Something went wrong. Try again.
Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
Something went wrong. Try again.
123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216217218219220221222223224225226227228229230231232233234235236237238239240241242243244245246247248249250251252253254255256257258259260261262263264265266267268269270271272273274275276277278279280281282283284285286287288289290291292293294295296297298299300301302303304305306307308309310311312313314315316317318319320321322323324325326327328329330331332333334335336337338339340341342343344345346347348349350351352353354355356357358359360361362363364365366367368369370371372373374375376377378379380381382383384385386387388389390391392393394395396397398399400401402403404405406407408409410411412413414415416417418419420421422423424425426427428429430431432433434435436437438439440441442443444445446447448449450451452453454455456457458459460461462463464465466467468469470471472473474475476477478479480481482483484485486487488489490491492493494495496497498499500501502503504505506507508509510511512513514515516517518519520521522523524525526527528529530531532533534535536537538539540541542543544545546547548549550551552553554555556557558559560561562563564565566567568569570571572573574575576577578579580581582583584585586587588589590591592593594595596597598599600601602603604605606607608609610611612613614615616617618619620621622623624625626627628629630631632633634635636637638639640641642643644645646647648649650651652653654655656657658659660661662663664665666667668669670671672673674675676677678679680681682683684685686687688689690691692693694695696697698699700701702703704705706707708709710711712713714// SPDX-License-Identifier: GPL-2.0-only/* * recordmcount.c: construct a table of the locations of calls to 'mcount' * so that ftrace can find them quickly. * Copyright 2009 John F. Reiser <jreiser@BitWagon.com>. All rights reserved. * * Restructured to fit Linux format, as well as other updates: * Copyright 2010 Steven Rostedt <srostedt@redhat.com>, Red Hat Inc. */
/* * Strategy: alter the .o file in-place. * * Append a new STRTAB that has the new section names, followed by a new array * ElfXX_Shdr[] that has the new section headers, followed by the section * contents for __mcount_loc and its relocations. The old shstrtab strings, * and the old ElfXX_Shdr[] array, remain as "garbage" (commonly, a couple * kilobytes.) Subsequent processing by /bin/ld (or the kernel module loader) * will ignore the garbage regions, because they are not designated by the * new .e_shoff nor the new ElfXX_Shdr[]. [In order to remove the garbage, * then use "ld -r" to create a new file that omits the garbage.] */
#include <sys/types.h>#include <sys/mman.h>#include <sys/stat.h>#include <getopt.h>#include <elf.h>#include <fcntl.h>#include <stdio.h>#include <stdlib.h>#include <string.h>#include <unistd.h>
#ifndef EM_AARCH64#define EM_AARCH64 183#define R_AARCH64_NONE 0#define R_AARCH64_ABS64 257#endif
#ifndef EM_LOONGARCH#define EM_LOONGARCH 258#define R_LARCH_32 1#define R_LARCH_64 2#define R_LARCH_MARK_LA 20#define R_LARCH_SOP_PUSH_PLT_PCREL 29#endif
#define R_ARM_PC24 1#define R_ARM_THM_CALL 10#define R_ARM_CALL 28
#define R_AARCH64_CALL26 283
static int fd_map; /* File descriptor for file being modified. */static int mmap_failed; /* Boolean flag. */static char gpfx; /* prefix for global symbol name (sometimes '_') */static struct stat sb; /* Remember .st_size, etc. */static const char *altmcount; /* alternate mcount symbol name */static int warn_on_notrace_sect; /* warn when section has mcount not being recorded */static void *file_map; /* pointer of the mapped file */static void *file_end; /* pointer to the end of the mapped file */static int file_updated; /* flag to state file was changed */static void *file_ptr; /* current file pointer location */
static void *file_append; /* added to the end of the file */static size_t file_append_size; /* how much is added to end of file */
/* Per-file resource cleanup when multiple files. */static void file_append_cleanup(void){ free(file_append); file_append = NULL; file_append_size = 0; file_updated = 0;}
static void mmap_cleanup(void){ if (!mmap_failed) munmap(file_map, sb.st_size); else free(file_map); file_map = NULL;}
/* ulseek, uwrite, ...: Check return value for errors. */
static off_t ulseek(off_t const offset, int const whence){ switch (whence) { case SEEK_SET: file_ptr = file_map + offset; break; case SEEK_CUR: file_ptr += offset; break; case SEEK_END: file_ptr = file_map + (sb.st_size - offset); break; } if (file_ptr < file_map) { fprintf(stderr, "lseek: seek before file\n"); return -1; } return file_ptr - file_map;}
static ssize_t uwrite(void const *const buf, size_t const count){ size_t cnt = count; off_t idx = 0; void *p = NULL;
file_updated = 1;
if (file_ptr + count >= file_end) { off_t aoffset = (file_ptr + count) - file_end;
if (aoffset > file_append_size) { p = realloc(file_append, aoffset); if (!p) free(file_append); file_append = p; file_append_size = aoffset; } if (!file_append) { perror("write"); file_append_cleanup(); mmap_cleanup(); return -1; } if (file_ptr < file_end) { cnt = file_end - file_ptr; } else { cnt = 0; idx = aoffset - count; } }
if (cnt) memcpy(file_ptr, buf, cnt);
if (cnt < count) memcpy(file_append + idx, buf + cnt, count - cnt);
file_ptr += count; return count;}
static void * umalloc(size_t size){ void *const addr = malloc(size); if (addr == 0) { fprintf(stderr, "malloc failed: %zu bytes\n", size); file_append_cleanup(); mmap_cleanup(); return NULL; } return addr;}
/* * Get the whole file as a programming convenience in order to avoid * malloc+lseek+read+free of many pieces. If successful, then mmap * avoids copying unused pieces; else just read the whole file. * Open for both read and write; new info will be appended to the file. * Use MAP_PRIVATE so that a few changes to the in-memory ElfXX_Ehdr * do not propagate to the file until an explicit overwrite at the last. * This preserves most aspects of consistency (all except .st_size) * for simultaneous readers of the file while we are appending to it. * However, multiple writers still are bad. We choose not to use * locking because it is expensive and the use case of kernel build * makes multiple writers unlikely. */static void *mmap_file(char const *fname){ /* Avoid problems if early cleanup() */ fd_map = -1; mmap_failed = 1; file_map = NULL; file_ptr = NULL; file_updated = 0; sb.st_size = 0;
fd_map = open(fname, O_RDONLY); if (fd_map < 0) { perror(fname); return NULL; } if (fstat(fd_map, &sb) < 0) { perror(fname); goto out; } if (!S_ISREG(sb.st_mode)) { fprintf(stderr, "not a regular file: %s\n", fname); goto out; } file_map = mmap(0, sb.st_size, PROT_READ|PROT_WRITE, MAP_PRIVATE, fd_map, 0); if (file_map == MAP_FAILED) { mmap_failed = 1; file_map = umalloc(sb.st_size); if (!file_map) { perror(fname); goto out; } if (read(fd_map, file_map, sb.st_size) != sb.st_size) { perror(fname); free(file_map); file_map = NULL; goto out; } } else mmap_failed = 0;out: close(fd_map); fd_map = -1;
file_end = file_map + sb.st_size;
return file_map;}
static unsigned char ideal_nop5_x86_64[5] = { 0x0f, 0x1f, 0x44, 0x00, 0x00 };static unsigned char ideal_nop5_x86_32[5] = { 0x3e, 0x8d, 0x74, 0x26, 0x00 };static unsigned char *ideal_nop;
static char rel_type_nop;
static int (*make_nop)(void *map, size_t const offset);
static int make_nop_x86(void *map, size_t const offset){ uint32_t *ptr; unsigned char *op;
/* Confirm we have 0xe8 0x0 0x0 0x0 0x0 */ ptr = map + offset; if (*ptr != 0) return -1;
op = map + offset - 1; if (*op != 0xe8) return -1;
/* convert to nop */ if (ulseek(offset - 1, SEEK_SET) < 0) return -1; if (uwrite(ideal_nop, 5) < 0) return -1; return 0;}
static unsigned char ideal_nop4_arm_le[4] = { 0x00, 0x00, 0xa0, 0xe1 }; /* mov r0, r0 */static unsigned char ideal_nop4_arm_be[4] = { 0xe1, 0xa0, 0x00, 0x00 }; /* mov r0, r0 */static unsigned char *ideal_nop4_arm;
static unsigned char bl_mcount_arm_le[4] = { 0xfe, 0xff, 0xff, 0xeb }; /* bl */static unsigned char bl_mcount_arm_be[4] = { 0xeb, 0xff, 0xff, 0xfe }; /* bl */static unsigned char *bl_mcount_arm;
static unsigned char push_arm_le[4] = { 0x04, 0xe0, 0x2d, 0xe5 }; /* push {lr} */static unsigned char push_arm_be[4] = { 0xe5, 0x2d, 0xe0, 0x04 }; /* push {lr} */static unsigned char *push_arm;
static unsigned char ideal_nop2_thumb_le[2] = { 0x00, 0xbf }; /* nop */static unsigned char ideal_nop2_thumb_be[2] = { 0xbf, 0x00 }; /* nop */static unsigned char *ideal_nop2_thumb;
static unsigned char push_bl_mcount_thumb_le[6] = { 0x00, 0xb5, 0xff, 0xf7, 0xfe, 0xff }; /* push {lr}, bl */static unsigned char push_bl_mcount_thumb_be[6] = { 0xb5, 0x00, 0xf7, 0xff, 0xff, 0xfe }; /* push {lr}, bl */static unsigned char *push_bl_mcount_thumb;
static int make_nop_arm(void *map, size_t const offset){ char *ptr; int cnt = 1; int nop_size; size_t off = offset;
ptr = map + offset; if (memcmp(ptr, bl_mcount_arm, 4) == 0) { if (memcmp(ptr - 4, push_arm, 4) == 0) { off -= 4; cnt = 2; } ideal_nop = ideal_nop4_arm; nop_size = 4; } else if (memcmp(ptr - 2, push_bl_mcount_thumb, 6) == 0) { cnt = 3; nop_size = 2; off -= 2; ideal_nop = ideal_nop2_thumb; } else return -1;
/* Convert to nop */ if (ulseek(off, SEEK_SET) < 0) return -1;
do { if (uwrite(ideal_nop, nop_size) < 0) return -1; } while (--cnt > 0);
return 0;}
static unsigned char ideal_nop4_arm64[4] = {0x1f, 0x20, 0x03, 0xd5};static int make_nop_arm64(void *map, size_t const offset){ uint32_t *ptr;
ptr = map + offset; /* bl <_mcount> is 0x94000000 before relocation */ if (*ptr != 0x94000000) return -1;
/* Convert to nop */ if (ulseek(offset, SEEK_SET) < 0) return -1; if (uwrite(ideal_nop, 4) < 0) return -1; return 0;}
static int write_file(const char *fname){ char tmp_file[strlen(fname) + 4]; size_t n;
if (!file_updated) return 0;
sprintf(tmp_file, "%s.rc", fname);
/* * After reading the entire file into memory, delete it * and write it back, to prevent weird side effects of modifying * an object file in place. */ fd_map = open(tmp_file, O_WRONLY | O_TRUNC | O_CREAT, sb.st_mode); if (fd_map < 0) { perror(fname); return -1; } n = write(fd_map, file_map, sb.st_size); if (n != sb.st_size) { perror("write"); close(fd_map); return -1; } if (file_append_size) { n = write(fd_map, file_append, file_append_size); if (n != file_append_size) { perror("write"); close(fd_map); return -1; } } close(fd_map); if (rename(tmp_file, fname) < 0) { perror(fname); return -1; } return 0;}
/* w8rev, w8nat, ...: Handle endianness. */
static uint64_t w8rev(uint64_t const x){ return ((0xff & (x >> (0 * 8))) << (7 * 8)) | ((0xff & (x >> (1 * 8))) << (6 * 8)) | ((0xff & (x >> (2 * 8))) << (5 * 8)) | ((0xff & (x >> (3 * 8))) << (4 * 8)) | ((0xff & (x >> (4 * 8))) << (3 * 8)) | ((0xff & (x >> (5 * 8))) << (2 * 8)) | ((0xff & (x >> (6 * 8))) << (1 * 8)) | ((0xff & (x >> (7 * 8))) << (0 * 8));}
static uint32_t w4rev(uint32_t const x){ return ((0xff & (x >> (0 * 8))) << (3 * 8)) | ((0xff & (x >> (1 * 8))) << (2 * 8)) | ((0xff & (x >> (2 * 8))) << (1 * 8)) | ((0xff & (x >> (3 * 8))) << (0 * 8));}
static uint32_t w2rev(uint16_t const x){ return ((0xff & (x >> (0 * 8))) << (1 * 8)) | ((0xff & (x >> (1 * 8))) << (0 * 8));}
static uint64_t w8nat(uint64_t const x){ return x;}
static uint32_t w4nat(uint32_t const x){ return x;}
static uint32_t w2nat(uint16_t const x){ return x;}
static uint64_t (*w8)(uint64_t);static uint32_t (*w)(uint32_t);static uint32_t (*w2)(uint16_t);
/* Names of the sections that could contain calls to mcount. */static int is_mcounted_section_name(char const *const txtname){ return strncmp(".text", txtname, 5) == 0 || strcmp(".init.text", txtname) == 0 || strcmp(".ref.text", txtname) == 0 || strcmp(".sched.text", txtname) == 0 || strcmp(".spinlock.text", txtname) == 0 || strcmp(".irqentry.text", txtname) == 0 || strcmp(".softirqentry.text", txtname) == 0 || strcmp(".kprobes.text", txtname) == 0 || strcmp(".cpuidle.text", txtname) == 0;}
static char const *already_has_rel_mcount = "success"; /* our work here is done! */
/* 32 bit and 64 bit are very similar */#include "recordmcount.h"#define RECORD_MCOUNT_64#include "recordmcount.h"
static int arm_is_fake_mcount(Elf32_Rel const *rp){ switch (ELF32_R_TYPE(w(rp->r_info))) { case R_ARM_THM_CALL: case R_ARM_CALL: case R_ARM_PC24: return 0; }
return 1;}
static int arm64_is_fake_mcount(Elf64_Rel const *rp){ return ELF64_R_TYPE(w8(rp->r_info)) != R_AARCH64_CALL26;}
static int LARCH32_is_fake_mcount(Elf32_Rel const *rp){ switch (ELF64_R_TYPE(w(rp->r_info))) { case R_LARCH_MARK_LA: case R_LARCH_SOP_PUSH_PLT_PCREL: return 0; }
return 1;}
static int LARCH64_is_fake_mcount(Elf64_Rel const *rp){ switch (ELF64_R_TYPE(w(rp->r_info))) { case R_LARCH_MARK_LA: case R_LARCH_SOP_PUSH_PLT_PCREL: return 0; }
return 1;}
/* 64-bit EM_MIPS has weird ELF64_Rela.r_info. * http://techpubs.sgi.com/library/manuals/4000/007-4658-001/pdf/007-4658-001.pdf * We interpret Table 29 Relocation Operation (Elf64_Rel, Elf64_Rela) [p.40] * to imply the order of the members; the spec does not say so. * typedef unsigned char Elf64_Byte; * fails on MIPS64 because their <elf.h> already has it! */
typedef uint8_t myElf64_Byte; /* Type for a 8-bit quantity. */
union mips_r_info { Elf64_Xword r_info; struct { Elf64_Word r_sym; /* Symbol index. */ myElf64_Byte r_ssym; /* Special symbol. */ myElf64_Byte r_type3; /* Third relocation. */ myElf64_Byte r_type2; /* Second relocation. */ myElf64_Byte r_type; /* First relocation. */ } r_mips;};
static uint64_t MIPS64_r_sym(Elf64_Rel const *rp){ return w(((union mips_r_info){ .r_info = rp->r_info }).r_mips.r_sym);}
static void MIPS64_r_info(Elf64_Rel *const rp, unsigned sym, unsigned type){ rp->r_info = ((union mips_r_info){ .r_mips = { .r_sym = w(sym), .r_type = type } }).r_info;}
static int do_file(char const *const fname){ unsigned int reltype = 0; Elf32_Ehdr *ehdr; int rc = -1;
ehdr = mmap_file(fname); if (!ehdr) goto out;
w = w4nat; w2 = w2nat; w8 = w8nat; switch (ehdr->e_ident[EI_DATA]) { static unsigned int const endian = 1; default: fprintf(stderr, "unrecognized ELF data encoding %d: %s\n", ehdr->e_ident[EI_DATA], fname); goto out; case ELFDATA2LSB: if (*(unsigned char const *)&endian != 1) { /* main() is big endian, file.o is little endian. */ w = w4rev; w2 = w2rev; w8 = w8rev; } ideal_nop4_arm = ideal_nop4_arm_le; bl_mcount_arm = bl_mcount_arm_le; push_arm = push_arm_le; ideal_nop2_thumb = ideal_nop2_thumb_le; push_bl_mcount_thumb = push_bl_mcount_thumb_le; break; case ELFDATA2MSB: if (*(unsigned char const *)&endian != 0) { /* main() is little endian, file.o is big endian. */ w = w4rev; w2 = w2rev; w8 = w8rev; } ideal_nop4_arm = ideal_nop4_arm_be; bl_mcount_arm = bl_mcount_arm_be; push_arm = push_arm_be; ideal_nop2_thumb = ideal_nop2_thumb_be; push_bl_mcount_thumb = push_bl_mcount_thumb_be; break; } /* end switch */ if (memcmp(ELFMAG, ehdr->e_ident, SELFMAG) != 0 || w2(ehdr->e_type) != ET_REL || ehdr->e_ident[EI_VERSION] != EV_CURRENT) { fprintf(stderr, "unrecognized ET_REL file %s\n", fname); goto out; }
gpfx = '_'; switch (w2(ehdr->e_machine)) { default: fprintf(stderr, "unrecognized e_machine %u %s\n", w2(ehdr->e_machine), fname); goto out; case EM_386: reltype = R_386_32; rel_type_nop = R_386_NONE; make_nop = make_nop_x86; ideal_nop = ideal_nop5_x86_32; mcount_adjust_32 = -1; gpfx = 0; break; case EM_ARM: reltype = R_ARM_ABS32; altmcount = "__gnu_mcount_nc"; make_nop = make_nop_arm; rel_type_nop = R_ARM_NONE; is_fake_mcount32 = arm_is_fake_mcount; gpfx = 0; break; case EM_AARCH64: reltype = R_AARCH64_ABS64; make_nop = make_nop_arm64; rel_type_nop = R_AARCH64_NONE; ideal_nop = ideal_nop4_arm64; is_fake_mcount64 = arm64_is_fake_mcount; break; case EM_MIPS: /* reltype: e_class */ break; case EM_LOONGARCH: /* reltype: e_class */ break; case EM_PPC: reltype = R_PPC_ADDR32; break; case EM_PPC64: reltype = R_PPC64_ADDR64; break; case EM_S390: /* reltype: e_class */ break; case EM_SH: reltype = R_SH_DIR32; gpfx = 0; break; case EM_SPARCV9: reltype = R_SPARC_64; break; case EM_X86_64: make_nop = make_nop_x86; ideal_nop = ideal_nop5_x86_64; reltype = R_X86_64_64; rel_type_nop = R_X86_64_NONE; mcount_adjust_64 = -1; gpfx = 0; break; } /* end switch */
switch (ehdr->e_ident[EI_CLASS]) { default: fprintf(stderr, "unrecognized ELF class %d %s\n", ehdr->e_ident[EI_CLASS], fname); goto out; case ELFCLASS32: if (w2(ehdr->e_ehsize) != sizeof(Elf32_Ehdr) || w2(ehdr->e_shentsize) != sizeof(Elf32_Shdr)) { fprintf(stderr, "unrecognized ET_REL file: %s\n", fname); goto out; } if (w2(ehdr->e_machine) == EM_MIPS) { reltype = R_MIPS_32; is_fake_mcount32 = MIPS32_is_fake_mcount; } if (w2(ehdr->e_machine) == EM_LOONGARCH) { reltype = R_LARCH_32; is_fake_mcount32 = LARCH32_is_fake_mcount; } if (do32(ehdr, fname, reltype) < 0) goto out; break; case ELFCLASS64: { Elf64_Ehdr *const ghdr = (Elf64_Ehdr *)ehdr; if (w2(ghdr->e_ehsize) != sizeof(Elf64_Ehdr) || w2(ghdr->e_shentsize) != sizeof(Elf64_Shdr)) { fprintf(stderr, "unrecognized ET_REL file: %s\n", fname); goto out; } if (w2(ghdr->e_machine) == EM_S390) { reltype = R_390_64; mcount_adjust_64 = -14; } if (w2(ghdr->e_machine) == EM_MIPS) { reltype = R_MIPS_64; Elf64_r_sym = MIPS64_r_sym; Elf64_r_info = MIPS64_r_info; is_fake_mcount64 = MIPS64_is_fake_mcount; } if (w2(ghdr->e_machine) == EM_LOONGARCH) { reltype = R_LARCH_64; is_fake_mcount64 = LARCH64_is_fake_mcount; } if (do64(ghdr, fname, reltype) < 0) goto out; break; } } /* end switch */
rc = write_file(fname);out: file_append_cleanup(); mmap_cleanup(); return rc;}
int main(int argc, char *argv[]){ const char ftrace[] = "/ftrace.o"; int ftrace_size = sizeof(ftrace) - 1; int n_error = 0; /* gcc-4.3.0 false positive complaint */ int c; int i;
while ((c = getopt(argc, argv, "w")) >= 0) { switch (c) { case 'w': warn_on_notrace_sect = 1; break; default: fprintf(stderr, "usage: recordmcount [-w] file.o...\n"); return 0; } }
if ((argc - optind) < 1) { fprintf(stderr, "usage: recordmcount [-w] file.o...\n"); return 0; }
/* Process each file in turn, allowing deep failure. */ for (i = optind; i < argc; i++) { char *file = argv[i]; int len;
/* * The file kernel/trace/ftrace.o references the mcount * function but does not call it. Since ftrace.o should * not be traced anyway, we just skip it. */ len = strlen(file); if (len >= ftrace_size && strcmp(file + (len - ftrace_size), ftrace) == 0) continue;
if (do_file(file)) { fprintf(stderr, "%s: failed\n", file); ++n_error; } } return !!n_error;}