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![libin](/assets/img/avatar_default.png)
In nop_mcount, shdr->sh_offset and welp->r_offset should handle endianness properly, otherwise it will trigger Segmentation fault if the recordmcount main and file.o have different endianness. Link: http://lkml.kernel.org/r/563806C7.7070606@huawei.com Cc: <stable@vger.kernel.org> # 3.0+ Signed-off-by: Li Bin <huawei.libin@huawei.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
555 lines
16 KiB
C
555 lines
16 KiB
C
/*
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* recordmcount.h
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*
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* This code was taken out of recordmcount.c written by
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* Copyright 2009 John F. Reiser <jreiser@BitWagon.com>. All rights reserved.
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*
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* The original code had the same algorithms for both 32bit
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* and 64bit ELF files, but the code was duplicated to support
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* the difference in structures that were used. This
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* file creates a macro of everything that is different between
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* the 64 and 32 bit code, such that by including this header
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* twice we can create both sets of functions by including this
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* header once with RECORD_MCOUNT_64 undefined, and again with
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* it defined.
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*
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* This conversion to macros was done by:
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* Copyright 2010 Steven Rostedt <srostedt@redhat.com>, Red Hat Inc.
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*
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* Licensed under the GNU General Public License, version 2 (GPLv2).
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*/
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#undef append_func
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#undef is_fake_mcount
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#undef fn_is_fake_mcount
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#undef MIPS_is_fake_mcount
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#undef mcount_adjust
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#undef sift_rel_mcount
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#undef nop_mcount
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#undef find_secsym_ndx
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#undef __has_rel_mcount
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#undef has_rel_mcount
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#undef tot_relsize
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#undef get_mcountsym
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#undef get_sym_str_and_relp
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#undef do_func
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#undef Elf_Addr
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#undef Elf_Ehdr
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#undef Elf_Shdr
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#undef Elf_Rel
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#undef Elf_Rela
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#undef Elf_Sym
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#undef ELF_R_SYM
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#undef Elf_r_sym
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#undef ELF_R_INFO
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#undef Elf_r_info
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#undef ELF_ST_BIND
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#undef ELF_ST_TYPE
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#undef fn_ELF_R_SYM
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#undef fn_ELF_R_INFO
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#undef uint_t
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#undef _w
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#undef _align
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#undef _size
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#ifdef RECORD_MCOUNT_64
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# define append_func append64
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# define sift_rel_mcount sift64_rel_mcount
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# define nop_mcount nop_mcount_64
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# define find_secsym_ndx find64_secsym_ndx
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# define __has_rel_mcount __has64_rel_mcount
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# define has_rel_mcount has64_rel_mcount
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# define tot_relsize tot64_relsize
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# define get_sym_str_and_relp get_sym_str_and_relp_64
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# define do_func do64
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# define get_mcountsym get_mcountsym_64
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# define is_fake_mcount is_fake_mcount64
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# define fn_is_fake_mcount fn_is_fake_mcount64
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# define MIPS_is_fake_mcount MIPS64_is_fake_mcount
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# define mcount_adjust mcount_adjust_64
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# define Elf_Addr Elf64_Addr
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# define Elf_Ehdr Elf64_Ehdr
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# define Elf_Shdr Elf64_Shdr
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# define Elf_Rel Elf64_Rel
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# define Elf_Rela Elf64_Rela
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# define Elf_Sym Elf64_Sym
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# define ELF_R_SYM ELF64_R_SYM
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# define Elf_r_sym Elf64_r_sym
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# define ELF_R_INFO ELF64_R_INFO
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# define Elf_r_info Elf64_r_info
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# define ELF_ST_BIND ELF64_ST_BIND
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# define ELF_ST_TYPE ELF64_ST_TYPE
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# define fn_ELF_R_SYM fn_ELF64_R_SYM
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# define fn_ELF_R_INFO fn_ELF64_R_INFO
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# define uint_t uint64_t
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# define _w w8
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# define _align 7u
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# define _size 8
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#else
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# define append_func append32
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# define sift_rel_mcount sift32_rel_mcount
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# define nop_mcount nop_mcount_32
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# define find_secsym_ndx find32_secsym_ndx
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# define __has_rel_mcount __has32_rel_mcount
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# define has_rel_mcount has32_rel_mcount
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# define tot_relsize tot32_relsize
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# define get_sym_str_and_relp get_sym_str_and_relp_32
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# define do_func do32
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# define get_mcountsym get_mcountsym_32
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# define is_fake_mcount is_fake_mcount32
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# define fn_is_fake_mcount fn_is_fake_mcount32
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# define MIPS_is_fake_mcount MIPS32_is_fake_mcount
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# define mcount_adjust mcount_adjust_32
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# define Elf_Addr Elf32_Addr
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# define Elf_Ehdr Elf32_Ehdr
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# define Elf_Shdr Elf32_Shdr
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# define Elf_Rel Elf32_Rel
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# define Elf_Rela Elf32_Rela
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# define Elf_Sym Elf32_Sym
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# define ELF_R_SYM ELF32_R_SYM
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# define Elf_r_sym Elf32_r_sym
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# define ELF_R_INFO ELF32_R_INFO
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# define Elf_r_info Elf32_r_info
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# define ELF_ST_BIND ELF32_ST_BIND
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# define ELF_ST_TYPE ELF32_ST_TYPE
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# define fn_ELF_R_SYM fn_ELF32_R_SYM
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# define fn_ELF_R_INFO fn_ELF32_R_INFO
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# define uint_t uint32_t
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# define _w w
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# define _align 3u
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# define _size 4
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#endif
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/* Functions and pointers that do_file() may override for specific e_machine. */
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static int fn_is_fake_mcount(Elf_Rel const *rp)
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{
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return 0;
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}
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static int (*is_fake_mcount)(Elf_Rel const *rp) = fn_is_fake_mcount;
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static uint_t fn_ELF_R_SYM(Elf_Rel const *rp)
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{
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return ELF_R_SYM(_w(rp->r_info));
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}
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static uint_t (*Elf_r_sym)(Elf_Rel const *rp) = fn_ELF_R_SYM;
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static void fn_ELF_R_INFO(Elf_Rel *const rp, unsigned sym, unsigned type)
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{
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rp->r_info = _w(ELF_R_INFO(sym, type));
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}
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static void (*Elf_r_info)(Elf_Rel *const rp, unsigned sym, unsigned type) = fn_ELF_R_INFO;
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static int mcount_adjust = 0;
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/*
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* MIPS mcount long call has 2 _mcount symbols, only the position of the 1st
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* _mcount symbol is needed for dynamic function tracer, with it, to disable
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* tracing(ftrace_make_nop), the instruction in the position is replaced with
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* the "b label" instruction, to enable tracing(ftrace_make_call), replace the
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* instruction back. So, here, we set the 2nd one as fake and filter it.
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*
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* c: 3c030000 lui v1,0x0 <--> b label
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* c: R_MIPS_HI16 _mcount
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* c: R_MIPS_NONE *ABS*
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* c: R_MIPS_NONE *ABS*
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* 10: 64630000 daddiu v1,v1,0
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* 10: R_MIPS_LO16 _mcount
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* 10: R_MIPS_NONE *ABS*
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* 10: R_MIPS_NONE *ABS*
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* 14: 03e0082d move at,ra
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* 18: 0060f809 jalr v1
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* label:
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*/
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#define MIPS_FAKEMCOUNT_OFFSET 4
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static int MIPS_is_fake_mcount(Elf_Rel const *rp)
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{
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static Elf_Addr old_r_offset = ~(Elf_Addr)0;
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Elf_Addr current_r_offset = _w(rp->r_offset);
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int is_fake;
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is_fake = (old_r_offset != ~(Elf_Addr)0) &&
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(current_r_offset - old_r_offset == MIPS_FAKEMCOUNT_OFFSET);
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old_r_offset = current_r_offset;
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return is_fake;
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}
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/* Append the new shstrtab, Elf_Shdr[], __mcount_loc and its relocations. */
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static void append_func(Elf_Ehdr *const ehdr,
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Elf_Shdr *const shstr,
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uint_t const *const mloc0,
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uint_t const *const mlocp,
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Elf_Rel const *const mrel0,
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Elf_Rel const *const mrelp,
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unsigned int const rel_entsize,
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unsigned int const symsec_sh_link)
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{
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/* Begin constructing output file */
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Elf_Shdr mcsec;
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char const *mc_name = (sizeof(Elf_Rela) == rel_entsize)
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? ".rela__mcount_loc"
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: ".rel__mcount_loc";
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unsigned const old_shnum = w2(ehdr->e_shnum);
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uint_t const old_shoff = _w(ehdr->e_shoff);
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uint_t const old_shstr_sh_size = _w(shstr->sh_size);
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uint_t const old_shstr_sh_offset = _w(shstr->sh_offset);
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uint_t t = 1 + strlen(mc_name) + _w(shstr->sh_size);
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uint_t new_e_shoff;
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shstr->sh_size = _w(t);
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shstr->sh_offset = _w(sb.st_size);
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t += sb.st_size;
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t += (_align & -t); /* word-byte align */
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new_e_shoff = t;
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/* body for new shstrtab */
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ulseek(fd_map, sb.st_size, SEEK_SET);
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uwrite(fd_map, old_shstr_sh_offset + (void *)ehdr, old_shstr_sh_size);
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uwrite(fd_map, mc_name, 1 + strlen(mc_name));
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/* old(modified) Elf_Shdr table, word-byte aligned */
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ulseek(fd_map, t, SEEK_SET);
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t += sizeof(Elf_Shdr) * old_shnum;
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uwrite(fd_map, old_shoff + (void *)ehdr,
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sizeof(Elf_Shdr) * old_shnum);
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/* new sections __mcount_loc and .rel__mcount_loc */
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t += 2*sizeof(mcsec);
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mcsec.sh_name = w((sizeof(Elf_Rela) == rel_entsize) + strlen(".rel")
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+ old_shstr_sh_size);
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mcsec.sh_type = w(SHT_PROGBITS);
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mcsec.sh_flags = _w(SHF_ALLOC);
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mcsec.sh_addr = 0;
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mcsec.sh_offset = _w(t);
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mcsec.sh_size = _w((void *)mlocp - (void *)mloc0);
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mcsec.sh_link = 0;
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mcsec.sh_info = 0;
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mcsec.sh_addralign = _w(_size);
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mcsec.sh_entsize = _w(_size);
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uwrite(fd_map, &mcsec, sizeof(mcsec));
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mcsec.sh_name = w(old_shstr_sh_size);
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mcsec.sh_type = (sizeof(Elf_Rela) == rel_entsize)
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? w(SHT_RELA)
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: w(SHT_REL);
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mcsec.sh_flags = 0;
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mcsec.sh_addr = 0;
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mcsec.sh_offset = _w((void *)mlocp - (void *)mloc0 + t);
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mcsec.sh_size = _w((void *)mrelp - (void *)mrel0);
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mcsec.sh_link = w(symsec_sh_link);
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mcsec.sh_info = w(old_shnum);
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mcsec.sh_addralign = _w(_size);
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mcsec.sh_entsize = _w(rel_entsize);
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uwrite(fd_map, &mcsec, sizeof(mcsec));
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uwrite(fd_map, mloc0, (void *)mlocp - (void *)mloc0);
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uwrite(fd_map, mrel0, (void *)mrelp - (void *)mrel0);
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ehdr->e_shoff = _w(new_e_shoff);
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ehdr->e_shnum = w2(2 + w2(ehdr->e_shnum)); /* {.rel,}__mcount_loc */
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ulseek(fd_map, 0, SEEK_SET);
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uwrite(fd_map, ehdr, sizeof(*ehdr));
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}
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static unsigned get_mcountsym(Elf_Sym const *const sym0,
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Elf_Rel const *relp,
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char const *const str0)
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{
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unsigned mcountsym = 0;
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Elf_Sym const *const symp =
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&sym0[Elf_r_sym(relp)];
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char const *symname = &str0[w(symp->st_name)];
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char const *mcount = gpfx == '_' ? "_mcount" : "mcount";
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char const *fentry = "__fentry__";
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if (symname[0] == '.')
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++symname; /* ppc64 hack */
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if (strcmp(mcount, symname) == 0 ||
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(altmcount && strcmp(altmcount, symname) == 0) ||
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(strcmp(fentry, symname) == 0))
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mcountsym = Elf_r_sym(relp);
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return mcountsym;
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}
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static void get_sym_str_and_relp(Elf_Shdr const *const relhdr,
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Elf_Ehdr const *const ehdr,
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Elf_Sym const **sym0,
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char const **str0,
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Elf_Rel const **relp)
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{
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Elf_Shdr *const shdr0 = (Elf_Shdr *)(_w(ehdr->e_shoff)
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+ (void *)ehdr);
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unsigned const symsec_sh_link = w(relhdr->sh_link);
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Elf_Shdr const *const symsec = &shdr0[symsec_sh_link];
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Elf_Shdr const *const strsec = &shdr0[w(symsec->sh_link)];
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Elf_Rel const *const rel0 = (Elf_Rel const *)(_w(relhdr->sh_offset)
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+ (void *)ehdr);
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*sym0 = (Elf_Sym const *)(_w(symsec->sh_offset)
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+ (void *)ehdr);
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*str0 = (char const *)(_w(strsec->sh_offset)
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+ (void *)ehdr);
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*relp = rel0;
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}
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/*
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* Look at the relocations in order to find the calls to mcount.
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* Accumulate the section offsets that are found, and their relocation info,
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* onto the end of the existing arrays.
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*/
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static uint_t *sift_rel_mcount(uint_t *mlocp,
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unsigned const offbase,
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Elf_Rel **const mrelpp,
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Elf_Shdr const *const relhdr,
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Elf_Ehdr const *const ehdr,
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unsigned const recsym,
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uint_t const recval,
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unsigned const reltype)
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{
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uint_t *const mloc0 = mlocp;
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Elf_Rel *mrelp = *mrelpp;
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Elf_Sym const *sym0;
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char const *str0;
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Elf_Rel const *relp;
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unsigned rel_entsize = _w(relhdr->sh_entsize);
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unsigned const nrel = _w(relhdr->sh_size) / rel_entsize;
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unsigned mcountsym = 0;
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unsigned t;
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get_sym_str_and_relp(relhdr, ehdr, &sym0, &str0, &relp);
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for (t = nrel; t; --t) {
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if (!mcountsym)
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mcountsym = get_mcountsym(sym0, relp, str0);
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if (mcountsym == Elf_r_sym(relp) && !is_fake_mcount(relp)) {
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uint_t const addend =
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_w(_w(relp->r_offset) - recval + mcount_adjust);
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mrelp->r_offset = _w(offbase
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+ ((void *)mlocp - (void *)mloc0));
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Elf_r_info(mrelp, recsym, reltype);
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if (rel_entsize == sizeof(Elf_Rela)) {
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((Elf_Rela *)mrelp)->r_addend = addend;
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*mlocp++ = 0;
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} else
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*mlocp++ = addend;
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mrelp = (Elf_Rel *)(rel_entsize + (void *)mrelp);
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}
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relp = (Elf_Rel const *)(rel_entsize + (void *)relp);
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}
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*mrelpp = mrelp;
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return mlocp;
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}
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/*
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* Read the relocation table again, but this time its called on sections
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* that are not going to be traced. The mcount calls here will be converted
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* into nops.
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*/
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static void nop_mcount(Elf_Shdr const *const relhdr,
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Elf_Ehdr const *const ehdr,
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const char *const txtname)
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{
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Elf_Shdr *const shdr0 = (Elf_Shdr *)(_w(ehdr->e_shoff)
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+ (void *)ehdr);
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Elf_Sym const *sym0;
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char const *str0;
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Elf_Rel const *relp;
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Elf_Shdr const *const shdr = &shdr0[w(relhdr->sh_info)];
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unsigned rel_entsize = _w(relhdr->sh_entsize);
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unsigned const nrel = _w(relhdr->sh_size) / rel_entsize;
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unsigned mcountsym = 0;
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unsigned t;
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int once = 0;
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get_sym_str_and_relp(relhdr, ehdr, &sym0, &str0, &relp);
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for (t = nrel; t; --t) {
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int ret = -1;
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if (!mcountsym)
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mcountsym = get_mcountsym(sym0, relp, str0);
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if (mcountsym == Elf_r_sym(relp) && !is_fake_mcount(relp)) {
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if (make_nop)
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ret = make_nop((void *)ehdr, _w(shdr->sh_offset) + _w(relp->r_offset));
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if (warn_on_notrace_sect && !once) {
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printf("Section %s has mcount callers being ignored\n",
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txtname);
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once = 1;
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/* just warn? */
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if (!make_nop)
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return;
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}
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}
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/*
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* If we successfully removed the mcount, mark the relocation
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* as a nop (don't do anything with it).
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*/
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if (!ret) {
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Elf_Rel rel;
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rel = *(Elf_Rel *)relp;
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Elf_r_info(&rel, Elf_r_sym(relp), rel_type_nop);
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ulseek(fd_map, (void *)relp - (void *)ehdr, SEEK_SET);
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uwrite(fd_map, &rel, sizeof(rel));
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}
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relp = (Elf_Rel const *)(rel_entsize + (void *)relp);
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}
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}
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/*
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* Find a symbol in the given section, to be used as the base for relocating
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* the table of offsets of calls to mcount. A local or global symbol suffices,
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* but avoid a Weak symbol because it may be overridden; the change in value
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* would invalidate the relocations of the offsets of the calls to mcount.
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* Often the found symbol will be the unnamed local symbol generated by
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* GNU 'as' for the start of each section. For example:
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* Num: Value Size Type Bind Vis Ndx Name
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* 2: 00000000 0 SECTION LOCAL DEFAULT 1
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*/
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static unsigned find_secsym_ndx(unsigned const txtndx,
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char const *const txtname,
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uint_t *const recvalp,
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Elf_Shdr const *const symhdr,
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Elf_Ehdr const *const ehdr)
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{
|
|
Elf_Sym const *const sym0 = (Elf_Sym const *)(_w(symhdr->sh_offset)
|
|
+ (void *)ehdr);
|
|
unsigned const nsym = _w(symhdr->sh_size) / _w(symhdr->sh_entsize);
|
|
Elf_Sym const *symp;
|
|
unsigned t;
|
|
|
|
for (symp = sym0, t = nsym; t; --t, ++symp) {
|
|
unsigned int const st_bind = ELF_ST_BIND(symp->st_info);
|
|
|
|
if (txtndx == w2(symp->st_shndx)
|
|
/* avoid STB_WEAK */
|
|
&& (STB_LOCAL == st_bind || STB_GLOBAL == st_bind)) {
|
|
/* function symbols on ARM have quirks, avoid them */
|
|
if (w2(ehdr->e_machine) == EM_ARM
|
|
&& ELF_ST_TYPE(symp->st_info) == STT_FUNC)
|
|
continue;
|
|
|
|
*recvalp = _w(symp->st_value);
|
|
return symp - sym0;
|
|
}
|
|
}
|
|
fprintf(stderr, "Cannot find symbol for section %d: %s.\n",
|
|
txtndx, txtname);
|
|
fail_file();
|
|
}
|
|
|
|
|
|
/* Evade ISO C restriction: no declaration after statement in has_rel_mcount. */
|
|
static char const *
|
|
__has_rel_mcount(Elf_Shdr const *const relhdr, /* is SHT_REL or SHT_RELA */
|
|
Elf_Shdr const *const shdr0,
|
|
char const *const shstrtab,
|
|
char const *const fname)
|
|
{
|
|
/* .sh_info depends on .sh_type == SHT_REL[,A] */
|
|
Elf_Shdr const *const txthdr = &shdr0[w(relhdr->sh_info)];
|
|
char const *const txtname = &shstrtab[w(txthdr->sh_name)];
|
|
|
|
if (strcmp("__mcount_loc", txtname) == 0) {
|
|
fprintf(stderr, "warning: __mcount_loc already exists: %s\n",
|
|
fname);
|
|
succeed_file();
|
|
}
|
|
if (w(txthdr->sh_type) != SHT_PROGBITS ||
|
|
!(_w(txthdr->sh_flags) & SHF_EXECINSTR))
|
|
return NULL;
|
|
return txtname;
|
|
}
|
|
|
|
static char const *has_rel_mcount(Elf_Shdr const *const relhdr,
|
|
Elf_Shdr const *const shdr0,
|
|
char const *const shstrtab,
|
|
char const *const fname)
|
|
{
|
|
if (w(relhdr->sh_type) != SHT_REL && w(relhdr->sh_type) != SHT_RELA)
|
|
return NULL;
|
|
return __has_rel_mcount(relhdr, shdr0, shstrtab, fname);
|
|
}
|
|
|
|
|
|
static unsigned tot_relsize(Elf_Shdr const *const shdr0,
|
|
unsigned nhdr,
|
|
const char *const shstrtab,
|
|
const char *const fname)
|
|
{
|
|
unsigned totrelsz = 0;
|
|
Elf_Shdr const *shdrp = shdr0;
|
|
char const *txtname;
|
|
|
|
for (; nhdr; --nhdr, ++shdrp) {
|
|
txtname = has_rel_mcount(shdrp, shdr0, shstrtab, fname);
|
|
if (txtname && is_mcounted_section_name(txtname))
|
|
totrelsz += _w(shdrp->sh_size);
|
|
}
|
|
return totrelsz;
|
|
}
|
|
|
|
|
|
/* Overall supervision for Elf32 ET_REL file. */
|
|
static void
|
|
do_func(Elf_Ehdr *const ehdr, char const *const fname, unsigned const reltype)
|
|
{
|
|
Elf_Shdr *const shdr0 = (Elf_Shdr *)(_w(ehdr->e_shoff)
|
|
+ (void *)ehdr);
|
|
unsigned const nhdr = w2(ehdr->e_shnum);
|
|
Elf_Shdr *const shstr = &shdr0[w2(ehdr->e_shstrndx)];
|
|
char const *const shstrtab = (char const *)(_w(shstr->sh_offset)
|
|
+ (void *)ehdr);
|
|
|
|
Elf_Shdr const *relhdr;
|
|
unsigned k;
|
|
|
|
/* Upper bound on space: assume all relevant relocs are for mcount. */
|
|
unsigned const totrelsz = tot_relsize(shdr0, nhdr, shstrtab, fname);
|
|
Elf_Rel *const mrel0 = umalloc(totrelsz);
|
|
Elf_Rel * mrelp = mrel0;
|
|
|
|
/* 2*sizeof(address) <= sizeof(Elf_Rel) */
|
|
uint_t *const mloc0 = umalloc(totrelsz>>1);
|
|
uint_t * mlocp = mloc0;
|
|
|
|
unsigned rel_entsize = 0;
|
|
unsigned symsec_sh_link = 0;
|
|
|
|
for (relhdr = shdr0, k = nhdr; k; --k, ++relhdr) {
|
|
char const *const txtname = has_rel_mcount(relhdr, shdr0,
|
|
shstrtab, fname);
|
|
if (txtname && is_mcounted_section_name(txtname)) {
|
|
uint_t recval = 0;
|
|
unsigned const recsym = find_secsym_ndx(
|
|
w(relhdr->sh_info), txtname, &recval,
|
|
&shdr0[symsec_sh_link = w(relhdr->sh_link)],
|
|
ehdr);
|
|
|
|
rel_entsize = _w(relhdr->sh_entsize);
|
|
mlocp = sift_rel_mcount(mlocp,
|
|
(void *)mlocp - (void *)mloc0, &mrelp,
|
|
relhdr, ehdr, recsym, recval, reltype);
|
|
} else if (txtname && (warn_on_notrace_sect || make_nop)) {
|
|
/*
|
|
* This section is ignored by ftrace, but still
|
|
* has mcount calls. Convert them to nops now.
|
|
*/
|
|
nop_mcount(relhdr, ehdr, txtname);
|
|
}
|
|
}
|
|
if (mloc0 != mlocp) {
|
|
append_func(ehdr, shstr, mloc0, mlocp, mrel0, mrelp,
|
|
rel_entsize, symsec_sh_link);
|
|
}
|
|
free(mrel0);
|
|
free(mloc0);
|
|
}
|