mirror of https://gitee.com/openkylin/linux.git
205 lines
5.4 KiB
C
205 lines
5.4 KiB
C
/*
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* Dynamic function tracing support.
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*
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* Copyright (C) 2008 Shaohua Li <shaohua.li@intel.com>
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*
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* For licencing details, see COPYING.
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*
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* Defines low-level handling of mcount calls when the kernel
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* is compiled with the -pg flag. When using dynamic ftrace, the
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* mcount call-sites get patched lazily with NOP till they are
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* enabled. All code mutation routines here take effect atomically.
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*/
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#include <linux/uaccess.h>
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#include <linux/ftrace.h>
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#include <asm/cacheflush.h>
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#include <asm/patch.h>
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/* In IA64, each function will be added below two bundles with -pg option */
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static unsigned char __attribute__((aligned(8)))
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ftrace_orig_code[MCOUNT_INSN_SIZE] = {
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0x02, 0x40, 0x31, 0x10, 0x80, 0x05, /* alloc r40=ar.pfs,12,8,0 */
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0xb0, 0x02, 0x00, 0x00, 0x42, 0x40, /* mov r43=r0;; */
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0x05, 0x00, 0xc4, 0x00, /* mov r42=b0 */
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0x11, 0x48, 0x01, 0x02, 0x00, 0x21, /* mov r41=r1 */
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0x00, 0x00, 0x00, 0x02, 0x00, 0x00, /* nop.i 0x0 */
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0x08, 0x00, 0x00, 0x50 /* br.call.sptk.many b0 = _mcount;; */
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};
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struct ftrace_orig_insn {
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u64 dummy1, dummy2, dummy3;
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u64 dummy4:64-41+13;
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u64 imm20:20;
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u64 dummy5:3;
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u64 sign:1;
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u64 dummy6:4;
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};
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/* mcount stub will be converted below for nop */
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static unsigned char ftrace_nop_code[MCOUNT_INSN_SIZE] = {
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0x00, 0x00, 0x00, 0x00, 0x01, 0x00, /* [MII] nop.m 0x0 */
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0x30, 0x00, 0x00, 0x60, 0x00, 0x00, /* mov r3=ip */
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0x00, 0x00, 0x04, 0x00, /* nop.i 0x0 */
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0x05, 0x00, 0x00, 0x00, 0x01, 0x00, /* [MLX] nop.m 0x0 */
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0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* nop.x 0x0;; */
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0x00, 0x00, 0x04, 0x00
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};
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static unsigned char *ftrace_nop_replace(void)
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{
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return ftrace_nop_code;
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}
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/*
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* mcount stub will be converted below for call
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* Note: Just the last instruction is changed against nop
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* */
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static unsigned char __attribute__((aligned(8)))
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ftrace_call_code[MCOUNT_INSN_SIZE] = {
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0x00, 0x00, 0x00, 0x00, 0x01, 0x00, /* [MII] nop.m 0x0 */
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0x30, 0x00, 0x00, 0x60, 0x00, 0x00, /* mov r3=ip */
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0x00, 0x00, 0x04, 0x00, /* nop.i 0x0 */
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0x05, 0x00, 0x00, 0x00, 0x01, 0x00, /* [MLX] nop.m 0x0 */
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0xff, 0xff, 0xff, 0xff, 0x7f, 0x00, /* brl.many .;;*/
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0xf8, 0xff, 0xff, 0xc8
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};
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struct ftrace_call_insn {
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u64 dummy1, dummy2;
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u64 dummy3:48;
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u64 imm39_l:16;
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u64 imm39_h:23;
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u64 dummy4:13;
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u64 imm20:20;
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u64 dummy5:3;
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u64 i:1;
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u64 dummy6:4;
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};
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static unsigned char *ftrace_call_replace(unsigned long ip, unsigned long addr)
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{
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struct ftrace_call_insn *code = (void *)ftrace_call_code;
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unsigned long offset = addr - (ip + 0x10);
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code->imm39_l = offset >> 24;
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code->imm39_h = offset >> 40;
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code->imm20 = offset >> 4;
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code->i = offset >> 63;
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return ftrace_call_code;
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}
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static int
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ftrace_modify_code(unsigned long ip, unsigned char *old_code,
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unsigned char *new_code, int do_check)
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{
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unsigned char replaced[MCOUNT_INSN_SIZE];
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/*
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* Note: Due to modules and __init, code can
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* disappear and change, we need to protect against faulting
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* as well as code changing. We do this by using the
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* probe_kernel_* functions.
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*
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* No real locking needed, this code is run through
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* kstop_machine, or before SMP starts.
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*/
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if (!do_check)
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goto skip_check;
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/* read the text we want to modify */
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if (probe_kernel_read(replaced, (void *)ip, MCOUNT_INSN_SIZE))
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return -EFAULT;
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/* Make sure it is what we expect it to be */
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if (memcmp(replaced, old_code, MCOUNT_INSN_SIZE) != 0)
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return -EINVAL;
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skip_check:
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/* replace the text with the new text */
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if (probe_kernel_write(((void *)ip), new_code, MCOUNT_INSN_SIZE))
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return -EPERM;
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flush_icache_range(ip, ip + MCOUNT_INSN_SIZE);
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return 0;
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}
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static int ftrace_make_nop_check(struct dyn_ftrace *rec, unsigned long addr)
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{
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unsigned char __attribute__((aligned(8))) replaced[MCOUNT_INSN_SIZE];
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unsigned long ip = rec->ip;
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if (probe_kernel_read(replaced, (void *)ip, MCOUNT_INSN_SIZE))
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return -EFAULT;
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if (rec->flags & FTRACE_FL_CONVERTED) {
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struct ftrace_call_insn *call_insn, *tmp_call;
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call_insn = (void *)ftrace_call_code;
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tmp_call = (void *)replaced;
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call_insn->imm39_l = tmp_call->imm39_l;
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call_insn->imm39_h = tmp_call->imm39_h;
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call_insn->imm20 = tmp_call->imm20;
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call_insn->i = tmp_call->i;
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if (memcmp(replaced, ftrace_call_code, MCOUNT_INSN_SIZE) != 0)
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return -EINVAL;
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return 0;
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} else {
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struct ftrace_orig_insn *call_insn, *tmp_call;
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call_insn = (void *)ftrace_orig_code;
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tmp_call = (void *)replaced;
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call_insn->sign = tmp_call->sign;
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call_insn->imm20 = tmp_call->imm20;
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if (memcmp(replaced, ftrace_orig_code, MCOUNT_INSN_SIZE) != 0)
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return -EINVAL;
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return 0;
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}
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}
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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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int ret;
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char *new;
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ret = ftrace_make_nop_check(rec, addr);
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if (ret)
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return ret;
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new = ftrace_nop_replace();
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return ftrace_modify_code(rec->ip, NULL, new, 0);
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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 long ip = rec->ip;
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unsigned char *old, *new;
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old= ftrace_nop_replace();
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new = ftrace_call_replace(ip, addr);
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return ftrace_modify_code(ip, old, new, 1);
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}
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/* in IA64, _mcount can't directly call ftrace_stub. Only jump is ok */
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int ftrace_update_ftrace_func(ftrace_func_t func)
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{
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unsigned long ip;
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unsigned long addr = ((struct fnptr *)ftrace_call)->ip;
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if (func == ftrace_stub)
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return 0;
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ip = ((struct fnptr *)func)->ip;
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ia64_patch_imm64(addr + 2, ip);
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flush_icache_range(addr, addr + 16);
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return 0;
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}
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/* run from kstop_machine */
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int __init ftrace_dyn_arch_init(void)
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{
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return 0;
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}
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