path: root/kernel/extable.c
diff options
authorSteven Rostedt (Red Hat) <>2014-11-18 21:14:11 -0500
committerSteven Rostedt <>2014-11-19 15:25:26 -0500
commitaec0be2d6e9f02dbef41ee54854c2e003e55c23e (patch)
treed99c09ba4247724e467ab497f2184068a64ef63b /kernel/extable.c
parent9960efeb80f73bd073483dab0855ee0ddc27085c (diff)
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: Cc: Ingo Molnar <> Cc: "H. Peter Anvin" <> Acked-by: Thomas Gleixner <> Signed-off-by: Steven Rostedt <>
Diffstat (limited to 'kernel/extable.c')
1 files changed, 6 insertions, 1 deletions
diff --git a/kernel/extable.c b/kernel/extable.c
index d8a6446adbcb..c98f926277a8 100644
--- a/kernel/extable.c
+++ b/kernel/extable.c
@@ -18,6 +18,7 @@
#include <linux/ftrace.h>
#include <linux/memory.h>
#include <linux/module.h>
+#include <linux/ftrace.h>
#include <linux/mutex.h>
#include <linux/init.h>
@@ -102,6 +103,8 @@ int __kernel_text_address(unsigned long addr)
return 1;
if (is_module_text_address(addr))
return 1;
+ if (is_ftrace_trampoline(addr))
+ return 1;
* There might be init symbols in saved stacktraces.
* Give those symbols a chance to be printed in
@@ -119,7 +122,9 @@ int kernel_text_address(unsigned long addr)
if (core_kernel_text(addr))
return 1;
- return is_module_text_address(addr);
+ if (is_module_text_address(addr))
+ return 1;
+ return is_ftrace_trampoline(addr);