418 lines
10 KiB
C
418 lines
10 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Code for replacing ftrace calls with jumps.
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*
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* Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com>
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* Copyright (C) 2009, 2010 DSLab, Lanzhou University, China
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* Author: Wu Zhangjin <wuzhangjin@gmail.com>
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*
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* Thanks goes to Steven Rostedt for writing the original x86 version.
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*/
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#include <linux/uaccess.h>
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#include <linux/init.h>
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#include <linux/ftrace.h>
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#include <linux/syscalls.h>
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#include <asm/asm.h>
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#include <asm/asm-offsets.h>
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#include <asm/cacheflush.h>
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#include <asm/syscall.h>
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#include <asm/uasm.h>
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#include <asm/unistd.h>
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#include <asm-generic/sections.h>
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#if defined(KBUILD_MCOUNT_RA_ADDRESS) && defined(CONFIG_32BIT)
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#define MCOUNT_OFFSET_INSNS 5
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#else
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#define MCOUNT_OFFSET_INSNS 4
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#endif
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#ifdef CONFIG_DYNAMIC_FTRACE
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/* Arch override because MIPS doesn't need to run this from stop_machine() */
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void arch_ftrace_update_code(int command)
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{
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ftrace_modify_all_code(command);
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}
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#endif
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#ifdef CONFIG_DYNAMIC_FTRACE
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#define JAL 0x0c000000 /* jump & link: ip --> ra, jump to target */
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#define ADDR_MASK 0x03ffffff /* op_code|addr : 31...26|25 ....0 */
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#define JUMP_RANGE_MASK ((1UL << 28) - 1)
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#define INSN_NOP 0x00000000 /* nop */
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#define INSN_JAL(addr) \
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((unsigned int)(JAL | (((addr) >> 2) & ADDR_MASK)))
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static unsigned int insn_jal_ftrace_caller __read_mostly;
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static unsigned int insn_la_mcount[2] __read_mostly;
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static unsigned int insn_j_ftrace_graph_caller __maybe_unused __read_mostly;
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static inline void ftrace_dyn_arch_init_insns(void)
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{
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u32 *buf;
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unsigned int v1;
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/* la v1, _mcount */
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v1 = 3;
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buf = (u32 *)&insn_la_mcount[0];
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UASM_i_LA(&buf, v1, MCOUNT_ADDR);
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/* jal (ftrace_caller + 8), jump over the first two instruction */
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buf = (u32 *)&insn_jal_ftrace_caller;
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uasm_i_jal(&buf, (FTRACE_ADDR + 8) & JUMP_RANGE_MASK);
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#ifdef CONFIG_FUNCTION_GRAPH_TRACER
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/* j ftrace_graph_caller */
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buf = (u32 *)&insn_j_ftrace_graph_caller;
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uasm_i_j(&buf, (unsigned long)ftrace_graph_caller & JUMP_RANGE_MASK);
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#endif
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}
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static int ftrace_modify_code(unsigned long ip, unsigned int new_code)
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{
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int faulted;
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mm_segment_t old_fs;
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/* *(unsigned int *)ip = new_code; */
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safe_store_code(new_code, ip, faulted);
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if (unlikely(faulted))
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return -EFAULT;
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old_fs = get_fs();
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set_fs(get_ds());
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flush_icache_range(ip, ip + 8);
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set_fs(old_fs);
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return 0;
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}
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#ifndef CONFIG_64BIT
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static int ftrace_modify_code_2(unsigned long ip, unsigned int new_code1,
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unsigned int new_code2)
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{
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int faulted;
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mm_segment_t old_fs;
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safe_store_code(new_code1, ip, faulted);
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if (unlikely(faulted))
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return -EFAULT;
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ip += 4;
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safe_store_code(new_code2, ip, faulted);
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if (unlikely(faulted))
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return -EFAULT;
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ip -= 4;
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old_fs = get_fs();
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set_fs(get_ds());
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flush_icache_range(ip, ip + 8);
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set_fs(old_fs);
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return 0;
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}
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static int ftrace_modify_code_2r(unsigned long ip, unsigned int new_code1,
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unsigned int new_code2)
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{
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int faulted;
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mm_segment_t old_fs;
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ip += 4;
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safe_store_code(new_code2, ip, faulted);
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if (unlikely(faulted))
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return -EFAULT;
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ip -= 4;
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safe_store_code(new_code1, ip, faulted);
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if (unlikely(faulted))
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return -EFAULT;
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old_fs = get_fs();
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set_fs(get_ds());
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flush_icache_range(ip, ip + 8);
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set_fs(old_fs);
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return 0;
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}
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#endif
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/*
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* The details about the calling site of mcount on MIPS
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*
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* 1. For kernel:
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*
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* move at, ra
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* jal _mcount --> nop
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* sub sp, sp, 8 --> nop (CONFIG_32BIT)
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*
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* 2. For modules:
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*
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* 2.1 For KBUILD_MCOUNT_RA_ADDRESS and CONFIG_32BIT
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*
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* lui v1, hi_16bit_of_mcount --> b 1f (0x10000005)
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* addiu v1, v1, low_16bit_of_mcount --> nop (CONFIG_32BIT)
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* move at, ra
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* move $12, ra_address
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* jalr v1
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* sub sp, sp, 8
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* 1: offset = 5 instructions
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* 2.2 For the Other situations
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*
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* lui v1, hi_16bit_of_mcount --> b 1f (0x10000004)
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* addiu v1, v1, low_16bit_of_mcount --> nop (CONFIG_32BIT)
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* move at, ra
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* jalr v1
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* nop | move $12, ra_address | sub sp, sp, 8
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* 1: offset = 4 instructions
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*/
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#define INSN_B_1F (0x10000000 | MCOUNT_OFFSET_INSNS)
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int ftrace_make_nop(struct module *mod,
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struct dyn_ftrace *rec, unsigned long addr)
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{
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unsigned int new;
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unsigned long ip = rec->ip;
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/*
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* If ip is in kernel space, no long call, otherwise, long call is
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* needed.
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*/
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new = core_kernel_text(ip) ? INSN_NOP : INSN_B_1F;
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#ifdef CONFIG_64BIT
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return ftrace_modify_code(ip, new);
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#else
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/*
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* On 32 bit MIPS platforms, gcc adds a stack adjust
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* instruction in the delay slot after the branch to
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* mcount and expects mcount to restore the sp on return.
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* This is based on a legacy API and does nothing but
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* waste instructions so it's being removed at runtime.
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*/
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return ftrace_modify_code_2(ip, new, INSN_NOP);
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#endif
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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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unsigned int new;
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unsigned long ip = rec->ip;
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new = core_kernel_text(ip) ? insn_jal_ftrace_caller : insn_la_mcount[0];
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#ifdef CONFIG_64BIT
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return ftrace_modify_code(ip, new);
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#else
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return ftrace_modify_code_2r(ip, new, core_kernel_text(ip) ?
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INSN_NOP : insn_la_mcount[1]);
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#endif
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}
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#define FTRACE_CALL_IP ((unsigned long)(&ftrace_call))
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int ftrace_update_ftrace_func(ftrace_func_t func)
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{
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unsigned int new;
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new = INSN_JAL((unsigned long)func);
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return ftrace_modify_code(FTRACE_CALL_IP, new);
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}
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int __init ftrace_dyn_arch_init(void)
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{
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/* Encode the instructions when booting */
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ftrace_dyn_arch_init_insns();
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/* Remove "b ftrace_stub" to ensure ftrace_caller() is executed */
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ftrace_modify_code(MCOUNT_ADDR, INSN_NOP);
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return 0;
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}
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#endif /* CONFIG_DYNAMIC_FTRACE */
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#ifdef CONFIG_FUNCTION_GRAPH_TRACER
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#ifdef CONFIG_DYNAMIC_FTRACE
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extern void ftrace_graph_call(void);
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#define FTRACE_GRAPH_CALL_IP ((unsigned long)(&ftrace_graph_call))
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int ftrace_enable_ftrace_graph_caller(void)
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{
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return ftrace_modify_code(FTRACE_GRAPH_CALL_IP,
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insn_j_ftrace_graph_caller);
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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_code(FTRACE_GRAPH_CALL_IP, INSN_NOP);
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}
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#endif /* CONFIG_DYNAMIC_FTRACE */
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#ifndef KBUILD_MCOUNT_RA_ADDRESS
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#define S_RA_SP (0xafbf << 16) /* s{d,w} ra, offset(sp) */
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#define S_R_SP (0xafb0 << 16) /* s{d,w} R, offset(sp) */
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#define OFFSET_MASK 0xffff /* stack offset range: 0 ~ PT_SIZE */
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unsigned long ftrace_get_parent_ra_addr(unsigned long self_ra, unsigned long
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old_parent_ra, unsigned long parent_ra_addr, unsigned long fp)
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{
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unsigned long sp, ip, tmp;
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unsigned int code;
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int faulted;
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/*
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* For module, move the ip from the return address after the
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* instruction "lui v1, hi_16bit_of_mcount"(offset is 24), but for
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* kernel, move after the instruction "move ra, at"(offset is 16)
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*/
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ip = self_ra - (core_kernel_text(self_ra) ? 16 : 24);
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/*
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* search the text until finding the non-store instruction or "s{d,w}
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* ra, offset(sp)" instruction
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*/
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do {
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/* get the code at "ip": code = *(unsigned int *)ip; */
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safe_load_code(code, ip, faulted);
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if (unlikely(faulted))
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return 0;
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/*
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* If we hit the non-store instruction before finding where the
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* ra is stored, then this is a leaf function and it does not
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* store the ra on the stack
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*/
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if ((code & S_R_SP) != S_R_SP)
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return parent_ra_addr;
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/* Move to the next instruction */
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ip -= 4;
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} while ((code & S_RA_SP) != S_RA_SP);
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sp = fp + (code & OFFSET_MASK);
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/* tmp = *(unsigned long *)sp; */
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safe_load_stack(tmp, sp, faulted);
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if (unlikely(faulted))
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return 0;
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if (tmp == old_parent_ra)
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return sp;
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return 0;
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}
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#endif /* !KBUILD_MCOUNT_RA_ADDRESS */
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/*
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* Hook the return address and push it in the stack of return addrs
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* in current thread info.
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*/
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void prepare_ftrace_return(unsigned long *parent_ra_addr, unsigned long self_ra,
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unsigned long fp)
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{
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unsigned long old_parent_ra;
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unsigned long return_hooker = (unsigned long)
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&return_to_handler;
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int faulted, insns;
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if (unlikely(ftrace_graph_is_dead()))
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return;
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if (unlikely(atomic_read(¤t->tracing_graph_pause)))
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return;
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/*
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* "parent_ra_addr" is the stack address saved the return address of
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* the caller of _mcount.
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*
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* if the gcc < 4.5, a leaf function does not save the return address
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* in the stack address, so, we "emulate" one in _mcount's stack space,
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* and hijack it directly, but for a non-leaf function, it save the
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* return address to the its own stack space, we can not hijack it
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* directly, but need to find the real stack address,
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* ftrace_get_parent_addr() does it!
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*
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* if gcc>= 4.5, with the new -mmcount-ra-address option, for a
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* non-leaf function, the location of the return address will be saved
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* to $12 for us, and for a leaf function, only put a zero into $12. we
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* do it in ftrace_graph_caller of mcount.S.
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*/
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/* old_parent_ra = *parent_ra_addr; */
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safe_load_stack(old_parent_ra, parent_ra_addr, faulted);
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if (unlikely(faulted))
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goto out;
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#ifndef KBUILD_MCOUNT_RA_ADDRESS
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parent_ra_addr = (unsigned long *)ftrace_get_parent_ra_addr(self_ra,
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old_parent_ra, (unsigned long)parent_ra_addr, fp);
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/*
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* If fails when getting the stack address of the non-leaf function's
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* ra, stop function graph tracer and return
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*/
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if (parent_ra_addr == NULL)
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goto out;
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#endif
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/* *parent_ra_addr = return_hooker; */
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safe_store_stack(return_hooker, parent_ra_addr, faulted);
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if (unlikely(faulted))
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goto out;
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/*
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* Get the recorded ip of the current mcount calling site in the
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* __mcount_loc section, which will be used to filter the function
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* entries configured through the tracing/set_graph_function interface.
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*/
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insns = core_kernel_text(self_ra) ? 2 : MCOUNT_OFFSET_INSNS + 1;
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self_ra -= (MCOUNT_INSN_SIZE * insns);
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if (function_graph_enter(old_parent_ra, self_ra, fp, NULL))
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*parent_ra_addr = old_parent_ra;
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return;
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out:
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ftrace_graph_stop();
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WARN_ON(1);
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}
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#endif /* CONFIG_FUNCTION_GRAPH_TRACER */
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#ifdef CONFIG_FTRACE_SYSCALLS
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#ifdef CONFIG_32BIT
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unsigned long __init arch_syscall_addr(int nr)
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{
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return (unsigned long)sys_call_table[nr - __NR_O32_Linux];
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}
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#endif
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#ifdef CONFIG_64BIT
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unsigned long __init arch_syscall_addr(int nr)
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{
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#ifdef CONFIG_MIPS32_N32
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if (nr >= __NR_N32_Linux && nr < __NR_N32_Linux + __NR_N32_Linux_syscalls)
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return (unsigned long)sysn32_call_table[nr - __NR_N32_Linux];
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#endif
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if (nr >= __NR_64_Linux && nr < __NR_64_Linux + __NR_64_Linux_syscalls)
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return (unsigned long)sys_call_table[nr - __NR_64_Linux];
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#ifdef CONFIG_MIPS32_O32
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if (nr >= __NR_O32_Linux && nr < __NR_O32_Linux + __NR_O32_Linux_syscalls)
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return (unsigned long)sys32_call_table[nr - __NR_O32_Linux];
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#endif
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return (unsigned long) &sys_ni_syscall;
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}
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#endif
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#endif /* CONFIG_FTRACE_SYSCALLS */
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