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When patching USDT probes, use non-unique names for aliases of weak symbols.

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Aliases are normally given names that include a key that's unique for each
input object file. This, for example, ensures that aliases for identically
named local symbols in different object files don't conflict. However, in
some cases the static linker will leave an undefined alias after merging
identical weak symbols, resulting in a link error. A non-unique name allows
the aliases to be merged as well.

PR:		216871
X-MFC With:	r313262
This commit is contained in:
Mark Johnston 2017-02-10 02:01:32 +00:00
parent cb6b8299fd
commit 281e4f2dd4
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=313504
1 changed files with 33 additions and 30 deletions
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63
cddl/contrib/opensolaris/lib/libdtrace/common/dt_link.c
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@ -261,7 +261,7 @@ printf("%s:%s(%d): DOODAD\n",__FUNCTION__,__FILE__,__LINE__);
sym->st_value = 0;
sym->st_size = 0;
sym->st_info = ELF32_ST_INFO(STB_GLOBAL, STT_FUNC);
sym->st_other = ELF32_ST_VISIBILITY(STV_HIDDEN);
sym->st_other = 0;
sym->st_shndx = SHN_UNDEF;
rel++;
@ -445,7 +445,7 @@ prepare_elf64(dtrace_hdl_t *dtp, const dof_hdr_t *dof, dof_elf64_t *dep)
sym->st_value = 0;
sym->st_size = 0;
sym->st_info = GELF_ST_INFO(STB_GLOBAL, STT_FUNC);
sym->st_other = ELF64_ST_VISIBILITY(STV_HIDDEN);
sym->st_other = 0;
sym->st_shndx = SHN_UNDEF;
rel++;
@ -1187,6 +1187,7 @@ process_obj(dtrace_hdl_t *dtp, const char *obj, int *eprobesp)
static const char dt_enabled[] = "enabled";
static const char dt_symprefix[] = "$dtrace";
static const char dt_symfmt[] = "%s%ld.%s";
static const char dt_weaksymfmt[] = "%s.%s";
char probename[DTRACE_NAMELEN];
int fd, i, ndx, eprobe, mod = 0;
Elf *elf = NULL;
@ -1548,44 +1549,46 @@ process_obj(dtrace_hdl_t *dtp, const char *obj, int *eprobesp)
if (dt_symtab_lookup(data_sym, osym, isym,
rela.r_offset, shdr_rel.sh_info, &fsym,
(emachine1 == EM_PPC64), elf) != 0 &&
dt_symtab_lookup(data_sym, 0, osym,
(emachine1 == EM_PPC64), elf) == 0) {
if (fsym.st_name > data_str->d_size)
goto err;
r = s = (char *) data_str->d_buf + fsym.st_name;
assert(strstr(s, dt_symprefix) == s);
s = strchr(s, '.') + 1;
} else if (dt_symtab_lookup(data_sym, 0, osym,
rela.r_offset, shdr_rel.sh_info, &fsym,
(emachine1 == EM_PPC64), elf) != 0)
goto err;
(emachine1 == EM_PPC64), elf) == 0) {
u_int bind;
if (fsym.st_name > data_str->d_size)
goto err;
assert(GELF_ST_TYPE(fsym.st_info) == STT_FUNC);
/*
* If this is our first time encountering this symbol,
* emit an alias.
*/
s = (char *)data_str->d_buf + fsym.st_name;
if (strncmp(s, dt_symprefix,
sizeof (dt_symprefix) - 1) != 0) {
u_int bind = GELF_ST_BIND(fsym.st_info);
bind = GELF_ST_BIND(fsym.st_info) == STB_WEAK ?
STB_WEAK : STB_GLOBAL;
/*
* Emit an alias for the symbol. It needs to be
* non-preemptible so that .SUNW_dof relocations
* may be resolved at static link time. Aliases
* of weak symbols are given a non-unique name
* so that they may be merged by the linker.
*/
dsym = fsym;
dsym.st_name = istr;
dsym.st_info = GELF_ST_INFO(bind == STB_LOCAL ?
STB_GLOBAL : bind, STT_FUNC);
dsym.st_info = GELF_ST_INFO(bind, STT_FUNC);
dsym.st_other = GELF_ST_VISIBILITY(STV_HIDDEN);
(void) gelf_update_sym(data_sym, isym, &dsym);
r = (char *) data_str->d_buf + istr;
istr += 1 + sprintf(r, dt_symfmt, dt_symprefix, objkey,
s);
s = (char *) data_str->d_buf + fsym.st_name;
if (bind == STB_WEAK)
istr += sprintf(r, dt_weaksymfmt,
dt_symprefix, s);
else
istr += sprintf(r, dt_symfmt,
dt_symprefix, objkey, s);
istr++;
isym++;
assert(isym <= nsym);
} else {
r = s;
s = strchr(s, '.');
assert(s != NULL);
s++;
}
} else
goto err;
if ((pvp = dt_provider_lookup(dtp, pname)) == NULL) {
return (dt_link_error(dtp, elf, fd, bufs,