MIPS: Loongson-3: Add some unaligned instructions emulation

1, Add unaligned gslq, gssq, gslqc1, gssqc1 emulation;
2, Add unaligned gsl{h, w, d}x, gss{h, w, d}x emulation;
3, Add unaligned gslwxc1, gsswxc1, gsldxc1, gssdxc1 emulation.

Signed-off-by: Huacai Chen <[e-mail]>
Signed-off-by: Pei Huang <[e-mail]>
Reviewed-by: Jiaxun Yang <[e-mail]>
Signed-off-by: Thomas Bogendoerfer <[e-mail]>

arch/mips/include/uapi/asm/inst.h

···
 };
 
 /*
+ * Loongson-3 overridden COP2 instruction formats (32-bit length)
+ */
+struct loongson3_lswc2_format {	/* Loongson-3 overridden lwc2/swc2 Load/Store format */
+	__BITFIELD_FIELD(unsigned int opcode : 6,
+	__BITFIELD_FIELD(unsigned int base : 5,
+	__BITFIELD_FIELD(unsigned int rt : 5,
+	__BITFIELD_FIELD(unsigned int fr : 1,
+	__BITFIELD_FIELD(unsigned int offset : 9,
+	__BITFIELD_FIELD(unsigned int ls : 1,
+	__BITFIELD_FIELD(unsigned int rq : 5,
+	;)))))))
+};
+
+struct loongson3_lsdc2_format {	/* Loongson-3 overridden ldc2/sdc2 Load/Store format */
+	__BITFIELD_FIELD(unsigned int opcode : 6,
+	__BITFIELD_FIELD(unsigned int base : 5,
+	__BITFIELD_FIELD(unsigned int rt : 5,
+	__BITFIELD_FIELD(unsigned int index : 5,
+	__BITFIELD_FIELD(unsigned int offset : 8,
+	__BITFIELD_FIELD(unsigned int opcode1 : 3,
+	;))))))
+};
+
+/*
  * MIPS16e instruction formats (16-bit length)
  */
 struct m16e_rr {
···
 	struct mm16_rb_format mm16_rb_format;
 	struct mm16_r3_format mm16_r3_format;
 	struct mm16_r5_format mm16_r5_format;
+	struct loongson3_lswc2_format loongson3_lswc2_format;
+	struct loongson3_lsdc2_format loongson3_lsdc2_format;
 };
 
 union mips16e_instruction {

arch/mips/loongson64/cop2-ex.c

···
 #include <linux/sched.h>
 #include <linux/notifier.h>
 #include <linux/ptrace.h>
+#include <linux/uaccess.h>
+#include <linux/sched/signal.h>
 
 #include <asm/fpu.h>
 #include <asm/cop2.h>
+#include <asm/inst.h>
+#include <asm/branch.h>
 #include <asm/current.h>
 #include <asm/mipsregs.h>
 
 static int loongson_cu2_call(struct notifier_block *nfb, unsigned long action,
 	void *data)
 {
-	int fpu_owned;
+	unsigned int res, fpu_owned;
+	unsigned long ra, value, value_next;
+	union mips_instruction insn;
 	int fr = !test_thread_flag(TIF_32BIT_FPREGS);
+	struct pt_regs *regs = (struct pt_regs *)data;
+	void __user *addr = (void __user *)regs->cp0_badvaddr;
+	unsigned int __user *pc = (unsigned int __user *)exception_epc(regs);
+
+	ra = regs->regs[31];
+	__get_user(insn.word, pc);
 
 	switch (action) {
 	case CU2_EXCEPTION:
···
 		preempt_enable();
 
 		return NOTIFY_STOP;	/* Don't call default notifier */
+
+	case CU2_LWC2_OP:
+		if (insn.loongson3_lswc2_format.ls == 0)
+			goto sigbus;
+
+		if (insn.loongson3_lswc2_format.fr == 0) {	/* gslq */
+			if (!access_ok(addr, 16))
+				goto sigbus;
+
+			LoadDW(addr, value, res);
+			if (res)
+				goto fault;
+
+			LoadDW(addr + 8, value_next, res);
+			if (res)
+				goto fault;
+
+			regs->regs[insn.loongson3_lswc2_format.rt] = value;
+			regs->regs[insn.loongson3_lswc2_format.rq] = value_next;
+			compute_return_epc(regs);
+		} else {					/* gslqc1 */
+			if (!access_ok(addr, 16))
+				goto sigbus;
+
+			lose_fpu(1);
+			LoadDW(addr, value, res);
+			if (res)
+				goto fault;
+
+			LoadDW(addr + 8, value_next, res);
+			if (res)
+				goto fault;
+
+			set_fpr64(current->thread.fpu.fpr,
+				insn.loongson3_lswc2_format.rt, value);
+			set_fpr64(current->thread.fpu.fpr,
+				insn.loongson3_lswc2_format.rq, value_next);
+			compute_return_epc(regs);
+			own_fpu(1);
+		}
+		return NOTIFY_STOP;	/* Don't call default notifier */
+
+	case CU2_SWC2_OP:
+		if (insn.loongson3_lswc2_format.ls == 0)
+			goto sigbus;
+
+		if (insn.loongson3_lswc2_format.fr == 0) {	/* gssq */
+			if (!access_ok(addr, 16))
+				goto sigbus;
+
+			/* write upper 8 bytes first */
+			value_next = regs->regs[insn.loongson3_lswc2_format.rq];
+
+			StoreDW(addr + 8, value_next, res);
+			if (res)
+				goto fault;
+			value = regs->regs[insn.loongson3_lswc2_format.rt];
+
+			StoreDW(addr, value, res);
+			if (res)
+				goto fault;
+
+			compute_return_epc(regs);
+		} else {					/* gssqc1 */
+			if (!access_ok(addr, 16))
+				goto sigbus;
+
+			lose_fpu(1);
+			value_next = get_fpr64(current->thread.fpu.fpr,
+					insn.loongson3_lswc2_format.rq);
+
+			StoreDW(addr + 8, value_next, res);
+			if (res)
+				goto fault;
+
+			value = get_fpr64(current->thread.fpu.fpr,
+					insn.loongson3_lswc2_format.rt);
+
+			StoreDW(addr, value, res);
+			if (res)
+				goto fault;
+
+			compute_return_epc(regs);
+			own_fpu(1);
+		}
+		return NOTIFY_STOP;	/* Don't call default notifier */
+
+	case CU2_LDC2_OP:
+		switch (insn.loongson3_lsdc2_format.opcode1) {
+		/*
+		 * Loongson-3 overridden ldc2 instructions.
+		 * opcode1              instruction
+		 *   0x1          gslhx: load 2 bytes to GPR
+		 *   0x2          gslwx: load 4 bytes to GPR
+		 *   0x3          gsldx: load 8 bytes to GPR
+		 *   0x6	  gslwxc1: load 4 bytes to FPR
+		 *   0x7	  gsldxc1: load 8 bytes to FPR
+		 */
+		case 0x1:
+			if (!access_ok(addr, 2))
+				goto sigbus;
+
+			LoadHW(addr, value, res);
+			if (res)
+				goto fault;
+
+			compute_return_epc(regs);
+			regs->regs[insn.loongson3_lsdc2_format.rt] = value;
+			break;
+		case 0x2:
+			if (!access_ok(addr, 4))
+				goto sigbus;
+
+			LoadW(addr, value, res);
+			if (res)
+				goto fault;
+
+			compute_return_epc(regs);
+			regs->regs[insn.loongson3_lsdc2_format.rt] = value;
+			break;
+		case 0x3:
+			if (!access_ok(addr, 8))
+				goto sigbus;
+
+			LoadDW(addr, value, res);
+			if (res)
+				goto fault;
+
+			compute_return_epc(regs);
+			regs->regs[insn.loongson3_lsdc2_format.rt] = value;
+			break;
+		case 0x6:
+			die_if_kernel("Unaligned FP access in kernel code", regs);
+			BUG_ON(!used_math());
+			if (!access_ok(addr, 4))
+				goto sigbus;
+
+			lose_fpu(1);
+			LoadW(addr, value, res);
+			if (res)
+				goto fault;
+
+			set_fpr64(current->thread.fpu.fpr,
+					insn.loongson3_lsdc2_format.rt, value);
+			compute_return_epc(regs);
+			own_fpu(1);
+
+			break;
+		case 0x7:
+			die_if_kernel("Unaligned FP access in kernel code", regs);
+			BUG_ON(!used_math());
+			if (!access_ok(addr, 8))
+				goto sigbus;
+
+			lose_fpu(1);
+			LoadDW(addr, value, res);
+			if (res)
+				goto fault;
+
+			set_fpr64(current->thread.fpu.fpr,
+					insn.loongson3_lsdc2_format.rt, value);
+			compute_return_epc(regs);
+			own_fpu(1);
+			break;
+
+		}
+		return NOTIFY_STOP;	/* Don't call default notifier */
+
+	case CU2_SDC2_OP:
+		switch (insn.loongson3_lsdc2_format.opcode1) {
+		/*
+		 * Loongson-3 overridden sdc2 instructions.
+		 * opcode1              instruction
+		 *   0x1          gsshx: store 2 bytes from GPR
+		 *   0x2          gsswx: store 4 bytes from GPR
+		 *   0x3          gssdx: store 8 bytes from GPR
+		 *   0x6          gsswxc1: store 4 bytes from FPR
+		 *   0x7          gssdxc1: store 8 bytes from FPR
+		 */
+		case 0x1:
+			if (!access_ok(addr, 2))
+				goto sigbus;
+
+			compute_return_epc(regs);
+			value = regs->regs[insn.loongson3_lsdc2_format.rt];
+
+			StoreHW(addr, value, res);
+			if (res)
+				goto fault;
+
+			break;
+		case 0x2:
+			if (!access_ok(addr, 4))
+				goto sigbus;
+
+			compute_return_epc(regs);
+			value = regs->regs[insn.loongson3_lsdc2_format.rt];
+
+			StoreW(addr, value, res);
+			if (res)
+				goto fault;
+
+			break;
+		case 0x3:
+			if (!access_ok(addr, 8))
+				goto sigbus;
+
+			compute_return_epc(regs);
+			value = regs->regs[insn.loongson3_lsdc2_format.rt];
+
+			StoreDW(addr, value, res);
+			if (res)
+				goto fault;
+
+			break;
+
+		case 0x6:
+			die_if_kernel("Unaligned FP access in kernel code", regs);
+			BUG_ON(!used_math());
+
+			if (!access_ok(addr, 4))
+				goto sigbus;
+
+			lose_fpu(1);
+			value = get_fpr64(current->thread.fpu.fpr,
+					insn.loongson3_lsdc2_format.rt);
+
+			StoreW(addr, value, res);
+			if (res)
+				goto fault;
+
+			compute_return_epc(regs);
+			own_fpu(1);
+
+			break;
+		case 0x7:
+			die_if_kernel("Unaligned FP access in kernel code", regs);
+			BUG_ON(!used_math());
+
+			if (!access_ok(addr, 8))
+				goto sigbus;
+
+			lose_fpu(1);
+			value = get_fpr64(current->thread.fpu.fpr,
+					insn.loongson3_lsdc2_format.rt);
+
+			StoreDW(addr, value, res);
+			if (res)
+				goto fault;
+
+			compute_return_epc(regs);
+			own_fpu(1);
+
+			break;
+		}
+		return NOTIFY_STOP;	/* Don't call default notifier */
 	}
 
 	return NOTIFY_OK;		/* Let default notifier send signals */
+
+fault:
+	/* roll back jump/branch */
+	regs->regs[31] = ra;
+	regs->cp0_epc = (unsigned long)pc;
+	/* Did we have an exception handler installed? */
+	if (fixup_exception(regs))
+		return NOTIFY_STOP;	/* Don't call default notifier */
+
+	die_if_kernel("Unhandled kernel unaligned access", regs);
+	force_sig(SIGSEGV);
+
+	return NOTIFY_STOP;	/* Don't call default notifier */
+
+sigbus:
+	die_if_kernel("Unhandled kernel unaligned access", regs);
+	force_sig(SIGBUS);
+
+	return NOTIFY_STOP;	/* Don't call default notifier */
 }
 
 static int __init loongson_cu2_setup(void)