1/* SPDX-License-Identifier: GPL-2.0 */ 2/* Copyright (C) 2017 Andes Technology Corporation */ 3 4#include <linux/init.h> 5#include <linux/linkage.h> 6#include <linux/cfi_types.h> 7#include <linux/export.h> 8#include <asm/asm.h> 9#include <asm/csr.h> 10#include <asm/unistd.h> 11#include <asm/thread_info.h> 12#include <asm/asm-offsets.h> 13#include <asm/ftrace.h> 14 15#define ABI_SIZE_ON_STACK 80 16 17 .text 18 19 .macro SAVE_ABI_STATE 20 addi sp, sp, -16 21 REG_S s0, 0*SZREG(sp) 22 REG_S ra, 1*SZREG(sp) 23 addi s0, sp, 16 24 .endm 25 26 /* 27 * The call to ftrace_return_to_handler would overwrite the return 28 * register if a0 was not saved. 29 */ 30 .macro SAVE_RET_ABI_STATE 31 addi sp, sp, -ABI_SIZE_ON_STACK 32 REG_S ra, 1*SZREG(sp) 33 REG_S s0, 8*SZREG(sp) 34 REG_S a0, 10*SZREG(sp) 35 REG_S a1, 11*SZREG(sp) 36 addi s0, sp, ABI_SIZE_ON_STACK 37 .endm 38 39 .macro RESTORE_ABI_STATE 40 REG_L ra, 1*SZREG(sp) 41 REG_L s0, 0*SZREG(sp) 42 addi sp, sp, 16 43 .endm 44 45 .macro RESTORE_RET_ABI_STATE 46 REG_L ra, 1*SZREG(sp) 47 REG_L s0, 8*SZREG(sp) 48 REG_L a0, 10*SZREG(sp) 49 REG_L a1, 11*SZREG(sp) 50 addi sp, sp, ABI_SIZE_ON_STACK 51 .endm 52 53SYM_TYPED_FUNC_START(ftrace_stub) 54#ifdef CONFIG_DYNAMIC_FTRACE 55 .global _mcount 56 .set _mcount, ftrace_stub 57#endif 58 ret 59SYM_FUNC_END(ftrace_stub) 60 61#ifdef CONFIG_FUNCTION_GRAPH_TRACER 62SYM_TYPED_FUNC_START(ftrace_stub_graph) 63 ret 64SYM_FUNC_END(ftrace_stub_graph) 65 66SYM_FUNC_START(return_to_handler) 67/* 68 * On implementing the frame point test, the ideal way is to compare the 69 * s0 (frame pointer, if enabled) on entry and the sp (stack pointer) on return. 70 * However, the psABI of variable-length-argument functions does not allow this. 71 * 72 * So alternatively we check the *old* frame pointer position, that is, the 73 * value stored in -16(s0) on entry, and the s0 on return. 74 */ 75 SAVE_RET_ABI_STATE 76 mv a0, sp 77 call ftrace_return_to_handler 78 mv a2, a0 79 RESTORE_RET_ABI_STATE 80 jalr a2 81SYM_FUNC_END(return_to_handler) 82#endif 83 84#ifndef CONFIG_DYNAMIC_FTRACE 85SYM_FUNC_START(_mcount) 86 la t4, ftrace_stub 87#ifdef CONFIG_FUNCTION_GRAPH_TRACER 88 la t0, ftrace_graph_return 89 REG_L t1, 0(t0) 90 bne t1, t4, .Ldo_ftrace_graph_caller 91 92 la t3, ftrace_graph_entry 93 REG_L t2, 0(t3) 94 la t6, ftrace_graph_entry_stub 95 bne t2, t6, .Ldo_ftrace_graph_caller 96#endif 97 la t3, ftrace_trace_function 98 REG_L t5, 0(t3) 99 bne t5, t4, .Ldo_trace 100 ret 101 102#ifdef CONFIG_FUNCTION_GRAPH_TRACER 103/* 104 * A pseudo representation for the function graph tracer: 105 * prepare_to_return(&ra_to_caller_of_caller, ra_to_caller) 106 */ 107.Ldo_ftrace_graph_caller: 108 addi a0, s0, -SZREG 109 mv a1, ra 110#ifdef HAVE_FUNCTION_GRAPH_FP_TEST 111 REG_L a2, -2*SZREG(s0) 112#endif 113 SAVE_ABI_STATE 114 call prepare_ftrace_return 115 RESTORE_ABI_STATE 116 ret 117#endif 118 119/* 120 * A pseudo representation for the function tracer: 121 * (*ftrace_trace_function)(ra_to_caller, ra_to_caller_of_caller) 122 */ 123.Ldo_trace: 124 REG_L a1, -SZREG(s0) 125 mv a0, ra 126 127 SAVE_ABI_STATE 128 jalr t5 129 RESTORE_ABI_STATE 130 ret 131SYM_FUNC_END(_mcount) 132#endif 133EXPORT_SYMBOL(_mcount) 134