xref: /linux/tools/objtool/tests/generic/fixtures/data_alignment.c (revision 5b6dca02b3e2254d2fd5706d76d7ab4610a67296)
1*8abe5c94SSong Liu // SPDX-License-Identifier: GPL-2.0
2*8abe5c94SSong Liu /*
3*8abe5c94SSong Liu  * Data with an alignment stricter than its size.
4*8abe5c94SSong Liu  *
5*8abe5c94SSong Liu  * A cloned data section has to keep its sh_addralign.  The kernel has plenty
6*8abe5c94SSong Liu  * of data whose alignment is a correctness property rather than an
7*8abe5c94SSong Liu  * optimisation -- per-CPU variables, anything touched by an aligned SSE move,
8*8abe5c94SSong Liu  * cacheline-aligned locks -- and a clone that lands under-aligned faults or
9*8abe5c94SSong Liu  * silently shares a cacheline it was written to avoid.
10*8abe5c94SSong Liu  *
11*8abe5c94SSong Liu  * The object is new in the patched build, so klp diff has to clone it rather
12*8abe5c94SSong Liu  * than reference the kernel's copy.
13*8abe5c94SSong Liu  */
14*8abe5c94SSong Liu 
15*8abe5c94SSong Liu static const char __modinfo[]
16*8abe5c94SSong Liu 	__attribute__((section(".modinfo"), used, aligned(1))) = "\0name=vmlinux";
17*8abe5c94SSong Liu 
18*8abe5c94SSong Liu #ifdef PATCHED
19*8abe5c94SSong Liu int aligned_data[2] __attribute__((aligned(64))) = { 1, 2 };
20*8abe5c94SSong Liu #endif
21*8abe5c94SSong Liu 
target(int x)22*8abe5c94SSong Liu int target(int x)
23*8abe5c94SSong Liu {
24*8abe5c94SSong Liu #ifdef PATCHED
25*8abe5c94SSong Liu 	return x + aligned_data[0];
26*8abe5c94SSong Liu #else
27*8abe5c94SSong Liu 	return x;
28*8abe5c94SSong Liu #endif
29*8abe5c94SSong Liu }
30