* Licensed under the GNU General Public License, version 2 (GPLv2).
*/
#undef append_func
+#undef is_fake_mcount
+#undef fn_is_fake_mcount
+#undef MIPS_is_fake_mcount
+#undef mcount_adjust
#undef sift_rel_mcount
+#undef nop_mcount
#undef find_secsym_ndx
#undef __has_rel_mcount
#undef has_rel_mcount
#undef tot_relsize
+#undef get_mcountsym
+#undef get_sym_str_and_relp
#undef do_func
+#undef Elf_Addr
#undef Elf_Ehdr
#undef Elf_Shdr
#undef Elf_Rel
#undef Elf_Rela
#undef Elf_Sym
#undef ELF_R_SYM
+#undef Elf_r_sym
#undef ELF_R_INFO
+#undef Elf_r_info
#undef ELF_ST_BIND
+#undef ELF_ST_TYPE
+#undef fn_ELF_R_SYM
+#undef fn_ELF_R_INFO
#undef uint_t
#undef _w
#undef _align
#ifdef RECORD_MCOUNT_64
# define append_func append64
# define sift_rel_mcount sift64_rel_mcount
+# define nop_mcount nop_mcount_64
# define find_secsym_ndx find64_secsym_ndx
# define __has_rel_mcount __has64_rel_mcount
# define has_rel_mcount has64_rel_mcount
# define tot_relsize tot64_relsize
+# define get_sym_str_and_relp get_sym_str_and_relp_64
# define do_func do64
+# define get_mcountsym get_mcountsym_64
+# define is_fake_mcount is_fake_mcount64
+# define fn_is_fake_mcount fn_is_fake_mcount64
+# define MIPS_is_fake_mcount MIPS64_is_fake_mcount
+# define mcount_adjust mcount_adjust_64
+# define Elf_Addr Elf64_Addr
# define Elf_Ehdr Elf64_Ehdr
# define Elf_Shdr Elf64_Shdr
# define Elf_Rel Elf64_Rel
# define Elf_Rela Elf64_Rela
# define Elf_Sym Elf64_Sym
# define ELF_R_SYM ELF64_R_SYM
+# define Elf_r_sym Elf64_r_sym
# define ELF_R_INFO ELF64_R_INFO
+# define Elf_r_info Elf64_r_info
# define ELF_ST_BIND ELF64_ST_BIND
+# define ELF_ST_TYPE ELF64_ST_TYPE
+# define fn_ELF_R_SYM fn_ELF64_R_SYM
+# define fn_ELF_R_INFO fn_ELF64_R_INFO
# define uint_t uint64_t
# define _w w8
# define _align 7u
#else
# define append_func append32
# define sift_rel_mcount sift32_rel_mcount
+# define nop_mcount nop_mcount_32
# define find_secsym_ndx find32_secsym_ndx
# define __has_rel_mcount __has32_rel_mcount
# define has_rel_mcount has32_rel_mcount
# define tot_relsize tot32_relsize
+# define get_sym_str_and_relp get_sym_str_and_relp_32
# define do_func do32
+# define get_mcountsym get_mcountsym_32
+# define is_fake_mcount is_fake_mcount32
+# define fn_is_fake_mcount fn_is_fake_mcount32
+# define MIPS_is_fake_mcount MIPS32_is_fake_mcount
+# define mcount_adjust mcount_adjust_32
+# define Elf_Addr Elf32_Addr
# define Elf_Ehdr Elf32_Ehdr
# define Elf_Shdr Elf32_Shdr
# define Elf_Rel Elf32_Rel
# define Elf_Rela Elf32_Rela
# define Elf_Sym Elf32_Sym
# define ELF_R_SYM ELF32_R_SYM
+# define Elf_r_sym Elf32_r_sym
# define ELF_R_INFO ELF32_R_INFO
+# define Elf_r_info Elf32_r_info
# define ELF_ST_BIND ELF32_ST_BIND
+# define ELF_ST_TYPE ELF32_ST_TYPE
+# define fn_ELF_R_SYM fn_ELF32_R_SYM
+# define fn_ELF_R_INFO fn_ELF32_R_INFO
# define uint_t uint32_t
# define _w w
# define _align 3u
# define _size 4
#endif
+/* Functions and pointers that do_file() may override for specific e_machine. */
+static int fn_is_fake_mcount(Elf_Rel const *rp)
+{
+ return 0;
+}
+static int (*is_fake_mcount)(Elf_Rel const *rp) = fn_is_fake_mcount;
+
+static uint_t fn_ELF_R_SYM(Elf_Rel const *rp)
+{
+ return ELF_R_SYM(_w(rp->r_info));
+}
+static uint_t (*Elf_r_sym)(Elf_Rel const *rp) = fn_ELF_R_SYM;
+
+static void fn_ELF_R_INFO(Elf_Rel *const rp, unsigned sym, unsigned type)
+{
+ rp->r_info = _w(ELF_R_INFO(sym, type));
+}
+static void (*Elf_r_info)(Elf_Rel *const rp, unsigned sym, unsigned type) = fn_ELF_R_INFO;
+
+static int mcount_adjust = 0;
+
+/*
+ * MIPS mcount long call has 2 _mcount symbols, only the position of the 1st
+ * _mcount symbol is needed for dynamic function tracer, with it, to disable
+ * tracing(ftrace_make_nop), the instruction in the position is replaced with
+ * the "b label" instruction, to enable tracing(ftrace_make_call), replace the
+ * instruction back. So, here, we set the 2nd one as fake and filter it.
+ *
+ * c: 3c030000 lui v1,0x0 <--> b label
+ * c: R_MIPS_HI16 _mcount
+ * c: R_MIPS_NONE *ABS*
+ * c: R_MIPS_NONE *ABS*
+ * 10: 64630000 daddiu v1,v1,0
+ * 10: R_MIPS_LO16 _mcount
+ * 10: R_MIPS_NONE *ABS*
+ * 10: R_MIPS_NONE *ABS*
+ * 14: 03e0082d move at,ra
+ * 18: 0060f809 jalr v1
+ * label:
+ */
+#define MIPS_FAKEMCOUNT_OFFSET 4
+
+static int MIPS_is_fake_mcount(Elf_Rel const *rp)
+{
+ static Elf_Addr old_r_offset;
+ Elf_Addr current_r_offset = _w(rp->r_offset);
+ int is_fake;
+
+ is_fake = old_r_offset &&
+ (current_r_offset - old_r_offset == MIPS_FAKEMCOUNT_OFFSET);
+ old_r_offset = current_r_offset;
+
+ return is_fake;
+}
+
/* Append the new shstrtab, Elf_Shdr[], __mcount_loc and its relocations. */
static void append_func(Elf_Ehdr *const ehdr,
Elf_Shdr *const shstr,
uwrite(fd_map, ehdr, sizeof(*ehdr));
}
+static unsigned get_mcountsym(Elf_Sym const *const sym0,
+ Elf_Rel const *relp,
+ char const *const str0)
+{
+ unsigned mcountsym = 0;
+
+ Elf_Sym const *const symp =
+ &sym0[Elf_r_sym(relp)];
+ char const *symname = &str0[w(symp->st_name)];
+ char const *mcount = gpfx == '_' ? "_mcount" : "mcount";
+
+ if (symname[0] == '.')
+ ++symname; /* ppc64 hack */
+ if (strcmp(mcount, symname) == 0 ||
+ (altmcount && strcmp(altmcount, symname) == 0))
+ mcountsym = Elf_r_sym(relp);
+
+ return mcountsym;
+}
+
+static void get_sym_str_and_relp(Elf_Shdr const *const relhdr,
+ Elf_Ehdr const *const ehdr,
+ Elf_Sym const **sym0,
+ char const **str0,
+ Elf_Rel const **relp)
+{
+ Elf_Shdr *const shdr0 = (Elf_Shdr *)(_w(ehdr->e_shoff)
+ + (void *)ehdr);
+ unsigned const symsec_sh_link = w(relhdr->sh_link);
+ Elf_Shdr const *const symsec = &shdr0[symsec_sh_link];
+ Elf_Shdr const *const strsec = &shdr0[w(symsec->sh_link)];
+ Elf_Rel const *const rel0 = (Elf_Rel const *)(_w(relhdr->sh_offset)
+ + (void *)ehdr);
+
+ *sym0 = (Elf_Sym const *)(_w(symsec->sh_offset)
+ + (void *)ehdr);
+
+ *str0 = (char const *)(_w(strsec->sh_offset)
+ + (void *)ehdr);
+
+ *relp = rel0;
+}
/*
* Look at the relocations in order to find the calls to mcount.
{
uint_t *const mloc0 = mlocp;
Elf_Rel *mrelp = *mrelpp;
- Elf_Shdr *const shdr0 = (Elf_Shdr *)(_w(ehdr->e_shoff)
- + (void *)ehdr);
- unsigned const symsec_sh_link = w(relhdr->sh_link);
- Elf_Shdr const *const symsec = &shdr0[symsec_sh_link];
- Elf_Sym const *const sym0 = (Elf_Sym const *)(_w(symsec->sh_offset)
- + (void *)ehdr);
-
- Elf_Shdr const *const strsec = &shdr0[w(symsec->sh_link)];
- char const *const str0 = (char const *)(_w(strsec->sh_offset)
- + (void *)ehdr);
-
- Elf_Rel const *const rel0 = (Elf_Rel const *)(_w(relhdr->sh_offset)
- + (void *)ehdr);
+ Elf_Sym const *sym0;
+ char const *str0;
+ Elf_Rel const *relp;
unsigned rel_entsize = _w(relhdr->sh_entsize);
unsigned const nrel = _w(relhdr->sh_size) / rel_entsize;
- Elf_Rel const *relp = rel0;
-
unsigned mcountsym = 0;
unsigned t;
- for (t = nrel; t; --t) {
- if (!mcountsym) {
- Elf_Sym const *const symp =
- &sym0[ELF_R_SYM(_w(relp->r_info))];
- char const *symname = &str0[w(symp->st_name)];
-
- if ('.' == symname[0])
- ++symname; /* ppc64 hack */
- if (0 == strcmp((('_' == gpfx) ? "_mcount" : "mcount"),
- symname))
- mcountsym = ELF_R_SYM(_w(relp->r_info));
- }
+ get_sym_str_and_relp(relhdr, ehdr, &sym0, &str0, &relp);
- if (mcountsym == ELF_R_SYM(_w(relp->r_info))) {
- uint_t const addend = _w(_w(relp->r_offset) - recval);
+ for (t = nrel; t; --t) {
+ if (!mcountsym)
+ mcountsym = get_mcountsym(sym0, relp, str0);
+ if (mcountsym == Elf_r_sym(relp) && !is_fake_mcount(relp)) {
+ uint_t const addend =
+ _w(_w(relp->r_offset) - recval + mcount_adjust);
mrelp->r_offset = _w(offbase
+ ((void *)mlocp - (void *)mloc0));
- mrelp->r_info = _w(ELF_R_INFO(recsym, reltype));
- if (sizeof(Elf_Rela) == rel_entsize) {
+ Elf_r_info(mrelp, recsym, reltype);
+ if (rel_entsize == sizeof(Elf_Rela)) {
((Elf_Rela *)mrelp)->r_addend = addend;
*mlocp++ = 0;
} else
return mlocp;
}
+/*
+ * Read the relocation table again, but this time its called on sections
+ * that are not going to be traced. The mcount calls here will be converted
+ * into nops.
+ */
+static void nop_mcount(Elf_Shdr const *const relhdr,
+ Elf_Ehdr const *const ehdr,
+ const char *const txtname)
+{
+ Elf_Shdr *const shdr0 = (Elf_Shdr *)(_w(ehdr->e_shoff)
+ + (void *)ehdr);
+ Elf_Sym const *sym0;
+ char const *str0;
+ Elf_Rel const *relp;
+ Elf_Shdr const *const shdr = &shdr0[w(relhdr->sh_info)];
+ unsigned rel_entsize = _w(relhdr->sh_entsize);
+ unsigned const nrel = _w(relhdr->sh_size) / rel_entsize;
+ unsigned mcountsym = 0;
+ unsigned t;
+ int once = 0;
+
+ get_sym_str_and_relp(relhdr, ehdr, &sym0, &str0, &relp);
+
+ for (t = nrel; t; --t) {
+ int ret = -1;
+
+ if (!mcountsym)
+ mcountsym = get_mcountsym(sym0, relp, str0);
+
+ if (mcountsym == Elf_r_sym(relp) && !is_fake_mcount(relp)) {
+ if (make_nop)
+ ret = make_nop((void *)ehdr, shdr->sh_offset + relp->r_offset);
+ if (warn_on_notrace_sect && !once) {
+ printf("Section %s has mcount callers being ignored\n",
+ txtname);
+ once = 1;
+ /* just warn? */
+ if (!make_nop)
+ return;
+ }
+ }
+
+ /*
+ * If we successfully removed the mcount, mark the relocation
+ * as a nop (don't do anything with it).
+ */
+ if (!ret) {
+ Elf_Rel rel;
+ rel = *(Elf_Rel *)relp;
+ Elf_r_info(&rel, Elf_r_sym(relp), rel_type_nop);
+ ulseek(fd_map, (void *)relp - (void *)ehdr, SEEK_SET);
+ uwrite(fd_map, &rel, sizeof(rel));
+ }
+ relp = (Elf_Rel const *)(rel_entsize + (void *)relp);
+ }
+}
+
/*
* Find a symbol in the given section, to be used as the base for relocating
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;
}
Elf_Shdr const *const txthdr = &shdr0[w(relhdr->sh_info)];
char const *const txtname = &shstrtab[w(txthdr->sh_name)];
- if (0 == strcmp("__mcount_loc", txtname)) {
+ if (strcmp("__mcount_loc", txtname) == 0) {
fprintf(stderr, "warning: __mcount_loc already exists: %s\n",
fname);
succeed_file();
}
- if (SHT_PROGBITS != w(txthdr->sh_type) ||
- !is_mcounted_section_name(txtname))
+ if (w(txthdr->sh_type) != SHT_PROGBITS ||
+ !(_w(txthdr->sh_flags) & SHF_EXECINSTR))
return NULL;
return txtname;
}
char const *const shstrtab,
char const *const fname)
{
- if (SHT_REL != w(relhdr->sh_type) && SHT_RELA != w(relhdr->sh_type))
+ if (w(relhdr->sh_type) != SHT_REL && w(relhdr->sh_type) != SHT_RELA)
return NULL;
return __has_rel_mcount(relhdr, shdr0, shstrtab, fname);
}
{
unsigned totrelsz = 0;
Elf_Shdr const *shdrp = shdr0;
+ char const *txtname;
for (; nhdr; --nhdr, ++shdrp) {
- if (has_rel_mcount(shdrp, shdr0, shstrtab, fname))
+ txtname = has_rel_mcount(shdrp, shdr0, shstrtab, fname);
+ if (txtname && is_mcounted_section_name(txtname))
totrelsz += _w(shdrp->sh_size);
}
return totrelsz;
for (relhdr = shdr0, k = nhdr; k; --k, ++relhdr) {
char const *const txtname = has_rel_mcount(relhdr, shdr0,
shstrtab, fname);
- if (txtname) {
+ if (txtname && is_mcounted_section_name(txtname)) {
uint_t recval = 0;
unsigned const recsym = find_secsym_ndx(
w(relhdr->sh_info), txtname, &recval,
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) {