diff options
Diffstat (limited to 'arch/mips/kernel/ftrace.c')
-rw-r--r-- | arch/mips/kernel/ftrace.c | 402 |
1 files changed, 402 insertions, 0 deletions
diff --git a/arch/mips/kernel/ftrace.c b/arch/mips/kernel/ftrace.c new file mode 100644 index 000000000..8c401e423 --- /dev/null +++ b/arch/mips/kernel/ftrace.c @@ -0,0 +1,402 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Code for replacing ftrace calls with jumps. + * + * Copyright (C) 2007-2008 Steven Rostedt <srostedt@redhat.com> + * Copyright (C) 2009, 2010 DSLab, Lanzhou University, China + * Author: Wu Zhangjin <wuzhangjin@gmail.com> + * + * Thanks goes to Steven Rostedt for writing the original x86 version. + */ + +#include <linux/uaccess.h> +#include <linux/init.h> +#include <linux/ftrace.h> +#include <linux/syscalls.h> + +#include <asm/asm.h> +#include <asm/asm-offsets.h> +#include <asm/cacheflush.h> +#include <asm/syscall.h> +#include <asm/uasm.h> +#include <asm/unistd.h> + +#include <asm-generic/sections.h> + +#if defined(KBUILD_MCOUNT_RA_ADDRESS) && defined(CONFIG_32BIT) +#define MCOUNT_OFFSET_INSNS 5 +#else +#define MCOUNT_OFFSET_INSNS 4 +#endif + +#ifdef CONFIG_DYNAMIC_FTRACE + +/* Arch override because MIPS doesn't need to run this from stop_machine() */ +void arch_ftrace_update_code(int command) +{ + ftrace_modify_all_code(command); +} + +#define JAL 0x0c000000 /* jump & link: ip --> ra, jump to target */ +#define ADDR_MASK 0x03ffffff /* op_code|addr : 31...26|25 ....0 */ +#define JUMP_RANGE_MASK ((1UL << 28) - 1) + +#define INSN_NOP 0x00000000 /* nop */ +#define INSN_JAL(addr) \ + ((unsigned int)(JAL | (((addr) >> 2) & ADDR_MASK))) + +static unsigned int insn_jal_ftrace_caller __read_mostly; +static unsigned int insn_la_mcount[2] __read_mostly; +static unsigned int insn_j_ftrace_graph_caller __maybe_unused __read_mostly; + +static inline void ftrace_dyn_arch_init_insns(void) +{ + u32 *buf; + unsigned int v1; + + /* la v1, _mcount */ + v1 = 3; + buf = (u32 *)&insn_la_mcount[0]; + UASM_i_LA(&buf, v1, MCOUNT_ADDR); + + /* jal (ftrace_caller + 8), jump over the first two instruction */ + buf = (u32 *)&insn_jal_ftrace_caller; + uasm_i_jal(&buf, (FTRACE_ADDR + 8) & JUMP_RANGE_MASK); + +#ifdef CONFIG_FUNCTION_GRAPH_TRACER + /* j ftrace_graph_caller */ + buf = (u32 *)&insn_j_ftrace_graph_caller; + uasm_i_j(&buf, (unsigned long)ftrace_graph_caller & JUMP_RANGE_MASK); +#endif +} + +static int ftrace_modify_code(unsigned long ip, unsigned int new_code) +{ + int faulted; + + /* *(unsigned int *)ip = new_code; */ + safe_store_code(new_code, ip, faulted); + + if (unlikely(faulted)) + return -EFAULT; + + flush_icache_range(ip, ip + 8); + + return 0; +} + +#ifndef CONFIG_64BIT +static int ftrace_modify_code_2(unsigned long ip, unsigned int new_code1, + unsigned int new_code2) +{ + int faulted; + + safe_store_code(new_code1, ip, faulted); + if (unlikely(faulted)) + return -EFAULT; + + ip += 4; + safe_store_code(new_code2, ip, faulted); + if (unlikely(faulted)) + return -EFAULT; + + ip -= 4; + flush_icache_range(ip, ip + 8); + + return 0; +} + +static int ftrace_modify_code_2r(unsigned long ip, unsigned int new_code1, + unsigned int new_code2) +{ + int faulted; + + ip += 4; + safe_store_code(new_code2, ip, faulted); + if (unlikely(faulted)) + return -EFAULT; + + ip -= 4; + safe_store_code(new_code1, ip, faulted); + if (unlikely(faulted)) + return -EFAULT; + + flush_icache_range(ip, ip + 8); + + return 0; +} +#endif + +/* + * The details about the calling site of mcount on MIPS + * + * 1. For kernel: + * + * move at, ra + * jal _mcount --> nop + * sub sp, sp, 8 --> nop (CONFIG_32BIT) + * + * 2. For modules: + * + * 2.1 For KBUILD_MCOUNT_RA_ADDRESS and CONFIG_32BIT + * + * lui v1, hi_16bit_of_mcount --> b 1f (0x10000005) + * addiu v1, v1, low_16bit_of_mcount --> nop (CONFIG_32BIT) + * move at, ra + * move $12, ra_address + * jalr v1 + * sub sp, sp, 8 + * 1: offset = 5 instructions + * 2.2 For the Other situations + * + * lui v1, hi_16bit_of_mcount --> b 1f (0x10000004) + * addiu v1, v1, low_16bit_of_mcount --> nop (CONFIG_32BIT) + * move at, ra + * jalr v1 + * nop | move $12, ra_address | sub sp, sp, 8 + * 1: offset = 4 instructions + */ + +#define INSN_B_1F (0x10000000 | MCOUNT_OFFSET_INSNS) + +int ftrace_make_nop(struct module *mod, + struct dyn_ftrace *rec, unsigned long addr) +{ + unsigned int new; + unsigned long ip = rec->ip; + + /* + * If ip is in kernel space, no long call, otherwise, long call is + * needed. + */ + new = core_kernel_text(ip) ? INSN_NOP : INSN_B_1F; +#ifdef CONFIG_64BIT + return ftrace_modify_code(ip, new); +#else + /* + * On 32 bit MIPS platforms, gcc adds a stack adjust + * instruction in the delay slot after the branch to + * mcount and expects mcount to restore the sp on return. + * This is based on a legacy API and does nothing but + * waste instructions so it's being removed at runtime. + */ + return ftrace_modify_code_2(ip, new, INSN_NOP); +#endif +} + +int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) +{ + unsigned int new; + unsigned long ip = rec->ip; + + new = core_kernel_text(ip) ? insn_jal_ftrace_caller : insn_la_mcount[0]; + +#ifdef CONFIG_64BIT + return ftrace_modify_code(ip, new); +#else + return ftrace_modify_code_2r(ip, new, core_kernel_text(ip) ? + INSN_NOP : insn_la_mcount[1]); +#endif +} + +#define FTRACE_CALL_IP ((unsigned long)(&ftrace_call)) + +int ftrace_update_ftrace_func(ftrace_func_t func) +{ + unsigned int new; + + new = INSN_JAL((unsigned long)func); + + return ftrace_modify_code(FTRACE_CALL_IP, new); +} + +int __init ftrace_dyn_arch_init(void) +{ + /* Encode the instructions when booting */ + ftrace_dyn_arch_init_insns(); + + /* Remove "b ftrace_stub" to ensure ftrace_caller() is executed */ + ftrace_modify_code(MCOUNT_ADDR, INSN_NOP); + + return 0; +} +#endif /* CONFIG_DYNAMIC_FTRACE */ + +#ifdef CONFIG_FUNCTION_GRAPH_TRACER + +#ifdef CONFIG_DYNAMIC_FTRACE + +extern void ftrace_graph_call(void); +#define FTRACE_GRAPH_CALL_IP ((unsigned long)(&ftrace_graph_call)) + +int ftrace_enable_ftrace_graph_caller(void) +{ + return ftrace_modify_code(FTRACE_GRAPH_CALL_IP, + insn_j_ftrace_graph_caller); +} + +int ftrace_disable_ftrace_graph_caller(void) +{ + return ftrace_modify_code(FTRACE_GRAPH_CALL_IP, INSN_NOP); +} + +#endif /* CONFIG_DYNAMIC_FTRACE */ + +#ifndef KBUILD_MCOUNT_RA_ADDRESS + +#define S_RA_SP (0xafbf << 16) /* s{d,w} ra, offset(sp) */ +#define S_R_SP (0xafb0 << 16) /* s{d,w} R, offset(sp) */ +#define OFFSET_MASK 0xffff /* stack offset range: 0 ~ PT_SIZE */ + +unsigned long ftrace_get_parent_ra_addr(unsigned long self_ra, unsigned long + old_parent_ra, unsigned long parent_ra_addr, unsigned long fp) +{ + unsigned long sp, ip, tmp; + unsigned int code; + int faulted; + + /* + * For module, move the ip from the return address after the + * instruction "lui v1, hi_16bit_of_mcount"(offset is 24), but for + * kernel, move after the instruction "move ra, at"(offset is 16) + */ + ip = self_ra - (core_kernel_text(self_ra) ? 16 : 24); + + /* + * search the text until finding the non-store instruction or "s{d,w} + * ra, offset(sp)" instruction + */ + do { + /* get the code at "ip": code = *(unsigned int *)ip; */ + safe_load_code(code, ip, faulted); + + if (unlikely(faulted)) + return 0; + /* + * If we hit the non-store instruction before finding where the + * ra is stored, then this is a leaf function and it does not + * store the ra on the stack + */ + if ((code & S_R_SP) != S_R_SP) + return parent_ra_addr; + + /* Move to the next instruction */ + ip -= 4; + } while ((code & S_RA_SP) != S_RA_SP); + + sp = fp + (code & OFFSET_MASK); + + /* tmp = *(unsigned long *)sp; */ + safe_load_stack(tmp, sp, faulted); + if (unlikely(faulted)) + return 0; + + if (tmp == old_parent_ra) + return sp; + return 0; +} + +#endif /* !KBUILD_MCOUNT_RA_ADDRESS */ + +/* + * Hook the return address and push it in the stack of return addrs + * in current thread info. + */ +void prepare_ftrace_return(unsigned long *parent_ra_addr, unsigned long self_ra, + unsigned long fp) +{ + unsigned long old_parent_ra; + unsigned long return_hooker = (unsigned long) + &return_to_handler; + int faulted, insns; + + if (unlikely(ftrace_graph_is_dead())) + return; + + if (unlikely(atomic_read(¤t->tracing_graph_pause))) + return; + + /* + * "parent_ra_addr" is the stack address where the return address of + * the caller of _mcount is saved. + * + * If gcc < 4.5, a leaf function does not save the return address + * in the stack address, so we "emulate" one in _mcount's stack space, + * and hijack it directly. + * For a non-leaf function, it does save the return address to its own + * stack space, so we can not hijack it directly, but need to find the + * real stack address, which is done by ftrace_get_parent_addr(). + * + * If gcc >= 4.5, with the new -mmcount-ra-address option, for a + * non-leaf function, the location of the return address will be saved + * to $12 for us. + * For a leaf function, it just puts a zero into $12, so we handle + * it in ftrace_graph_caller() of mcount.S. + */ + + /* old_parent_ra = *parent_ra_addr; */ + safe_load_stack(old_parent_ra, parent_ra_addr, faulted); + if (unlikely(faulted)) + goto out; +#ifndef KBUILD_MCOUNT_RA_ADDRESS + parent_ra_addr = (unsigned long *)ftrace_get_parent_ra_addr(self_ra, + old_parent_ra, (unsigned long)parent_ra_addr, fp); + /* + * If fails when getting the stack address of the non-leaf function's + * ra, stop function graph tracer and return + */ + if (parent_ra_addr == NULL) + goto out; +#endif + /* *parent_ra_addr = return_hooker; */ + safe_store_stack(return_hooker, parent_ra_addr, faulted); + if (unlikely(faulted)) + goto out; + + /* + * Get the recorded ip of the current mcount calling site in the + * __mcount_loc section, which will be used to filter the function + * entries configured through the tracing/set_graph_function interface. + */ + + insns = core_kernel_text(self_ra) ? 2 : MCOUNT_OFFSET_INSNS + 1; + self_ra -= (MCOUNT_INSN_SIZE * insns); + + if (function_graph_enter(old_parent_ra, self_ra, fp, NULL)) + *parent_ra_addr = old_parent_ra; + return; +out: + ftrace_graph_stop(); + WARN_ON(1); +} +#endif /* CONFIG_FUNCTION_GRAPH_TRACER */ + +#ifdef CONFIG_FTRACE_SYSCALLS + +#ifdef CONFIG_32BIT +unsigned long __init arch_syscall_addr(int nr) +{ + return (unsigned long)sys_call_table[nr - __NR_O32_Linux]; +} +#endif + +#ifdef CONFIG_64BIT + +unsigned long __init arch_syscall_addr(int nr) +{ +#ifdef CONFIG_MIPS32_N32 + if (nr >= __NR_N32_Linux && nr < __NR_N32_Linux + __NR_N32_Linux_syscalls) + return (unsigned long)sysn32_call_table[nr - __NR_N32_Linux]; +#endif + if (nr >= __NR_64_Linux && nr < __NR_64_Linux + __NR_64_Linux_syscalls) + return (unsigned long)sys_call_table[nr - __NR_64_Linux]; +#ifdef CONFIG_MIPS32_O32 + if (nr >= __NR_O32_Linux && nr < __NR_O32_Linux + __NR_O32_Linux_syscalls) + return (unsigned long)sys32_call_table[nr - __NR_O32_Linux]; +#endif + + return (unsigned long) &sys_ni_syscall; +} +#endif + +#endif /* CONFIG_FTRACE_SYSCALLS */ |