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124 lines
5.1 KiB
124 lines
5.1 KiB
6 years ago
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commit 37f8abad1c7b274e66eaf2d04684bd8a7ba0bcef
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Author: Adhemerval Zanella <adhemerval.zanella@linaro.org>
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Date: Mon Jan 30 18:07:32 2017 -0200
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nptl: Remove COLORING_INCREMENT
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This patch removes the COLORING_INCREMENT define and usage on allocatestack.c.
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It has not been used since 564cd8b67ec487f (glibc-2.3.3) by any architecture.
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The idea is to simplify the code by removing obsolete code.
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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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Conflicts:
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nptl/allocatestack.c
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Textual conflict due to missing backport of commit
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a1ffb40e32741f992c743e7b16c061fefa3747ac (Use glibc_likely instead
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__builtin_expect.).
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diff --git a/nptl/allocatestack.c b/nptl/allocatestack.c
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index 0fba6ce3474e8b35..00f9dcffe721a6b3 100644
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--- a/nptl/allocatestack.c
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+++ b/nptl/allocatestack.c
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@@ -124,11 +124,6 @@ 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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-
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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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@@ -456,14 +451,6 @@ 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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-
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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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@@ -506,34 +493,11 @@ 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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-
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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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-
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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 (__builtin_expect ((coloring & __static_tls_align_m1) != 0, 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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-
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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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diff --git a/nptl/stack-aliasing.h b/nptl/stack-aliasing.h
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index 526b54e18f7e0a27..62fdc9265e0038e6 100644
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--- a/nptl/stack-aliasing.h
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+++ b/nptl/stack-aliasing.h
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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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-
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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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diff --git a/sysdeps/i386/i686/stack-aliasing.h b/sysdeps/i386/i686/stack-aliasing.h
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index 1e35ceb2061d60f9..d73e45461f928a6a 100644
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--- a/sysdeps/i386/i686/stack-aliasing.h
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+++ b/sysdeps/i386/i686/stack-aliasing.h
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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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-
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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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