commit 37f8abad1c7b274e66eaf2d04684bd8a7ba0bcef

Author: Adhemerval Zanella <adhemerval.zanella@linaro.org>

Date:   Mon Jan 30 18:07:32 2017 -0200

    nptl: Remove COLORING_INCREMENT

    This patch removes the COLORING_INCREMENT define and usage on allocatestack.c.

    It has not been used since 564cd8b67ec487f (glibc-2.3.3) by any architecture.

    The idea is to simplify the code by removing obsolete code.

            * nptl/allocatestack.c [COLORING_INCREMENT] (nptl_ncreated): Remove.

            (allocate_stack): Remove COLORING_INCREMENT usage.

            * nptl/stack-aliasing.h (COLORING_INCREMENT). Likewise.

            * sysdeps/i386/i686/stack-aliasing.h (COLORING_INCREMENT): Likewise.

Conflicts:

	nptl/allocatestack.c

Textual conflict due to missing backport of commit

a1ffb40e32741f992c743e7b16c061fefa3747ac (Use glibc_likely instead

__builtin_expect.).

diff --git a/nptl/allocatestack.c b/nptl/allocatestack.c

index 0fba6ce3474e8b35..00f9dcffe721a6b3 100644

--- a/nptl/allocatestack.c

+++ b/nptl/allocatestack.c

@@ -124,11 +124,6 @@ static uintptr_t in_flight_stack;

 list_t __stack_user __attribute__ ((nocommon));

 hidden_data_def (__stack_user)

-#if COLORING_INCREMENT != 0

-/* Number of threads created.  */

-static unsigned int nptl_ncreated;

-#endif

-

 /* Check whether the stack is still used or not.  */

 #define FREE_P(descr) ((descr)->tid <= 0)

@@ -456,14 +451,6 @@ allocate_stack (const struct pthread_attr *attr, struct pthread **pdp,

       const int prot = (PROT_READ | PROT_WRITE

 			| ((GL(dl_stack_flags) & PF_X) ? PROT_EXEC : 0));

-#if COLORING_INCREMENT != 0

-      /* Add one more page for stack coloring.  Don't do it for stacks

-	 with 16 times pagesize or larger.  This might just cause

-	 unnecessary misalignment.  */

-      if (size <= 16 * pagesize_m1)

-	size += pagesize_m1 + 1;

-#endif

-

       /* Adjust the stack size for alignment.  */

       size &= ~__static_tls_align_m1;

       assert (size != 0);

@@ -506,34 +493,11 @@ allocate_stack (const struct pthread_attr *attr, struct pthread **pdp,

 	     So we can never get a null pointer back from mmap.  */

 	  assert (mem != NULL);

-#if COLORING_INCREMENT != 0

-	  /* Atomically increment NCREATED.  */

-	  unsigned int ncreated = atomic_increment_val (&nptl_ncreated);

-

-	  /* We chose the offset for coloring by incrementing it for

-	     every new thread by a fixed amount.  The offset used

-	     module the page size.  Even if coloring would be better

-	     relative to higher alignment values it makes no sense to

-	     do it since the mmap() interface does not allow us to

-	     specify any alignment for the returned memory block.  */

-	  size_t coloring = (ncreated * COLORING_INCREMENT) & pagesize_m1;

-

-	  /* Make sure the coloring offsets does not disturb the alignment

-	     of the TCB and static TLS block.  */

-	  if (__builtin_expect ((coloring & __static_tls_align_m1) != 0, 0))

-	    coloring = (((coloring + __static_tls_align_m1)

-			 & ~(__static_tls_align_m1))

-			& ~pagesize_m1);

-#else

-	  /* Unless specified we do not make any adjustments.  */

-# define coloring 0

-#endif

-

 	  /* Place the thread descriptor at the end of the stack.  */

 #if TLS_TCB_AT_TP

-	  pd = (struct pthread *) ((char *) mem + size - coloring) - 1;

+	  pd = (struct pthread *) ((char *) mem + size) - 1;

 #elif TLS_DTV_AT_TP

-	  pd = (struct pthread *) ((((uintptr_t) mem + size - coloring

+	  pd = (struct pthread *) ((((uintptr_t) mem + size

 				    - __static_tls_size)

 				    & ~__static_tls_align_m1)

 				   - TLS_PRE_TCB_SIZE);

diff --git a/nptl/stack-aliasing.h b/nptl/stack-aliasing.h

index 526b54e18f7e0a27..62fdc9265e0038e6 100644

--- a/nptl/stack-aliasing.h

+++ b/nptl/stack-aliasing.h

@@ -16,12 +16,6 @@

    License along with the GNU C Library; if not, see

    <http://www.gnu.org/licenses/>.  */

-/* This is a number of bytes (less than a page) by which to "color" the

-   starting stack address of new threads.  This number is multiplied by the

-   number of threads created so far and then truncated modulo page size,

-   to get a roughly even distribution of values for different threads.  */

-#define COLORING_INCREMENT      0

-

 /* This is a number of bytes that is an alignment that should be avoided

    when choosing the exact size of a new thread's stack.  If the size

    chosen is aligned to this, an extra page will be added to render the

diff --git a/sysdeps/i386/i686/stack-aliasing.h b/sysdeps/i386/i686/stack-aliasing.h

index 1e35ceb2061d60f9..d73e45461f928a6a 100644

--- a/sysdeps/i386/i686/stack-aliasing.h

+++ b/sysdeps/i386/i686/stack-aliasing.h

@@ -16,11 +16,6 @@

    License along with the GNU C Library; if not, see

    <http://www.gnu.org/licenses/>.  */

-/* It turns out that stack coloring is in general not good on P4s.  Some

-   applications will benefit.  We will probably have a configuration option

-   at some point.  To enable coloring, set this to 128.  */

-#define COLORING_INCREMENT      0

-

 /* What is useful is to avoid the 64k aliasing problem which reliably

    happens if all stacks use sizes which are a multiple of 64k.  Tell

    the stack allocator to disturb this by allocation one more page if