diff mbox series

elf: Drop elf/tls-macros.h in favor of __thread and tls_model attributes [BZ #28152] [BZ #28205]

Message ID 20210811213159.1647462-1-maskray@google.com
State Superseded
Delegated to: Szabolcs Nagy
Headers
Series elf: Drop elf/tls-macros.h in favor of __thread and tls_model attributes [BZ #28152] [BZ #28205] |

Checks

Context Check Description
dj/TryBot-apply_patch success Patch applied to master at the time it was sent
dj/TryBot-32bit fail Patch caused testsuite regressions

Commit Message

Fangrui Song Aug. 11, 2021, 9:31 p.m. UTC 
  elf/tls-macros.h was added for TLS testing when GCC did not support
__thread. __thread and tls_model attributes are mature now and have been
used by many newer tests.

Also delete tst-tls2.c which tests .tls_common which is unused by modern
GCC and unsupported by Clang/LLD. .tls_common and .tbss definition are
almost identical after linking, so the runtime test doesn't add
additional coverage.  Assembler and linker tests should be on the
binutils side.

When LLD 13.0.0 is allowed in configure.ac
(https://sourceware.org/pipermail/libc-alpha/2021-August/129866.html),
`make check` result is on par with glibc built with GNU ld.

As a future clean-up, TLS_LD/TLS_IE/TLS_IE macros can be removed from
sysdeps/*/tls-macros.h. aarch64 TLS_GD definition should be retained to
test traditional TLS GD while the toolchain default is TLSDESC.

Tested on x86_64-linux-gnu and aarch64-linux-gnu.
---
 elf/Makefile      |  4 +--
 elf/tls-macros.h  | 25 ---------------
 elf/tst-tls1.c    | 64 ++++++++++++++++++------------------
 elf/tst-tls2.c    | 82 -----------------------------------------------
 elf/tst-tls3.c    | 26 +++++++--------
 elf/tst-tlsmod1.c | 24 +++++++-------
 elf/tst-tlsmod2.c |  6 ++--
 elf/tst-tlsmod3.c |  8 ++---
 elf/tst-tlsmod4.c |  6 ++--
 elf/tst-tlsmod5.c |  4 +--
 elf/tst-tlsmod6.c |  4 +--
 11 files changed, 68 insertions(+), 185 deletions(-)
 delete mode 100644 elf/tls-macros.h
 delete mode 100644 elf/tst-tls2.c

Comments

Joseph Myers Aug. 11, 2021, 9:54 p.m. UTC | #1 
On Wed, 11 Aug 2021, Fangrui Song via Libc-alpha wrote:

> As a future clean-up, TLS_LD/TLS_IE/TLS_IE macros can be removed from
> sysdeps/*/tls-macros.h. aarch64 TLS_GD definition should be retained to
> test traditional TLS GD while the toolchain default is TLSDESC.

It might be better to test different TLS dialects through the compiler 
generating appropriate code rather than keeping such macros around.  E.g., 
have a way for architectures to declare a set of supported -mtls-dialect= 
arguments (or detect them at configure time, at present there's a test for 
-mtls-dialect=gnu2 support), and, when more than one dialect is supported, 
run various tests explicitly for each dialect supported by the compiler, 
in addition to testing whatever the default dialect is.
Fangrui Song Aug. 11, 2021, 10:11 p.m. UTC | #2 
On 2021-08-11, Joseph Myers wrote:
>On Wed, 11 Aug 2021, Fangrui Song via Libc-alpha wrote:
>
>> As a future clean-up, TLS_LD/TLS_IE/TLS_IE macros can be removed from
>> sysdeps/*/tls-macros.h. aarch64 TLS_GD definition should be retained to
>> test traditional TLS GD while the toolchain default is TLSDESC.
>
>It might be better to test different TLS dialects through the compiler
>generating appropriate code rather than keeping such macros around.  E.g.,
>have a way for architectures to declare a set of supported -mtls-dialect=
>arguments (or detect them at configure time, at present there's a test for
>-mtls-dialect=gnu2 support), and, when more than one dialect is supported,
>run various tests explicitly for each dialect supported by the compiler,
>in addition to testing whatever the default dialect is.

Hi Joseph,

Thanks for the your comments. Do you have specific suggestion on this
patch?

   __thread int foo, bar;
   extern __thread int foo_gd asm ("foo") __attribute__ ((tls_model("global-dynamic")));
   extern __thread int foo_ld asm ("foo") __attribute__ ((tls_model("local-dynamic")));
   extern __thread int foo_ie asm ("foo") __attribute__ ((tls_model("initial-exec")));
   extern __thread int bar_gd asm ("bar") __attribute__ ((tls_model("global-dynamic")));
   extern __thread int bar_ld asm ("bar") __attribute__ ((tls_model("local-dynamic")));
   extern __thread int bar_ie asm ("bar") __attribute__ ((tls_model("initial-exec")));

Add 

   extern __thread int foo_le asm ("foo") __attribute__ ((tls_model("local-exec")));

even if the default foo for non-PIC is local-exec?
Szabolcs Nagy Aug. 12, 2021, 9:16 a.m. UTC | #3 
The 08/11/2021 15:11, Fangrui Song via Libc-alpha wrote:
> On 2021-08-11, Joseph Myers wrote:
> > On Wed, 11 Aug 2021, Fangrui Song via Libc-alpha wrote:
> > 
> > > As a future clean-up, TLS_LD/TLS_IE/TLS_IE macros can be removed from
> > > sysdeps/*/tls-macros.h. aarch64 TLS_GD definition should be retained to
> > > test traditional TLS GD while the toolchain default is TLSDESC.
> > 
> > It might be better to test different TLS dialects through the compiler
> > generating appropriate code rather than keeping such macros around.  E.g.,
> > have a way for architectures to declare a set of supported -mtls-dialect=
> > arguments (or detect them at configure time, at present there's a test for
> > -mtls-dialect=gnu2 support), and, when more than one dialect is supported,
> > run various tests explicitly for each dialect supported by the compiler,
> > in addition to testing whatever the default dialect is.

yeah i prefer not to keep TLS_GD for aarch64 but
use -mtls-dialect= for tests if we care enough.

>   __thread int foo, bar;
>   extern __thread int foo_gd asm ("foo") __attribute__ ((tls_model("global-dynamic")));
>   extern __thread int foo_ld asm ("foo") __attribute__ ((tls_model("local-dynamic")));
>   extern __thread int foo_ie asm ("foo") __attribute__ ((tls_model("initial-exec")));
>   extern __thread int bar_gd asm ("bar") __attribute__ ((tls_model("global-dynamic")));
>   extern __thread int bar_ld asm ("bar") __attribute__ ((tls_model("local-dynamic")));
>   extern __thread int bar_ie asm ("bar") __attribute__ ((tls_model("initial-exec")));
> 
> Add
> 
>   extern __thread int foo_le asm ("foo") __attribute__ ((tls_model("local-exec")));
> 
> even if the default foo for non-PIC is local-exec?

i think adding an explicit declaration like that is clearer.
Joseph Myers Aug. 12, 2021, 3:36 p.m. UTC | #4 
On Wed, 11 Aug 2021, Fangrui Song via Libc-alpha wrote:

> Thanks for the your comments. Do you have specific suggestion on this
> patch?

I do not have a specific suggestion on this patch.
diff mbox series

Patch

diff --git a/elf/Makefile b/elf/Makefile
index d05f410592..725537c40b 100644
--- a/elf/Makefile
+++ b/elf/Makefile
@@ -163,7 +163,7 @@  tests-static-normal := tst-array1-static tst-array5-static \
 	       tst-single_threaded-static tst-single_threaded-pthread-static \
 	       tst-dst-static tst-getauxval-static
 
-tests-static-internal := tst-tls1-static tst-tls2-static \
+tests-static-internal := tst-tls1-static \
 	       tst-ptrguard1-static tst-stackguard1-static \
 	       tst-tls1-static-non-pie
 
@@ -183,7 +183,7 @@  endif
 tests := tst-tls9 tst-leaks1 \
 	tst-array1 tst-array2 tst-array3 tst-array4 tst-array5 \
 	tst-auxv tst-stringtable
-tests-internal := tst-tls1 tst-tls2 $(tests-static-internal)
+tests-internal := tst-tls1 $(tests-static-internal)
 tests-static := $(tests-static-normal) $(tests-static-internal)
 
 ifeq (yes,$(build-shared))
diff --git a/elf/tls-macros.h b/elf/tls-macros.h
deleted file mode 100644
index e25e33b0f0..0000000000
--- a/elf/tls-macros.h
+++ /dev/null
@@ -1,25 +0,0 @@ 
-/* Macros to support TLS testing in times of missing compiler support.  */
-
-#define COMMON_INT_DEF(x) \
-  asm (".tls_common " #x ",4,4")
-/* XXX Until we get compiler support we don't need declarations.  */
-#define COMMON_INT_DECL(x)
-
-/* XXX This definition will probably be machine specific, too.  */
-#define VAR_INT_DEF(x) \
-  asm (".section .tdata\n\t"						      \
-       ".globl " #x "\n"						      \
-       ".balign 4\n"							      \
-       #x ":\t.long 0\n\t"						      \
-       ".size " #x ",4\n\t"						      \
-       ".previous")
-/* XXX Until we get compiler support we don't need declarations.  */
-#define VAR_INT_DECL(x)
-
-#include_next <tls-macros.h>
-
-  /* XXX Each architecture must have its own asm for now.  */
-#if !defined TLS_LE || !defined TLS_IE \
-      || !defined TLS_LD || !defined TLS_GD
-# error "No support for this architecture so far."
-#endif
diff --git a/elf/tst-tls1.c b/elf/tst-tls1.c
index c31da56ce9..23389e5b4c 100644
--- a/elf/tst-tls1.c
+++ b/elf/tst-tls1.c
@@ -4,10 +4,13 @@ 
 #include "tls-macros.h"
 
 
-/* Two common 'int' variables in TLS.  */
-COMMON_INT_DEF(foo);
-COMMON_INT_DEF(bar);
-
+__thread int foo, bar;
+extern __thread int foo_gd asm ("foo") __attribute__ ((tls_model("global-dynamic")));
+extern __thread int foo_ld asm ("foo") __attribute__ ((tls_model("local-dynamic")));
+extern __thread int foo_ie asm ("foo") __attribute__ ((tls_model("initial-exec")));
+extern __thread int bar_gd asm ("bar") __attribute__ ((tls_model("global-dynamic")));
+extern __thread int bar_ld asm ("bar") __attribute__ ((tls_model("local-dynamic")));
+extern __thread int bar_ie asm ("bar") __attribute__ ((tls_model("initial-exec")));
 
 static int
 do_test (void)
@@ -18,62 +21,61 @@  do_test (void)
 
   /* Set the variable using the local exec model.  */
   puts ("set bar to 1 (LE)");
-  ap = TLS_LE (bar);
-  *ap = 1;
+  bar = 1;
 
 
   /* Get variables using initial exec model.  */
   fputs ("get sum of foo and bar (IE)", stdout);
-  ap = TLS_IE (foo);
-  bp = TLS_IE (bar);
+  ap = &foo_ie;
+  bp = &bar_ie;
   printf (" = %d\n", *ap + *bp);
   result |= *ap + *bp != 1;
-  if (*ap != 0)
+  if (*ap != 0 || *bp != 1)
     {
-      printf ("foo = %d\n", *ap);
-      result = 1;
-    }
-  if (*bp != 1)
-    {
-      printf ("bar = %d\n", *bp);
+      printf ("foo = %d\nbar = %d\n", *ap, *bp);
       result = 1;
     }
 
 
-  /* Get variables using local dynamic model.  */
-  fputs ("get sum of foo and bar (LD)", stdout);
-  ap = TLS_LD (foo);
-  bp = TLS_LD (bar);
+  /* Get variables using local dynamic model or TLSDESC.  */
+  fputs ("get sum of foo and bar (LD or TLSDESC)", stdout);
+  ap = &foo_ld;
+  bp = &bar_ld;
   printf (" = %d\n", *ap + *bp);
   result |= *ap + *bp != 1;
-  if (*ap != 0)
+  if (*ap != 0 || *bp != 1)
     {
-      printf ("foo = %d\n", *ap);
+      printf ("foo = %d\nbar = %d\n", *ap, *bp);
       result = 1;
     }
-  if (*bp != 1)
+
+
+  /* Get variables using general dynamic model or TLSDESC.  */
+  fputs ("get sum of foo and bar (GD or TLSDESC)", stdout);
+  ap = &foo_gd;
+  bp = &bar_gd;
+  printf (" = %d\n", *ap + *bp);
+  result |= *ap + *bp != 1;
+  if (*ap != 0 || *bp != 1)
     {
-      printf ("bar = %d\n", *bp);
+      printf ("foo = %d\nbar = %d\n", *ap, *bp);
       result = 1;
     }
 
 
-  /* Get variables using generic dynamic model.  */
+#ifdef TLS_GD
+  /* Get variables using traditional generic dynamic model.  */
   fputs ("get sum of foo and bar (GD)", stdout);
   ap = TLS_GD (foo);
   bp = TLS_GD (bar);
   printf (" = %d\n", *ap + *bp);
   result |= *ap + *bp != 1;
-  if (*ap != 0)
+  if (*ap != 0 || *bp != 1)
     {
-      printf ("foo = %d\n", *ap);
-      result = 1;
-    }
-  if (*bp != 1)
-    {
-      printf ("bar = %d\n", *bp);
+      printf ("foo = %d\nbar = %d\n", *ap, *bp);
       result = 1;
     }
+#endif
 
   return result;
 }
diff --git a/elf/tst-tls2.c b/elf/tst-tls2.c
deleted file mode 100644
index 963b8d6c88..0000000000
--- a/elf/tst-tls2.c
+++ /dev/null
@@ -1,82 +0,0 @@ 
-/* glibc test for TLS in ld.so.  */
-#include <stdio.h>
-
-#include "tls-macros.h"
-
-
-/* Two 'int' variables in TLS.  */
-VAR_INT_DEF(foo);
-VAR_INT_DEF(bar);
-
-
-static int
-do_test (void)
-{
-  int result = 0;
-  int *ap, *bp;
-
-
-  /* Set the variable using the local exec model.  */
-  puts ("set bar to 1 (LE)");
-  ap = TLS_LE (bar);
-  *ap = 1;
-
-
-  /* Get variables using initial exec model.  */
-  fputs ("get sum of foo and bar (IE)", stdout);
-  ap = TLS_IE (foo);
-  bp = TLS_IE (bar);
-  printf (" = %d\n", *ap + *bp);
-  result |= *ap + *bp != 1;
-  if (*ap != 0)
-    {
-      printf ("foo = %d\n", *ap);
-      result = 1;
-    }
-  if (*bp != 1)
-    {
-      printf ("bar = %d\n", *bp);
-      result = 1;
-    }
-
-
-  /* Get variables using local dynamic model.  */
-  fputs ("get sum of foo and bar (LD)", stdout);
-  ap = TLS_LD (foo);
-  bp = TLS_LD (bar);
-  printf (" = %d\n", *ap + *bp);
-  result |= *ap + *bp != 1;
-  if (*ap != 0)
-    {
-      printf ("foo = %d\n", *ap);
-      result = 1;
-    }
-  if (*bp != 1)
-    {
-      printf ("bar = %d\n", *bp);
-      result = 1;
-    }
-
-
-  /* Get variables using generic dynamic model.  */
-  fputs ("get sum of foo and bar (GD)", stdout);
-  ap = TLS_GD (foo);
-  bp = TLS_GD (bar);
-  printf (" = %d\n", *ap + *bp);
-  result |= *ap + *bp != 1;
-  if (*ap != 0)
-    {
-      printf ("foo = %d\n", *ap);
-      result = 1;
-    }
-  if (*bp != 1)
-    {
-      printf ("bar = %d\n", *bp);
-      result = 1;
-    }
-
-  return result;
-}
-
-
-#include <support/test-driver.c>
diff --git a/elf/tst-tls3.c b/elf/tst-tls3.c
index 7e0abb4c58..222b179626 100644
--- a/elf/tst-tls3.c
+++ b/elf/tst-tls3.c
@@ -1,13 +1,12 @@ 
 /* glibc test for TLS in ld.so.  */
 #include <stdio.h>
 
-#include "tls-macros.h"
 
-
-/* One define int variable, two externs.  */
-COMMON_INT_DECL(foo);
-VAR_INT_DECL(bar);
-VAR_INT_DEF(baz);
+__thread int foo, bar __attribute__ ((tls_model("initial-exec")));
+__thread int baz __attribute__ ((tls_model("local-exec")));
+extern __thread int foo_gd __attribute__ ((alias("foo"), tls_model("global-dynamic")));
+extern __thread int bar_gd __attribute__ ((alias("bar"), tls_model("global-dynamic")));
+extern __thread int baz_ld __attribute__ ((alias("baz"), tls_model("local-dynamic")));
 
 
 extern int in_dso (void);
@@ -22,23 +21,20 @@  do_test (void)
 
   /* Set the variable using the local exec model.  */
   puts ("set baz to 3 (LE)");
-  ap = TLS_LE (baz);
-  *ap = 3;
+  baz = 3;
 
 
   /* Get variables using initial exec model.  */
   puts ("set variables foo and bar (IE)");
-  ap = TLS_IE (foo);
-  *ap = 1;
-  bp = TLS_IE (bar);
-  *bp = 2;
+  foo = 1;
+  bar = 2;
 
 
   /* Get variables using local dynamic model.  */
   fputs ("get sum of foo, bar (GD) and baz (LD)", stdout);
-  ap = TLS_GD (foo);
-  bp = TLS_GD (bar);
-  cp = TLS_LD (baz);
+  ap = &foo_gd;
+  bp = &bar_gd;
+  cp = &baz_ld;
   printf (" = %d\n", *ap + *bp + *cp);
   result |= *ap + *bp + *cp != 6;
   if (*ap != 1)
diff --git a/elf/tst-tlsmod1.c b/elf/tst-tlsmod1.c
index 8d9156791b..c0e99ea475 100644
--- a/elf/tst-tlsmod1.c
+++ b/elf/tst-tlsmod1.c
@@ -1,12 +1,12 @@ 
 #include <stdio.h>
 
-#include "tls-macros.h"
 
+__thread int foo, bar;
+extern __thread int baz;
+extern __thread int foo_ie asm ("foo") __attribute__ ((tls_model("initial-exec")));
+extern __thread int bar_ie asm ("bar") __attribute__ ((tls_model("initial-exec")));
+extern __thread int baz_ie asm ("baz") __attribute__ ((tls_model("initial-exec")));
 
-/* One define int variable, two externs.  */
-COMMON_INT_DEF(foo);
-VAR_INT_DEF(bar);
-VAR_INT_DECL(baz);
 
 extern int in_dso (void);
 
@@ -19,8 +19,8 @@  in_dso (void)
   /* Get variables using initial exec model.  */
   fputs ("get sum of foo and bar (IE)", stdout);
   asm ("" ::: "memory");
-  ap = TLS_IE (foo);
-  bp = TLS_IE (bar);
+  ap = &foo_ie;
+  bp = &bar_ie;
   printf (" = %d\n", *ap + *bp);
   result |= *ap + *bp != 3;
   if (*ap != 1)
@@ -35,11 +35,11 @@  in_dso (void)
     }
 
 
-  /* Get variables using generic dynamic model.  */
-  fputs ("get sum of foo and bar and baz (GD)", stdout);
-  ap = TLS_GD (foo);
-  bp = TLS_GD (bar);
-  cp = TLS_GD (baz);
+  /* Get variables using generic dynamic model or TLSDESC.  */
+  fputs ("get sum of foo and bar and baz (GD or TLSDESC)", stdout);
+  ap = &foo;
+  bp = &bar;
+  cp = &baz;
   printf (" = %d\n", *ap + *bp + *cp);
   result |= *ap + *bp + *cp != 6;
   if (*ap != 1)
diff --git a/elf/tst-tlsmod2.c b/elf/tst-tlsmod2.c
index 40eb1407f8..3223fe494b 100644
--- a/elf/tst-tlsmod2.c
+++ b/elf/tst-tlsmod2.c
@@ -1,9 +1,7 @@ 
 #include <stdio.h>
 
-#include "tls-macros.h"
 
-
-COMMON_INT_DEF(foo);
+__thread int foo;
 
 
 int
@@ -15,7 +13,7 @@  in_dso (int n, int *caller_foop)
   puts ("foo");			/* Make sure PLT is used before macros.  */
   asm ("" ::: "memory");
 
-  foop = TLS_GD (foo);
+  foop = &foo;
 
   if (caller_foop != NULL && foop != caller_foop)
     {
diff --git a/elf/tst-tlsmod3.c b/elf/tst-tlsmod3.c
index 6d186c47ee..d6e7498fd8 100644
--- a/elf/tst-tlsmod3.c
+++ b/elf/tst-tlsmod3.c
@@ -1,10 +1,10 @@ 
 #include <stdio.h>
 
-#include "tls-macros.h"
 
 extern int in_dso (int n, int *caller_foop);
 
-COMMON_INT_DEF(comm_n);
+extern __thread int foo;
+__thread int comm_n;
 
 
 
@@ -20,8 +20,8 @@  in_dso2 (void)
   puts ("foo");			/* Make sure PLT is used before macros.  */
   asm ("" ::: "memory");
 
-  foop = TLS_GD (foo);
-  np = TLS_GD (comm_n);
+  foop = &foo;
+  np = &comm_n;
 
   if (n != *np)
     {
diff --git a/elf/tst-tlsmod4.c b/elf/tst-tlsmod4.c
index 86889aac7e..f38919a8a9 100644
--- a/elf/tst-tlsmod4.c
+++ b/elf/tst-tlsmod4.c
@@ -1,9 +1,7 @@ 
 #include <stdio.h>
 
-#include "tls-macros.h"
 
-
-COMMON_INT_DEF(baz);
+__thread int baz;
 
 
 int
@@ -15,7 +13,7 @@  in_dso (int n, int *caller_bazp)
   puts ("foo");			/* Make sure PLT is used before macros.  */
   asm ("" ::: "memory");
 
-  bazp = TLS_GD (baz);
+  bazp = &baz;
 
   if (caller_bazp != NULL && bazp != caller_bazp)
     {
diff --git a/elf/tst-tlsmod5.c b/elf/tst-tlsmod5.c
index a97c7e5e0c..3f39c5bdb7 100644
--- a/elf/tst-tlsmod5.c
+++ b/elf/tst-tlsmod5.c
@@ -1,3 +1 @@ 
-#include "tls-macros.h"
-
-COMMON_INT_DEF(foo);
+__thread int foo;
diff --git a/elf/tst-tlsmod6.c b/elf/tst-tlsmod6.c
index e968596dd4..7b3571f428 100644
--- a/elf/tst-tlsmod6.c
+++ b/elf/tst-tlsmod6.c
@@ -1,3 +1 @@ 
-#include "tls-macros.h"
-
-COMMON_INT_DEF(bar);
+__thread int bar;