From ee3e2469b3463d28ca4cde20e0283319ac6a562d Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Thu, 15 Sep 2022 13:11:37 +0200 Subject: x86/ftrace: Make it call depth tracking aware Since ftrace has trampolines, don't use thunks for the __fentry__ site but instead require that every function called from there includes accounting. This very much includes all the direct-call functions. Additionally, ftrace uses ROP tricks in two places: - return_to_handler(), and - ftrace_regs_caller() when pt_regs->orig_ax is set by a direct-call. return_to_handler() already uses a retpoline to replace an indirect-jump to defeat IBT, since this is a jump-type retpoline, make sure there is no accounting done and ALTERNATIVE the RET into a ret. ftrace_regs_caller() does much the same and gets the same treatment. Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Thomas Gleixner Signed-off-by: Peter Zijlstra (Intel) Link: https://lore.kernel.org/r/20220915111148.927545073@infradead.org --- samples/ftrace/ftrace-direct-modify.c | 3 +++ 1 file changed, 3 insertions(+) (limited to 'samples/ftrace/ftrace-direct-modify.c') diff --git a/samples/ftrace/ftrace-direct-modify.c b/samples/ftrace/ftrace-direct-modify.c index 39146fa83e20..de5a0f67f320 100644 --- a/samples/ftrace/ftrace-direct-modify.c +++ b/samples/ftrace/ftrace-direct-modify.c @@ -3,6 +3,7 @@ #include #include #include +#include extern void my_direct_func1(void); extern void my_direct_func2(void); @@ -34,6 +35,7 @@ asm ( ASM_ENDBR " pushq %rbp\n" " movq %rsp, %rbp\n" + CALL_DEPTH_ACCOUNT " call my_direct_func1\n" " leave\n" " .size my_tramp1, .-my_tramp1\n" @@ -45,6 +47,7 @@ asm ( ASM_ENDBR " pushq %rbp\n" " movq %rsp, %rbp\n" + CALL_DEPTH_ACCOUNT " call my_direct_func2\n" " leave\n" ASM_RET -- cgit