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09e679c28a
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 <xiehuan09@gmail.com> Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn> Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
338 lines
7.5 KiB
C
338 lines
7.5 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Based on arch/arm64/kernel/ftrace.c
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*
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* Copyright (C) 2022 Loongson Technology Corporation Limited
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*/
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#include <linux/ftrace.h>
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#include <linux/kprobes.h>
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#include <linux/uaccess.h>
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#include <asm/inst.h>
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#include <asm/module.h>
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static int ftrace_modify_code(unsigned long pc, u32 old, u32 new, bool validate)
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{
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u32 replaced;
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if (validate) {
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if (larch_insn_read((void *)pc, &replaced))
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return -EFAULT;
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if (replaced != old)
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return -EINVAL;
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}
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if (larch_insn_patch_text((void *)pc, new))
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return -EPERM;
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return 0;
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}
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#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
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#ifdef CONFIG_MODULES
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static inline int __get_mod(struct module **mod, unsigned long addr)
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{
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preempt_disable();
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*mod = __module_text_address(addr);
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preempt_enable();
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if (WARN_ON(!(*mod)))
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return -EINVAL;
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return 0;
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}
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static struct plt_entry *get_ftrace_plt(struct module *mod, unsigned long addr)
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{
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struct plt_entry *plt = mod->arch.ftrace_trampolines;
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if (addr == FTRACE_ADDR)
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return &plt[FTRACE_PLT_IDX];
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if (addr == FTRACE_REGS_ADDR &&
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IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS))
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return &plt[FTRACE_REGS_PLT_IDX];
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return NULL;
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}
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static unsigned long get_plt_addr(struct module *mod, unsigned long addr)
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{
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struct plt_entry *plt;
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plt = get_ftrace_plt(mod, addr);
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if (!plt) {
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pr_err("ftrace: no module PLT for %ps\n", (void *)addr);
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return -EINVAL;
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}
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return (unsigned long)plt;
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}
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#endif
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int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr, unsigned long addr)
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{
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u32 old, new;
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unsigned long pc;
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long offset __maybe_unused;
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pc = rec->ip + LOONGARCH_INSN_SIZE;
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#ifdef CONFIG_MODULES
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offset = (long)pc - (long)addr;
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if (offset < -SZ_128M || offset >= SZ_128M) {
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int ret;
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struct module *mod;
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ret = __get_mod(&mod, pc);
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if (ret)
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return ret;
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addr = get_plt_addr(mod, addr);
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old_addr = get_plt_addr(mod, old_addr);
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}
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#endif
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new = larch_insn_gen_bl(pc, addr);
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old = larch_insn_gen_bl(pc, old_addr);
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return ftrace_modify_code(pc, old, new, true);
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}
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#endif /* CONFIG_DYNAMIC_FTRACE_WITH_REGS */
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int ftrace_update_ftrace_func(ftrace_func_t func)
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{
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u32 new;
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unsigned long pc;
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pc = (unsigned long)&ftrace_call;
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new = larch_insn_gen_bl(pc, (unsigned long)func);
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return ftrace_modify_code(pc, 0, new, false);
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}
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/*
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* The compiler has inserted 2 NOPs before the regular function prologue.
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* T series registers are available and safe because of LoongArch's psABI.
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*
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* At runtime, we can replace nop with bl to enable ftrace call and replace bl
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* with nop to disable ftrace call. The bl requires us to save the original RA
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* value, so it saves RA at t0 here.
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*
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* Details are:
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*
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* | Compiled | Disabled | Enabled |
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* +------------+------------------------+------------------------+
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* | nop | move t0, ra | move t0, ra |
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* | nop | nop | bl ftrace_caller |
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* | func_body | func_body | func_body |
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*
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* The RA value will be recovered by ftrace_regs_entry, and restored into RA
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* before returning to the regular function prologue. When a function is not
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* being traced, the "move t0, ra" is not harmful.
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*/
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int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec)
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{
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u32 old, new;
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unsigned long pc;
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pc = rec->ip;
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old = larch_insn_gen_nop();
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new = larch_insn_gen_move(LOONGARCH_GPR_T0, LOONGARCH_GPR_RA);
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return ftrace_modify_code(pc, old, new, true);
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}
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int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
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{
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u32 old, new;
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unsigned long pc;
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long offset __maybe_unused;
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pc = rec->ip + LOONGARCH_INSN_SIZE;
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#ifdef CONFIG_MODULES
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offset = (long)pc - (long)addr;
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if (offset < -SZ_128M || offset >= SZ_128M) {
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int ret;
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struct module *mod;
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ret = __get_mod(&mod, pc);
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if (ret)
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return ret;
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addr = get_plt_addr(mod, addr);
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}
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#endif
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old = larch_insn_gen_nop();
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new = larch_insn_gen_bl(pc, addr);
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return ftrace_modify_code(pc, old, new, true);
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}
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int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec, unsigned long addr)
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{
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u32 old, new;
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unsigned long pc;
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long offset __maybe_unused;
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pc = rec->ip + LOONGARCH_INSN_SIZE;
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#ifdef CONFIG_MODULES
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offset = (long)pc - (long)addr;
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if (offset < -SZ_128M || offset >= SZ_128M) {
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int ret;
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struct module *mod;
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ret = __get_mod(&mod, pc);
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if (ret)
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return ret;
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addr = get_plt_addr(mod, addr);
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}
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#endif
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new = larch_insn_gen_nop();
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old = larch_insn_gen_bl(pc, addr);
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return ftrace_modify_code(pc, old, new, true);
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}
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void arch_ftrace_update_code(int command)
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{
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command |= FTRACE_MAY_SLEEP;
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ftrace_modify_all_code(command);
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}
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int __init ftrace_dyn_arch_init(void)
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{
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return 0;
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}
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#ifdef CONFIG_FUNCTION_GRAPH_TRACER
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void prepare_ftrace_return(unsigned long self_addr, unsigned long *parent)
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{
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unsigned long old;
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unsigned long return_hooker = (unsigned long)&return_to_handler;
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if (unlikely(atomic_read(¤t->tracing_graph_pause)))
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return;
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old = *parent;
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if (!function_graph_enter(old, self_addr, 0, parent))
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*parent = return_hooker;
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}
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#ifdef CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS
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void ftrace_graph_func(unsigned long ip, unsigned long parent_ip,
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struct ftrace_ops *op, struct ftrace_regs *fregs)
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{
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struct pt_regs *regs = &fregs->regs;
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unsigned long *parent = (unsigned long *)®s->regs[1];
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prepare_ftrace_return(ip, (unsigned long *)parent);
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}
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#else
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static int ftrace_modify_graph_caller(bool enable)
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{
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u32 branch, nop;
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unsigned long pc, func;
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extern void ftrace_graph_call(void);
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pc = (unsigned long)&ftrace_graph_call;
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func = (unsigned long)&ftrace_graph_caller;
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nop = larch_insn_gen_nop();
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branch = larch_insn_gen_b(pc, func);
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if (enable)
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return ftrace_modify_code(pc, nop, branch, true);
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else
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return ftrace_modify_code(pc, branch, nop, true);
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}
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int ftrace_enable_ftrace_graph_caller(void)
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{
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return ftrace_modify_graph_caller(true);
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}
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int ftrace_disable_ftrace_graph_caller(void)
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{
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return ftrace_modify_graph_caller(false);
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}
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#endif /* CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS */
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#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
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#ifdef CONFIG_KPROBES_ON_FTRACE
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/* Ftrace callback handler for kprobes -- called under preepmt disabled */
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void kprobe_ftrace_handler(unsigned long ip, unsigned long parent_ip,
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struct ftrace_ops *ops, struct ftrace_regs *fregs)
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{
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int bit;
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struct pt_regs *regs;
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struct kprobe *p;
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struct kprobe_ctlblk *kcb;
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bit = ftrace_test_recursion_trylock(ip, parent_ip);
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if (bit < 0)
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return;
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p = get_kprobe((kprobe_opcode_t *)ip);
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if (unlikely(!p) || kprobe_disabled(p))
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goto out;
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regs = ftrace_get_regs(fregs);
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if (!regs)
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goto out;
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kcb = get_kprobe_ctlblk();
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if (kprobe_running()) {
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kprobes_inc_nmissed_count(p);
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} else {
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unsigned long orig_ip = instruction_pointer(regs);
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instruction_pointer_set(regs, ip);
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__this_cpu_write(current_kprobe, p);
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kcb->kprobe_status = KPROBE_HIT_ACTIVE;
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if (!p->pre_handler || !p->pre_handler(p, regs)) {
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/*
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* Emulate singlestep (and also recover regs->csr_era)
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* as if there is a nop
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*/
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instruction_pointer_set(regs, (unsigned long)p->addr + MCOUNT_INSN_SIZE);
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if (unlikely(p->post_handler)) {
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kcb->kprobe_status = KPROBE_HIT_SSDONE;
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p->post_handler(p, regs, 0);
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}
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instruction_pointer_set(regs, orig_ip);
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}
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/*
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* If pre_handler returns !0, it changes regs->csr_era. We have to
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* skip emulating post_handler.
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*/
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__this_cpu_write(current_kprobe, NULL);
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}
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out:
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ftrace_test_recursion_unlock(bit);
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}
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NOKPROBE_SYMBOL(kprobe_ftrace_handler);
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int arch_prepare_kprobe_ftrace(struct kprobe *p)
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{
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p->ainsn.insn = NULL;
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return 0;
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}
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#endif /* CONFIG_KPROBES_ON_FTRACE */
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