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Steven Rostedt (Red Hat) authored
In __ftrace_replace_code(), when converting the call to a nop in a function it needs to compare against the "curr" (current) value of the ftrace ops, and not the "new" one. It currently does not affect x86 which is the only arch to do the trampolines with function graph tracer, but when other archs that do depend on this code implement the function graph trampoline, it can crash. Here's an example when ARM uses the trampolines (in the future): ------------[ cut here ]------------ WARNING: CPU: 0 PID: 9 at kernel/trace/ftrace.c:1716 ftrace_bug+0x17c/0x1f4() Modules linked in: omap_rng rng_core ipv6 CPU: 0 PID: 9 Comm: migration/0 Not tainted 3.16.0-test-10959-gf0094b28-dirty #52 [<c02188f4>] (unwind_backtrace) from [<c021343c>] (show_stack+0x20/0x24) [<c021343c>] (show_stack) from [<c095a674>] (dump_stack+0x78/0x94) [<c095a674>] (dump_stack) from [<c02532a0>] (warn_slowpath_common+0x7c/0x9c) [<c02532a0>] (warn_slowpath_common) from [<c02532ec>] (warn_slowpath_null+0x2c/0x34) [<c02532ec>] (warn_slowpath_null) from [<c02cbac4>] (ftrace_bug+0x17c/0x1f4) [<c02cbac4>] (ftrace_bug) from [<c02cc44c>] (ftrace_replace_code+0x80/0x9c) [<c02cc44c>] (ftrace_replace_code) from [<c02cc658>] (ftrace_modify_all_code+0xb8/0x164) [<c02cc658>] (ftrace_modify_all_code) from [<c02cc718>] (__ftrace_modify_code+0x14/0x1c) [<c02cc718>] (__ftrace_modify_code) from [<c02c7244>] (multi_cpu_stop+0xf4/0x134) [<c02c7244>] (multi_cpu_stop) from [<c02c6e90>] (cpu_stopper_thread+0x54/0x130) [<c02c6e90>] (cpu_stopper_thread) from [<c0271cd4>] (smpboot_thread_fn+0x1ac/0x1bc) [<c0271cd4>] (smpboot_thread_fn) from [<c026ddf0>] (kthread+0xe0/0xfc) [<c026ddf0>] (kthread) from [<c020f318>] (ret_from_fork+0x14/0x20) ---[ end trace dc9ce72c5b617d8f ]--- [ 65.047264] ftrace failed to modify [<c0208580>] asm_do_IRQ+0x10/0x1c [ 65.054070] actual: 85:1b:00:eb Fixes: 7413af1f "ftrace: Make get_ftrace_addr() and get_ftrace_addr_old() global" Signed-off-by:
Steven Rostedt <rostedt@goodmis.org>
39b5552c