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| author | Heiko Carstens <heiko.carstens@de.ibm.com> | 2015-01-29 14:10:22 +0100 |
|---|---|---|
| committer | Ben Hutchings <ben@decadent.org.uk> | 2019-05-22 23:15:02 +0100 |
| commit | 5df2fdb4502bbd0b99837b49f3e8207d71b238bd (patch) | |
| tree | f2bdd196f0a0d163fc2eb6557158076f43d6606e /arch/s390/kernel | |
| parent | 702c8fb2fd8004dc906f86fdbbe004c292755b2b (diff) | |
| download | linux-stable-5df2fdb4502bbd0b99837b49f3e8207d71b238bd.tar.gz linux-stable-5df2fdb4502bbd0b99837b49f3e8207d71b238bd.tar.bz2 linux-stable-5df2fdb4502bbd0b99837b49f3e8207d71b238bd.zip | |
s390/jump label: use different nop instruction
commit d5caa4dbf9bd2ad8cd7f6be0ca76722be947182b upstream.
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>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Diffstat (limited to 'arch/s390/kernel')
| -rw-r--r-- | arch/s390/kernel/jump_label.c | 19 |
1 files changed, 13 insertions, 6 deletions
diff --git a/arch/s390/kernel/jump_label.c b/arch/s390/kernel/jump_label.c index 25aef40584f7..cb2d51e779df 100644 --- a/arch/s390/kernel/jump_label.c +++ b/arch/s390/kernel/jump_label.c @@ -49,6 +49,11 @@ static void jump_label_bug(struct jump_entry *entry, struct insn *insn) panic("Corrupted kernel text"); } +static struct insn orignop = { + .opcode = 0xc004, + .offset = JUMP_LABEL_NOP_OFFSET >> 1, +}; + static void __jump_label_transform(struct jump_entry *entry, enum jump_label_type type, int init) @@ -59,14 +64,16 @@ static void __jump_label_transform(struct jump_entry *entry, jump_label_make_nop(entry, &old); jump_label_make_branch(entry, &new); } else { - if (init) - jump_label_make_nop(entry, &old); - else - jump_label_make_branch(entry, &old); + jump_label_make_branch(entry, &old); jump_label_make_nop(entry, &new); } - if (memcmp((void *)entry->code, &old, sizeof(old))) - jump_label_bug(entry, &old); + if (init) { + if (memcmp((void *)entry->code, &orignop, sizeof(orignop))) + jump_label_bug(entry, &old); + } else { + if (memcmp((void *)entry->code, &old, sizeof(old))) + jump_label_bug(entry, &old); + } probe_kernel_write((void *)entry->code, &new, sizeof(new)); } |