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| author | Heiko Carstens <heiko.carstens@de.ibm.com> | 2015-01-29 14:10:22 +0100 |
|---|---|---|
| committer | Martin Schwidefsky <schwidefsky@de.ibm.com> | 2015-01-29 16:33:34 +0100 |
| commit | d5caa4dbf9bd2ad8cd7f6be0ca76722be947182b (patch) | |
| tree | 6d58cdd140333e17c881667e9691b17f7dcd6e4d /arch/s390/include/asm/jump_label.h | |
| parent | s390/jump label: add sanity checks (diff) | |
| download | linux-d5caa4dbf9bd2ad8cd7f6be0ca76722be947182b.tar.xz linux-d5caa4dbf9bd2ad8cd7f6be0ca76722be947182b.zip | |
s390/jump label: use different nop instruction
Use a brcl 0,2 instruction for jump label nops during compile time,
so we don't mix up the different nops during mcount/hotpatch call
site detection.
The initial jump label code instruction replacement will exchange
these instructions with either a branch or a brcl 0,0 instruction.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'arch/s390/include/asm/jump_label.h')
| -rw-r--r-- | arch/s390/include/asm/jump_label.h | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/arch/s390/include/asm/jump_label.h b/arch/s390/include/asm/jump_label.h index 346b1c85ffb4..58642fd29c87 100644 --- a/arch/s390/include/asm/jump_label.h +++ b/arch/s390/include/asm/jump_label.h @@ -4,6 +4,7 @@ #include <linux/types.h> #define JUMP_LABEL_NOP_SIZE 6 +#define JUMP_LABEL_NOP_OFFSET 2 #ifdef CONFIG_64BIT #define ASM_PTR ".quad" @@ -13,9 +14,13 @@ #define ASM_ALIGN ".balign 4" #endif +/* + * We use a brcl 0,2 instruction for jump labels at compile time so it + * can be easily distinguished from a hotpatch generated instruction. + */ static __always_inline bool arch_static_branch(struct static_key *key) { - asm_volatile_goto("0: brcl 0,0\n" + asm_volatile_goto("0: brcl 0,"__stringify(JUMP_LABEL_NOP_OFFSET)"\n" ".pushsection __jump_table, \"aw\"\n" ASM_ALIGN "\n" ASM_PTR " 0b, %l[label], %0\n" |