diff options
Diffstat (limited to 'arch/mips/kernel/branch.c')
| -rw-r--r-- | arch/mips/kernel/branch.c | 908 |
1 files changed, 908 insertions, 0 deletions
diff --git a/arch/mips/kernel/branch.c b/arch/mips/kernel/branch.c new file mode 100644 index 000000000..0216ff24c --- /dev/null +++ b/arch/mips/kernel/branch.c @@ -0,0 +1,908 @@ +/* + * 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/signal.h> +#include <linux/signal.h> +#include <linux/export.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/mips-r2-to-r6-emul.h> +#include <asm/ptrace.h> +#include <linux/uaccess.h> + +#include "probes-common.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); + return epc; + } + if (cpu_has_mips16) { + union mips16e_instruction inst_mips16e; + + inst_mips16e.full = inst; + if (inst_mips16e.ri.opcode == MIPS16e_jal_op) + epc += 4; + else + epc += 2; + } else if (mm_insn_16bit(inst)) + epc += 2; + else + epc += 4; + + return epc; +} + +/* (microMIPS) Convert 16-bit register encoding to 32-bit register encoding. */ +static const unsigned int reg16to32map[8] = {16, 17, 2, 3, 4, 5, 6, 7}; + +int __mm_isBranchInstr(struct pt_regs *regs, struct mm_decoded_insn dec_insn, + unsigned long *contpc) +{ + union mips_instruction insn = (union mips_instruction)dec_insn.insn; + int __maybe_unused bc_false = 0; + + if (!cpu_has_mmips) + return 0; + + switch (insn.mm_i_format.opcode) { + case mm_pool32a_op: + if ((insn.mm_i_format.simmediate & MM_POOL32A_MINOR_MASK) == + mm_pool32axf_op) { + switch (insn.mm_i_format.simmediate >> + MM_POOL32A_MINOR_SHIFT) { + case mm_jalr_op: + case mm_jalrhb_op: + case mm_jalrs_op: + case mm_jalrshb_op: + if (insn.mm_i_format.rt != 0) /* Not mm_jr */ + regs->regs[insn.mm_i_format.rt] = + regs->cp0_epc + + dec_insn.pc_inc + + dec_insn.next_pc_inc; + *contpc = regs->regs[insn.mm_i_format.rs]; + return 1; + } + } + break; + case mm_pool32i_op: + switch (insn.mm_i_format.rt) { + case mm_bltzals_op: + case mm_bltzal_op: + regs->regs[31] = regs->cp0_epc + + dec_insn.pc_inc + + dec_insn.next_pc_inc; + fallthrough; + case mm_bltz_op: + if ((long)regs->regs[insn.mm_i_format.rs] < 0) + *contpc = regs->cp0_epc + + dec_insn.pc_inc + + (insn.mm_i_format.simmediate << 1); + else + *contpc = regs->cp0_epc + + dec_insn.pc_inc + + dec_insn.next_pc_inc; + return 1; + case mm_bgezals_op: + case mm_bgezal_op: + regs->regs[31] = regs->cp0_epc + + dec_insn.pc_inc + + dec_insn.next_pc_inc; + fallthrough; + case mm_bgez_op: + if ((long)regs->regs[insn.mm_i_format.rs] >= 0) + *contpc = regs->cp0_epc + + dec_insn.pc_inc + + (insn.mm_i_format.simmediate << 1); + else + *contpc = regs->cp0_epc + + dec_insn.pc_inc + + dec_insn.next_pc_inc; + return 1; + case mm_blez_op: + if ((long)regs->regs[insn.mm_i_format.rs] <= 0) + *contpc = regs->cp0_epc + + dec_insn.pc_inc + + (insn.mm_i_format.simmediate << 1); + else + *contpc = regs->cp0_epc + + dec_insn.pc_inc + + dec_insn.next_pc_inc; + return 1; + case mm_bgtz_op: + if ((long)regs->regs[insn.mm_i_format.rs] <= 0) + *contpc = regs->cp0_epc + + dec_insn.pc_inc + + (insn.mm_i_format.simmediate << 1); + else + *contpc = regs->cp0_epc + + dec_insn.pc_inc + + dec_insn.next_pc_inc; + return 1; +#ifdef CONFIG_MIPS_FP_SUPPORT + case mm_bc2f_op: + case mm_bc1f_op: { + unsigned int fcr31; + unsigned int bit; + + bc_false = 1; + fallthrough; + case mm_bc2t_op: + case mm_bc1t_op: + preempt_disable(); + if (is_fpu_owner()) + fcr31 = read_32bit_cp1_register(CP1_STATUS); + else + fcr31 = current->thread.fpu.fcr31; + preempt_enable(); + + if (bc_false) + fcr31 = ~fcr31; + + bit = (insn.mm_i_format.rs >> 2); + bit += (bit != 0); + bit += 23; + if (fcr31 & (1 << bit)) + *contpc = regs->cp0_epc + + dec_insn.pc_inc + + (insn.mm_i_format.simmediate << 1); + else + *contpc = regs->cp0_epc + + dec_insn.pc_inc + dec_insn.next_pc_inc; + return 1; + } +#endif /* CONFIG_MIPS_FP_SUPPORT */ + } + break; + case mm_pool16c_op: + switch (insn.mm_i_format.rt) { + case mm_jalr16_op: + case mm_jalrs16_op: + regs->regs[31] = regs->cp0_epc + + dec_insn.pc_inc + dec_insn.next_pc_inc; + fallthrough; + case mm_jr16_op: + *contpc = regs->regs[insn.mm_i_format.rs]; + return 1; + } + break; + case mm_beqz16_op: + if ((long)regs->regs[reg16to32map[insn.mm_b1_format.rs]] == 0) + *contpc = regs->cp0_epc + + dec_insn.pc_inc + + (insn.mm_b1_format.simmediate << 1); + else + *contpc = regs->cp0_epc + + dec_insn.pc_inc + dec_insn.next_pc_inc; + return 1; + case mm_bnez16_op: + if ((long)regs->regs[reg16to32map[insn.mm_b1_format.rs]] != 0) + *contpc = regs->cp0_epc + + dec_insn.pc_inc + + (insn.mm_b1_format.simmediate << 1); + else + *contpc = regs->cp0_epc + + dec_insn.pc_inc + dec_insn.next_pc_inc; + return 1; + case mm_b16_op: + *contpc = regs->cp0_epc + dec_insn.pc_inc + + (insn.mm_b0_format.simmediate << 1); + return 1; + case mm_beq32_op: + if (regs->regs[insn.mm_i_format.rs] == + regs->regs[insn.mm_i_format.rt]) + *contpc = regs->cp0_epc + + dec_insn.pc_inc + + (insn.mm_i_format.simmediate << 1); + else + *contpc = regs->cp0_epc + + dec_insn.pc_inc + + dec_insn.next_pc_inc; + return 1; + case mm_bne32_op: + if (regs->regs[insn.mm_i_format.rs] != + regs->regs[insn.mm_i_format.rt]) + *contpc = regs->cp0_epc + + dec_insn.pc_inc + + (insn.mm_i_format.simmediate << 1); + else + *contpc = regs->cp0_epc + + dec_insn.pc_inc + dec_insn.next_pc_inc; + return 1; + case mm_jalx32_op: + regs->regs[31] = regs->cp0_epc + + dec_insn.pc_inc + dec_insn.next_pc_inc; + *contpc = regs->cp0_epc + dec_insn.pc_inc; + *contpc >>= 28; + *contpc <<= 28; + *contpc |= (insn.j_format.target << 2); + return 1; + case mm_jals32_op: + case mm_jal32_op: + regs->regs[31] = regs->cp0_epc + + dec_insn.pc_inc + dec_insn.next_pc_inc; + fallthrough; + case mm_j32_op: + *contpc = regs->cp0_epc + dec_insn.pc_inc; + *contpc >>= 27; + *contpc <<= 27; + *contpc |= (insn.j_format.target << 1); + set_isa16_mode(*contpc); + return 1; + } + return 0; +} + +/* + * 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); + 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); + 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); + 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 + * Return: -EFAULT on error and forces SIGILL, and on success + * returns 0 or BRANCH_LIKELY_TAKEN as appropriate after + * evaluating the branch. + * + * MIPS R6 Compact branches and forbidden slots: + * Compact branches do not throw exceptions because they do + * not have delay slots. The forbidden slot instruction ($PC+4) + * is only executed if the branch was not taken. Otherwise the + * forbidden slot is skipped entirely. This means that the + * only possible reason to be here because of a MIPS R6 compact + * branch instruction is that the forbidden slot has thrown one. + * In that case the branch was not taken, so the EPC can be safely + * set to EPC + 8. + */ +int __compute_return_epc_for_insn(struct pt_regs *regs, + union mips_instruction insn) +{ + long epc = regs->cp0_epc; + unsigned int dspcontrol; + 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; + fallthrough; + case jr_op: + if (NO_R6EMU && insn.r_format.func == jr_op) + goto sigill_r2r6; + 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 bltzl_op: + if (NO_R6EMU) + goto sigill_r2r6; + fallthrough; + case bltz_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 bgezl_op: + if (NO_R6EMU) + goto sigill_r2r6; + fallthrough; + case bgez_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: + if (NO_R6EMU && (insn.i_format.rs || + insn.i_format.rt == bltzall_op)) + goto sigill_r2r6; + regs->regs[31] = epc + 8; + /* + * OK we are here either because we hit a NAL + * instruction or because we are emulating an + * old bltzal{,l} one. Let's figure out what the + * case really is. + */ + if (!insn.i_format.rs) { + /* + * NAL or BLTZAL with rs == 0 + * Doesn't matter if we are R6 or not. The + * result is the same + */ + regs->cp0_epc += 4 + + (insn.i_format.simmediate << 2); + break; + } + /* Now do the real thing for non-R6 BLTZAL{,L} */ + 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: + if (NO_R6EMU && (insn.i_format.rs || + insn.i_format.rt == bgezall_op)) + goto sigill_r2r6; + regs->regs[31] = epc + 8; + /* + * OK we are here either because we hit a BAL + * instruction or because we are emulating an + * old bgezal{,l} one. Let's figure out what the + * case really is. + */ + if (!insn.i_format.rs) { + /* + * BAL or BGEZAL with rs == 0 + * Doesn't matter if we are R6 or not. The + * result is the same + */ + regs->cp0_epc += 4 + + (insn.i_format.simmediate << 2); + break; + } + /* Now do the real thing for non-R6 BGEZAL{,L} */ + 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_dsp; + + 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 jalx_op: + case jal_op: + regs->regs[31] = regs->cp0_epc + 8; + fallthrough; + 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 beql_op: + if (NO_R6EMU) + goto sigill_r2r6; + fallthrough; + case beq_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.opcode == beql_op) + ret = BRANCH_LIKELY_TAKEN; + } else + epc += 8; + regs->cp0_epc = epc; + break; + + case bnel_op: + if (NO_R6EMU) + goto sigill_r2r6; + fallthrough; + case bne_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.opcode == bnel_op) + ret = BRANCH_LIKELY_TAKEN; + } else + epc += 8; + regs->cp0_epc = epc; + break; + + case blezl_op: /* not really i_format */ + if (!insn.i_format.rt && NO_R6EMU) + goto sigill_r2r6; + fallthrough; + case blez_op: + /* + * Compact branches for R6 for the + * blez and blezl opcodes. + * BLEZ | rs = 0 | rt != 0 == BLEZALC + * BLEZ | rs = rt != 0 == BGEZALC + * BLEZ | rs != 0 | rt != 0 == BGEUC + * BLEZL | rs = 0 | rt != 0 == BLEZC + * BLEZL | rs = rt != 0 == BGEZC + * BLEZL | rs != 0 | rt != 0 == BGEC + * + * For real BLEZ{,L}, rt is always 0. + */ + + if (cpu_has_mips_r6 && insn.i_format.rt) { + if ((insn.i_format.opcode == blez_op) && + ((!insn.i_format.rs && insn.i_format.rt) || + (insn.i_format.rs == insn.i_format.rt))) + regs->regs[31] = epc + 4; + regs->cp0_epc += 8; + break; + } + /* 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.opcode == blezl_op) + ret = BRANCH_LIKELY_TAKEN; + } else + epc += 8; + regs->cp0_epc = epc; + break; + + case bgtzl_op: + if (!insn.i_format.rt && NO_R6EMU) + goto sigill_r2r6; + fallthrough; + case bgtz_op: + /* + * Compact branches for R6 for the + * bgtz and bgtzl opcodes. + * BGTZ | rs = 0 | rt != 0 == BGTZALC + * BGTZ | rs = rt != 0 == BLTZALC + * BGTZ | rs != 0 | rt != 0 == BLTUC + * BGTZL | rs = 0 | rt != 0 == BGTZC + * BGTZL | rs = rt != 0 == BLTZC + * BGTZL | rs != 0 | rt != 0 == BLTC + * + * *ZALC varint for BGTZ &&& rt != 0 + * For real GTZ{,L}, rt is always 0. + */ + if (cpu_has_mips_r6 && insn.i_format.rt) { + if ((insn.i_format.opcode == blez_op) && + ((!insn.i_format.rs && insn.i_format.rt) || + (insn.i_format.rs == insn.i_format.rt))) + regs->regs[31] = epc + 4; + regs->cp0_epc += 8; + break; + } + + /* 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.opcode == bgtzl_op) + ret = BRANCH_LIKELY_TAKEN; + } else + epc += 8; + regs->cp0_epc = epc; + break; + +#ifdef CONFIG_MIPS_FP_SUPPORT + /* + * And now the FPA/cp1 branch instructions. + */ + case cop1_op: { + unsigned int bit, fcr31, reg; + + if (cpu_has_mips_r6 && + ((insn.i_format.rs == bc1eqz_op) || + (insn.i_format.rs == bc1nez_op))) { + if (!init_fp_ctx(current)) + lose_fpu(1); + reg = insn.i_format.rt; + bit = get_fpr32(¤t->thread.fpu.fpr[reg], 0) & 0x1; + if (insn.i_format.rs == bc1eqz_op) + bit = !bit; + own_fpu(1); + if (bit) + epc = epc + 4 + + (insn.i_format.simmediate << 2); + else + epc += 8; + regs->cp0_epc = epc; + + break; + } else { + + preempt_disable(); + if (is_fpu_owner()) + fcr31 = read_32bit_cp1_register(CP1_STATUS); + 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; + } + } +#endif /* CONFIG_MIPS_FP_SUPPORT */ + +#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; +#else + case bc6_op: + /* Only valid for MIPS R6 */ + if (!cpu_has_mips_r6) + goto sigill_r6; + regs->cp0_epc += 8; + break; + case balc6_op: + if (!cpu_has_mips_r6) + goto sigill_r6; + /* Compact branch: BALC */ + regs->regs[31] = epc + 4; + epc += 4 + (insn.i_format.simmediate << 2); + regs->cp0_epc = epc; + break; + case pop66_op: + if (!cpu_has_mips_r6) + goto sigill_r6; + /* Compact branch: BEQZC || JIC */ + regs->cp0_epc += 8; + break; + case pop76_op: + if (!cpu_has_mips_r6) + goto sigill_r6; + /* Compact branch: BNEZC || JIALC */ + if (!insn.i_format.rs) { + /* JIALC: set $31/ra */ + regs->regs[31] = epc + 4; + } + regs->cp0_epc += 8; + break; +#endif + case pop10_op: + case pop30_op: + /* Only valid for MIPS R6 */ + if (!cpu_has_mips_r6) + goto sigill_r6; + /* + * Compact branches: + * bovc, beqc, beqzalc, bnvc, bnec, bnezlac + */ + if (insn.i_format.rt && !insn.i_format.rs) + regs->regs[31] = epc + 4; + regs->cp0_epc += 8; + break; + } + + return ret; + +sigill_dsp: + pr_debug("%s: DSP branch but not DSP ASE - sending SIGILL.\n", + current->comm); + force_sig(SIGILL); + return -EFAULT; +sigill_r2r6: + pr_debug("%s: R2 branch but r2-to-r6 emulator is not present - sending SIGILL.\n", + current->comm); + force_sig(SIGILL); + return -EFAULT; +sigill_r6: + pr_debug("%s: R6 branch but no MIPSr6 ISA support - sending SIGILL.\n", + current->comm); + force_sig(SIGILL); + 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); + return -EFAULT; + } + + return __compute_return_epc_for_insn(regs, insn); + +unaligned: + printk("%s: unaligned epc - sending SIGBUS.\n", current->comm); + force_sig(SIGBUS); + return -EFAULT; +} + +#if (defined CONFIG_KPROBES) || (defined CONFIG_UPROBES) + +int __insn_is_compact_branch(union mips_instruction insn) +{ + if (!cpu_has_mips_r6) + return 0; + + switch (insn.i_format.opcode) { + case blezl_op: + case bgtzl_op: + case blez_op: + case bgtz_op: + /* + * blez[l] and bgtz[l] opcodes with non-zero rt + * are MIPS R6 compact branches + */ + if (insn.i_format.rt) + return 1; + break; + case bc6_op: + case balc6_op: + case pop10_op: + case pop30_op: + case pop66_op: + case pop76_op: + return 1; + } + + return 0; +} +EXPORT_SYMBOL_GPL(__insn_is_compact_branch); + +#endif /* CONFIG_KPROBES || CONFIG_UPROBES */ |