mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-27 11:19:37 +00:00
![Geert Uytterhoeven](/assets/img/avatar_default.png)
Improve the comment block for prepare_ftrace_return(). Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> Signed-off-by: Paul Burton <paul.burton@mips.com> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: James Hogan <jhogan@kernel.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: linux-mips@vger.kernel.org Cc: linux-kernel@vger.kernel.org
418 lines
10 KiB
C
418 lines
10 KiB
C
// 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);
|
|
}
|
|
|
|
#endif
|
|
|
|
#ifdef CONFIG_DYNAMIC_FTRACE
|
|
|
|
#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;
|
|
mm_segment_t old_fs;
|
|
|
|
/* *(unsigned int *)ip = new_code; */
|
|
safe_store_code(new_code, ip, faulted);
|
|
|
|
if (unlikely(faulted))
|
|
return -EFAULT;
|
|
|
|
old_fs = get_fs();
|
|
set_fs(KERNEL_DS);
|
|
flush_icache_range(ip, ip + 8);
|
|
set_fs(old_fs);
|
|
|
|
return 0;
|
|
}
|
|
|
|
#ifndef CONFIG_64BIT
|
|
static int ftrace_modify_code_2(unsigned long ip, unsigned int new_code1,
|
|
unsigned int new_code2)
|
|
{
|
|
int faulted;
|
|
mm_segment_t old_fs;
|
|
|
|
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;
|
|
old_fs = get_fs();
|
|
set_fs(KERNEL_DS);
|
|
flush_icache_range(ip, ip + 8);
|
|
set_fs(old_fs);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int ftrace_modify_code_2r(unsigned long ip, unsigned int new_code1,
|
|
unsigned int new_code2)
|
|
{
|
|
int faulted;
|
|
mm_segment_t old_fs;
|
|
|
|
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;
|
|
|
|
old_fs = get_fs();
|
|
set_fs(KERNEL_DS);
|
|
flush_icache_range(ip, ip + 8);
|
|
set_fs(old_fs);
|
|
|
|
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 */
|