From 4d8ebeddc56f49aa0b4d7cec506cab14320e1bb4 Mon Sep 17 00:00:00 2001
From: Juergen Werner <juergen@opensourcerouting.org>
Date: Tue, 1 Oct 2019 14:24:20 +0200
Subject: [PATCH] lib: Revert usage of asm-code in MTYPE definitions
The asm-code was interpreted inconsistently for different platforms.
In particular for AArch64 this caused UB, if multiple static MTYPEs
where defined in one file. All static MTYPE_* could point to the same
memory location (namely the first defined MTYPE) OR to their respective
(correct) locations depending on the context of their usage.
Signed-off-by: Juergen Werner <juergen@opensourcerouting.org>
---
doc/developer/memtypes.rst | 2 +-
lib/memory.h | 16 ++++------------
2 files changed, 5 insertions(+), 13 deletions(-)
diff --git a/doc/developer/memtypes.rst b/doc/developer/memtypes.rst
index 13f6b43bbf..1af871963a 100644
--- a/doc/developer/memtypes.rst
+++ b/doc/developer/memtypes.rst
@@ -48,7 +48,7 @@ Definition
should be used to create these, but in some cases it is useful to pass a
``struct memtype *`` pointer to some helper function.
- The ``MTYPE_name`` created by the macros is declared as an array, i.e.
+ The ``MTYPE_name`` created by the macros is declared as a pointer, i.e.
a function taking a ``struct memtype *`` argument can be called with an
``MTYPE_name`` argument (as opposed to ``&MTYPE_name``.)
diff --git a/lib/memory.h b/lib/memory.h
index 14cd76f2f5..8de5c4c2bf 100644
--- a/lib/memory.h
+++ b/lib/memory.h
@@ -101,14 +101,9 @@ struct memgroup {
*_mg_##mname.ref = _mg_##mname.next; \
}
-
-/* the array is a trick to make the "MTYPE_FOO" name work as a pointer without
- * putting a & in front of it, so we can do "XMALLOC(MTYPE_FOO, ...)" instead
- * of "XMALLOC(&MTYPE_FOO, ...)".
- */
#define DECLARE_MTYPE(name) \
extern struct memtype _mt_##name; \
- extern struct memtype MTYPE_##name[1]; \
+ extern struct memtype *const MTYPE_##name; \
/* end */
#define DEFINE_MTYPE_ATTR(group, mname, attr, desc) \
@@ -138,17 +133,14 @@ struct memgroup {
} \
/* end */
-/* can't quite get gcc to emit the alias correctly, so asm-alias it is :/ */
#define DEFINE_MTYPE(group, name, desc) \
DEFINE_MTYPE_ATTR(group, name, , desc) \
- __asm__(".equiv MTYPE_" #name ", _mt_" #name "\n\t" \
- ".global MTYPE_" #name "\n"); \
+ struct memtype *const MTYPE_##name = &_mt_##name; \
/* end */
-/* and this one's borked on clang, it drops static on aliases :/, so... asm */
+
#define DEFINE_MTYPE_STATIC(group, name, desc) \
DEFINE_MTYPE_ATTR(group, name, static, desc) \
- extern struct memtype MTYPE_##name[1]; \
- __asm__(".equiv MTYPE_" #name ", _mt_" #name "\n"); \
+ static struct memtype *const MTYPE_##name = &_mt_##name; \
/* end */
DECLARE_MGROUP(LIB)