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-rw-r--r--arch/Kconfig6
-rw-r--r--arch/x86/Kconfig1
-rw-r--r--arch/x86/include/asm/unwind.h6
-rw-r--r--arch/x86/kernel/stacktrace.c96
-rw-r--r--arch/x86/kernel/unwind_frame.c2
-rw-r--r--include/linux/stacktrace.h9
-rw-r--r--kernel/stacktrace.c12
7 files changed, 126 insertions, 6 deletions
diff --git a/arch/Kconfig b/arch/Kconfig
index cd211a14a88f..6ad00ad73459 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -713,6 +713,12 @@ config HAVE_STACK_VALIDATION
Architecture supports the 'objtool check' host tool command, which
performs compile-time stack metadata validation.
+config HAVE_RELIABLE_STACKTRACE
+ bool
+ help
+ Architecture has a save_stack_trace_tsk_reliable() function which
+ only returns a stack trace if it can guarantee the trace is reliable.
+
config HAVE_ARCH_HASH
bool
default n
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index cc98d5a294ee..2a26852c11b6 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -160,6 +160,7 @@ config X86
select HAVE_PERF_REGS
select HAVE_PERF_USER_STACK_DUMP
select HAVE_REGS_AND_STACK_ACCESS_API
+ select HAVE_RELIABLE_STACKTRACE if X86_64 && FRAME_POINTER && STACK_VALIDATION
select HAVE_STACK_VALIDATION if X86_64
select HAVE_SYSCALL_TRACEPOINTS
select HAVE_UNSTABLE_SCHED_CLOCK
diff --git a/arch/x86/include/asm/unwind.h b/arch/x86/include/asm/unwind.h
index 6fa75b17aec3..137e9cce2ab4 100644
--- a/arch/x86/include/asm/unwind.h
+++ b/arch/x86/include/asm/unwind.h
@@ -11,6 +11,7 @@ struct unwind_state {
unsigned long stack_mask;
struct task_struct *task;
int graph_idx;
+ bool error;
#ifdef CONFIG_FRAME_POINTER
unsigned long *bp, *orig_sp;
struct pt_regs *regs;
@@ -40,6 +41,11 @@ void unwind_start(struct unwind_state *state, struct task_struct *task,
__unwind_start(state, task, regs, first_frame);
}
+static inline bool unwind_error(struct unwind_state *state)
+{
+ return state->error;
+}
+
#ifdef CONFIG_FRAME_POINTER
static inline
diff --git a/arch/x86/kernel/stacktrace.c b/arch/x86/kernel/stacktrace.c
index 8e2b79b88e51..8dabd7bf1673 100644
--- a/arch/x86/kernel/stacktrace.c
+++ b/arch/x86/kernel/stacktrace.c
@@ -76,6 +76,101 @@ void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
}
EXPORT_SYMBOL_GPL(save_stack_trace_tsk);
+#ifdef CONFIG_HAVE_RELIABLE_STACKTRACE
+
+#define STACKTRACE_DUMP_ONCE(task) ({ \
+ static bool __section(.data.unlikely) __dumped; \
+ \
+ if (!__dumped) { \
+ __dumped = true; \
+ WARN_ON(1); \
+ show_stack(task, NULL); \
+ } \
+})
+
+static int __save_stack_trace_reliable(struct stack_trace *trace,
+ struct task_struct *task)
+{
+ struct unwind_state state;
+ struct pt_regs *regs;
+ unsigned long addr;
+
+ for (unwind_start(&state, task, NULL, NULL); !unwind_done(&state);
+ unwind_next_frame(&state)) {
+
+ regs = unwind_get_entry_regs(&state);
+ if (regs) {
+ /*
+ * Kernel mode registers on the stack indicate an
+ * in-kernel interrupt or exception (e.g., preemption
+ * or a page fault), which can make frame pointers
+ * unreliable.
+ */
+ if (!user_mode(regs))
+ return -EINVAL;
+
+ /*
+ * The last frame contains the user mode syscall
+ * pt_regs. Skip it and finish the unwind.
+ */
+ unwind_next_frame(&state);
+ if (!unwind_done(&state)) {
+ STACKTRACE_DUMP_ONCE(task);
+ return -EINVAL;
+ }
+ break;
+ }
+
+ addr = unwind_get_return_address(&state);
+
+ /*
+ * A NULL or invalid return address probably means there's some
+ * generated code which __kernel_text_address() doesn't know
+ * about.
+ */
+ if (!addr) {
+ STACKTRACE_DUMP_ONCE(task);
+ return -EINVAL;
+ }
+
+ if (save_stack_address(trace, addr, false))
+ return -EINVAL;
+ }
+
+ /* Check for stack corruption */
+ if (unwind_error(&state)) {
+ STACKTRACE_DUMP_ONCE(task);
+ return -EINVAL;
+ }
+
+ if (trace->nr_entries < trace->max_entries)
+ trace->entries[trace->nr_entries++] = ULONG_MAX;
+
+ return 0;
+}
+
+/*
+ * This function returns an error if it detects any unreliable features of the
+ * stack. Otherwise it guarantees that the stack trace is reliable.
+ *
+ * If the task is not 'current', the caller *must* ensure the task is inactive.
+ */
+int save_stack_trace_tsk_reliable(struct task_struct *tsk,
+ struct stack_trace *trace)
+{
+ int ret;
+
+ if (!try_get_task_stack(tsk))
+ return -EINVAL;
+
+ ret = __save_stack_trace_reliable(trace, tsk);
+
+ put_task_stack(tsk);
+
+ return ret;
+}
+#endif /* CONFIG_HAVE_RELIABLE_STACKTRACE */
+
/* Userspace stacktrace - based on kernel/trace/trace_sysprof.c */
struct stack_frame_user {
@@ -138,4 +233,3 @@ void save_stack_trace_user(struct stack_trace *trace)
if (trace->nr_entries < trace->max_entries)
trace->entries[trace->nr_entries++] = ULONG_MAX;
}
-
diff --git a/arch/x86/kernel/unwind_frame.c b/arch/x86/kernel/unwind_frame.c
index 478d15dbaee4..5ed43910e04b 100644
--- a/arch/x86/kernel/unwind_frame.c
+++ b/arch/x86/kernel/unwind_frame.c
@@ -225,6 +225,8 @@ bool unwind_next_frame(struct unwind_state *state)
return true;
bad_address:
+ state->error = true;
+
/*
* When unwinding a non-current task, the task might actually be
* running on another CPU, in which case it could be modifying its
diff --git a/include/linux/stacktrace.h b/include/linux/stacktrace.h
index 0a34489a46b6..4205f71a5f0e 100644
--- a/include/linux/stacktrace.h
+++ b/include/linux/stacktrace.h
@@ -18,6 +18,8 @@ extern void save_stack_trace_regs(struct pt_regs *regs,
struct stack_trace *trace);
extern void save_stack_trace_tsk(struct task_struct *tsk,
struct stack_trace *trace);
+extern int save_stack_trace_tsk_reliable(struct task_struct *tsk,
+ struct stack_trace *trace);
extern void print_stack_trace(struct stack_trace *trace, int spaces);
extern int snprint_stack_trace(char *buf, size_t size,
@@ -29,12 +31,13 @@ extern void save_stack_trace_user(struct stack_trace *trace);
# define save_stack_trace_user(trace) do { } while (0)
#endif
-#else
+#else /* !CONFIG_STACKTRACE */
# define save_stack_trace(trace) do { } while (0)
# define save_stack_trace_tsk(tsk, trace) do { } while (0)
# define save_stack_trace_user(trace) do { } while (0)
# define print_stack_trace(trace, spaces) do { } while (0)
# define snprint_stack_trace(buf, size, trace, spaces) do { } while (0)
-#endif
+# define save_stack_trace_tsk_reliable(tsk, trace) ({ -ENOSYS; })
+#endif /* CONFIG_STACKTRACE */
-#endif
+#endif /* __LINUX_STACKTRACE_H */
diff --git a/kernel/stacktrace.c b/kernel/stacktrace.c
index 9c15a9124e83..f8edee9c792d 100644
--- a/kernel/stacktrace.c
+++ b/kernel/stacktrace.c
@@ -54,8 +54,8 @@ int snprint_stack_trace(char *buf, size_t size,
EXPORT_SYMBOL_GPL(snprint_stack_trace);
/*
- * Architectures that do not implement save_stack_trace_tsk or
- * save_stack_trace_regs get this weak alias and a once-per-bootup warning
+ * Architectures that do not implement save_stack_trace_*()
+ * get these weak aliases and once-per-bootup warnings
* (whenever this facility is utilized - for example by procfs):
*/
__weak void
@@ -69,3 +69,11 @@ save_stack_trace_regs(struct pt_regs *regs, struct stack_trace *trace)
{
WARN_ONCE(1, KERN_INFO "save_stack_trace_regs() not implemented yet.\n");
}
+
+__weak int
+save_stack_trace_tsk_reliable(struct task_struct *tsk,
+ struct stack_trace *trace)
+{
+ WARN_ONCE(1, KERN_INFO "save_stack_tsk_reliable() not implemented yet.\n");
+ return -ENOSYS;
+}

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