summaryrefslogtreecommitdiffstats
path: root/scripts/recordmcount.c
diff options
context:
space:
mode:
Diffstat (limited to 'scripts/recordmcount.c')
-rw-r--r--scripts/recordmcount.c670
1 files changed, 670 insertions, 0 deletions
diff --git a/scripts/recordmcount.c b/scripts/recordmcount.c
new file mode 100644
index 000000000..d3e61dcc6
--- /dev/null
+++ b/scripts/recordmcount.c
@@ -0,0 +1,670 @@
+/*
+ * 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.
+ * Licensed under the GNU General Public License, version 2 (GPLv2).
+ *
+ * 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 <setjmp.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
+
+#define R_ARM_PC24 1
+#define R_ARM_THM_CALL 10
+#define R_ARM_CALL 28
+
+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 jmp_buf jmpenv; /* setjmp/longjmp per-file error escape */
+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 */
+
+/* setjmp() return values */
+enum {
+ SJ_SETJMP = 0, /* hardwired first return */
+ SJ_FAIL,
+ SJ_SUCCEED
+};
+
+/* Per-file resource cleanup when multiple files. */
+static void
+cleanup(void)
+{
+ if (!mmap_failed)
+ munmap(file_map, sb.st_size);
+ else
+ free(file_map);
+ file_map = NULL;
+ free(file_append);
+ file_append = NULL;
+ file_append_size = 0;
+ file_updated = 0;
+}
+
+static void __attribute__((noreturn))
+fail_file(void)
+{
+ cleanup();
+ longjmp(jmpenv, SJ_FAIL);
+}
+
+static void __attribute__((noreturn))
+succeed_file(void)
+{
+ cleanup();
+ longjmp(jmpenv, SJ_SUCCEED);
+}
+
+/* ulseek, uread, ...: Check return value for errors. */
+
+static off_t
+ulseek(int const fd, 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");
+ fail_file();
+ }
+ return file_ptr - file_map;
+}
+
+static size_t
+uread(int const fd, void *const buf, size_t const count)
+{
+ size_t const n = read(fd, buf, count);
+ if (n != count) {
+ perror("read");
+ fail_file();
+ }
+ return n;
+}
+
+static size_t
+uwrite(int const fd, void const *const buf, size_t const count)
+{
+ size_t cnt = count;
+ off_t idx = 0;
+
+ file_updated = 1;
+
+ if (file_ptr + count >= file_end) {
+ off_t aoffset = (file_ptr + count) - file_end;
+
+ if (aoffset > file_append_size) {
+ file_append = realloc(file_append, aoffset);
+ file_append_size = aoffset;
+ }
+ if (!file_append) {
+ perror("write");
+ fail_file();
+ }
+ 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);
+ fail_file();
+ }
+ return addr;
+}
+
+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 */
+ ulseek(fd_map, offset - 1, SEEK_SET);
+ uwrite(fd_map, ideal_nop, 5);
+ 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 */
+ ulseek(fd_map, off, SEEK_SET);
+
+ do {
+ uwrite(fd_map, ideal_nop, nop_size);
+ } 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 */
+ ulseek(fd_map, offset, SEEK_SET);
+ uwrite(fd_map, ideal_nop, 4);
+ return 0;
+}
+
+/*
+ * 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)
+{
+ fd_map = open(fname, O_RDONLY);
+ if (fd_map < 0 || fstat(fd_map, &sb) < 0) {
+ perror(fname);
+ fail_file();
+ }
+ if (!S_ISREG(sb.st_mode)) {
+ fprintf(stderr, "not a regular file: %s\n", fname);
+ fail_file();
+ }
+ file_map = mmap(0, sb.st_size, PROT_READ|PROT_WRITE, MAP_PRIVATE,
+ fd_map, 0);
+ mmap_failed = 0;
+ if (file_map == MAP_FAILED) {
+ mmap_failed = 1;
+ file_map = umalloc(sb.st_size);
+ uread(fd_map, file_map, sb.st_size);
+ }
+ close(fd_map);
+
+ file_end = file_map + sb.st_size;
+
+ return file_map;
+}
+
+static void write_file(const char *fname)
+{
+ char tmp_file[strlen(fname) + 4];
+ size_t n;
+
+ if (!file_updated)
+ return;
+
+ 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);
+ fail_file();
+ }
+ n = write(fd_map, file_map, sb.st_size);
+ if (n != sb.st_size) {
+ perror("write");
+ fail_file();
+ }
+ if (file_append_size) {
+ n = write(fd_map, file_append, file_append_size);
+ if (n != file_append_size) {
+ perror("write");
+ fail_file();
+ }
+ }
+ close(fd_map);
+ if (rename(tmp_file, fname) < 0) {
+ perror(fname);
+ fail_file();
+ }
+}
+
+/* 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 ||
+ strcmp(".text.unlikely", txtname) == 0;
+}
+
+/* 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;
+}
+
+/* 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 void
+do_file(char const *const fname)
+{
+ Elf32_Ehdr *const ehdr = mmap_file(fname);
+ unsigned int reltype = 0;
+
+ 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);
+ fail_file();
+ break;
+ 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);
+ fail_file();
+ }
+
+ gpfx = 0;
+ switch (w2(ehdr->e_machine)) {
+ default:
+ fprintf(stderr, "unrecognized e_machine %u %s\n",
+ w2(ehdr->e_machine), fname);
+ fail_file();
+ break;
+ 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;
+ 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;
+ break;
+ case EM_AARCH64:
+ reltype = R_AARCH64_ABS64;
+ make_nop = make_nop_arm64;
+ rel_type_nop = R_AARCH64_NONE;
+ ideal_nop = ideal_nop4_arm64;
+ gpfx = '_';
+ break;
+ case EM_IA_64: reltype = R_IA64_IMM64; gpfx = '_'; break;
+ case EM_MIPS: /* reltype: e_class */ gpfx = '_'; break;
+ case EM_PPC: reltype = R_PPC_ADDR32; gpfx = '_'; break;
+ case EM_PPC64: reltype = R_PPC64_ADDR64; gpfx = '_'; break;
+ case EM_S390: /* reltype: e_class */ gpfx = '_'; break;
+ case EM_SH: reltype = R_SH_DIR32; break;
+ case EM_SPARCV9: reltype = R_SPARC_64; gpfx = '_'; 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;
+ break;
+ } /* end switch */
+
+ switch (ehdr->e_ident[EI_CLASS]) {
+ default:
+ fprintf(stderr, "unrecognized ELF class %d %s\n",
+ ehdr->e_ident[EI_CLASS], fname);
+ fail_file();
+ break;
+ 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);
+ fail_file();
+ }
+ if (w2(ehdr->e_machine) == EM_MIPS) {
+ reltype = R_MIPS_32;
+ is_fake_mcount32 = MIPS32_is_fake_mcount;
+ }
+ do32(ehdr, fname, reltype);
+ 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);
+ fail_file();
+ }
+ 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;
+ }
+ do64(ghdr, fname, reltype);
+ break;
+ }
+ } /* end switch */
+
+ write_file(fname);
+ cleanup();
+}
+
+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 const sjval = setjmp(jmpenv);
+ 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;
+
+ switch (sjval) {
+ default:
+ fprintf(stderr, "internal error: %s\n", file);
+ exit(1);
+ break;
+ case SJ_SETJMP: /* normal sequence */
+ /* Avoid problems if early cleanup() */
+ fd_map = -1;
+ mmap_failed = 1;
+ file_map = NULL;
+ file_ptr = NULL;
+ file_updated = 0;
+ do_file(file);
+ break;
+ case SJ_FAIL: /* error in do_file or below */
+ fprintf(stderr, "%s: failed\n", file);
+ ++n_error;
+ break;
+ case SJ_SUCCEED: /* premature success */
+ /* do nothing */
+ break;
+ } /* end switch */
+ }
+ return !!n_error;
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-24 08:19:15 +0000