Allow architectures to implement handling of kprobes on function tracer call sites on their own, without depending on common code.
This patch removes the kprobes check if a kprobe is being placed on a function tracer call site and therefore gives full responsibility of handling this correctly to the architecture. This patch also introduces a user space visible change: if a kprobe is placed into the middle of an ftrace instruction the return value is changed from -EINVAL to -EILSEQ also for architectures which do not support KPROBES_ON_FTRACE. However in reality this change shouldn't matter at all. Signed-off-by: Heiko Carstens <heiko.carst...@de.ibm.com> --- arch/Kconfig | 8 ++++++++ kernel/kprobes.c | 36 +++++++++++++++++++++--------------- 2 files changed, 29 insertions(+), 15 deletions(-) diff --git a/arch/Kconfig b/arch/Kconfig index 05d7a8a458d5..e1a8e0edf03f 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -85,6 +85,14 @@ config KPROBES_ON_FTRACE passing of pt_regs to function tracing, then kprobes can optimize on top of function tracing. +config ARCH_HANDLES_KPROBES_ON_FTRACE + def_bool n + help + If an architecture can handle kprobes on function tracer call + sites on own, then this option should be selected. This option + removes the check which otherwise prevents to set kprobes on + function tracer call sites. + config UPROBES def_bool n select PERCPU_RWSEM diff --git a/kernel/kprobes.c b/kernel/kprobes.c index 3995f546d0f3..4b57fe9fbeb7 100644 --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -1410,28 +1410,34 @@ static inline int check_kprobe_rereg(struct kprobe *p) return ret; } -static int check_kprobe_address_safe(struct kprobe *p, - struct module **probed_mod) +static int check_ftrace_location(struct kprobe *p) { - int ret = 0; unsigned long ftrace_addr; - /* - * If the address is located on a ftrace nop, set the - * breakpoint to the following instruction. - */ ftrace_addr = ftrace_location((unsigned long)p->addr); - if (ftrace_addr) { -#ifdef CONFIG_KPROBES_ON_FTRACE - /* Given address is not on the instruction boundary */ - if ((unsigned long)p->addr != ftrace_addr) - return -EILSEQ; + if (!ftrace_addr) + return 0; + /* Given address is not on the instruction boundary */ + if ((unsigned long)p->addr != ftrace_addr) + return -EILSEQ; + /* If an architecture handles kprobes on ftrace, we're done */ + if (IS_ENABLED(CONFIG_ARCH_HANDLES_KPROBES_ON_FTRACE)) + return 0; + if (IS_ENABLED(CONFIG_KPROBES_ON_FTRACE)) { p->flags |= KPROBE_FLAG_FTRACE; -#else /* !CONFIG_KPROBES_ON_FTRACE */ - return -EINVAL; -#endif + return 0; } + return -EINVAL; +} + +static int check_kprobe_address_safe(struct kprobe *p, + struct module **probed_mod) +{ + int ret; + ret = check_ftrace_location(p); + if (ret) + return ret; jump_label_lock(); preempt_disable(); -- 1.8.5.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/