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935c2dbec4
Implement the microMIPS encoding of the J instruction for the purpose of the static keys feature, fixing a crash early on in bootstrap as the kernel is unhappy seeing the ISA bit set in jump table entries. Make sure the ISA bit correctly reflects the instruction encoding chosen for the kernel, 0 for the standard MIPS and 1 for the microMIPS encoding. Also make sure the instruction to patch is a 32-bit NOP in the microMIPS mode as by default the 16-bit short encoding is assumed Signed-off-by: Maciej W. Rozycki <macro@codesourcery.com> Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/8516/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
76 lines
2.1 KiB
C
76 lines
2.1 KiB
C
/*
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* This file is subject to the terms and conditions of the GNU General Public
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* License. See the file "COPYING" in the main directory of this archive
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* for more details.
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*
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* Copyright (c) 2010 Cavium Networks, Inc.
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*/
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#include <linux/jump_label.h>
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#include <linux/kernel.h>
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#include <linux/memory.h>
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#include <linux/mutex.h>
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#include <linux/types.h>
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#include <linux/cpu.h>
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#include <asm/cacheflush.h>
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#include <asm/inst.h>
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#ifdef HAVE_JUMP_LABEL
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/*
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* Define parameters for the standard MIPS and the microMIPS jump
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* instruction encoding respectively:
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*
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* - the ISA bit of the target, either 0 or 1 respectively,
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*
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* - the amount the jump target address is shifted right to fit in the
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* immediate field of the machine instruction, either 2 or 1,
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*
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* - the mask determining the size of the jump region relative to the
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* delay-slot instruction, either 256MB or 128MB,
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*
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* - the jump target alignment, either 4 or 2 bytes.
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*/
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#define J_ISA_BIT IS_ENABLED(CONFIG_CPU_MICROMIPS)
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#define J_RANGE_SHIFT (2 - J_ISA_BIT)
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#define J_RANGE_MASK ((1ul << (26 + J_RANGE_SHIFT)) - 1)
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#define J_ALIGN_MASK ((1ul << J_RANGE_SHIFT) - 1)
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void arch_jump_label_transform(struct jump_entry *e,
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enum jump_label_type type)
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{
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union mips_instruction *insn_p;
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union mips_instruction insn;
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insn_p = (union mips_instruction *)msk_isa16_mode(e->code);
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/* Jump only works within an aligned region its delay slot is in. */
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BUG_ON((e->target & ~J_RANGE_MASK) != ((e->code + 4) & ~J_RANGE_MASK));
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/* Target must have the right alignment and ISA must be preserved. */
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BUG_ON((e->target & J_ALIGN_MASK) != J_ISA_BIT);
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if (type == JUMP_LABEL_ENABLE) {
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insn.j_format.opcode = J_ISA_BIT ? mm_j32_op : j_op;
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insn.j_format.target = e->target >> J_RANGE_SHIFT;
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} else {
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insn.word = 0; /* nop */
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}
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get_online_cpus();
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mutex_lock(&text_mutex);
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if (IS_ENABLED(CONFIG_CPU_MICROMIPS)) {
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insn_p->halfword[0] = insn.word >> 16;
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insn_p->halfword[1] = insn.word;
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} else
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*insn_p = insn;
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flush_icache_range((unsigned long)insn_p,
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(unsigned long)insn_p + sizeof(*insn_p));
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mutex_unlock(&text_mutex);
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put_online_cpus();
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}
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#endif /* HAVE_JUMP_LABEL */
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