// SPDX-License-Identifier: GPL-2.0 /* * Copyright (C) 2022 Loongson Technology Corporation Limited */ #include <linux/init.h> #include <linux/ftrace.h> #include <linux/syscalls.h> #include <linux/uaccess.h> #include <asm/asm.h> #include <asm/asm-offsets.h> #include <asm/cacheflush.h> #include <asm/inst.h> #include <asm/loongarch.h> #include <asm/syscall.h> #include <asm-generic/sections.h> #ifdef CONFIG_FUNCTION_GRAPH_TRACER /* * As `call _mcount` follows LoongArch psABI, ra-saved operation and * stack operation can be found before this insn. */ static int ftrace_get_parent_ra_addr(unsigned long insn_addr, int *ra_off) { int limit = 32; union loongarch_instruction *insn; insn = (union loongarch_instruction *)insn_addr; do { insn--; limit--; if (is_ra_save_ins(insn)) *ra_off = -((1 << 12) - insn->reg2i12_format.immediate); } while (!is_stack_alloc_ins(insn) && limit); if (!limit) return -EINVAL; return 0; } void prepare_ftrace_return(unsigned long self_addr, unsigned long callsite_sp, unsigned long old) { int ra_off; unsigned long return_hooker = (unsigned long)&return_to_handler; if (unlikely(ftrace_graph_is_dead())) return; if (unlikely(atomic_read(¤t->tracing_graph_pause))) return; if (ftrace_get_parent_ra_addr(self_addr, &ra_off)) goto out; if (!function_graph_enter(old, self_addr, 0, NULL)) *(unsigned long *)(callsite_sp + ra_off) = return_hooker; return; out: ftrace_graph_stop(); WARN_ON(1); } #endif /* CONFIG_FUNCTION_GRAPH_TRACER */