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b6f04d3d21
The i386 ABI disagrees with most other ABIs regarding alignment of data types larger than 4 bytes: on most ABIs a padding must be added at end of the structures, while it is not required on i386. So for most ABI struct c4iw_create_cq_resp gets implicitly padded to be aligned on a 8 bytes multiple, while for i386, such padding is not added. The tool pahole can be used to find such implicit padding: $ pahole --anon_include \ --nested_anon_include \ --recursive \ --class_name c4iw_create_cq_resp \ drivers/infiniband/hw/cxgb4/iw_cxgb4.o Then, structure layout can be compared between i386 and x86_64: +++ obj-i386/drivers/infiniband/hw/cxgb4/iw_cxgb4.o.pahole.txt 2014-03-28 11:43:05.547432195 +0100 --- obj-x86_64/drivers/infiniband/hw/cxgb4/iw_cxgb4.o.pahole.txt 2014-03-28 10:55:10.990133017 +0100 @@ -14,9 +13,8 @@ struct c4iw_create_cq_resp { __u32 size; /* 28 4 */ __u32 qid_mask; /* 32 4 */ - /* size: 36, cachelines: 1, members: 6 */ - /* last cacheline: 36 bytes */ + /* size: 40, cachelines: 1, members: 6 */ + /* padding: 4 */ + /* last cacheline: 40 bytes */ }; This ABI disagreement will make an x86_64 kernel try to write past the buffer provided by an i386 binary. When boundary check will be implemented, the x86_64 kernel will refuse to write past the i386 userspace provided buffer and the uverbs will fail. If the structure is on a page boundary and the next page is not mapped, ib_copy_to_udata() will fail and the uverb will fail. This patch adds an explicit padding at end of structure c4iw_create_cq_resp, and, like |
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amso1100 | ||
cxgb3 | ||
cxgb4 | ||
ehca | ||
ipath | ||
mlx4 | ||
mlx5 | ||
mthca | ||
nes | ||
ocrdma | ||
qib | ||
usnic |