nptl: Remove COLORING_INCREMENT
This patch removes the COLORING_INCREMENT define and usage on allocatestack.c.
It has not been used since 564cd8b67e (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.
This commit is contained in:
Adhemerval Zanella
parent
2b7dc4c868
commit
37f8abad1c
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@ -1,3 +1,10 @@
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2016-02-06 Adhemerval Zanella <adhemerval.zanella@linaro.org>
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* nptl/allocatestack.c [COLORING_INCREMENT] (nptl_ncreated): Remove.
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(allocate_stack): Remove COLORING_INCREMENT usage.
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* nptl/stack-aliasing.h (COLORING_INCREMENT). Likewise.
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* sysdeps/i386/i686/stack-aliasing.h (COLORING_INCREMENT): Likewise.
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2017-02-06 Joseph Myers <joseph@codesourcery.com>
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* manual/libm-err-tab.pl (@all_functions): Change to
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@ -125,11 +125,6 @@ static uintptr_t in_flight_stack;
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list_t __stack_user __attribute__ ((nocommon));
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hidden_data_def (__stack_user)
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#if COLORING_INCREMENT != 0
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/* Number of threads created. */
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static unsigned int nptl_ncreated;
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#endif
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/* Check whether the stack is still used or not. */
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#define FREE_P(descr) ((descr)->tid <= 0)
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@ -467,14 +462,6 @@ allocate_stack (const struct pthread_attr *attr, struct pthread **pdp,
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const int prot = (PROT_READ | PROT_WRITE
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| ((GL(dl_stack_flags) & PF_X) ? PROT_EXEC : 0));
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#if COLORING_INCREMENT != 0
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/* Add one more page for stack coloring. Don't do it for stacks
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with 16 times pagesize or larger. This might just cause
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unnecessary misalignment. */
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if (size <= 16 * pagesize_m1)
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size += pagesize_m1 + 1;
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#endif
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/* Adjust the stack size for alignment. */
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size &= ~__static_tls_align_m1;
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assert (size != 0);
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@ -513,34 +500,11 @@ allocate_stack (const struct pthread_attr *attr, struct pthread **pdp,
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So we can never get a null pointer back from mmap. */
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assert (mem != NULL);
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#if COLORING_INCREMENT != 0
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/* Atomically increment NCREATED. */
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unsigned int ncreated = atomic_increment_val (&nptl_ncreated);
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/* We chose the offset for coloring by incrementing it for
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every new thread by a fixed amount. The offset used
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module the page size. Even if coloring would be better
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relative to higher alignment values it makes no sense to
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do it since the mmap() interface does not allow us to
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specify any alignment for the returned memory block. */
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size_t coloring = (ncreated * COLORING_INCREMENT) & pagesize_m1;
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/* Make sure the coloring offsets does not disturb the alignment
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of the TCB and static TLS block. */
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if (__glibc_unlikely ((coloring & __static_tls_align_m1) != 0))
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coloring = (((coloring + __static_tls_align_m1)
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& ~(__static_tls_align_m1))
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& ~pagesize_m1);
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#else
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/* Unless specified we do not make any adjustments. */
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# define coloring 0
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#endif
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/* Place the thread descriptor at the end of the stack. */
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#if TLS_TCB_AT_TP
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pd = (struct pthread *) ((char *) mem + size - coloring) - 1;
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pd = (struct pthread *) ((char *) mem + size) - 1;
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#elif TLS_DTV_AT_TP
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pd = (struct pthread *) ((((uintptr_t) mem + size - coloring
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pd = (struct pthread *) ((((uintptr_t) mem + size
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- __static_tls_size)
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& ~__static_tls_align_m1)
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- TLS_PRE_TCB_SIZE);
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@ -16,12 +16,6 @@
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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/* This is a number of bytes (less than a page) by which to "color" the
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starting stack address of new threads. This number is multiplied by the
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number of threads created so far and then truncated modulo page size,
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to get a roughly even distribution of values for different threads. */
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#define COLORING_INCREMENT 0
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/* This is a number of bytes that is an alignment that should be avoided
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when choosing the exact size of a new thread's stack. If the size
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chosen is aligned to this, an extra page will be added to render the
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@ -16,11 +16,6 @@
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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/* It turns out that stack coloring is in general not good on P4s. Some
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applications will benefit. We will probably have a configuration option
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at some point. To enable coloring, set this to 128. */
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#define COLORING_INCREMENT 0
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/* What is useful is to avoid the 64k aliasing problem which reliably
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happens if all stacks use sizes which are a multiple of 64k. Tell
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the stack allocator to disturb this by allocation one more page if
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