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authorSteven Rostedt (Red Hat) <rostedt@goodmis.org>2014-11-18 21:14:11 -0500
committerSteven Rostedt <rostedt@goodmis.org>2014-11-19 15:25:26 -0500
commitaec0be2d6e9f02dbef41ee54854c2e003e55c23e (patch)
treed99c09ba4247724e467ab497f2184068a64ef63b /include/linux/ftrace.h
parent9960efeb80f73bd073483dab0855ee0ddc27085c (diff)
downloadop-kernel-dev-aec0be2d6e9f02dbef41ee54854c2e003e55c23e.zip
op-kernel-dev-aec0be2d6e9f02dbef41ee54854c2e003e55c23e.tar.gz
ftrace/x86/extable: Add is_ftrace_trampoline() function
Stack traces that happen from function tracing check if the address on the stack is a __kernel_text_address(). That is, is the address kernel code. This calls core_kernel_text() which returns true if the address is part of the builtin kernel code. It also calls is_module_text_address() which returns true if the address belongs to module code. But what is missing is ftrace dynamically allocated trampolines. These trampolines are allocated for individual ftrace_ops that call the ftrace_ops callback functions directly. But if they do a stack trace, the code checking the stack wont detect them as they are neither core kernel code nor module address space. Adding another field to ftrace_ops that also stores the size of the trampoline assigned to it we can create a new function called is_ftrace_trampoline() that returns true if the address is a dynamically allocate ftrace trampoline. Note, it ignores trampolines that are not dynamically allocated as they will return true with the core_kernel_text() function. Link: http://lkml.kernel.org/r/20141119034829.497125839@goodmis.org Cc: Ingo Molnar <mingo@redhat.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Acked-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Diffstat (limited to 'include/linux/ftrace.h')
-rw-r--r--include/linux/ftrace.h8
1 files changed, 8 insertions, 0 deletions
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index 619e37c..7b2616f 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -150,6 +150,7 @@ struct ftrace_ops {
struct ftrace_ops_hash *func_hash;
struct ftrace_ops_hash old_hash;
unsigned long trampoline;
+ unsigned long trampoline_size;
#endif
};
@@ -297,6 +298,8 @@ extern int ftrace_text_reserved(const void *start, const void *end);
extern int ftrace_nr_registered_ops(void);
+bool is_ftrace_trampoline(unsigned long addr);
+
/*
* The dyn_ftrace record's flags field is split into two parts.
* the first part which is '0-FTRACE_REF_MAX' is a counter of
@@ -596,6 +599,11 @@ static inline ssize_t ftrace_notrace_write(struct file *file, const char __user
size_t cnt, loff_t *ppos) { return -ENODEV; }
static inline int
ftrace_regex_release(struct inode *inode, struct file *file) { return -ENODEV; }
+
+static inline bool is_ftrace_trampoline(unsigned long addr)
+{
+ return false;
+}
#endif /* CONFIG_DYNAMIC_FTRACE */
/* totally disable ftrace - can not re-enable after this */
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