1*4882a593Smuzhiyun /* SPDX-License-Identifier: GPL-2.0 */
2*4882a593Smuzhiyun #ifndef _ASM_S390_JUMP_LABEL_H
3*4882a593Smuzhiyun #define _ASM_S390_JUMP_LABEL_H
4*4882a593Smuzhiyun
5*4882a593Smuzhiyun #ifndef __ASSEMBLY__
6*4882a593Smuzhiyun
7*4882a593Smuzhiyun #include <linux/types.h>
8*4882a593Smuzhiyun #include <linux/stringify.h>
9*4882a593Smuzhiyun
10*4882a593Smuzhiyun #define JUMP_LABEL_NOP_SIZE 6
11*4882a593Smuzhiyun #define JUMP_LABEL_NOP_OFFSET 2
12*4882a593Smuzhiyun
13*4882a593Smuzhiyun #ifdef CONFIG_CC_IS_CLANG
14*4882a593Smuzhiyun #define JUMP_LABEL_STATIC_KEY_CONSTRAINT "i"
15*4882a593Smuzhiyun #elif __GNUC__ < 9
16*4882a593Smuzhiyun #define JUMP_LABEL_STATIC_KEY_CONSTRAINT "X"
17*4882a593Smuzhiyun #else
18*4882a593Smuzhiyun #define JUMP_LABEL_STATIC_KEY_CONSTRAINT "jdd"
19*4882a593Smuzhiyun #endif
20*4882a593Smuzhiyun
21*4882a593Smuzhiyun /*
22*4882a593Smuzhiyun * We use a brcl 0,2 instruction for jump labels at compile time so it
23*4882a593Smuzhiyun * can be easily distinguished from a hotpatch generated instruction.
24*4882a593Smuzhiyun */
arch_static_branch(struct static_key * key,bool branch)25*4882a593Smuzhiyun static __always_inline bool arch_static_branch(struct static_key *key, bool branch)
26*4882a593Smuzhiyun {
27*4882a593Smuzhiyun asm_volatile_goto("0: brcl 0,"__stringify(JUMP_LABEL_NOP_OFFSET)"\n"
28*4882a593Smuzhiyun ".pushsection __jump_table,\"aw\"\n"
29*4882a593Smuzhiyun ".balign 8\n"
30*4882a593Smuzhiyun ".long 0b-.,%l[label]-.\n"
31*4882a593Smuzhiyun ".quad %0+%1-.\n"
32*4882a593Smuzhiyun ".popsection\n"
33*4882a593Smuzhiyun : : JUMP_LABEL_STATIC_KEY_CONSTRAINT (key), "i" (branch) : : label);
34*4882a593Smuzhiyun return false;
35*4882a593Smuzhiyun label:
36*4882a593Smuzhiyun return true;
37*4882a593Smuzhiyun }
38*4882a593Smuzhiyun
arch_static_branch_jump(struct static_key * key,bool branch)39*4882a593Smuzhiyun static __always_inline bool arch_static_branch_jump(struct static_key *key, bool branch)
40*4882a593Smuzhiyun {
41*4882a593Smuzhiyun asm_volatile_goto("0: brcl 15,%l[label]\n"
42*4882a593Smuzhiyun ".pushsection __jump_table,\"aw\"\n"
43*4882a593Smuzhiyun ".balign 8\n"
44*4882a593Smuzhiyun ".long 0b-.,%l[label]-.\n"
45*4882a593Smuzhiyun ".quad %0+%1-.\n"
46*4882a593Smuzhiyun ".popsection\n"
47*4882a593Smuzhiyun : : JUMP_LABEL_STATIC_KEY_CONSTRAINT (key), "i" (branch) : : label);
48*4882a593Smuzhiyun return false;
49*4882a593Smuzhiyun label:
50*4882a593Smuzhiyun return true;
51*4882a593Smuzhiyun }
52*4882a593Smuzhiyun
53*4882a593Smuzhiyun #endif /* __ASSEMBLY__ */
54*4882a593Smuzhiyun #endif
55