[patch 7/7] stacktrace filtering for fault-injection capabilities

Akinobu Mita
2006-10-12T07:44:21Z

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From: Akinobu Mita <akinobu.mita@gmail.com>

This patch provides stacktrace filtering feature.
The stacktrace filter allows failing only for the caller you are
interested in.

stacktrace filter is enabled by setting the value of
/debugfs/*/stacktrace-depth more than 0.
and specify the range of the virtual address
by the /debugfs/*/address-start and /debugfs/*/address-end

Please see the example that demostrates how to inject slab allocation
failures only for a specific module
in Documentation/fault-injection/fault-injection.txt

Cc: Valdis.Kletnieks@vt.edu
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: Don Mullis <dwm@meer.net>

include/linux/fault-inject.h | 7 ++
lib/Kconfig.debug | 2
lib/fault-inject.c | 111 +++++++++++++++++++++++++++++++++++++++++++
3 files changed, 120 insertions(+)

Index: work-fault-inject/lib/fault-inject.c
===================================================================
--- work-fault-inject.orig/lib/fault-inject.c
+++ work-fault-inject/lib/fault-inject.c
@@ -6,6 +6,9 @@
#include <linux/fs.h>
#include <linux/module.h>
#include <linux/interrupt.h>
+#include <linux/unwind.h>
+#include <linux/stacktrace.h>
+#include <linux/kallsyms.h>
#include <linux/fault-inject.h>

int setup_fault_attr(struct fault_attr *attr, char *str)
@@ -64,6 +67,82 @@ static int fail_task(struct fault_attr *
return !in_interrupt() && task->make_it_fail;
}

+static int fail_any_address(struct fault_attr *attr)
+{
+ return (attr->address_start == 0 && attr->address_end == ULONG_MAX);
+}
+
+#ifdef CONFIG_STACK_UNWIND
+
+static asmlinkage int fail_stacktrace_callback(struct unwind_frame_info *info,
+ void *arg)
+{
+ int depth;
+ struct fault_attr *attr = arg;
+
+ for (depth = 0; depth < attr->stacktrace_depth
+ && unwind(info) == 0 && UNW_PC(info); depth++) {
+ if (arch_unw_user_mode(info))
+ break;
+ if (attr->address_start <= UNW_PC(info) &&
+ UNW_PC(info) < attr->address_end)
+ return 1;
+ }
+ return 0;
+}
+
+static int fail_stacktrace(struct fault_attr *attr)
+{
+ struct unwind_frame_info info;
+
+ return unwind_init_running(&info, fail_stacktrace_callback, attr);
+}
+
+#elif defined(CONFIG_STACKTRACE)
+
+#define MAX_STACK_TRACE_DEPTH 10
+
+static int fail_stacktrace(struct fault_attr *attr)
+{
+ struct stack_trace trace;
+ int depth = attr->stacktrace_depth;
+ unsigned long entries[MAX_STACK_TRACE_DEPTH];
+ int n;
+
+ if (depth == 0)
+ return 0;
+
+ trace.nr_entries = 0;
+ trace.entries = entries;
+ trace.max_entries = (depth < MAX_STACK_TRACE_DEPTH) ?
+ depth : MAX_STACK_TRACE_DEPTH;
+ trace.skip = 1;
+ trace.all_contexts = 0;
+
+ save_stack_trace(&trace, NULL);
+ for (n = 0; n < trace.nr_entries; n++)
+ if (attr->address_start <= entries[n] &&
+ entries[n] < attr->address_end)
+ return 1;
+ return 0;
+}
+
+#else
+
+static inline int fail_stacktrace(struct fault_attr *attr)
+{
+ static int firsttime = 1;
+
+ if (firsttime) {
+ printk(KERN_WARNING
+ "This architecture does not implement save_stack_trace()"\n");
+ firsttime = 0;
+ }
+ return 0;
+}
+
+#endif
+
/*
* This code is stolen from failmalloc-1.0
* http://www.nongnu.org/failmalloc/
@@ -74,6 +153,9 @@ int should_fail(struct fault_attr *attr,
if (attr->task_filter && !fail_task(attr, current))
return 0;

+ if (!fail_any_address(attr) && !fail_stacktrace(attr))
+ return 0;
+
if (atomic_read(&max_failures(attr)) == 0)
return 0;

@@ -168,6 +250,18 @@ void cleanup_fault_attr_entries(struct f
debugfs_remove(attr->entries.task_filter_file);
attr->entries.task_filter_file = NULL;
}
+ if (attr->entries.stacktrace_depth_file) {
+ debugfs_remove(attr->entries.stacktrace_depth_file);
+ attr->entries.stacktrace_depth_file = NULL;
+ }
+ if (attr->entries.address_start_file) {
+ debugfs_remove(attr->entries.address_start_file);
+ attr->entries.address_start_file = NULL;
+ }
+ if (attr->entries.address_end_file) {
+ debugfs_remove(attr->entries.address_end_file);
+ attr->entries.address_end_file = NULL;
+ }
debugfs_remove(attr->entries.dir);
attr->entries.dir = NULL;
}
@@ -217,6 +311,23 @@ int init_fault_attr_entries(struct fault
goto fail;
attr->entries.task_filter_file = file;

+ file = debugfs_create_ul("stacktrace-depth", mode, dir,
+ &attr->stacktrace_depth);
+ if (!file)
+ goto fail;
+ attr->entries.stacktrace_depth_file = file;
+
+ file = debugfs_create_ul("address-start", mode, dir,
+ &attr->address_start);
+ if (!file)
+ goto fail;
+ attr->entries.address_start_file = file;
+
+ file = debugfs_create_ul("address-end", mode, dir, &attr->address_end);
+ if (!file)
+ goto fail;
+ attr->entries.address_end_file = file;
+
return 0;
fail:
cleanup_fault_attr_entries(attr);
Index: work-fault-inject/include/linux/fault-inject.h
===================================================================
--- work-fault-inject.orig/include/linux/fault-inject.h
+++ work-fault-inject/include/linux/fault-inject.h
@@ -18,6 +18,9 @@ struct fault_attr {
atomic_t space;
unsigned long verbose;
u32 task_filter;
+ unsigned long stacktrace_depth;
+ unsigned long address_start;
+ unsigned long address_end;

unsigned long count;

@@ -32,6 +35,9 @@ struct fault_attr {
struct dentry *space_file;
struct dentry *verbose_file;
struct dentry *task_filter_file;
+ struct dentry *stacktrace_depth_file;
+ struct dentry *address_start_file;
+ struct dentry *address_end_file;
} entries;

#endif
@@ -41,6 +47,7 @@ struct fault_attr {
struct fault_attr name = { \
.interval = 1, \
.times = ATOMIC_INIT(1), \
+ .address_end = ULONG_MAX, \
}

int setup_fault_attr(struct fault_attr *attr, char *str);
Index: work-fault-inject/lib/Kconfig.debug
===================================================================
--- work-fault-inject.orig/lib/Kconfig.debug
+++ work-fault-inject/lib/Kconfig.debug
@@ -472,6 +472,8 @@ config LKDTM

config FAULT_INJECTION
bool
+ select STACKTRACE
+ select FRAME_POINTER

config FAILSLAB
bool "fault-injection capabilitiy for kmalloc"

--