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| author | Martin Schwidefsky <schwidefsky@de.ibm.com> | 2019-05-17 12:50:43 +0200 |
|---|---|---|
| committer | Heiko Carstens <heiko.carstens@de.ibm.com> | 2019-06-04 15:03:12 +0200 |
| commit | a646ef398e72a2ac40bea974808ffcf1bea4e7f4 (patch) | |
| tree | 6799167289a134b5c6f7c3d4cf4e1e52165f46b4 | |
| parent | Linux 5.2-rc3 (diff) | |
| download | linux-a646ef398e72a2ac40bea974808ffcf1bea4e7f4.tar.xz linux-a646ef398e72a2ac40bea974808ffcf1bea4e7f4.zip | |
s390/jump_label: replace stop_machine with smp_call_function
The use of stop_machine to replace the mask bits of the jump label branch
is a very heavy-weight operation. This is in fact not necessary, the
mask of the branch can simply be updated, followed by a signal processor
to all the other CPUs to force them to pick up the modified instruction.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
[heiko.carstens@de.ibm.com]: Change jump_label_make_nop() so we get
brcl 0,offset instead of brcl 0,0. This
makes sure that only the mask part of the
instruction gets changed when updated.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
| -rw-r--r-- | arch/s390/kernel/jump_label.c | 18 | ||||
| -rw-r--r-- | arch/s390/mm/maccess.c | 9 |
2 files changed, 10 insertions, 17 deletions
diff --git a/arch/s390/kernel/jump_label.c b/arch/s390/kernel/jump_label.c index 3f10b56bd5a3..e193630a7d2a 100644 --- a/arch/s390/kernel/jump_label.c +++ b/arch/s390/kernel/jump_label.c @@ -22,9 +22,9 @@ struct insn_args { static void jump_label_make_nop(struct jump_entry *entry, struct insn *insn) { - /* brcl 0,0 */ + /* brcl 0,offset */ insn->opcode = 0xc004; - insn->offset = 0; + insn->offset = (jump_entry_target(entry) - jump_entry_code(entry)) >> 1; } static void jump_label_make_branch(struct jump_entry *entry, struct insn *insn) @@ -77,23 +77,15 @@ static void __jump_label_transform(struct jump_entry *entry, s390_kernel_write(code, &new, sizeof(new)); } -static int __sm_arch_jump_label_transform(void *data) +static void __jump_label_sync(void *dummy) { - struct insn_args *args = data; - - __jump_label_transform(args->entry, args->type, 0); - return 0; } void arch_jump_label_transform(struct jump_entry *entry, enum jump_label_type type) { - struct insn_args args; - - args.entry = entry; - args.type = type; - - stop_machine_cpuslocked(__sm_arch_jump_label_transform, &args, NULL); + __jump_label_transform(entry, type, 0); + smp_call_function(__jump_label_sync, NULL, 1); } void arch_jump_label_transform_static(struct jump_entry *entry, diff --git a/arch/s390/mm/maccess.c b/arch/s390/mm/maccess.c index 818deeb1ebc3..1864a8bb9622 100644 --- a/arch/s390/mm/maccess.c +++ b/arch/s390/mm/maccess.c @@ -52,21 +52,22 @@ static notrace long s390_kernel_write_odd(void *dst, const void *src, size_t siz * Therefore we have a read-modify-write sequence: the function reads eight * bytes from destination at an eight byte boundary, modifies the bytes * requested and writes the result back in a loop. - * - * Note: this means that this function may not be called concurrently on - * several cpus with overlapping words, since this may potentially - * cause data corruption. */ +static DEFINE_SPINLOCK(s390_kernel_write_lock); + void notrace s390_kernel_write(void *dst, const void *src, size_t size) { + unsigned long flags; long copied; + spin_lock_irqsave(&s390_kernel_write_lock, flags); while (size) { copied = s390_kernel_write_odd(dst, src, size); dst += copied; src += copied; size -= copied; } + spin_unlock_irqrestore(&s390_kernel_write_lock, flags); } static int __memcpy_real(void *dest, void *src, size_t count) |