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/*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*
* Copyright (c) 2010 Cavium Networks, Inc.
*/
#include <linux/jump_label.h>
#include <linux/kernel.h>
#include <linux/memory.h>
#include <linux/mutex.h>
#include <linux/types.h>
#include <linux/cpu.h>
#include <asm/cacheflush.h>
#include <asm/inst.h>
/*
* Define parameters for the standard MIPS and the microMIPS jump
* instruction encoding respectively:
*
* - the ISA bit of the target, either 0 or 1 respectively,
*
* - the amount the jump target address is shifted right to fit in the
* immediate field of the machine instruction, either 2 or 1,
*
* - the mask determining the size of the jump region relative to the
* delay-slot instruction, either 256MB or 128MB,
*
* - the jump target alignment, either 4 or 2 bytes.
*/
#define J_ISA_BIT IS_ENABLED(CONFIG_CPU_MICROMIPS)
#define J_RANGE_SHIFT (2 - J_ISA_BIT)
#define J_RANGE_MASK ((1ul << (26 + J_RANGE_SHIFT)) - 1)
#define J_ALIGN_MASK ((1ul << J_RANGE_SHIFT) - 1)
void arch_jump_label_transform(struct jump_entry *e,
enum jump_label_type type)
{
union mips_instruction *insn_p;
union mips_instruction insn;
long offset;
insn_p = (union mips_instruction *)msk_isa16_mode(e->code);
/* Target must have the right alignment and ISA must be preserved. */
BUG_ON((e->target & J_ALIGN_MASK) != J_ISA_BIT);
if (type == JUMP_LABEL_JMP) {
if (!IS_ENABLED(CONFIG_CPU_MICROMIPS) && MIPS_ISA_REV >= 6) {
offset = e->target - ((unsigned long)insn_p + 4);
offset >>= 2;
/*
* The branch offset must fit in the instruction's 26
* bit field.
*/
WARN_ON((offset >= (long)BIT(25)) ||
(offset < -(long)BIT(25)));
insn.j_format.opcode = bc6_op;
insn.j_format.target = offset;
} else {
/*
* Jump only works within an aligned region its delay
* slot is in.
*/
WARN_ON((e->target & ~J_RANGE_MASK) !=
((e->code + 4) & ~J_RANGE_MASK));
insn.j_format.opcode = J_ISA_BIT ? mm_j32_op : j_op;
insn.j_format.target = e->target >> J_RANGE_SHIFT;
}
} else {
insn.word = 0; /* nop */
}
mutex_lock(&text_mutex);
if (IS_ENABLED(CONFIG_CPU_MICROMIPS)) {
insn_p->halfword[0] = insn.word >> 16;
insn_p->halfword[1] = insn.word;
} else
*insn_p = insn;
flush_icache_range((unsigned long)insn_p,
(unsigned long)insn_p + sizeof(*insn_p));
mutex_unlock(&text_mutex);
}
#ifdef CONFIG_MODULES
void jump_label_apply_nops(struct module *mod)
{
struct jump_entry *iter_start = mod->jump_entries;
struct jump_entry *iter_stop = iter_start + mod->num_jump_entries;
struct jump_entry *iter;
/* if the module doesn't have jump label entries, just return */
if (iter_start == iter_stop)
return;
for (iter = iter_start; iter < iter_stop; iter++) {
/* Only write NOPs for arch_branch_static(). */
if (jump_label_init_type(iter) == JUMP_LABEL_NOP)
arch_jump_label_transform(iter, JUMP_LABEL_NOP);
}
}
#endif
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