diff mbox series

[Concept,16/37] malloc: use hidden visibility

Message ID	20251201170529.3237986-17-sjg@u-boot.org
State	New
Headers	From: Simon Glass <sjg@u-boot.org> To: U-Boot Concept <concept@u-boot.org> Date: Mon, 1 Dec 2025 10:04:55 -0700 Message-ID: <20251201170529.3237986-17-sjg@u-boot.org> In-Reply-To: <20251201170529.3237986-1-sjg@u-boot.org> References: <20251201170529.3237986-1-sjg@u-boot.org> MIME-Version: 1.0 Message-ID-Hash: I7EGZ3IO4SBZVC7MTF5E6YQW6IN352Y3 CC: Heinrich Schuchardt <xypron.glpk@gmx.de>, Simon Glass <simon.glass@canonical.com>, Rabin Vincent <rabin@rab.in>, Stephen Warren <swarren@wwwdotorg.org>, Tom Rini <trini@konsulko.com>, Simon Glass <sjg@chromium.org>, Claude <noreply@anthropic.com> Precedence: list Subject: [Concept] [PATCH 16/37] malloc: use hidden visibility Archived-At: <https://lists.u-boot.org/archives/list/concept@u-boot.org/message/I7EGZ3IO4SBZVC7MTF5E6YQW6IN352Y3/> Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit
Series	malloc: Import dlmalloc 2.8.6 \| [Concept,00/37] malloc: Import dlmalloc 2.8.6 [Concept,01/37] test: hooks: Add a symlink for tasman [Concept,02/37] treewide: Add missing string.h includes [Concept,03/37] imx8mp: Increase the BSS limit for a few boards [Concept,04/37] test: Use TOTAL_MALLOC_LEN for abuf and alist tests [Concept,05/37] malloc: Rename dlmalloc.c to dlmalloc_old.c [Concept,06/37] malloc: Rename malloc.h to malloc_old.h [Concept,07/37] malloc: Import dlmalloc 2.8.6 [Concept,08/37] malloc: Add mem_malloc_init() and sbrk() [Concept,09/37] malloc: Add U-Boot configuration for dlmalloc 2.8.6 [Concept,10/37] malloc: Fix assert warning [Concept,11/37] malloc: return NULL if not initialized yet [Concept,12/37] Add a simple malloc() implementation for pre-relocation [Concept,13/37] malloc: Enable assertions if UNIT_TEST is enabled [Concept,14/37] malloc: Reduce code size with INSECURE and NO_MALLINFO [Concept,15/37] malloc: work around some memalign fragmentation issues [Concept,16/37] malloc: use hidden visibility [Concept,17/37] dlmalloc: calloc: fix zeroing early allocations [Concept,18/37] sandbox: Use a prefix for all allocation functions [Concept,19/37] malloc: Annotate allocator for valgrind [Concept,20/37] test: Support testing malloc() failures [Concept,21/37] dlmalloc: Fix a warning with clang-15 [Concept,22/37] mcheck: prepare +1 tier for mcheck-wrappers, in dl-*alloc commands [Concept,23/37] mcheck: Use memset/memcpy instead of MALLOC_ZERO/MALLOC_COPY for mcheck. [Concept,24/37] mcheck: integrate mcheck into dlmalloc.c [Concept,25/37] mcheck: support memalign [Concept,26/37] mcheck: add pedantic mode support [Concept,27/37] malloc: Avoid defining calloc() [Concept,28/37] malloc: Set up the malloc() state in mem_malloc_init() [Concept,29/37] malloc: Allow building dlmalloc with SPL_SYS_MALLOC_SIMPLE [Concept,30/37] malloc: Add a way to control the size of dlmalloc [Concept,31/37] malloc: Add NO_REALLOC_IN_PLACE option to reduce code size [Concept,32/37] malloc: Add NO_TREE_BINS option to reduce code size [Concept,33/37] malloc: Add SIMPLE_MEMALIGN to simplify memalign for code size [Concept,34/37] malloc: Add SMALLCHUNKS_AS_FUNCS to convert macros to funcs [Concept,35/37] test: Add some tests for dlmalloc [Concept,36/37] malloc: Switch to the new malloc() implementation [Concept,37/37] doc: Add malloc documentation

Commit Message

Simon Glass Dec. 1, 2025, 5:04 p.m. UTC

  From: Simon Glass <simon.glass@canonical.com>

When running sandbox, U-Boot's malloc symbols can be hooked into the
GOT before U-Boot code runs. This causes issues because the dynamic
linker may call malloc/free before gd is initialized.

Use hidden visibility for malloc symbols to prevent them from being
hooked into the GOT, so only code in the U-Boot binary itself calls
them; any other code calls the standard C library malloc().

Changes from original commit:
- Use DLMALLOC_EXPORT mechanism instead of #pragma in malloc.h

Cc: Rabin Vincent <rabin@rab.in>
Signed-off-by: Stephen Warren <swarren@wwwdotorg.org>
Reviewed-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Co-developed-by: Claude <noreply@anthropic.com>
Signed-off-by: Simon Glass <simon.glass@canonical.com>
(cherry picked from commit 2f0bcd4de1a5b990e58d12cd0c7f9d7e9248fec4)
---

 common/dlmalloc.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff mbox series

Patch

diff --git a/common/dlmalloc.c b/common/dlmalloc.c
index 5a8e463671c..d53cbf2f2e1 100644
--- a/common/dlmalloc.c
+++ b/common/dlmalloc.c
@@ -538,6 +538,15 @@  MAX_RELEASE_CHECK_RATE   default: 4095 unless not HAVE_MMAP
 #define DLMALLOC_VERSION 20806
 #endif /* DLMALLOC_VERSION */
 
+/*
+ * For U-Boot, use hidden visibility to prevent malloc symbols from being
+ * hooked into the GOT, avoiding issues during early initialization before
+ * gd is set up.
+ */
+#ifdef __UBOOT__
+#define DLMALLOC_EXPORT extern __attribute__((visibility("hidden")))
+#endif
+
 #ifndef DLMALLOC_EXPORT
 #define DLMALLOC_EXPORT extern
 #endif