@@ -12,6 +12,7 @@ enum {
struct error_injection_entry {
unsigned long addr;
+ unsigned long static_key_addr;
int etype;
};
@@ -25,16 +26,26 @@ struct pt_regs;
* 'Error Injectable Functions' section.
*/
#define ALLOW_ERROR_INJECTION(fname, _etype) \
-static struct error_injection_entry __used \
+static struct error_injection_entry __used __aligned(8) \
__section("_error_injection_whitelist") \
_eil_addr_##fname = { \
.addr = (unsigned long)fname, \
.etype = EI_ETYPE_##_etype, \
}
+#define ALLOW_ERROR_INJECTION_KEY(fname, _etype, key) \
+static struct error_injection_entry __used __aligned(8) \
+ __section("_error_injection_whitelist") \
+ _eil_addr_##fname = { \
+ .addr = (unsigned long)fname, \
+ .static_key_addr = (unsigned long)key, \
+ .etype = EI_ETYPE_##_etype, \
+ }
+
void override_function_with_return(struct pt_regs *regs);
#else
#define ALLOW_ERROR_INJECTION(fname, _etype)
+#define ALLOW_ERROR_INJECTION_KEY(fname, _etype, key)
static inline void override_function_with_return(struct pt_regs *regs) { }
#endif
@@ -248,7 +248,7 @@
#ifdef CONFIG_FUNCTION_ERROR_INJECTION
#define ERROR_INJECT_WHITELIST() \
- STRUCT_ALIGN(); \
+ . = ALIGN(8); \
BOUNDED_SECTION(_error_injection_whitelist)
#else
#define ERROR_INJECT_WHITELIST()
@@ -6,10 +6,13 @@
#include <linux/errno.h>
#include <asm-generic/error-injection.h>
+struct static_key;
+
#ifdef CONFIG_FUNCTION_ERROR_INJECTION
-extern bool within_error_injection_list(unsigned long addr);
-extern int get_injectable_error_type(unsigned long addr);
+bool within_error_injection_list(unsigned long addr);
+int get_injectable_error_type(unsigned long addr);
+struct static_key *get_injection_key(unsigned long addr);
#else /* !CONFIG_FUNCTION_ERROR_INJECTION */
@@ -23,6 +26,11 @@ static inline int get_injectable_error_type(unsigned long addr)
return -EOPNOTSUPP;
}
+static inline struct static_key *get_injection_key(unsigned long addr)
+{
+ return NULL;
+}
+
#endif
#endif /* _LINUX_ERROR_INJECTION_H */
@@ -27,6 +27,7 @@ struct fei_attr {
struct list_head list;
struct kprobe kp;
unsigned long retval;
+ struct static_key *key;
};
static DEFINE_MUTEX(fei_lock);
static LIST_HEAD(fei_attr_list);
@@ -67,6 +68,11 @@ static struct fei_attr *fei_attr_new(const char *sym, unsigned long addr)
attr->kp.pre_handler = fei_kprobe_handler;
attr->kp.post_handler = fei_post_handler;
attr->retval = adjust_error_retval(addr, 0);
+
+ attr->key = get_injection_key(addr);
+ if (IS_ERR(attr->key))
+ attr->key = NULL;
+
INIT_LIST_HEAD(&attr->list);
}
return attr;
@@ -218,6 +224,8 @@ static int fei_open(struct inode *inode, struct file *file)
static void fei_attr_remove(struct fei_attr *attr)
{
+ if (attr->key)
+ static_key_slow_dec(attr->key);
fei_debugfs_remove_attr(attr);
unregister_kprobe(&attr->kp);
list_del(&attr->list);
@@ -295,6 +303,8 @@ static ssize_t fei_write(struct file *file, const char __user *buffer,
fei_attr_free(attr);
goto out;
}
+ if (attr->key)
+ static_key_slow_inc(attr->key);
fei_debugfs_add_attr(attr);
list_add_tail(&attr->list, &fei_attr_list);
ret = count;
@@ -17,6 +17,7 @@ struct ei_entry {
struct list_head list;
unsigned long start_addr;
unsigned long end_addr;
+ struct static_key *key;
int etype;
void *priv;
};
@@ -54,6 +55,23 @@ int get_injectable_error_type(unsigned long addr)
return ei_type;
}
+struct static_key *get_injection_key(unsigned long addr)
+{
+ struct ei_entry *ent;
+ struct static_key *ei_key = ERR_PTR(-EINVAL);
+
+ mutex_lock(&ei_mutex);
+ list_for_each_entry(ent, &error_injection_list, list) {
+ if (addr >= ent->start_addr && addr < ent->end_addr) {
+ ei_key = ent->key;
+ break;
+ }
+ }
+ mutex_unlock(&ei_mutex);
+
+ return ei_key;
+}
+
/*
* Lookup and populate the error_injection_list.
*
@@ -86,6 +104,7 @@ static void populate_error_injection_list(struct error_injection_entry *start,
ent->start_addr = entry;
ent->end_addr = entry + size;
ent->etype = iter->etype;
+ ent->key = (struct static_key *) iter->static_key_addr;
ent->priv = priv;
INIT_LIST_HEAD(&ent->list);
list_add_tail(&ent->list, &error_injection_list);
Error injectable functions cannot be inlined and since some are called from hot paths, this incurs overhead even if no error injection is enabled for them. To avoid this overhead when disabled, allow the callsites of error injectable functions to put the calls behind a static key, which the framework can control when error injection is enabled or disabled for the function. Introduce a new ALLOW_ERROR_INJECTION_KEY() macro that adds a parameter with the static key's address, and store it in struct error_injection_entry. This new field has caused a mismatch when populating the injection list from the _error_injection_whitelist section using the current STRUCT_ALIGN(), so change the alignment to 8. During the population, copy the key's address also to struct ei_entry, and make it possible to retrieve it by get_injection_key(). Finally, make the processing of writes to the debugfs inject file enable the static key when the function is added to the injection list, and disable when removed. Signed-off-by: Vlastimil Babka <vbabka@suse.cz> --- include/asm-generic/error-injection.h | 13 ++++++++++++- include/asm-generic/vmlinux.lds.h | 2 +- include/linux/error-injection.h | 12 ++++++++++-- kernel/fail_function.c | 10 ++++++++++ lib/error-inject.c | 19 +++++++++++++++++++ 5 files changed, 52 insertions(+), 4 deletions(-)