first commit

1 files changed, 471 insertions, 0 deletions

diff --git a/arch/mips/kernel/branch.c b/arch/mips/kernel/branch.c
new file mode 100644
index 000000000..46c2ad070
--- /dev/null
+++ b/arch/mips/kernel/branch.c
@@ -0,0 +1,471 @@
+/*
+ * 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) 1996, 97, 2000, 2001 by Ralf Baechle
+ * Copyright (C) 2001 MIPS Technologies, Inc.
+ */
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/signal.h>
+#include <linux/module.h>
+#include <asm/branch.h>
+#include <asm/cpu.h>
+#include <asm/cpu-features.h>
+#include <asm/fpu.h>
+#include <asm/fpu_emulator.h>
+#include <asm/inst.h>
+#include <asm/ptrace.h>
+#include <asm/uaccess.h>
+
+/*
+ * Calculate and return exception PC in case of branch delay slot
+ * for microMIPS and MIPS16e. It does not clear the ISA mode bit.
+ */
+int __isa_exception_epc(struct pt_regs *regs)
+{
+	unsigned short inst;
+	long epc = regs->cp0_epc;
+
+	/* Calculate exception PC in branch delay slot. */
+	if (__get_user(inst, (u16 __user *) msk_isa16_mode(epc))) {
+		/* This should never happen because delay slot was checked. */
+		force_sig(SIGSEGV, current);
+		return epc;
+	}
+	if (cpu_has_mips16) {
+		if (((union mips16e_instruction)inst).ri.opcode
+				== MIPS16e_jal_op)
+			epc += 4;
+		else
+			epc += 2;
+	} else if (mm_insn_16bit(inst))
+		epc += 2;
+	else
+		epc += 4;
+
+	return epc;
+}
+
+/*
+ * Compute return address and emulate branch in microMIPS mode after an
+ * exception only. It does not handle compact branches/jumps and cannot
+ * be used in interrupt context. (Compact branches/jumps do not cause
+ * exceptions.)
+ */
+int __microMIPS_compute_return_epc(struct pt_regs *regs)
+{
+	u16 __user *pc16;
+	u16 halfword;
+	unsigned int word;
+	unsigned long contpc;
+	struct mm_decoded_insn mminsn = { 0 };
+
+	mminsn.micro_mips_mode = 1;
+
+	/* This load never faults. */
+	pc16 = (unsigned short __user *)msk_isa16_mode(regs->cp0_epc);
+	__get_user(halfword, pc16);
+	pc16++;
+	contpc = regs->cp0_epc + 2;
+	word = ((unsigned int)halfword << 16);
+	mminsn.pc_inc = 2;
+
+	if (!mm_insn_16bit(halfword)) {
+		__get_user(halfword, pc16);
+		pc16++;
+		contpc = regs->cp0_epc + 4;
+		mminsn.pc_inc = 4;
+		word |= halfword;
+	}
+	mminsn.insn = word;
+
+	if (get_user(halfword, pc16))
+		goto sigsegv;
+	mminsn.next_pc_inc = 2;
+	word = ((unsigned int)halfword << 16);
+
+	if (!mm_insn_16bit(halfword)) {
+		pc16++;
+		if (get_user(halfword, pc16))
+			goto sigsegv;
+		mminsn.next_pc_inc = 4;
+		word |= halfword;
+	}
+	mminsn.next_insn = word;
+
+	mm_isBranchInstr(regs, mminsn, &contpc);
+
+	regs->cp0_epc = contpc;
+
+	return 0;
+
+sigsegv:
+	force_sig(SIGSEGV, current);
+	return -EFAULT;
+}
+
+/*
+ * Compute return address and emulate branch in MIPS16e mode after an
+ * exception only. It does not handle compact branches/jumps and cannot
+ * be used in interrupt context. (Compact branches/jumps do not cause
+ * exceptions.)
+ */
+int __MIPS16e_compute_return_epc(struct pt_regs *regs)
+{
+	u16 __user *addr;
+	union mips16e_instruction inst;
+	u16 inst2;
+	u32 fullinst;
+	long epc;
+
+	epc = regs->cp0_epc;
+
+	/* Read the instruction. */
+	addr = (u16 __user *)msk_isa16_mode(epc);
+	if (__get_user(inst.full, addr)) {
+		force_sig(SIGSEGV, current);
+		return -EFAULT;
+	}
+
+	switch (inst.ri.opcode) {
+	case MIPS16e_extend_op:
+		regs->cp0_epc += 4;
+		return 0;
+
+		/*
+		 *  JAL and JALX in MIPS16e mode
+		 */
+	case MIPS16e_jal_op:
+		addr += 1;
+		if (__get_user(inst2, addr)) {
+			force_sig(SIGSEGV, current);
+			return -EFAULT;
+		}
+		fullinst = ((unsigned)inst.full << 16) | inst2;
+		regs->regs[31] = epc + 6;
+		epc += 4;
+		epc >>= 28;
+		epc <<= 28;
+		/*
+		 * JAL:5 X:1 TARGET[20-16]:5 TARGET[25:21]:5 TARGET[15:0]:16
+		 *
+		 * ......TARGET[15:0].................TARGET[20:16]...........
+		 * ......TARGET[25:21]
+		 */
+		epc |=
+		    ((fullinst & 0xffff) << 2) | ((fullinst & 0x3e00000) >> 3) |
+		    ((fullinst & 0x1f0000) << 7);
+		if (!inst.jal.x)
+			set_isa16_mode(epc);	/* Set ISA mode bit. */
+		regs->cp0_epc = epc;
+		return 0;
+
+		/*
+		 *  J(AL)R(C)
+		 */
+	case MIPS16e_rr_op:
+		if (inst.rr.func == MIPS16e_jr_func) {
+
+			if (inst.rr.ra)
+				regs->cp0_epc = regs->regs[31];
+			else
+				regs->cp0_epc =
+				    regs->regs[reg16to32[inst.rr.rx]];
+
+			if (inst.rr.l) {
+				if (inst.rr.nd)
+					regs->regs[31] = epc + 2;
+				else
+					regs->regs[31] = epc + 4;
+			}
+			return 0;
+		}
+		break;
+	}
+
+	/*
+	 * All other cases have no branch delay slot and are 16-bits.
+	 * Branches do not cause an exception.
+	 */
+	regs->cp0_epc += 2;
+
+	return 0;
+}
+
+/**
+ * __compute_return_epc_for_insn - Computes the return address and do emulate
+ *				    branch simulation, if required.
+ *
+ * @regs:	Pointer to pt_regs
+ * @insn:	branch instruction to decode
+ * @returns:	-EFAULT on error and forces SIGBUS, and on success
+ *		returns 0 or BRANCH_LIKELY_TAKEN as appropriate after
+ *		evaluating the branch.
+ */
+int __compute_return_epc_for_insn(struct pt_regs *regs,
+				   union mips_instruction insn)
+{
+	unsigned int bit, fcr31, dspcontrol;
+	long epc = regs->cp0_epc;
+	int ret = 0;
+
+	switch (insn.i_format.opcode) {
+	/*
+	 * jr and jalr are in r_format format.
+	 */
+	case spec_op:
+		switch (insn.r_format.func) {
+		case jalr_op:
+			regs->regs[insn.r_format.rd] = epc + 8;
+			/* Fall through */
+		case jr_op:
+			regs->cp0_epc = regs->regs[insn.r_format.rs];
+			break;
+		}
+		break;
+
+	/*
+	 * This group contains:
+	 * bltz_op, bgez_op, bltzl_op, bgezl_op,
+	 * bltzal_op, bgezal_op, bltzall_op, bgezall_op.
+	 */
+	case bcond_op:
+		switch (insn.i_format.rt) {
+		case bltz_op:
+		case bltzl_op:
+			if ((long)regs->regs[insn.i_format.rs] < 0) {
+				epc = epc + 4 + (insn.i_format.simmediate << 2);
+				if (insn.i_format.rt == bltzl_op)
+					ret = BRANCH_LIKELY_TAKEN;
+			} else
+				epc += 8;
+			regs->cp0_epc = epc;
+			break;
+
+		case bgez_op:
+		case bgezl_op:
+			if ((long)regs->regs[insn.i_format.rs] >= 0) {
+				epc = epc + 4 + (insn.i_format.simmediate << 2);
+				if (insn.i_format.rt == bgezl_op)
+					ret = BRANCH_LIKELY_TAKEN;
+			} else
+				epc += 8;
+			regs->cp0_epc = epc;
+			break;
+
+		case bltzal_op:
+		case bltzall_op:
+			regs->regs[31] = epc + 8;
+			if ((long)regs->regs[insn.i_format.rs] < 0) {
+				epc = epc + 4 + (insn.i_format.simmediate << 2);
+				if (insn.i_format.rt == bltzall_op)
+					ret = BRANCH_LIKELY_TAKEN;
+			} else
+				epc += 8;
+			regs->cp0_epc = epc;
+			break;
+
+		case bgezal_op:
+		case bgezall_op:
+			regs->regs[31] = epc + 8;
+			if ((long)regs->regs[insn.i_format.rs] >= 0) {
+				epc = epc + 4 + (insn.i_format.simmediate << 2);
+				if (insn.i_format.rt == bgezall_op)
+					ret = BRANCH_LIKELY_TAKEN;
+			} else
+				epc += 8;
+			regs->cp0_epc = epc;
+			break;
+
+		case bposge32_op:
+			if (!cpu_has_dsp)
+				goto sigill;
+
+			dspcontrol = rddsp(0x01);
+
+			if (dspcontrol >= 32) {
+				epc = epc + 4 + (insn.i_format.simmediate << 2);
+			} else
+				epc += 8;
+			regs->cp0_epc = epc;
+			break;
+		}
+		break;
+
+	/*
+	 * These are unconditional and in j_format.
+	 */
+	case jal_op:
+		regs->regs[31] = regs->cp0_epc + 8;
+	case j_op:
+		epc += 4;
+		epc >>= 28;
+		epc <<= 28;
+		epc |= (insn.j_format.target << 2);
+		regs->cp0_epc = epc;
+		if (insn.i_format.opcode == jalx_op)
+			set_isa16_mode(regs->cp0_epc);
+		break;
+
+	/*
+	 * These are conditional and in i_format.
+	 */
+	case beq_op:
+	case beql_op:
+		if (regs->regs[insn.i_format.rs] ==
+		    regs->regs[insn.i_format.rt]) {
+			epc = epc + 4 + (insn.i_format.simmediate << 2);
+			if (insn.i_format.rt == beql_op)
+				ret = BRANCH_LIKELY_TAKEN;
+		} else
+			epc += 8;
+		regs->cp0_epc = epc;
+		break;
+
+	case bne_op:
+	case bnel_op:
+		if (regs->regs[insn.i_format.rs] !=
+		    regs->regs[insn.i_format.rt]) {
+			epc = epc + 4 + (insn.i_format.simmediate << 2);
+			if (insn.i_format.rt == bnel_op)
+				ret = BRANCH_LIKELY_TAKEN;
+		} else
+			epc += 8;
+		regs->cp0_epc = epc;
+		break;
+
+	case blez_op: /* not really i_format */
+	case blezl_op:
+		/* rt field assumed to be zero */
+		if ((long)regs->regs[insn.i_format.rs] <= 0) {
+			epc = epc + 4 + (insn.i_format.simmediate << 2);
+			if (insn.i_format.rt == bnel_op)
+				ret = BRANCH_LIKELY_TAKEN;
+		} else
+			epc += 8;
+		regs->cp0_epc = epc;
+		break;
+
+	case bgtz_op:
+	case bgtzl_op:
+		/* rt field assumed to be zero */
+		if ((long)regs->regs[insn.i_format.rs] > 0) {
+			epc = epc + 4 + (insn.i_format.simmediate << 2);
+			if (insn.i_format.rt == bnel_op)
+				ret = BRANCH_LIKELY_TAKEN;
+		} else
+			epc += 8;
+		regs->cp0_epc = epc;
+		break;
+
+	/*
+	 * And now the FPA/cp1 branch instructions.
+	 */
+	case cop1_op:
+		preempt_disable();
+		if (is_fpu_owner())
+			asm volatile("cfc1\t%0,$31" : "=r" (fcr31));
+		else
+			fcr31 = current->thread.fpu.fcr31;
+		preempt_enable();
+
+		bit = (insn.i_format.rt >> 2);
+		bit += (bit != 0);
+		bit += 23;
+		switch (insn.i_format.rt & 3) {
+		case 0: /* bc1f */
+		case 2: /* bc1fl */
+			if (~fcr31 & (1 << bit)) {
+				epc = epc + 4 + (insn.i_format.simmediate << 2);
+				if (insn.i_format.rt == 2)
+					ret = BRANCH_LIKELY_TAKEN;
+			} else
+				epc += 8;
+			regs->cp0_epc = epc;
+			break;
+
+		case 1: /* bc1t */
+		case 3: /* bc1tl */
+			if (fcr31 & (1 << bit)) {
+				epc = epc + 4 + (insn.i_format.simmediate << 2);
+				if (insn.i_format.rt == 3)
+					ret = BRANCH_LIKELY_TAKEN;
+			} else
+				epc += 8;
+			regs->cp0_epc = epc;
+			break;
+		}
+		break;
+#ifdef CONFIG_CPU_CAVIUM_OCTEON
+	case lwc2_op: /* This is bbit0 on Octeon */
+		if ((regs->regs[insn.i_format.rs] & (1ull<<insn.i_format.rt))
+		     == 0)
+			epc = epc + 4 + (insn.i_format.simmediate << 2);
+		else
+			epc += 8;
+		regs->cp0_epc = epc;
+		break;
+	case ldc2_op: /* This is bbit032 on Octeon */
+		if ((regs->regs[insn.i_format.rs] &
+		    (1ull<<(insn.i_format.rt+32))) == 0)
+			epc = epc + 4 + (insn.i_format.simmediate << 2);
+		else
+			epc += 8;
+		regs->cp0_epc = epc;
+		break;
+	case swc2_op: /* This is bbit1 on Octeon */
+		if (regs->regs[insn.i_format.rs] & (1ull<<insn.i_format.rt))
+			epc = epc + 4 + (insn.i_format.simmediate << 2);
+		else
+			epc += 8;
+		regs->cp0_epc = epc;
+		break;
+	case sdc2_op: /* This is bbit132 on Octeon */
+		if (regs->regs[insn.i_format.rs] &
+		    (1ull<<(insn.i_format.rt+32)))
+			epc = epc + 4 + (insn.i_format.simmediate << 2);
+		else
+			epc += 8;
+		regs->cp0_epc = epc;
+		break;
+#endif
+	}
+
+	return ret;
+
+sigill:
+	printk("%s: DSP branch but not DSP ASE - sending SIGBUS.\n", current->comm);
+	force_sig(SIGBUS, current);
+	return -EFAULT;
+}
+EXPORT_SYMBOL_GPL(__compute_return_epc_for_insn);
+
+int __compute_return_epc(struct pt_regs *regs)
+{
+	unsigned int __user *addr;
+	long epc;
+	union mips_instruction insn;
+
+	epc = regs->cp0_epc;
+	if (epc & 3)
+		goto unaligned;
+
+	/*
+	 * Read the instruction
+	 */
+	addr = (unsigned int __user *) epc;
+	if (__get_user(insn.word, addr)) {
+		force_sig(SIGSEGV, current);
+		return -EFAULT;
+	}
+
+	return __compute_return_epc_for_insn(regs, insn);
+
+unaligned:
+	printk("%s: unaligned epc - sending SIGBUS.\n", current->comm);
+	force_sig(SIGBUS, current);
+	return -EFAULT;
+
+}