From 09e679c28a4def4ea8d4f618503c1d55c355ae5c Mon Sep 17 00:00:00 2001 From: Tiezhu Yang Date: Sat, 25 Feb 2023 15:52:57 +0800 Subject: [PATCH] LoongArch: Add kprobes on ftrace support Add kprobe_ftrace_handler() and arch_prepare_kprobe_ftrace() to support kprobes on ftrace, the code is similar with x86 and riscv. Here is a simple example: # echo 'p:myprobe kernel_clone' > /sys/kernel/debug/tracing/kprobe_events # echo 'r:myretprobe kernel_clone $retval' >> /sys/kernel/debug/tracing/kprobe_events # echo 1 > /sys/kernel/debug/tracing/events/kprobes/myprobe/enable # echo 1 > /sys/kernel/debug/tracing/events/kprobes/myretprobe/enable # echo 1 > /sys/kernel/debug/tracing/tracing_on # cat /sys/kernel/debug/tracing/trace # tracer: nop # # entries-in-buffer/entries-written: 2/2 #P:4 # # _-----=> irqs-off/BH-disabled # / _----=> need-resched # | / _---=> hardirq/softirq # || / _--=> preempt-depth # ||| / _-=> migrate-disable # |||| / delay # TASK-PID CPU# ||||| TIMESTAMP FUNCTION # | | | ||||| | | bash-488 [002] ..... 2041.190681: myprobe: (kernel_clone+0x0/0x40c) bash-488 [002] ..... 2041.190788: myretprobe: (__do_sys_clone+0x84/0xb8 <- kernel_clone) arg1=0x200 Tested-by: Jeff Xie Signed-off-by: Tiezhu Yang Signed-off-by: Huacai Chen --- arch/loongarch/Kconfig | 1 + arch/loongarch/kernel/ftrace_dyn.c | 64 ++++++++++++++++++++++++++++++++++++++ 2 files changed, 65 insertions(+) diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig index d90bb47f1dc3..7fd51257e0ed 100644 --- a/arch/loongarch/Kconfig +++ b/arch/loongarch/Kconfig @@ -107,6 +107,7 @@ config LOONGARCH select HAVE_IRQ_EXIT_ON_IRQ_STACK select HAVE_IRQ_TIME_ACCOUNTING select HAVE_KPROBES + select HAVE_KPROBES_ON_FTRACE select HAVE_KRETPROBES select HAVE_MOD_ARCH_SPECIFIC select HAVE_NMI diff --git a/arch/loongarch/kernel/ftrace_dyn.c b/arch/loongarch/kernel/ftrace_dyn.c index 0f07591cab30..4a3ef8516ccc 100644 --- a/arch/loongarch/kernel/ftrace_dyn.c +++ b/arch/loongarch/kernel/ftrace_dyn.c @@ -6,6 +6,7 @@ */ #include +#include #include #include @@ -271,3 +272,66 @@ int ftrace_disable_ftrace_graph_caller(void) } #endif /* CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS */ #endif /* CONFIG_FUNCTION_GRAPH_TRACER */ + +#ifdef CONFIG_KPROBES_ON_FTRACE +/* Ftrace callback handler for kprobes -- called under preepmt disabled */ +void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip, + struct ftrace_ops *ops, struct ftrace_regs *fregs) +{ + int bit; + struct pt_regs *regs; + struct kprobe *p; + struct kprobe_ctlblk *kcb; + + bit = ftrace_test_recursion_trylock(ip, parent_ip); + if (bit < 0) + return; + + p = get_kprobe((kprobe_opcode_t *)ip); + if (unlikely(!p) || kprobe_disabled(p)) + goto out; + + regs = ftrace_get_regs(fregs); + if (!regs) + goto out; + + kcb = get_kprobe_ctlblk(); + if (kprobe_running()) { + kprobes_inc_nmissed_count(p); + } else { + unsigned long orig_ip = instruction_pointer(regs); + + instruction_pointer_set(regs, ip); + + __this_cpu_write(current_kprobe, p); + kcb->kprobe_status = KPROBE_HIT_ACTIVE; + if (!p->pre_handler || !p->pre_handler(p, regs)) { + /* + * Emulate singlestep (and also recover regs->csr_era) + * as if there is a nop + */ + instruction_pointer_set(regs, (unsigned long)p->addr + MCOUNT_INSN_SIZE); + if (unlikely(p->post_handler)) { + kcb->kprobe_status = KPROBE_HIT_SSDONE; + p->post_handler(p, regs, 0); + } + instruction_pointer_set(regs, orig_ip); + } + + /* + * If pre_handler returns !0, it changes regs->csr_era. We have to + * skip emulating post_handler. + */ + __this_cpu_write(current_kprobe, NULL); + } +out: + ftrace_test_recursion_unlock(bit); +} +NOKPROBE_SYMBOL(kprobe_ftrace_handler); + +int arch_prepare_kprobe_ftrace(struct kprobe *p) +{ + p->ainsn.insn = NULL; + return 0; +} +#endif /* CONFIG_KPROBES_ON_FTRACE */ -- 2.11.0