mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-10-30 08:02:30 +00:00
55 lines
1.5 KiB
C
55 lines
1.5 KiB
C
// SPDX-License-Identifier: GPL-2.0+
|
|
/*
|
|
* Copyright (C) 2019 Helge Deller <deller@gmx.de>
|
|
*
|
|
* Based on arch/arm64/kernel/jump_label.c
|
|
*/
|
|
#include <linux/kernel.h>
|
|
#include <linux/jump_label.h>
|
|
#include <linux/bug.h>
|
|
#include <asm/alternative.h>
|
|
#include <asm/patch.h>
|
|
|
|
static inline int reassemble_17(int as17)
|
|
{
|
|
return (((as17 & 0x10000) >> 16) |
|
|
((as17 & 0x0f800) << 5) |
|
|
((as17 & 0x00400) >> 8) |
|
|
((as17 & 0x003ff) << 3));
|
|
}
|
|
|
|
void arch_jump_label_transform(struct jump_entry *entry,
|
|
enum jump_label_type type)
|
|
{
|
|
void *addr = (void *)jump_entry_code(entry);
|
|
u32 insn;
|
|
|
|
if (type == JUMP_LABEL_JMP) {
|
|
void *target = (void *)jump_entry_target(entry);
|
|
int distance = target - addr;
|
|
/*
|
|
* Encode the PA1.1 "b,n" instruction with a 17-bit
|
|
* displacement. In case we hit the BUG(), we could use
|
|
* another branch instruction with a 22-bit displacement on
|
|
* 64-bit CPUs instead. But this seems sufficient for now.
|
|
*/
|
|
distance -= 8;
|
|
BUG_ON(distance > 262143 || distance < -262144);
|
|
insn = 0xe8000002 | reassemble_17(distance >> 2);
|
|
} else {
|
|
insn = INSN_NOP;
|
|
}
|
|
|
|
patch_text(addr, insn);
|
|
}
|
|
|
|
void arch_jump_label_transform_static(struct jump_entry *entry,
|
|
enum jump_label_type type)
|
|
{
|
|
/*
|
|
* We use the architected NOP in arch_static_branch, so there's no
|
|
* need to patch an identical NOP over the top of it here. The core
|
|
* will call arch_jump_label_transform from a module notifier if the
|
|
* NOP needs to be replaced by a branch.
|
|
*/
|
|
}
|