1819e50e2SAKASHI Takahiro/* 2819e50e2SAKASHI Takahiro * arch/arm64/kernel/entry-ftrace.S 3819e50e2SAKASHI Takahiro * 4819e50e2SAKASHI Takahiro * Copyright (C) 2013 Linaro Limited 5819e50e2SAKASHI Takahiro * Author: AKASHI Takahiro <takahiro.akashi@linaro.org> 6819e50e2SAKASHI Takahiro * 7819e50e2SAKASHI Takahiro * This program is free software; you can redistribute it and/or modify 8819e50e2SAKASHI Takahiro * it under the terms of the GNU General Public License version 2 as 9819e50e2SAKASHI Takahiro * published by the Free Software Foundation. 10819e50e2SAKASHI Takahiro */ 11819e50e2SAKASHI Takahiro 12819e50e2SAKASHI Takahiro#include <linux/linkage.h> 13819e50e2SAKASHI Takahiro#include <asm/ftrace.h> 14819e50e2SAKASHI Takahiro#include <asm/insn.h> 15819e50e2SAKASHI Takahiro 16819e50e2SAKASHI Takahiro/* 17819e50e2SAKASHI Takahiro * Gcc with -pg will put the following code in the beginning of each function: 18819e50e2SAKASHI Takahiro * mov x0, x30 19819e50e2SAKASHI Takahiro * bl _mcount 20819e50e2SAKASHI Takahiro * [function's body ...] 21819e50e2SAKASHI Takahiro * "bl _mcount" may be replaced to "bl ftrace_caller" or NOP if dynamic 22819e50e2SAKASHI Takahiro * ftrace is enabled. 23819e50e2SAKASHI Takahiro * 24819e50e2SAKASHI Takahiro * Please note that x0 as an argument will not be used here because we can 25819e50e2SAKASHI Takahiro * get lr(x30) of instrumented function at any time by winding up call stack 26819e50e2SAKASHI Takahiro * as long as the kernel is compiled without -fomit-frame-pointer. 27819e50e2SAKASHI Takahiro * (or CONFIG_FRAME_POINTER, this is forced on arm64) 28819e50e2SAKASHI Takahiro * 29819e50e2SAKASHI Takahiro * stack layout after mcount_enter in _mcount(): 30819e50e2SAKASHI Takahiro * 31819e50e2SAKASHI Takahiro * current sp/fp => 0:+-----+ 32819e50e2SAKASHI Takahiro * in _mcount() | x29 | -> instrumented function's fp 33819e50e2SAKASHI Takahiro * +-----+ 34819e50e2SAKASHI Takahiro * | x30 | -> _mcount()'s lr (= instrumented function's pc) 35819e50e2SAKASHI Takahiro * old sp => +16:+-----+ 36819e50e2SAKASHI Takahiro * when instrumented | | 37819e50e2SAKASHI Takahiro * function calls | ... | 38819e50e2SAKASHI Takahiro * _mcount() | | 39819e50e2SAKASHI Takahiro * | | 40819e50e2SAKASHI Takahiro * instrumented => +xx:+-----+ 41819e50e2SAKASHI Takahiro * function's fp | x29 | -> parent's fp 42819e50e2SAKASHI Takahiro * +-----+ 43819e50e2SAKASHI Takahiro * | x30 | -> instrumented function's lr (= parent's pc) 44819e50e2SAKASHI Takahiro * +-----+ 45819e50e2SAKASHI Takahiro * | ... | 46819e50e2SAKASHI Takahiro */ 47819e50e2SAKASHI Takahiro 48819e50e2SAKASHI Takahiro .macro mcount_enter 49819e50e2SAKASHI Takahiro stp x29, x30, [sp, #-16]! 50819e50e2SAKASHI Takahiro mov x29, sp 51819e50e2SAKASHI Takahiro .endm 52819e50e2SAKASHI Takahiro 53819e50e2SAKASHI Takahiro .macro mcount_exit 54819e50e2SAKASHI Takahiro ldp x29, x30, [sp], #16 55819e50e2SAKASHI Takahiro ret 56819e50e2SAKASHI Takahiro .endm 57819e50e2SAKASHI Takahiro 58819e50e2SAKASHI Takahiro .macro mcount_adjust_addr rd, rn 59819e50e2SAKASHI Takahiro sub \rd, \rn, #AARCH64_INSN_SIZE 60819e50e2SAKASHI Takahiro .endm 61819e50e2SAKASHI Takahiro 62819e50e2SAKASHI Takahiro /* for instrumented function's parent */ 63819e50e2SAKASHI Takahiro .macro mcount_get_parent_fp reg 64819e50e2SAKASHI Takahiro ldr \reg, [x29] 65819e50e2SAKASHI Takahiro ldr \reg, [\reg] 66819e50e2SAKASHI Takahiro .endm 67819e50e2SAKASHI Takahiro 68819e50e2SAKASHI Takahiro /* for instrumented function */ 69819e50e2SAKASHI Takahiro .macro mcount_get_pc0 reg 70819e50e2SAKASHI Takahiro mcount_adjust_addr \reg, x30 71819e50e2SAKASHI Takahiro .endm 72819e50e2SAKASHI Takahiro 73819e50e2SAKASHI Takahiro .macro mcount_get_pc reg 74819e50e2SAKASHI Takahiro ldr \reg, [x29, #8] 75819e50e2SAKASHI Takahiro mcount_adjust_addr \reg, \reg 76819e50e2SAKASHI Takahiro .endm 77819e50e2SAKASHI Takahiro 78819e50e2SAKASHI Takahiro .macro mcount_get_lr reg 79819e50e2SAKASHI Takahiro ldr \reg, [x29] 80819e50e2SAKASHI Takahiro ldr \reg, [\reg, #8] 81819e50e2SAKASHI Takahiro mcount_adjust_addr \reg, \reg 82819e50e2SAKASHI Takahiro .endm 83819e50e2SAKASHI Takahiro 84819e50e2SAKASHI Takahiro .macro mcount_get_lr_addr reg 85819e50e2SAKASHI Takahiro ldr \reg, [x29] 86819e50e2SAKASHI Takahiro add \reg, \reg, #8 87819e50e2SAKASHI Takahiro .endm 88819e50e2SAKASHI Takahiro 89819e50e2SAKASHI Takahiro/* 90819e50e2SAKASHI Takahiro * void _mcount(unsigned long return_address) 91819e50e2SAKASHI Takahiro * @return_address: return address to instrumented function 92819e50e2SAKASHI Takahiro * 93819e50e2SAKASHI Takahiro * This function makes calls, if enabled, to: 94819e50e2SAKASHI Takahiro * - tracer function to probe instrumented function's entry, 95819e50e2SAKASHI Takahiro * - ftrace_graph_caller to set up an exit hook 96819e50e2SAKASHI Takahiro */ 97819e50e2SAKASHI TakahiroENTRY(_mcount) 98819e50e2SAKASHI Takahiro#ifdef CONFIG_HAVE_FUNCTION_TRACE_MCOUNT_TEST 99819e50e2SAKASHI Takahiro ldr x0, =ftrace_trace_stop 100819e50e2SAKASHI Takahiro ldr x0, [x0] // if ftrace_trace_stop 101819e50e2SAKASHI Takahiro ret // return; 102819e50e2SAKASHI Takahiro#endif 103819e50e2SAKASHI Takahiro mcount_enter 104819e50e2SAKASHI Takahiro 105819e50e2SAKASHI Takahiro ldr x0, =ftrace_trace_function 106819e50e2SAKASHI Takahiro ldr x2, [x0] 107819e50e2SAKASHI Takahiro adr x0, ftrace_stub 108819e50e2SAKASHI Takahiro cmp x0, x2 // if (ftrace_trace_function 109819e50e2SAKASHI Takahiro b.eq skip_ftrace_call // != ftrace_stub) { 110819e50e2SAKASHI Takahiro 111819e50e2SAKASHI Takahiro mcount_get_pc x0 // function's pc 112819e50e2SAKASHI Takahiro mcount_get_lr x1 // function's lr (= parent's pc) 113819e50e2SAKASHI Takahiro blr x2 // (*ftrace_trace_function)(pc, lr); 114819e50e2SAKASHI Takahiro 115819e50e2SAKASHI Takahiro#ifndef CONFIG_FUNCTION_GRAPH_TRACER 116819e50e2SAKASHI Takahiroskip_ftrace_call: // return; 117819e50e2SAKASHI Takahiro mcount_exit // } 118819e50e2SAKASHI Takahiro#else 119819e50e2SAKASHI Takahiro mcount_exit // return; 120819e50e2SAKASHI Takahiro // } 121819e50e2SAKASHI Takahiroskip_ftrace_call: 122819e50e2SAKASHI Takahiro ldr x1, =ftrace_graph_return 123819e50e2SAKASHI Takahiro ldr x2, [x1] // if ((ftrace_graph_return 124819e50e2SAKASHI Takahiro cmp x0, x2 // != ftrace_stub) 125819e50e2SAKASHI Takahiro b.ne ftrace_graph_caller 126819e50e2SAKASHI Takahiro 127819e50e2SAKASHI Takahiro ldr x1, =ftrace_graph_entry // || (ftrace_graph_entry 128819e50e2SAKASHI Takahiro ldr x2, [x1] // != ftrace_graph_entry_stub)) 129819e50e2SAKASHI Takahiro ldr x0, =ftrace_graph_entry_stub 130819e50e2SAKASHI Takahiro cmp x0, x2 131819e50e2SAKASHI Takahiro b.ne ftrace_graph_caller // ftrace_graph_caller(); 132819e50e2SAKASHI Takahiro 133819e50e2SAKASHI Takahiro mcount_exit 134819e50e2SAKASHI Takahiro#endif /* CONFIG_FUNCTION_GRAPH_TRACER */ 135819e50e2SAKASHI TakahiroENDPROC(_mcount) 136819e50e2SAKASHI Takahiro 137819e50e2SAKASHI TakahiroENTRY(ftrace_stub) 138819e50e2SAKASHI Takahiro ret 139819e50e2SAKASHI TakahiroENDPROC(ftrace_stub) 140819e50e2SAKASHI Takahiro 141819e50e2SAKASHI Takahiro#ifdef CONFIG_FUNCTION_GRAPH_TRACER 142819e50e2SAKASHI Takahiro/* 143819e50e2SAKASHI Takahiro * void ftrace_graph_caller(void) 144819e50e2SAKASHI Takahiro * 145819e50e2SAKASHI Takahiro * Called from _mcount() or ftrace_caller() when function_graph tracer is 146819e50e2SAKASHI Takahiro * selected. 147819e50e2SAKASHI Takahiro * This function w/ prepare_ftrace_return() fakes link register's value on 148819e50e2SAKASHI Takahiro * the call stack in order to intercept instrumented function's return path 149819e50e2SAKASHI Takahiro * and run return_to_handler() later on its exit. 150819e50e2SAKASHI Takahiro */ 151819e50e2SAKASHI TakahiroENTRY(ftrace_graph_caller) 152819e50e2SAKASHI Takahiro mcount_get_lr_addr x0 // pointer to function's saved lr 153819e50e2SAKASHI Takahiro mcount_get_pc x1 // function's pc 154819e50e2SAKASHI Takahiro mcount_get_parent_fp x2 // parent's fp 155819e50e2SAKASHI Takahiro bl prepare_ftrace_return // prepare_ftrace_return(&lr, pc, fp) 156819e50e2SAKASHI Takahiro 157819e50e2SAKASHI Takahiro mcount_exit 158819e50e2SAKASHI TakahiroENDPROC(ftrace_graph_caller) 159819e50e2SAKASHI Takahiro 160819e50e2SAKASHI Takahiro/* 161819e50e2SAKASHI Takahiro * void return_to_handler(void) 162819e50e2SAKASHI Takahiro * 163819e50e2SAKASHI Takahiro * Run ftrace_return_to_handler() before going back to parent. 164819e50e2SAKASHI Takahiro * @fp is checked against the value passed by ftrace_graph_caller() 165819e50e2SAKASHI Takahiro * only when CONFIG_FUNCTION_GRAPH_FP_TEST is enabled. 166819e50e2SAKASHI Takahiro */ 167819e50e2SAKASHI TakahiroENTRY(return_to_handler) 168819e50e2SAKASHI Takahiro str x0, [sp, #-16]! 169819e50e2SAKASHI Takahiro mov x0, x29 // parent's fp 170819e50e2SAKASHI Takahiro bl ftrace_return_to_handler// addr = ftrace_return_to_hander(fp); 171819e50e2SAKASHI Takahiro mov x30, x0 // restore the original return address 172819e50e2SAKASHI Takahiro ldr x0, [sp], #16 173819e50e2SAKASHI Takahiro ret 174819e50e2SAKASHI TakahiroEND(return_to_handler) 175819e50e2SAKASHI Takahiro#endif /* CONFIG_FUNCTION_GRAPH_TRACER */ 176