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-rw-r--r--arch/mips/kernel/branch.c178
1 files changed, 178 insertions, 0 deletions
diff --git a/arch/mips/kernel/branch.c b/arch/mips/kernel/branch.c
index 83ffe950f710..46c2ad0703a0 100644
--- a/arch/mips/kernel/branch.c
+++ b/arch/mips/kernel/branch.c
@@ -14,10 +14,186 @@
#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.
@@ -129,6 +305,8 @@ int __compute_return_epc_for_insn(struct pt_regs *regs,
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;
/*