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202 lines
5.4 KiB
202 lines
5.4 KiB
/* |
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* Dynamic function tracing support. |
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* |
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* Copyright (C) 2008 Shaohua Li <[email protected]> |
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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: |
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* We are paranoid about modifying text, as if a bug was to happen, it |
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* could cause us to read or write to someplace that could cause harm. |
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* Carefully read and modify the code with probe_kernel_*(), and make |
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* sure what we read is what we expected it to be before modifying it. |
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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 (copy_from_kernel_nofault(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 (copy_to_kernel_nofault(((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 (copy_from_kernel_nofault(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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