diff options
Diffstat (limited to 'arch/mips/kernel/branch.c')
| -rw-r--r-- | arch/mips/kernel/branch.c | 178 |
1 files changed, 178 insertions, 0 deletions
diff --git a/arch/mips/kernel/branch.c b/arch/mips/kernel/branch.c index 83ffe950f71..46c2ad0703a 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; /* |