diff mbox series

[3/3] elf: Remove LD_USE_LOAD_BIAS

Message ID 20220121172951.285848-4-adhemerval.zanella@linaro.org
State Superseded
Headers show
Series Remove prelink support | expand

Checks

Context Check Description
dj/TryBot-apply_patch success Patch applied to master at the time it was sent
dj/TryBot-32bit success Build for i686

Commit Message

Adhemerval Zanella Jan. 21, 2022, 5:29 p.m. UTC
It is used only for prelink with PIE exectuables [1].

[1] https://sourceware.org/legacy-ml/libc-hacker/2003-11/msg00127.html
---
 NEWS                        |  3 +++
 elf/dl-map-segments.h       |  3 +--
 elf/dl-support.c            |  1 -
 elf/rtld.c                  | 13 -------------
 sysdeps/generic/ldsodefs.h  |  5 -----
 sysdeps/generic/unsecvars.h |  1 -
 6 files changed, 4 insertions(+), 22 deletions(-)
diff mbox series

Patch

diff --git a/NEWS b/NEWS
index ee2bcabda7..68a7f2b752 100644
--- a/NEWS
+++ b/NEWS
@@ -156,6 +156,9 @@  Deprecated and removed features, and other changes affecting compatibility:
 * The prelink support has been removed.  Prelinked binaries and libraries
   work as if prelinked is disabled.
 
+* The LD_USE_LOAD_BIAS has been removed.  The variable was mainly used to
+  support prelink PIE binaries.
+
 Changes to build and runtime requirements:
 
   [Add changes to build and runtime requirements here]
diff --git a/elf/dl-map-segments.h b/elf/dl-map-segments.h
index 172692b120..b3513e7909 100644
--- a/elf/dl-map-segments.h
+++ b/elf/dl-map-segments.h
@@ -94,8 +94,7 @@  _dl_map_segments (struct link_map *l, int fd,
          prefer to map such objects at; but this is only a preference,
          the OS can do whatever it likes. */
       ElfW(Addr) mappref
-        = (ELF_PREFERRED_ADDRESS (loader, maplength,
-                                  c->mapstart & GLRO(dl_use_load_bias))
+        = (ELF_PREFERRED_ADDRESS (loader, maplength, c->mapstart)
            - MAP_BASE_ADDR (l));
 
       /* Remember which part of the address space this object uses.  */
diff --git a/elf/dl-support.c b/elf/dl-support.c
index fb64765537..6d2c4baf81 100644
--- a/elf/dl-support.c
+++ b/elf/dl-support.c
@@ -54,7 +54,6 @@  size_t _dl_platformlen;
 
 int _dl_debug_mask;
 int _dl_lazy;
-ElfW(Addr) _dl_use_load_bias = -2;
 int _dl_dynamic_weak;
 
 /* If nonzero print warnings about problematic situations.  */
diff --git a/elf/rtld.c b/elf/rtld.c
index 9fea138619..04976b8673 100644
--- a/elf/rtld.c
+++ b/elf/rtld.c
@@ -364,7 +364,6 @@  struct rtld_global_ro _rtld_global_ro attribute_relro =
     ._dl_sysinfo = DL_SYSINFO_DEFAULT,
 #endif
     ._dl_debug_fd = STDERR_FILENO,
-    ._dl_use_load_bias = -2,
     ._dl_correct_cache_id = _DL_CACHE_DEFAULT_ID,
 #if !HAVE_TUNABLES
     ._dl_hwcap_mask = HWCAP_IMPORTANT,
@@ -1741,12 +1740,6 @@  dl_main (const ElfW(Phdr) *phdr,
   ++GL(dl_ns)[LM_ID_BASE]._ns_nloaded;
   ++GL(dl_load_adds);
 
-  /* If LD_USE_LOAD_BIAS env variable has not been seen, default
-     to not using bias for non-prelinked PIEs and libraries
-     and using it for executables or prelinked PIEs or libraries.  */
-  if (GLRO(dl_use_load_bias) == (ElfW(Addr)) -2)
-    GLRO(dl_use_load_bias) = main_map->l_addr == 0 ? -1 : 0;
-
   /* Starting from binutils-2.23, the linker will define the magic symbol
      __ehdr_start to point to our own ELF header if it is visible in a
      segment that also includes the phdrs.  If that's not available, we use
@@ -2656,12 +2649,6 @@  process_envvars (struct dl_main_state *state)
 #ifdef EXTRA_LD_ENVVARS_13
 	  EXTRA_LD_ENVVARS_13
 #endif
-	  if (!__libc_enable_secure
-	      && memcmp (envline, "USE_LOAD_BIAS", 13) == 0)
-	    {
-	      GLRO(dl_use_load_bias) = envline[14] == '1' ? -1 : 0;
-	      break;
-	    }
 	  break;
 
 	case 14:
diff --git a/sysdeps/generic/ldsodefs.h b/sysdeps/generic/ldsodefs.h
index 139eed8d3f..4c028f9d06 100644
--- a/sysdeps/generic/ldsodefs.h
+++ b/sysdeps/generic/ldsodefs.h
@@ -628,11 +628,6 @@  struct rtld_global_ro
   /* Location of the binary.  */
   EXTERN const char *_dl_origin_path;
 
-  /* -1 if the dynamic linker should honor library load bias,
-     0 if not, -2 use the default (honor biases for normal
-     binaries, don't honor for PIEs).  */
-  EXTERN ElfW(Addr) _dl_use_load_bias;
-
   /* Size of the static TLS block.  */
   EXTERN size_t _dl_tls_static_size;
 
diff --git a/sysdeps/generic/unsecvars.h b/sysdeps/generic/unsecvars.h
index 5ea8a4a259..b50331b50f 100644
--- a/sysdeps/generic/unsecvars.h
+++ b/sysdeps/generic/unsecvars.h
@@ -22,7 +22,6 @@ 
   "LD_PRELOAD\0"							      \
   "LD_PROFILE\0"							      \
   "LD_SHOW_AUXV\0"							      \
-  "LD_USE_LOAD_BIAS\0"							      \
   "LOCALDOMAIN\0"							      \
   "LOCPATH\0"								      \
   "MALLOC_TRACE\0"							      \