diff options
Diffstat (limited to 'arch/loongarch/kernel/ftrace_dyn.c')
| -rw-r--r-- | arch/loongarch/kernel/ftrace_dyn.c | 273 |
1 files changed, 273 insertions, 0 deletions
diff --git a/arch/loongarch/kernel/ftrace_dyn.c b/arch/loongarch/kernel/ftrace_dyn.c new file mode 100644 index 000000000000..0f07591cab30 --- /dev/null +++ b/arch/loongarch/kernel/ftrace_dyn.c @@ -0,0 +1,273 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Based on arch/arm64/kernel/ftrace.c + * + * Copyright (C) 2022 Loongson Technology Corporation Limited + */ + +#include <linux/ftrace.h> +#include <linux/uaccess.h> + +#include <asm/inst.h> +#include <asm/module.h> + +static int ftrace_modify_code(unsigned long pc, u32 old, u32 new, bool validate) +{ + u32 replaced; + + if (validate) { + if (larch_insn_read((void *)pc, &replaced)) + return -EFAULT; + + if (replaced != old) + return -EINVAL; + } + + if (larch_insn_patch_text((void *)pc, new)) + return -EPERM; + + return 0; +} + +#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS + +#ifdef CONFIG_MODULES +static inline int __get_mod(struct module **mod, unsigned long addr) +{ + preempt_disable(); + *mod = __module_text_address(addr); + preempt_enable(); + + if (WARN_ON(!(*mod))) + return -EINVAL; + + return 0; +} + +static struct plt_entry *get_ftrace_plt(struct module *mod, unsigned long addr) +{ + struct plt_entry *plt = mod->arch.ftrace_trampolines; + + if (addr == FTRACE_ADDR) + return &plt[FTRACE_PLT_IDX]; + if (addr == FTRACE_REGS_ADDR && + IS_ENABLED(CONFIG_DYNAMIC_FTRACE_WITH_REGS)) + return &plt[FTRACE_REGS_PLT_IDX]; + + return NULL; +} + +static unsigned long get_plt_addr(struct module *mod, unsigned long addr) +{ + struct plt_entry *plt; + + plt = get_ftrace_plt(mod, addr); + if (!plt) { + pr_err("ftrace: no module PLT for %ps\n", (void *)addr); + return -EINVAL; + } + + return (unsigned long)plt; +} +#endif + +int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr, unsigned long addr) +{ + u32 old, new; + unsigned long pc; + long offset __maybe_unused; + + pc = rec->ip + LOONGARCH_INSN_SIZE; + +#ifdef CONFIG_MODULES + offset = (long)pc - (long)addr; + + if (offset < -SZ_128M || offset >= SZ_128M) { + int ret; + struct module *mod; + + ret = __get_mod(&mod, pc); + if (ret) + return ret; + + addr = get_plt_addr(mod, addr); + + old_addr = get_plt_addr(mod, old_addr); + } +#endif + + new = larch_insn_gen_bl(pc, addr); + old = larch_insn_gen_bl(pc, old_addr); + + return ftrace_modify_code(pc, old, new, true); +} + +#endif /* CONFIG_DYNAMIC_FTRACE_WITH_REGS */ + +int ftrace_update_ftrace_func(ftrace_func_t func) +{ + u32 new; + unsigned long pc; + + pc = (unsigned long)&ftrace_call; + new = larch_insn_gen_bl(pc, (unsigned long)func); + + return ftrace_modify_code(pc, 0, new, false); +} + +/* + * The compiler has inserted 2 NOPs before the regular function prologue. + * T series registers are available and safe because of LoongArch's psABI. + * + * At runtime, we can replace nop with bl to enable ftrace call and replace bl + * with nop to disable ftrace call. The bl requires us to save the original RA + * value, so it saves RA at t0 here. + * + * Details are: + * + * | Compiled | Disabled | Enabled | + * +------------+------------------------+------------------------+ + * | nop | move t0, ra | move t0, ra | + * | nop | nop | bl ftrace_caller | + * | func_body | func_body | func_body | + * + * The RA value will be recovered by ftrace_regs_entry, and restored into RA + * before returning to the regular function prologue. When a function is not + * being traced, the "move t0, ra" is not harmful. + */ + +int ftrace_init_nop(struct module *mod, struct dyn_ftrace *rec) +{ + u32 old, new; + unsigned long pc; + + pc = rec->ip; + old = larch_insn_gen_nop(); + new = larch_insn_gen_move(LOONGARCH_GPR_T0, LOONGARCH_GPR_RA); + + return ftrace_modify_code(pc, old, new, true); +} + +int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) +{ + u32 old, new; + unsigned long pc; + long offset __maybe_unused; + + pc = rec->ip + LOONGARCH_INSN_SIZE; + +#ifdef CONFIG_MODULES + offset = (long)pc - (long)addr; + + if (offset < -SZ_128M || offset >= SZ_128M) { + int ret; + struct module *mod; + + ret = __get_mod(&mod, pc); + if (ret) + return ret; + + addr = get_plt_addr(mod, addr); + } +#endif + + old = larch_insn_gen_nop(); + new = larch_insn_gen_bl(pc, addr); + + return ftrace_modify_code(pc, old, new, true); +} + +int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec, unsigned long addr) +{ + u32 old, new; + unsigned long pc; + long offset __maybe_unused; + + pc = rec->ip + LOONGARCH_INSN_SIZE; + +#ifdef CONFIG_MODULES + offset = (long)pc - (long)addr; + + if (offset < -SZ_128M || offset >= SZ_128M) { + int ret; + struct module *mod; + + ret = __get_mod(&mod, pc); + if (ret) + return ret; + + addr = get_plt_addr(mod, addr); + } +#endif + + new = larch_insn_gen_nop(); + old = larch_insn_gen_bl(pc, addr); + + return ftrace_modify_code(pc, old, new, true); +} + +void arch_ftrace_update_code(int command) +{ + command |= FTRACE_MAY_SLEEP; + ftrace_modify_all_code(command); +} + +int __init ftrace_dyn_arch_init(void) +{ + return 0; +} + +#ifdef CONFIG_FUNCTION_GRAPH_TRACER +void prepare_ftrace_return(unsigned long self_addr, unsigned long *parent) +{ + unsigned long old; + unsigned long return_hooker = (unsigned long)&return_to_handler; + + if (unlikely(atomic_read(¤t->tracing_graph_pause))) + return; + + old = *parent; + + if (!function_graph_enter(old, self_addr, 0, parent)) + *parent = return_hooker; +} + +#ifdef CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS +void ftrace_graph_func(unsigned long ip, unsigned long parent_ip, + struct ftrace_ops *op, struct ftrace_regs *fregs) +{ + struct pt_regs *regs = &fregs->regs; + unsigned long *parent = (unsigned long *)®s->regs[1]; + + prepare_ftrace_return(ip, (unsigned long *)parent); +} +#else +static int ftrace_modify_graph_caller(bool enable) +{ + u32 branch, nop; + unsigned long pc, func; + extern void ftrace_graph_call(void); + + pc = (unsigned long)&ftrace_graph_call; + func = (unsigned long)&ftrace_graph_caller; + + nop = larch_insn_gen_nop(); + branch = larch_insn_gen_b(pc, func); + + if (enable) + return ftrace_modify_code(pc, nop, branch, true); + else + return ftrace_modify_code(pc, branch, nop, true); +} + +int ftrace_enable_ftrace_graph_caller(void) +{ + return ftrace_modify_graph_caller(true); +} + +int ftrace_disable_ftrace_graph_caller(void) +{ + return ftrace_modify_graph_caller(false); +} +#endif /* CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS */ +#endif /* CONFIG_FUNCTION_GRAPH_TRACER */ |