linux/scripts/recordmcount.c
<<
>>
Prefs
   1/*
   2 * recordmcount.c: construct a table of the locations of calls to 'mcount'
   3 * so that ftrace can find them quickly.
   4 * Copyright 2009 John F. Reiser <jreiser@BitWagon.com>.  All rights reserved.
   5 * Licensed under the GNU General Public License, version 2 (GPLv2).
   6 *
   7 * Restructured to fit Linux format, as well as other updates:
   8 *  Copyright 2010 Steven Rostedt <srostedt@redhat.com>, Red Hat Inc.
   9 */
  10
  11/*
  12 * Strategy: alter the .o file in-place.
  13 *
  14 * Append a new STRTAB that has the new section names, followed by a new array
  15 * ElfXX_Shdr[] that has the new section headers, followed by the section
  16 * contents for __mcount_loc and its relocations.  The old shstrtab strings,
  17 * and the old ElfXX_Shdr[] array, remain as "garbage" (commonly, a couple
  18 * kilobytes.)  Subsequent processing by /bin/ld (or the kernel module loader)
  19 * will ignore the garbage regions, because they are not designated by the
  20 * new .e_shoff nor the new ElfXX_Shdr[].  [In order to remove the garbage,
  21 * then use "ld -r" to create a new file that omits the garbage.]
  22 */
  23
  24#include <sys/types.h>
  25#include <sys/mman.h>
  26#include <sys/stat.h>
  27#include <getopt.h>
  28#include <elf.h>
  29#include <fcntl.h>
  30#include <setjmp.h>
  31#include <stdio.h>
  32#include <stdlib.h>
  33#include <string.h>
  34#include <unistd.h>
  35
  36static int fd_map;      /* File descriptor for file being modified. */
  37static int mmap_failed; /* Boolean flag. */
  38static void *ehdr_curr; /* current ElfXX_Ehdr *  for resource cleanup */
  39static char gpfx;       /* prefix for global symbol name (sometimes '_') */
  40static struct stat sb;  /* Remember .st_size, etc. */
  41static jmp_buf jmpenv;  /* setjmp/longjmp per-file error escape */
  42static const char *altmcount;   /* alternate mcount symbol name */
  43static int warn_on_notrace_sect; /* warn when section has mcount not being recorded */
  44
  45/* setjmp() return values */
  46enum {
  47        SJ_SETJMP = 0,  /* hardwired first return */
  48        SJ_FAIL,
  49        SJ_SUCCEED
  50};
  51
  52/* Per-file resource cleanup when multiple files. */
  53static void
  54cleanup(void)
  55{
  56        if (!mmap_failed)
  57                munmap(ehdr_curr, sb.st_size);
  58        else
  59                free(ehdr_curr);
  60        close(fd_map);
  61}
  62
  63static void __attribute__((noreturn))
  64fail_file(void)
  65{
  66        cleanup();
  67        longjmp(jmpenv, SJ_FAIL);
  68}
  69
  70static void __attribute__((noreturn))
  71succeed_file(void)
  72{
  73        cleanup();
  74        longjmp(jmpenv, SJ_SUCCEED);
  75}
  76
  77/* ulseek, uread, ...:  Check return value for errors. */
  78
  79static off_t
  80ulseek(int const fd, off_t const offset, int const whence)
  81{
  82        off_t const w = lseek(fd, offset, whence);
  83        if (w == (off_t)-1) {
  84                perror("lseek");
  85                fail_file();
  86        }
  87        return w;
  88}
  89
  90static size_t
  91uread(int const fd, void *const buf, size_t const count)
  92{
  93        size_t const n = read(fd, buf, count);
  94        if (n != count) {
  95                perror("read");
  96                fail_file();
  97        }
  98        return n;
  99}
 100
 101static size_t
 102uwrite(int const fd, void const *const buf, size_t const count)
 103{
 104        size_t const n = write(fd, buf, count);
 105        if (n != count) {
 106                perror("write");
 107                fail_file();
 108        }
 109        return n;
 110}
 111
 112static void *
 113umalloc(size_t size)
 114{
 115        void *const addr = malloc(size);
 116        if (addr == 0) {
 117                fprintf(stderr, "malloc failed: %zu bytes\n", size);
 118                fail_file();
 119        }
 120        return addr;
 121}
 122
 123static unsigned char ideal_nop5_x86_64[5] = { 0x0f, 0x1f, 0x44, 0x00, 0x00 };
 124static unsigned char ideal_nop5_x86_32[5] = { 0x3e, 0x8d, 0x74, 0x26, 0x00 };
 125static unsigned char *ideal_nop;
 126
 127static char rel_type_nop;
 128
 129static int (*make_nop)(void *map, size_t const offset);
 130
 131static int make_nop_x86(void *map, size_t const offset)
 132{
 133        uint32_t *ptr;
 134        unsigned char *op;
 135
 136        /* Confirm we have 0xe8 0x0 0x0 0x0 0x0 */
 137        ptr = map + offset;
 138        if (*ptr != 0)
 139                return -1;
 140
 141        op = map + offset - 1;
 142        if (*op != 0xe8)
 143                return -1;
 144
 145        /* convert to nop */
 146        ulseek(fd_map, offset - 1, SEEK_SET);
 147        uwrite(fd_map, ideal_nop, 5);
 148        return 0;
 149}
 150
 151/*
 152 * Get the whole file as a programming convenience in order to avoid
 153 * malloc+lseek+read+free of many pieces.  If successful, then mmap
 154 * avoids copying unused pieces; else just read the whole file.
 155 * Open for both read and write; new info will be appended to the file.
 156 * Use MAP_PRIVATE so that a few changes to the in-memory ElfXX_Ehdr
 157 * do not propagate to the file until an explicit overwrite at the last.
 158 * This preserves most aspects of consistency (all except .st_size)
 159 * for simultaneous readers of the file while we are appending to it.
 160 * However, multiple writers still are bad.  We choose not to use
 161 * locking because it is expensive and the use case of kernel build
 162 * makes multiple writers unlikely.
 163 */
 164static void *mmap_file(char const *fname)
 165{
 166        void *addr;
 167
 168        fd_map = open(fname, O_RDWR);
 169        if (fd_map < 0 || fstat(fd_map, &sb) < 0) {
 170                perror(fname);
 171                fail_file();
 172        }
 173        if (!S_ISREG(sb.st_mode)) {
 174                fprintf(stderr, "not a regular file: %s\n", fname);
 175                fail_file();
 176        }
 177        addr = mmap(0, sb.st_size, PROT_READ|PROT_WRITE, MAP_PRIVATE,
 178                    fd_map, 0);
 179        mmap_failed = 0;
 180        if (addr == MAP_FAILED) {
 181                mmap_failed = 1;
 182                addr = umalloc(sb.st_size);
 183                uread(fd_map, addr, sb.st_size);
 184        }
 185        return addr;
 186}
 187
 188/* w8rev, w8nat, ...: Handle endianness. */
 189
 190static uint64_t w8rev(uint64_t const x)
 191{
 192        return   ((0xff & (x >> (0 * 8))) << (7 * 8))
 193               | ((0xff & (x >> (1 * 8))) << (6 * 8))
 194               | ((0xff & (x >> (2 * 8))) << (5 * 8))
 195               | ((0xff & (x >> (3 * 8))) << (4 * 8))
 196               | ((0xff & (x >> (4 * 8))) << (3 * 8))
 197               | ((0xff & (x >> (5 * 8))) << (2 * 8))
 198               | ((0xff & (x >> (6 * 8))) << (1 * 8))
 199               | ((0xff & (x >> (7 * 8))) << (0 * 8));
 200}
 201
 202static uint32_t w4rev(uint32_t const x)
 203{
 204        return   ((0xff & (x >> (0 * 8))) << (3 * 8))
 205               | ((0xff & (x >> (1 * 8))) << (2 * 8))
 206               | ((0xff & (x >> (2 * 8))) << (1 * 8))
 207               | ((0xff & (x >> (3 * 8))) << (0 * 8));
 208}
 209
 210static uint32_t w2rev(uint16_t const x)
 211{
 212        return   ((0xff & (x >> (0 * 8))) << (1 * 8))
 213               | ((0xff & (x >> (1 * 8))) << (0 * 8));
 214}
 215
 216static uint64_t w8nat(uint64_t const x)
 217{
 218        return x;
 219}
 220
 221static uint32_t w4nat(uint32_t const x)
 222{
 223        return x;
 224}
 225
 226static uint32_t w2nat(uint16_t const x)
 227{
 228        return x;
 229}
 230
 231static uint64_t (*w8)(uint64_t);
 232static uint32_t (*w)(uint32_t);
 233static uint32_t (*w2)(uint16_t);
 234
 235/* Names of the sections that could contain calls to mcount. */
 236static int
 237is_mcounted_section_name(char const *const txtname)
 238{
 239        return strcmp(".text",           txtname) == 0 ||
 240                strcmp(".ref.text",      txtname) == 0 ||
 241                strcmp(".sched.text",    txtname) == 0 ||
 242                strcmp(".spinlock.text", txtname) == 0 ||
 243                strcmp(".irqentry.text", txtname) == 0 ||
 244                strcmp(".kprobes.text", txtname) == 0 ||
 245                strcmp(".text.unlikely", txtname) == 0;
 246}
 247
 248/* 32 bit and 64 bit are very similar */
 249#include "recordmcount.h"
 250#define RECORD_MCOUNT_64
 251#include "recordmcount.h"
 252
 253/* 64-bit EM_MIPS has weird ELF64_Rela.r_info.
 254 * http://techpubs.sgi.com/library/manuals/4000/007-4658-001/pdf/007-4658-001.pdf
 255 * We interpret Table 29 Relocation Operation (Elf64_Rel, Elf64_Rela) [p.40]
 256 * to imply the order of the members; the spec does not say so.
 257 *      typedef unsigned char Elf64_Byte;
 258 * fails on MIPS64 because their <elf.h> already has it!
 259 */
 260
 261typedef uint8_t myElf64_Byte;           /* Type for a 8-bit quantity.  */
 262
 263union mips_r_info {
 264        Elf64_Xword r_info;
 265        struct {
 266                Elf64_Word r_sym;               /* Symbol index.  */
 267                myElf64_Byte r_ssym;            /* Special symbol.  */
 268                myElf64_Byte r_type3;           /* Third relocation.  */
 269                myElf64_Byte r_type2;           /* Second relocation.  */
 270                myElf64_Byte r_type;            /* First relocation.  */
 271        } r_mips;
 272};
 273
 274static uint64_t MIPS64_r_sym(Elf64_Rel const *rp)
 275{
 276        return w(((union mips_r_info){ .r_info = rp->r_info }).r_mips.r_sym);
 277}
 278
 279static void MIPS64_r_info(Elf64_Rel *const rp, unsigned sym, unsigned type)
 280{
 281        rp->r_info = ((union mips_r_info){
 282                .r_mips = { .r_sym = w(sym), .r_type = type }
 283        }).r_info;
 284}
 285
 286static void
 287do_file(char const *const fname)
 288{
 289        Elf32_Ehdr *const ehdr = mmap_file(fname);
 290        unsigned int reltype = 0;
 291
 292        ehdr_curr = ehdr;
 293        w = w4nat;
 294        w2 = w2nat;
 295        w8 = w8nat;
 296        switch (ehdr->e_ident[EI_DATA]) {
 297                static unsigned int const endian = 1;
 298        default:
 299                fprintf(stderr, "unrecognized ELF data encoding %d: %s\n",
 300                        ehdr->e_ident[EI_DATA], fname);
 301                fail_file();
 302                break;
 303        case ELFDATA2LSB:
 304                if (*(unsigned char const *)&endian != 1) {
 305                        /* main() is big endian, file.o is little endian. */
 306                        w = w4rev;
 307                        w2 = w2rev;
 308                        w8 = w8rev;
 309                }
 310                break;
 311        case ELFDATA2MSB:
 312                if (*(unsigned char const *)&endian != 0) {
 313                        /* main() is little endian, file.o is big endian. */
 314                        w = w4rev;
 315                        w2 = w2rev;
 316                        w8 = w8rev;
 317                }
 318                break;
 319        }  /* end switch */
 320        if (memcmp(ELFMAG, ehdr->e_ident, SELFMAG) != 0
 321        ||  w2(ehdr->e_type) != ET_REL
 322        ||  ehdr->e_ident[EI_VERSION] != EV_CURRENT) {
 323                fprintf(stderr, "unrecognized ET_REL file %s\n", fname);
 324                fail_file();
 325        }
 326
 327        gpfx = 0;
 328        switch (w2(ehdr->e_machine)) {
 329        default:
 330                fprintf(stderr, "unrecognized e_machine %d %s\n",
 331                        w2(ehdr->e_machine), fname);
 332                fail_file();
 333                break;
 334        case EM_386:
 335                reltype = R_386_32;
 336                make_nop = make_nop_x86;
 337                ideal_nop = ideal_nop5_x86_32;
 338                mcount_adjust_32 = -1;
 339                break;
 340        case EM_ARM:     reltype = R_ARM_ABS32;
 341                         altmcount = "__gnu_mcount_nc";
 342                         break;
 343        case EM_IA_64:   reltype = R_IA64_IMM64;   gpfx = '_'; break;
 344        case EM_MIPS:    /* reltype: e_class    */ gpfx = '_'; break;
mips_r_info){
reltype = R_ARM_ABf="_ADDR;
gpfx = '_'; break;
 336}
reltype = R_IA64_t.c <_ADDR>;   gpfx = '_'; break;
 337
      code=reltS30<* reltype: e_class    */ gpfx = '_'; break;
 338/* 348){
reltype = R_IA64_SH_DIR;
 339#include "      code=reltSPARCV9" clasref">reltype = R_IA64_SPARC64
gpfx = '_'; break;
 230#define EM_ARM:   Xrdm  231#include "mmap_faa> = make_nop_x86;
 232
fail_filp = ideal_nop5_x86_  343/* 35ode=fprintf" class="sref">fprintf = R_IA64_Xrdm <64
 344 * 35ode=fail_file" class="sref">fail_filef="scripts/re4
 235 * 35ode=reltype" class="sount.c#L34 href="+c45" class="line" name="L336"> 336 * 35recordmcount.cwitch */
 237 * 35unt.c#L248" id="L248" class="line" name3"L258"> 238 * 35ode=w2" class="sref">w2(e_ident[EI_VERSIONCLAS 239 */35cripts/recordmcount.c#L330" id="L330" class="line" name="L260"> 230
fprintf(stderr, "unrecognized e_machine %d %s\n"<\n&qe=gpfx href="scripts/recordmcount.c#L331" id="L331" class="line" name="L261"> 231typedef w2(e_ident[EI_VERSIONCLASfname);
 232
fail_file();
 233union  234        EM_MIPSLFCLAS<;
 235        struct {
memcmp("+code=ehdr" class="sref">ehdr->e_machineElf64_Rel *const  236                w2(ehdr->e_type) !shN" 
Elf64_Rel 237                fprintf(stderr, "unre#L329" id="L329" class="line" name="L258"> 238                fname);
 239                fail_file();
 230                 231        } memcmp("+code=ehdr" class="sref">ehdr->e_machine),  232};
reltype = R_386_3290 233
/* main() iclass="sref">mcount_adjust_32 = -1;
 234static  235{
memcmp("+code=ehdr" class="sref">ehdr->e_machine), /* ret.c#L329" id="L329" class="line" name="L266"> 236        return w8 =  = R_386_32// 237}
fprintf;
R_386_32/e=ess_fs/reline" ;
/e=ess_fs/reline" unt.c#L337" id="L337" class="line" name="L258"> 238
 239static void fprintf;
ehdr->fname);
fname);
> =  230{
 231        ELFDATA2MCLAS<  232                .Elf64_Rel *const ehdr = Elf64_Rel > *const ehdr-> 233        })./*="sref">memcmp("+code=ehdr" class="sref">ehdr->g *const e_machineElf64_Rel > *const  234}
w2(ehdr->g *const e_machineElf64_Rel 235
w2 = (stderr, "unre#L329" id="L329" class="line" name="L286"> 236static void
="sref">wgnized ET_REL file %s\n", fname);
 237fprintf();
 238{
 239        memcmp("+code=ehdr" class="sref">ehdr->g *const e_machine),  230        unsigned in3 ehdr->> = R_386_3290<4
 231
w2(
 232         233        /*="sref">memcmp("+code=ehdr" class="sref">ehdr->g *const e_machine), /* ret.c#L329" id="L329" class="line" name="L294"> 234        w =  = R_386_32/<4
/<4 235        w2 = R_386_32/sym( 236        switch (w8 = R_386_32/sym( 237                sta3ic un3igned int const w8 = R_386_32/symss_fs/reline" ;
/symss_fs/reline" lassc#L311" id="L311" class="line" name="L288"> 238        default:
 239                fprintfehdr->g *const fname);
fname);
> =  340                   4    <4 href="+code=ehdr" claount.c#L311" id="L311" class="line" name4"L301"> 341                 342                bre4k;

 343        case  344                if 4*(uns4gned char consf">fname);
cleanu 345                   4    <4pan clc#L326" id="L326" class="line" name4"6305"> 345        switch ( 347                   4    <4 href=t.c#L237" id="L237" class="line" name4"L308"> 348                   4    <4 href=w2(reltypereltype 349                }
<4 href4"scripc#L329" id="L329" class="line" name4"L310"> 340                bre4k;
fname);
;
 341        case reltypeElf64_Re 342                if 4*(uns4gned char conss="sref">reltype
 343                   4    <4pan class="coms="sref">reltype 344                   4    <4 href="+code=ws="sref">reltype 345                   4    <41unt.c#L286" id="L286" class="line" name4"L316"> 346                   4    <4 href="+code=wwhef="(="sref">Elf64_Rec{
R_386_32;
ehdr->argc{
reltype 347                }
<4 href4"scripts/recordmcount.="sref">w2( 348                bre4k;
; break;
 349        }  fail_filwarn_on_notracr_
ecef="scripts/recorarn_on_notracr_
ecelasss=".c#L298" id="L298" class="line" name4"L320"> 340        if ( 341        ||   342        ||  reltype(stderr, "unrecognized e_machine %d sage: lass="line"  [-w]
 343                w.c#L328" id="L328" class="line" name4"L324"> 344                 345        }
 346
 347        ehdr->argc{
ehdr->op ina href="+code=r_op inalasst.pan>unt.c#L305" id="L305" class="line" name4"L328"> 348        switch (m>(stderr, "unrecognized e_machine %d sage: lass="line"  [-w]
 349        default:
w.c#L328" id="L328" class="line" name4"L330"> 340                 341                   4    <43unt.c#L292" id="L292" class="line" name4"L332"> 342                , allow>,
 343                bre4k;
stderr,ia href="+code=rilasss="sref">R_386_32gpfx = ehdr->argc{
gpfx =  344        case reltypeR_386_32gpfx =  345                endian sjvaonst R_386_32stderr,jreenef="scripts/recojreeneclas.c#L333" id="L333" class="line" name4"L336"> 346                reltype 347                 348                
 349                bre4k;

 340        case  341                   4     4a href ch */
 342                   4     4reak;
 ch */
 343        case fprintfR_386_32stderr,();
 344        case memcmp(le {
reltype 340>&quol3Cclass="sref">mi4s_r_i44href="+code=w2" class="srsref">R_386_32stderr,();
memcmp(le {
ehdr->otracr_
fname);
 346}
ss= inuer#L333" id="L333" class="line" name4"L337"> 347
 348/* 44ode=mcount_adjust_32"="sref">w2( 349#include " 240#define ehdr->>(stderr, "unrecognized e_machine %d &#claernal erroc="scripts/recordmcount.cef">fname);
<);
 241#include "ehdr->exiref="+code=EI_VERxirs="sr1.c#L333" id="L333" class="line" name4"L332"> 342
 343/* 45ode=fprintf" class="s class="sref">ELFDATSJ_SETJMPef="+code=EI_VESJ_SETJMPde=fltype: e_class    */  344 * 45ode=fail_file" class=ss="sref" e_class    */  345 * 45ode=reltype" class="sss="sref">ehdr->>d_maef="+code=ELFMAG>d_maelasss="t.c#L339" id="L339" class="line" name4"L336"> 346 * 45href="+code=w8" class="sref">w8 =  = ehdr;
 247 * 45gned int const w8 =  248 * 45href="+code=w8" class="sref">w8 = (char const *const fname);
<);
 349 */45ode=myElf64_Byte" cla" class=ount.c#L311" id="L311" class="line" name4"L260"> 240
ELFDATSJ_FAIef="scripts/recoSJ_FAIede=fltype: e_class    */  241typedef ++ref">reltype 342
 343union ELFDATSJ_SUCCEEDef="+code=EI_VESJ_SUCCEEDde=fltype: e_class    */  344         ,
 345        struct {
 346                
 247                 248                w!!ref">reltype 349                 240                 241        }  242};

hre"original LXR software by tre"L292" id=http://sourceforge.net/projec" clxr">LXR 
s experi hreal vers/re by"L292" id=mardto:lxr@hreux.no">lxr@hreux.no;unr.
}; lxr.hreux.no kindly hosted by"L292" id=http://www.redpill-hrepro.no">Redpill Lrepro AS;unrecproviquo of Lreuxass="nt.>,