MIPS: microMIPS: uasm: Add microMIPS micro assembler support.

Add new file 'uasm-micromips.c' that allows the micro assembler
to generate microMIPS ISA code. It can be included in the kernel
alongside the classic ISA as long as the platform supports the
microMIPS ISA.

Signed-off-by: Steven J. Hill <sjhill@mips.com>
Cc: linux-mips@linux-mips.org
Cc: cernekee@gmail.com
Cc: kevink@paralogos.com
Cc: ddaney.cavm@gmail.com
Patchwork: https://patchwork.linux-mips.org/patch/4923/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
(cherry picked from commit 5f011a866afbd03a5379f67f4e70e5efbdfc16e9)

2 files changed, 222 insertions, 0 deletions

diff --git a/arch/mips/mm/Makefile b/arch/mips/mm/Makefile
index 9e90c2182aa..e87aae1f2e8 100644
--- a/arch/mips/mm/Makefile
+++ b/arch/mips/mm/Makefile
@@ -22,3 +22,5 @@ obj-$(CONFIG_IP22_CPU_SCACHE)	+= sc-ip22.o
 obj-$(CONFIG_R5000_CPU_SCACHE)	+= sc-r5k.o
 obj-$(CONFIG_RM7000_CPU_SCACHE) += sc-rm7k.o
 obj-$(CONFIG_MIPS_CPU_SCACHE)	+= sc-mips.o
+
+obj-$(CONFIG_SYS_SUPPORTS_MICROMIPS) += uasm-micromips.o
diff --git a/arch/mips/mm/uasm-micromips.c b/arch/mips/mm/uasm-micromips.c
new file mode 100644
index 00000000000..476d50c5fac
--- /dev/null
+++ b/arch/mips/mm/uasm-micromips.c
@@ -0,0 +1,220 @@
+/*
+ * 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.
+ *
+ * A small micro-assembler. It is intentionally kept simple, does only
+ * support a subset of instructions, and does not try to hide pipeline
+ * effects like branch delay slots.
+ *
+ * Copyright (C) 2004, 2005, 2006, 2008	 Thiemo Seufer
+ * Copyright (C) 2005, 2007  Maciej W. Rozycki
+ * Copyright (C) 2006  Ralf Baechle (ralf@linux-mips.org)
+ * Copyright (C) 2012, 2013   MIPS Technologies, Inc.  All rights reserved.
+ */
+
+#include <linux/kernel.h>
+#include <linux/types.h>
+#include <linux/init.h>
+
+#include <asm/inst.h>
+#include <asm/elf.h>
+#include <asm/bugs.h>
+#define UASM_ISA	_UASM_ISA_MICROMIPS
+#include <asm/uasm.h>
+
+#define RS_MASK		0x1f
+#define RS_SH		16
+#define RT_MASK		0x1f
+#define RT_SH		21
+#define SCIMM_MASK	0x3ff
+#define SCIMM_SH	16
+
+/* This macro sets the non-variable bits of an instruction. */
+#define M(a, b, c, d, e, f)					\
+	((a) << OP_SH						\
+	 | (b) << RT_SH						\
+	 | (c) << RS_SH						\
+	 | (d) << RD_SH						\
+	 | (e) << RE_SH						\
+	 | (f) << FUNC_SH)
+
+/* Define these when we are not the ISA the kernel is being compiled with. */
+#ifndef CONFIG_CPU_MICROMIPS
+#define MM_uasm_i_b(buf, off) ISAOPC(_beq)(buf, 0, 0, off)
+#define MM_uasm_i_beqz(buf, rs, off) ISAOPC(_beq)(buf, rs, 0, off)
+#define MM_uasm_i_beqzl(buf, rs, off) ISAOPC(_beql)(buf, rs, 0, off)
+#define MM_uasm_i_bnez(buf, rs, off) ISAOPC(_bne)(buf, rs, 0, off)
+#endif
+
+#include "uasm.c"
+
+static struct insn insn_table_MM[] __uasminitdata = {
+	{ insn_addu, M(mm_pool32a_op, 0, 0, 0, 0, mm_addu32_op), RT | RS | RD },
+	{ insn_addiu, M(mm_addiu32_op, 0, 0, 0, 0, 0), RT | RS | SIMM },
+	{ insn_and, M(mm_pool32a_op, 0, 0, 0, 0, mm_and_op), RT | RS | RD },
+	{ insn_andi, M(mm_andi32_op, 0, 0, 0, 0, 0), RT | RS | UIMM },
+	{ insn_beq, M(mm_beq32_op, 0, 0, 0, 0, 0), RS | RT | BIMM },
+	{ insn_beql, 0, 0 },
+	{ insn_bgez, M(mm_pool32i_op, mm_bgez_op, 0, 0, 0, 0), RS | BIMM },
+	{ insn_bgezl, 0, 0 },
+	{ insn_bltz, M(mm_pool32i_op, mm_bltz_op, 0, 0, 0, 0), RS | BIMM },
+	{ insn_bltzl, 0, 0 },
+	{ insn_bne, M(mm_bne32_op, 0, 0, 0, 0, 0), RT | RS | BIMM },
+	{ insn_cache, M(mm_pool32b_op, 0, 0, mm_cache_func, 0, 0), RT | RS | SIMM },
+	{ insn_daddu, 0, 0 },
+	{ insn_daddiu, 0, 0 },
+	{ insn_dmfc0, 0, 0 },
+	{ insn_dmtc0, 0, 0 },
+	{ insn_dsll, 0, 0 },
+	{ insn_dsll32, 0, 0 },
+	{ insn_dsra, 0, 0 },
+	{ insn_dsrl, 0, 0 },
+	{ insn_dsrl32, 0, 0 },
+	{ insn_drotr, 0, 0 },
+	{ insn_drotr32, 0, 0 },
+	{ insn_dsubu, 0, 0 },
+	{ insn_eret, M(mm_pool32a_op, 0, 0, 0, mm_eret_op, mm_pool32axf_op), 0 },
+	{ insn_ins, M(mm_pool32a_op, 0, 0, 0, 0, mm_ins_op), RT | RS | RD | RE },
+	{ insn_ext, M(mm_pool32a_op, 0, 0, 0, 0, mm_ext_op), RT | RS | RD | RE },
+	{ insn_j, M(mm_j32_op, 0, 0, 0, 0, 0), JIMM },
+	{ insn_jal, M(mm_jal32_op, 0, 0, 0, 0, 0), JIMM },
+	{ insn_jr, M(mm_pool32a_op, 0, 0, 0, mm_jalr_op, mm_pool32axf_op), RS },
+	{ insn_ld, 0, 0 },
+	{ insn_ll, M(mm_pool32c_op, 0, 0, (mm_ll_func << 1), 0, 0), RS | RT | SIMM },
+	{ insn_lld, 0, 0 },
+	{ insn_lui, M(mm_pool32i_op, mm_lui_op, 0, 0, 0, 0), RS | SIMM },
+	{ insn_lw, M(mm_lw32_op, 0, 0, 0, 0, 0), RT | RS | SIMM },
+	{ insn_mfc0, M(mm_pool32a_op, 0, 0, 0, mm_mfc0_op, mm_pool32axf_op), RT | RS | RD },
+	{ insn_mtc0, M(mm_pool32a_op, 0, 0, 0, mm_mtc0_op, mm_pool32axf_op), RT | RS | RD },
+	{ insn_or, M(mm_pool32a_op, 0, 0, 0, 0, mm_or32_op), RT | RS | RD },
+	{ insn_ori, M(mm_ori32_op, 0, 0, 0, 0, 0), RT | RS | UIMM },
+	{ insn_pref, M(mm_pool32c_op, 0, 0, (mm_pref_func << 1), 0, 0), RT | RS | SIMM },
+	{ insn_rfe, 0, 0 },
+	{ insn_sc, M(mm_pool32c_op, 0, 0, (mm_sc_func << 1), 0, 0), RT | RS | SIMM },
+	{ insn_scd, 0, 0 },
+	{ insn_sd, 0, 0 },
+	{ insn_sll, M(mm_pool32a_op, 0, 0, 0, 0, mm_sll32_op), RT | RS | RD },
+	{ insn_sra, M(mm_pool32a_op, 0, 0, 0, 0, mm_sra_op), RT | RS | RD },
+	{ insn_srl, M(mm_pool32a_op, 0, 0, 0, 0, mm_srl32_op), RT | RS | RD },
+	{ insn_rotr, M(mm_pool32a_op, 0, 0, 0, 0, mm_rotr_op), RT | RS | RD },
+	{ insn_subu, M(mm_pool32a_op, 0, 0, 0, 0, mm_subu32_op), RT | RS | RD },
+	{ insn_sw, M(mm_sw32_op, 0, 0, 0, 0, 0), RT | RS | SIMM },
+	{ insn_tlbp, M(mm_pool32a_op, 0, 0, 0, mm_tlbp_op, mm_pool32axf_op), 0 },
+	{ insn_tlbr, M(mm_pool32a_op, 0, 0, 0, mm_tlbr_op, mm_pool32axf_op), 0 },
+	{ insn_tlbwi, M(mm_pool32a_op, 0, 0, 0, mm_tlbwi_op, mm_pool32axf_op), 0 },
+	{ insn_tlbwr, M(mm_pool32a_op, 0, 0, 0, mm_tlbwr_op, mm_pool32axf_op), 0 },
+	{ insn_xor, M(mm_pool32a_op, 0, 0, 0, 0, mm_xor32_op), RT | RS | RD },
+	{ insn_xori, M(mm_xori32_op, 0, 0, 0, 0, 0), RT | RS | UIMM },
+	{ insn_dins, 0, 0 },
+	{ insn_dinsm, 0, 0 },
+	{ insn_syscall, M(mm_pool32a_op, 0, 0, 0, mm_syscall_op, mm_pool32axf_op), SCIMM},
+	{ insn_bbit0, 0, 0 },
+	{ insn_bbit1, 0, 0 },
+	{ insn_lwx, 0, 0 },
+	{ insn_ldx, 0, 0 },
+	{ insn_invalid, 0, 0 }
+};
+
+#undef M
+
+static inline __uasminit u32 build_bimm(s32 arg)
+{
+	WARN(arg > 0xffff || arg < -0x10000,
+	     KERN_WARNING "Micro-assembler field overflow\n");
+
+	WARN(arg & 0x3, KERN_WARNING "Invalid micro-assembler branch target\n");
+
+	return ((arg < 0) ? (1 << 15) : 0) | ((arg >> 1) & 0x7fff);
+}
+
+static inline __uasminit u32 build_jimm(u32 arg)
+{
+	WARN(arg & ~(JIMM_MASK << 2),
+	     KERN_WARNING "Micro-assembler field overflow\n");
+
+	return (arg >> 1) & JIMM_MASK;
+}
+
+/*
+ * The order of opcode arguments is implicitly left to right,
+ * starting with RS and ending with FUNC or IMM.
+ */
+static void __uasminit build_insn(u32 **buf, enum opcode opc, ...)
+{
+	struct insn *ip = NULL;
+	unsigned int i;
+	va_list ap;
+	u32 op;
+
+	for (i = 0; insn_table_MM[i].opcode != insn_invalid; i++)
+		if (insn_table_MM[i].opcode == opc) {
+			ip = &insn_table_MM[i];
+			break;
+		}
+
+	if (!ip || (opc == insn_daddiu && r4k_daddiu_bug()))
+		panic("Unsupported Micro-assembler instruction %d", opc);
+
+	op = ip->match;
+	va_start(ap, opc);
+	if (ip->fields & RS) {
+		if (opc == insn_mfc0 || opc == insn_mtc0)
+			op |= build_rt(va_arg(ap, u32));
+		else
+			op |= build_rs(va_arg(ap, u32));
+	}
+	if (ip->fields & RT) {
+		if (opc == insn_mfc0 || opc == insn_mtc0)
+			op |= build_rs(va_arg(ap, u32));
+		else
+			op |= build_rt(va_arg(ap, u32));
+	}
+	if (ip->fields & RD)
+		op |= build_rd(va_arg(ap, u32));
+	if (ip->fields & RE)
+		op |= build_re(va_arg(ap, u32));
+	if (ip->fields & SIMM)
+		op |= build_simm(va_arg(ap, s32));
+	if (ip->fields & UIMM)
+		op |= build_uimm(va_arg(ap, u32));
+	if (ip->fields & BIMM)
+		op |= build_bimm(va_arg(ap, s32));
+	if (ip->fields & JIMM)
+		op |= build_jimm(va_arg(ap, u32));
+	if (ip->fields & FUNC)
+		op |= build_func(va_arg(ap, u32));
+	if (ip->fields & SET)
+		op |= build_set(va_arg(ap, u32));
+	if (ip->fields & SCIMM)
+		op |= build_scimm(va_arg(ap, u32));
+	va_end(ap);
+
+#ifdef CONFIG_CPU_LITTLE_ENDIAN
+	**buf = ((op & 0xffff) << 16) | (op >> 16);
+#else
+	**buf = op;
+#endif
+	(*buf)++;
+}
+
+static inline void __uasminit
+__resolve_relocs(struct uasm_reloc *rel, struct uasm_label *lab)
+{
+	long laddr = (long)lab->addr;
+	long raddr = (long)rel->addr;
+
+	switch (rel->type) {
+	case R_MIPS_PC16:
+#ifdef CONFIG_CPU_LITTLE_ENDIAN
+		*rel->addr |= (build_bimm(laddr - (raddr + 4)) << 16);
+#else
+		*rel->addr |= build_bimm(laddr - (raddr + 4));
+#endif
+		break;
+
+	default:
+		panic("Unsupported Micro-assembler relocation %d",
+		      rel->type);
+	}
+}