From: Thomas Neumann <thomas.neumann@in.tum.de>
To: "gcc-patches@gcc.gnu.org" <gcc-patches@gcc.gnu.org>
Cc: Jakub Jelinek <jakub@redhat.com>
Subject: [PATCH] handle unwind tables that are embedded within unwinding code, [PR111731]
Date: Fri, 15 Mar 2024 11:29:48 +0100 [thread overview]
Message-ID: <dcc20aec-ce49-4497-b329-4bab4a6a05dc@in.tum.de> (raw)
In-Reply-To: <87sfibqu1s.fsf@oldenburg.str.redhat.com>
Original bug report: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111731
Given that this is a regression, is this okay for gcc 13 and mainline?
The unwinding mechanism registers both the code range and the unwind
table itself within a b-tree lookup structure. That data structure
assumes that is consists of non-overlappping intervals. This
becomes a problem if the unwinding table is embedded within the
code itself, as now the intervals do overlap.
To fix this problem we now keep the unwind tables in a separate
b-tree, which prevents the overlap.
libgcc/ChangeLog:
PR libgcc/111731
* unwind-dw2-fde.c: Split unwind ranges if they contain the
unwind table.
---
libgcc/unwind-dw2-fde.c | 37 +++++++++++++++++++++----------------
1 file changed, 21 insertions(+), 16 deletions(-)
diff --git a/libgcc/unwind-dw2-fde.c b/libgcc/unwind-dw2-fde.c
index 61a578d097e..9d503545677 100644
--- a/libgcc/unwind-dw2-fde.c
+++ b/libgcc/unwind-dw2-fde.c
@@ -48,6 +48,7 @@ typedef __UINTPTR_TYPE__ uintptr_type;
#include "unwind-dw2-btree.h"
static struct btree registered_frames;
+static struct btree registered_objects;
static bool in_shutdown;
static void
@@ -58,6 +59,7 @@ release_registered_frames (void)
/* Release the b-tree and all frames. Frame releases that happen later are
* silently ignored */
btree_destroy (®istered_frames);
+ btree_destroy (®istered_objects);
in_shutdown = true;
}
@@ -103,6 +105,21 @@ static __gthread_mutex_t object_mutex;
#endif
#endif
+#ifdef ATOMIC_FDE_FAST_PATH
+// Register the pc range for a given object in the lookup structure.
+static void
+register_pc_range_for_object (uintptr_type begin, struct object *ob)
+{
+ // Register the object itself to know the base pointer on deregistration.
+ btree_insert (®istered_objects, begin, 1, ob);
+
+ // Register the frame in the b-tree
+ uintptr_type range[2];
+ get_pc_range (ob, range);
+ btree_insert (®istered_frames, range[0], range[1] - range[0], ob);
+}
+#endif
+
/* Called from crtbegin.o to register the unwind info for an object. */
void
@@ -124,13 +141,7 @@ __register_frame_info_bases (const void *begin, struct object *ob,
#endif
#ifdef ATOMIC_FDE_FAST_PATH
- // Register the object itself to know the base pointer on deregistration.
- btree_insert (®istered_frames, (uintptr_type) begin, 1, ob);
-
- // Register the frame in the b-tree
- uintptr_type range[2];
- get_pc_range (ob, range);
- btree_insert (®istered_frames, range[0], range[1] - range[0], ob);
+ register_pc_range_for_object ((uintptr_type) begin, ob);
#else
init_object_mutex_once ();
__gthread_mutex_lock (&object_mutex);
@@ -178,13 +189,7 @@ __register_frame_info_table_bases (void *begin, struct object *ob,
ob->s.b.encoding = DW_EH_PE_omit;
#ifdef ATOMIC_FDE_FAST_PATH
- // Register the object itself to know the base pointer on deregistration.
- btree_insert (®istered_frames, (uintptr_type) begin, 1, ob);
-
- // Register the frame in the b-tree
- uintptr_type range[2];
- get_pc_range (ob, range);
- btree_insert (®istered_frames, range[0], range[1] - range[0], ob);
+ register_pc_range_for_object ((uintptr_type) begin, ob);
#else
init_object_mutex_once ();
__gthread_mutex_lock (&object_mutex);
@@ -232,7 +237,7 @@ __deregister_frame_info_bases (const void *begin)
#ifdef ATOMIC_FDE_FAST_PATH
// Find the originally registered object to get the base pointer.
- ob = btree_remove (®istered_frames, (uintptr_type) begin);
+ ob = btree_remove (®istered_objects, (uintptr_type) begin);
// Remove the corresponding PC range.
if (ob)
@@ -240,7 +245,7 @@ __deregister_frame_info_bases (const void *begin)
uintptr_type range[2];
get_pc_range (ob, range);
if (range[0] != range[1])
- btree_remove (®istered_frames, range[0]);
+ btree_remove (®istered_frames, range[0]);
}
// Deallocate the sort array if any.
--
2.43.0
next prev parent reply other threads:[~2024-03-15 10:30 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-16 10:19 [PATCH v4] eliminate mutex in fast path of __register_frame Thomas Neumann
2022-09-16 14:49 ` Jason Merrill
2022-09-18 8:59 ` Dimitar Dimitrov
2022-09-18 9:20 ` Thomas Neumann
2022-09-18 10:02 ` Thomas Neumann
2022-09-19 13:46 ` Stephan Bergmann
2022-09-19 13:55 ` Thomas Neumann
2022-09-19 14:00 ` Stephan Bergmann
2022-09-19 15:33 ` Thomas Neumann
2022-09-20 5:39 ` Stephan Bergmann
2022-11-21 11:14 ` Tamar Christina
2022-11-21 11:22 ` Thomas Neumann
2022-11-21 11:48 ` Jakub Jelinek
2022-11-21 17:13 ` H.J. Lu
2022-11-22 0:31 ` Thomas Neumann
2022-11-22 8:20 ` Florian Weimer
2022-11-22 9:12 ` Thomas Neumann
2022-12-09 17:34 ` [PATCH] initialize fde objects lazily Thomas Neumann
2022-12-15 16:11 ` Tamar Christina
2022-12-16 17:25 ` Jason Merrill
2023-05-02 14:32 ` [PATCH] release the sorted FDE array when deregistering a frame [PR109685] Thomas Neumann
2023-05-10 10:49 ` [PATCH] fix radix sort on 32bit platforms [PR109670] Thomas Neumann
2023-08-10 11:33 ` [PATCH] preserve base pointer for __deregister_frame [PR110956] Thomas Neumann
2023-08-11 15:21 ` Jeff Law
2024-03-15 10:29 ` Thomas Neumann [this message]
2024-03-20 8:25 ` [PATCH] handle unwind tables that are embedded within unwinding code, [PR111731] Richard Biener
2024-03-22 13:35 ` Jeff Law
2024-03-22 13:36 ` Jeff Law
2024-03-22 14:43 ` Thomas Neumann
2022-11-22 8:00 ` [PATCH] speed up end_fde_sort using radix sort Thomas Neumann
2022-12-16 18:02 ` Jason Merrill
2022-11-21 11:49 ` [PATCH v4] eliminate mutex in fast path of __register_frame Tamar Christina
2022-11-21 11:53 ` Thomas Neumann
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