <mhiramat@...nel.org>
Cc: Naveen N. Rao <naveen.n.rao@...ux.ibm.com>
---
arch/Kconfig | 2 +-
kernel/kprobes.c | 12 +++++++++++-
kernel/trace/trace_kprobe.c | 15 +++++++++++++--
3 files changed, 25 insertions(+), 4 deletions(-)
diff --git a/arch/Kconfig b/arch/Kconfig
index 85bb59f7b8c07..cf43de9ffb5b9 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -52,7 +52,7 @@ config GENERIC_ENTRY
config KPROBES
bool "Kprobes"
- depends on MODULES
+ depends on MODULES || !KPROBES_USE_MODULE_ALLOC
depends on HAVE_KPROBES
select KALLSYMS
select TASKS_RCU if PREEMPTION
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index fa2ee4e59eca2..7c2f0b504cdcb 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -1582,6 +1582,7 @@ 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) {
@@ -1605,6 +1606,8 @@ static int check_kprobe_address_safe(struct kprobe *p,
ret = -ENOENT;
}
}
+#endif
+
out:
preempt_enable();
jump_label_unlock();
@@ -2484,6 +2487,7 @@ int kprobe_add_area_blacklist(unsigned long start, unsigned long end)
return 0;
}
+#ifdef CONFIG_MODULES
/* Remove all symbols in given area from kprobe blacklist */
static void kprobe_remove_area_blacklist(unsigned long start, unsigned long end)
{
@@ -2501,6 +2505,7 @@ static void kprobe_remove_ksym_blacklist(unsigned long entry)
{
kprobe_remove_area_blacklist(entry, entry + 1);
}
+#endif /* CONFIG_MODULES */
int __weak arch_kprobe_get_kallsym(unsigned int *symnum, unsigned long *value,
char *type, char *sym)
@@ -2566,6 +2571,7 @@ static int __init populate_kprobe_blacklist(unsigned long *start,
return ret ? : arch_populate_kprobe_blacklist();
}
+#ifdef CONFIG_MODULES
static void add_module_kprobe_blacklist(struct module *mod)
{
unsigned long start, end;
@@ -2662,6 +2668,9 @@ 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 +2735,8 @@ 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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