diff options
author | Paul Burton <paul.burton@mips.com> | 2019-04-05 22:50:36 +0000 |
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committer | Paul Burton <paul.burton@mips.com> | 2019-04-09 16:21:30 -0700 |
commit | 9b6584e35f407a391de39938fd0b4fb29671924f (patch) | |
tree | a0c653c452daa4462b38e6bc2a50c281474d98e5 /arch/mips/kernel | |
parent | c838b580ca9dcf16b07aa72bb61a914e9db0fd2c (diff) | |
download | linux-next-9b6584e35f407a391de39938fd0b4fb29671924f.tar.gz |
MIPS: jump_label: Use compact branches for >= r6
MIPSr6 introduced compact branches which have no delay slots. Make use
of them for jump labels in order to avoid the need for a nop to fill the
branch or jump delay slot, saving 4 bytes of code for each static branch.
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: linux-mips@vger.kernel.org
Diffstat (limited to 'arch/mips/kernel')
-rw-r--r-- | arch/mips/kernel/jump_label.c | 30 |
1 files changed, 25 insertions, 5 deletions
diff --git a/arch/mips/kernel/jump_label.c b/arch/mips/kernel/jump_label.c index ab943927f97a..662c8db9f45b 100644 --- a/arch/mips/kernel/jump_label.c +++ b/arch/mips/kernel/jump_label.c @@ -40,18 +40,38 @@ void arch_jump_label_transform(struct jump_entry *e, { union mips_instruction *insn_p; union mips_instruction insn; + long offset; insn_p = (union mips_instruction *)msk_isa16_mode(e->code); - /* Jump only works within an aligned region its delay slot is in. */ - BUG_ON((e->target & ~J_RANGE_MASK) != ((e->code + 4) & ~J_RANGE_MASK)); - /* 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) { - insn.j_format.opcode = J_ISA_BIT ? mm_j32_op : j_op; - insn.j_format.target = e->target >> J_RANGE_SHIFT; + 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 >= 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 */ } |