From 6be7fa3c74d1e0cd50f2157b5c1524f152bf641e Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (VMware)" Date: Mon, 22 Jan 2018 22:32:51 -0500 Subject: ftrace, orc, x86: Handle ftrace dynamically allocated trampolines The function tracer can create a dynamically allocated trampoline that is called by the function mcount or fentry hook that is used to call the function callback that is registered. The problem is that the orc undwinder will bail if it encounters one of these trampolines. This breaks the stack trace of function callbacks, which include the stack tracer and setting the stack trace for individual functions. Since these dynamic trampolines are basically copies of the static ftrace trampolines defined in ftrace_*.S, we do not need to create new orc entries for the dynamic trampolines. Finding the return address on the stack will be identical as the functions that were copied to create the dynamic trampolines. When encountering a ftrace dynamic trampoline, we can just use the orc entry of the ftrace static function that was copied for that trampoline. Signed-off-by: Steven Rostedt (VMware) --- include/linux/ftrace.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'include/linux') diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h index 2bab81951ced..3319df9727aa 100644 --- a/include/linux/ftrace.h +++ b/include/linux/ftrace.h @@ -332,6 +332,8 @@ extern int ftrace_text_reserved(const void *start, const void *end); extern int ftrace_nr_registered_ops(void); +struct ftrace_ops *ftrace_ops_trampoline(unsigned long addr); + bool is_ftrace_trampoline(unsigned long addr); /* -- cgit v1.2.3 From 5132ede0fe8092b043dae09a7cc32b8ae7272baa Mon Sep 17 00:00:00 2001 From: Greg Kroah-Hartman Date: Wed, 24 Jan 2018 15:28:17 +0100 Subject: Revert "module: Add retpoline tag to VERMAGIC" This reverts commit 6cfb521ac0d5b97470883ff9b7facae264b7ab12. Turns out distros do not want to make retpoline as part of their "ABI", so this patch should not have been merged. Sorry Andi, this was my fault, I suggested it when your original patch was the "correct" way of doing this instead. Reported-by: Jiri Kosina Fixes: 6cfb521ac0d5 ("module: Add retpoline tag to VERMAGIC") Acked-by: Andi Kleen Cc: Thomas Gleixner Cc: David Woodhouse Cc: rusty@rustcorp.com.au Cc: arjan.van.de.ven@intel.com Cc: jeyu@kernel.org Cc: stable Signed-off-by: Greg Kroah-Hartman Signed-off-by: Linus Torvalds --- include/linux/vermagic.h | 8 +------- 1 file changed, 1 insertion(+), 7 deletions(-) (limited to 'include/linux') diff --git a/include/linux/vermagic.h b/include/linux/vermagic.h index 853291714ae0..bae807eb2933 100644 --- a/include/linux/vermagic.h +++ b/include/linux/vermagic.h @@ -31,17 +31,11 @@ #else #define MODULE_RANDSTRUCT_PLUGIN #endif -#ifdef RETPOLINE -#define MODULE_VERMAGIC_RETPOLINE "retpoline " -#else -#define MODULE_VERMAGIC_RETPOLINE "" -#endif #define VERMAGIC_STRING \ UTS_RELEASE " " \ MODULE_VERMAGIC_SMP MODULE_VERMAGIC_PREEMPT \ MODULE_VERMAGIC_MODULE_UNLOAD MODULE_VERMAGIC_MODVERSIONS \ MODULE_ARCH_VERMAGIC \ - MODULE_RANDSTRUCT_PLUGIN \ - MODULE_VERMAGIC_RETPOLINE + MODULE_RANDSTRUCT_PLUGIN -- cgit v1.2.3