From ce61a2ad2e078a19454411832b167444b6c9ae66 Mon Sep 17 00:00:00 2001 From: Nathan Froyd Date: Fri, 28 Jun 2013 21:42:19 +0000 Subject: [PATCH] Mark packed structure element used with atomic operation aligned. --- ChangeLog | 6 ++++++ elf/dl-profile.c | 13 ++++++++++++- 2 files changed, 18 insertions(+), 1 deletion(-) diff --git a/ChangeLog b/ChangeLog index ec42b6cc75..4ca386461d 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,9 @@ +2013-06-28 Nathan Froyd + Joseph Myers + + * elf/dl-profile.c (struct here_cg_arc_record): Declare 'count' + as being properly aligned. + 2013-06-28 Maciej W. Rozycki * dlfcn/modstatic5.c: New file. diff --git a/elf/dl-profile.c b/elf/dl-profile.c index 9034be229a..8fa6efca42 100644 --- a/elf/dl-profile.c +++ b/elf/dl-profile.c @@ -131,7 +131,18 @@ struct here_cg_arc_record { uintptr_t from_pc; uintptr_t self_pc; - uint32_t count; + /* The count field is atomically incremented in _dl_mcount, which + requires it to be properly aligned for its type, and for this + alignment to be visible to the compiler. The amount of data + before an array of this structure is calculated as + expected_size in _dl_start_profile. Everything in that + calculation is a multiple of 4 bytes (in the case of + kcountsize, because it is derived from a subtraction of + page-aligned values, and the corresponding calculation in + __monstartup also ensures it is at least a multiple of the size + of u_long), so all copies of this field do in fact have the + appropriate alignment. */ + uint32_t count __attribute__ ((aligned (__alignof__ (uint32_t)))); } __attribute__ ((packed)); static struct here_cg_arc_record *data; -- 2.43.5