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Subject[PATCH v3] FLAT: tweak default stack alignment
The recent commit 1f0ce8b3dd667dca7 which moved the ARCH_SLAB_MINALIGN
default into the global header inadvertently broke FLAT for a bunch of
systems. Blackfin systems now fail on any FLAT exec with:
Unable to read code+data+bss, errno 14
When your /init is a FLAT binary, obviously this can be annoying ;).

This stems from the alignment usage in the FLAT loader. The behavior
before was that FLAT would default to ARCH_SLAB_MINALIGN only if it was
defined, and this was only defined by arches when they wanted a larger
alignment value. Otherwise it'd default to pointer alignment. Arguably,
this is kind of hokey that the FLAT is semi-abusing defines it shouldn't.

So let's merge the two alignment requirements so the floor is never 0.

Signed-off-by: Mike Frysinger <>
- split changes & document better

- combine the diff align values via max_t

fs/binfmt_flat.c | 6 +-----
1 files changed, 1 insertions(+), 5 deletions(-)

diff --git a/fs/binfmt_flat.c b/fs/binfmt_flat.c
index b6ab27c..811384b 100644
--- a/fs/binfmt_flat.c
+++ b/fs/binfmt_flat.c
@@ -68,11 +68,7 @@
* Here we can be a bit looser than the data sections since this
* needs to only meet arch ABI requirements.
-#define FLAT_STACK_ALIGN (sizeof(void *))
+#define FLAT_STACK_ALIGN max_t(unsigned long, sizeof(void *), ARCH_SLAB_MINALIGN)

#define RELOC_FAILED 0xff00ff01 /* Relocation incorrect somewhere */
#define UNLOADED_LIB 0x7ff000ff /* Placeholder for unused library */

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