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Fix alignment issue causing failures on x86-64

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This commit is contained in:
Petr Viktorin 2021-02-25 13:14:30 +01:00
commit c4909577da
2 changed files with 79 additions and 1 deletions
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63
00358-align-allocations-and-pygc_head-to-16-bytes-on-64-bit-platforms.patch Normal file
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@ -0,0 +1,63 @@
From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Inada Naoki <songofacandy@gmail.com>
Date: Mon, 3 Jun 2019 10:51:32 +0900
Subject: [PATCH] 00358: align allocations and PyGC_Head to 16 bytes on 64-bit
platforms
Upstream bug: https://bugs.python.org/issue27987
Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1923658
Combination of two upstream commits:
- 1b85f4ec45a5d63188ee3866bd55eb29fdec7fbf
- 8766cb74e186d3820db0a855ccd780d6d84461f7
---
Include/objimpl.h | 6 +++++-
.../2019-05-15-18-28-43.bpo-27987.FaxuLy.rst | 2 ++
Objects/obmalloc.c | 6 ++++++
3 files changed, 13 insertions(+), 1 deletion(-)
create mode 100644 Misc/NEWS.d/next/Core and Builtins/2019-05-15-18-28-43.bpo-27987.FaxuLy.rst
diff --git a/Include/objimpl.h b/Include/objimpl.h
index e7a3696d7a..90d71b87ea 100644
--- a/Include/objimpl.h
+++ b/Include/objimpl.h
@@ -255,7 +255,11 @@ typedef union _gc_head {
union _gc_head *gc_prev;
Py_ssize_t gc_refs;
} gc;
- double dummy; /* force worst-case alignment */
+ long double dummy; /* force worst-case alignment */
+ // malloc returns memory block aligned for any built-in types and
+ // long double is the largest standard C type.
+ // On amd64 linux, long double requires 16 byte alignment.
+ // See bpo-27987 for more discussion.
} PyGC_Head;
extern PyGC_Head *_PyGC_generation0;
diff --git a/Misc/NEWS.d/next/Core and Builtins/2019-05-15-18-28-43.bpo-27987.FaxuLy.rst b/Misc/NEWS.d/next/Core and Builtins/2019-05-15-18-28-43.bpo-27987.FaxuLy.rst
new file mode 100644
index 0000000000..98073471ca
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and Builtins/2019-05-15-18-28-43.bpo-27987.FaxuLy.rst
@@ -0,0 +1,2 @@
+``PyGC_Head`` structure is aligned to ``long double``. This is needed to
+ensure GC-ed objects are aligned properly. Patch by Inada Naoki.
diff --git a/Objects/obmalloc.c b/Objects/obmalloc.c
index d46d149311..47283354f4 100644
--- a/Objects/obmalloc.c
+++ b/Objects/obmalloc.c
@@ -650,8 +650,14 @@ static int running_on_valgrind = -1;
*
* You shouldn't change this unless you know what you are doing.
*/
+
+#if SIZEOF_VOID_P > 4
+#define ALIGNMENT 16 /* must be 2^N */
+#define ALIGNMENT_SHIFT 4
+#else
#define ALIGNMENT 8 /* must be 2^N */
#define ALIGNMENT_SHIFT 3
+#endif
/* Return the number of bytes in size class I, as a uint. */
#define INDEX2SIZE(I) (((uint)(I) + 1) << ALIGNMENT_SHIFT)

17
python3.6.spec
View file

@ -17,7 +17,7 @@ URL: https://www.python.org/
#global prerel ...
%global upstream_version %{general_version}%{?prerel}
Version: %{general_version}%{?prerel:~%{prerel}}
Release: 1%{?dist}
Release: 2%{?dist}
License: Python
@ -437,6 +437,17 @@ Patch343: 00343-faulthandler-gcc10.patch
# a nightmare because it's basically a binary file.
Patch353: 00353-architecture-names-upstream-downstream.patch
# 00358 # cd155152db2f3f64831ecc5bd174a72c3bac401f
# align allocations and PyGC_Head to 16 bytes on 64-bit platforms
#
# Upstream bug: https://bugs.python.org/issue27987
# Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1923658
#
# Combination of two upstream commits:
# - 1b85f4ec45a5d63188ee3866bd55eb29fdec7fbf
# - 8766cb74e186d3820db0a855ccd780d6d84461f7
Patch358: 00358-align-allocations-and-pygc_head-to-16-bytes-on-64-bit-platforms.patch
# (New patches go here ^^^)
#
# When adding new patches to "python" and "python3" in Fedora, EL, etc.,
@ -1611,6 +1622,10 @@ CheckPython optimized
# ======================================================
%changelog
* Thu Feb 25 2021 Petr Viktorin <pviktori@redhat.com> - 3.6.13-2
- Fix alignment issue causing failures on x86-64
Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1923658
* Tue Feb 16 2021 Tomas Hrnciar <thrnciar@redhat.com> - 3.6.13-1
- Update to 3.6.13