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GNU C Library master sources branch master updated. glibc-2.19-101-g8e25d1e
- From: carlos at sourceware dot org
- To: glibc-cvs at sourceware dot org
- Date: 28 Feb 2014 23:15:23 -0000
- Subject: GNU C Library master sources branch master updated. glibc-2.19-101-g8e25d1e
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http://sourceware.org/git/gitweb.cgi?p=glibc.git;a=commitdiff;h=8e25d1e7721d8078d8925e325799740dd53a5801
commit 8e25d1e7721d8078d8925e325799740dd53a5801
Author: Carlos O'Donell <carlos@redhat.com>
Date: Fri Feb 28 18:11:06 2014 -0500
Promote do_lookup_x:check_match to a full function.
While it may be argued that nested functions make the resulting
code easier to read, or worse to read the following two bugs
make it difficult to debug:
Bug 8300 - no local symbol information within nested or nesting
procedures
https://sourceware.org/bugzilla/show_bug.cgi?id=8300
Bug 53927 - wrong value for DW_AT_static_link
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53927
Until these are fixed I've made check_match a full function.
After they are fixed we can resume arguing about the merits
of nested functions on readability and maintenance.
diff --git a/ChangeLog b/ChangeLog
index a5b1de2..60d63db 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2014-02-28 Carlos O'Donell <carlos@redhat.com>
+
+ * elf/dl-lookup.c (check_match): New function.
+ (ELF_MACHINE_SYM_NO_MATCH): Adjust comment.
+ (do_lookup_x): Remove nested function check_match. Use non-nested
+ function check_match.
+
2014-02-28 Roland McGrath <roland@hack.frob.com>
* csu/Makefile (generated, before-compile): Use += rather than =.
diff --git a/elf/dl-lookup.c b/elf/dl-lookup.c
index 0b43db8..d1b8efc 100644
--- a/elf/dl-lookup.c
+++ b/elf/dl-lookup.c
@@ -31,9 +31,8 @@
#include <assert.h>
-/* Return nonzero if do_lookup_x:check_match should consider SYM to
- fail to match a symbol reference for some machine-specific
- reason. */
+/* Return nonzero if check_match should consider SYM to fail to match a
+ symbol reference for some machine-specific reason. */
#ifndef ELF_MACHINE_SYM_NO_MATCH
# define ELF_MACHINE_SYM_NO_MATCH(sym) 0
#endif
@@ -75,6 +74,118 @@ struct sym_val
# define bump_num_relocations() ((void) 0)
#endif
+/* Utility function for do_lookup_x. The caller is called with undef_name,
+ ref, version, flags and type_class, and those are passed as the first
+ five arguments. The caller then computes sym, symidx, strtab, and map
+ and passes them as the next four arguments. Lastly the caller passes in
+ versioned_sym and num_versions which are modified by check_match during
+ the checking process. */
+static const ElfW(Sym) *
+check_match (const char *const undef_name,
+ const ElfW(Sym) *const ref,
+ const struct r_found_version *const version,
+ const int flags,
+ const int type_class,
+ const ElfW(Sym) *const sym,
+ const Elf_Symndx symidx,
+ const char *const strtab,
+ const struct link_map *const map,
+ const ElfW(Sym) **const versioned_sym,
+ int *const num_versions)
+{
+ unsigned int stt = ELFW(ST_TYPE) (sym->st_info);
+ assert (ELF_RTYPE_CLASS_PLT == 1);
+ if (__builtin_expect ((sym->st_value == 0 /* No value. */
+ && stt != STT_TLS)
+ || ELF_MACHINE_SYM_NO_MATCH (sym)
+ || (type_class & (sym->st_shndx == SHN_UNDEF)),
+ 0))
+ return NULL;
+
+ /* Ignore all but STT_NOTYPE, STT_OBJECT, STT_FUNC,
+ STT_COMMON, STT_TLS, and STT_GNU_IFUNC since these are no
+ code/data definitions. */
+#define ALLOWED_STT \
+ ((1 << STT_NOTYPE) | (1 << STT_OBJECT) | (1 << STT_FUNC) \
+ | (1 << STT_COMMON) | (1 << STT_TLS) | (1 << STT_GNU_IFUNC))
+ if (__glibc_unlikely (((1 << stt) & ALLOWED_STT) == 0))
+ return NULL;
+
+ if (sym != ref && strcmp (strtab + sym->st_name, undef_name))
+ /* Not the symbol we are looking for. */
+ return NULL;
+
+ const ElfW(Half) *verstab = map->l_versyms;
+ if (version != NULL)
+ {
+ if (__glibc_unlikely (verstab == NULL))
+ {
+ /* We need a versioned symbol but haven't found any. If
+ this is the object which is referenced in the verneed
+ entry it is a bug in the library since a symbol must
+ not simply disappear.
+
+ It would also be a bug in the object since it means that
+ the list of required versions is incomplete and so the
+ tests in dl-version.c haven't found a problem.*/
+ assert (version->filename == NULL
+ || ! _dl_name_match_p (version->filename, map));
+
+ /* Otherwise we accept the symbol. */
+ }
+ else
+ {
+ /* We can match the version information or use the
+ default one if it is not hidden. */
+ ElfW(Half) ndx = verstab[symidx] & 0x7fff;
+ if ((map->l_versions[ndx].hash != version->hash
+ || strcmp (map->l_versions[ndx].name, version->name))
+ && (version->hidden || map->l_versions[ndx].hash
+ || (verstab[symidx] & 0x8000)))
+ /* It's not the version we want. */
+ return NULL;
+ }
+ }
+ else
+ {
+ /* No specific version is selected. There are two ways we
+ can got here:
+
+ - a binary which does not include versioning information
+ is loaded
+
+ - dlsym() instead of dlvsym() is used to get a symbol which
+ might exist in more than one form
+
+ If the library does not provide symbol version information
+ there is no problem at all: we simply use the symbol if it
+ is defined.
+
+ These two lookups need to be handled differently if the
+ library defines versions. In the case of the old
+ unversioned application the oldest (default) version
+ should be used. In case of a dlsym() call the latest and
+ public interface should be returned. */
+ if (verstab != NULL)
+ {
+ if ((verstab[symidx] & 0x7fff)
+ >= ((flags & DL_LOOKUP_RETURN_NEWEST) ? 2 : 3))
+ {
+ /* Don't accept hidden symbols. */
+ if ((verstab[symidx] & 0x8000) == 0
+ && (*num_versions)++ == 0)
+ /* No version so far. */
+ *versioned_sym = sym;
+
+ return NULL;
+ }
+ }
+ }
+
+ /* There cannot be another entry for this symbol so stop here. */
+ return sym;
+}
+
/* Inner part of the lookup functions. We return a value > 0 if we
found the symbol, the value 0 if nothing is found and < 0 if
@@ -130,105 +241,6 @@ do_lookup_x (const char *undef_name, uint_fast32_t new_hash,
const ElfW(Sym) *symtab = (const void *) D_PTR (map, l_info[DT_SYMTAB]);
const char *strtab = (const void *) D_PTR (map, l_info[DT_STRTAB]);
-
- /* Nested routine to check whether the symbol matches. */
- const ElfW(Sym) *
- __attribute_noinline__
- check_match (const ElfW(Sym) *sym)
- {
- unsigned int stt = ELFW(ST_TYPE) (sym->st_info);
- assert (ELF_RTYPE_CLASS_PLT == 1);
- if (__builtin_expect ((sym->st_value == 0 /* No value. */
- && stt != STT_TLS)
- || ELF_MACHINE_SYM_NO_MATCH (sym)
- || (type_class & (sym->st_shndx == SHN_UNDEF)),
- 0))
- return NULL;
-
- /* Ignore all but STT_NOTYPE, STT_OBJECT, STT_FUNC,
- STT_COMMON, STT_TLS, and STT_GNU_IFUNC since these are no
- code/data definitions. */
-#define ALLOWED_STT \
- ((1 << STT_NOTYPE) | (1 << STT_OBJECT) | (1 << STT_FUNC) \
- | (1 << STT_COMMON) | (1 << STT_TLS) | (1 << STT_GNU_IFUNC))
- if (__glibc_unlikely (((1 << stt) & ALLOWED_STT) == 0))
- return NULL;
-
- if (sym != ref && strcmp (strtab + sym->st_name, undef_name))
- /* Not the symbol we are looking for. */
- return NULL;
-
- const ElfW(Half) *verstab = map->l_versyms;
- if (version != NULL)
- {
- if (__glibc_unlikely (verstab == NULL))
- {
- /* We need a versioned symbol but haven't found any. If
- this is the object which is referenced in the verneed
- entry it is a bug in the library since a symbol must
- not simply disappear.
-
- It would also be a bug in the object since it means that
- the list of required versions is incomplete and so the
- tests in dl-version.c haven't found a problem.*/
- assert (version->filename == NULL
- || ! _dl_name_match_p (version->filename, map));
-
- /* Otherwise we accept the symbol. */
- }
- else
- {
- /* We can match the version information or use the
- default one if it is not hidden. */
- ElfW(Half) ndx = verstab[symidx] & 0x7fff;
- if ((map->l_versions[ndx].hash != version->hash
- || strcmp (map->l_versions[ndx].name, version->name))
- && (version->hidden || map->l_versions[ndx].hash
- || (verstab[symidx] & 0x8000)))
- /* It's not the version we want. */
- return NULL;
- }
- }
- else
- {
- /* No specific version is selected. There are two ways we
- can got here:
-
- - a binary which does not include versioning information
- is loaded
-
- - dlsym() instead of dlvsym() is used to get a symbol which
- might exist in more than one form
-
- If the library does not provide symbol version information
- there is no problem at all: we simply use the symbol if it
- is defined.
-
- These two lookups need to be handled differently if the
- library defines versions. In the case of the old
- unversioned application the oldest (default) version
- should be used. In case of a dlsym() call the latest and
- public interface should be returned. */
- if (verstab != NULL)
- {
- if ((verstab[symidx] & 0x7fff)
- >= ((flags & DL_LOOKUP_RETURN_NEWEST) ? 2 : 3))
- {
- /* Don't accept hidden symbols. */
- if ((verstab[symidx] & 0x8000) == 0
- && num_versions++ == 0)
- /* No version so far. */
- versioned_sym = sym;
-
- return NULL;
- }
- }
- }
-
- /* There cannot be another entry for this symbol so stop here. */
- return sym;
- }
-
const ElfW(Sym) *sym;
const ElfW(Addr) *bitmask = map->l_gnu_bitmask;
if (__glibc_likely (bitmask != NULL))
@@ -254,7 +266,10 @@ do_lookup_x (const char *undef_name, uint_fast32_t new_hash,
if (((*hasharr ^ new_hash) >> 1) == 0)
{
symidx = hasharr - map->l_gnu_chain_zero;
- sym = check_match (&symtab[symidx]);
+ sym = check_match (undef_name, ref, version, flags,
+ type_class, &symtab[symidx], symidx,
+ strtab, map, &versioned_sym,
+ &num_versions);
if (sym != NULL)
goto found_it;
}
@@ -276,7 +291,10 @@ do_lookup_x (const char *undef_name, uint_fast32_t new_hash,
symidx != STN_UNDEF;
symidx = map->l_chain[symidx])
{
- sym = check_match (&symtab[symidx]);
+ sym = check_match (undef_name, ref, version, flags,
+ type_class, &symtab[symidx], symidx,
+ strtab, map, &versioned_sym,
+ &num_versions);
if (sym != NULL)
goto found_it;
}
-----------------------------------------------------------------------
Summary of changes:
ChangeLog | 7 ++
elf/dl-lookup.c | 226 ++++++++++++++++++++++++++++++-------------------------
2 files changed, 129 insertions(+), 104 deletions(-)
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