From fcbb27b0ec6dcbc5a5108cb8fb19eae64593d204 Mon Sep 17 00:00:00 2001 From: Timothy Pearson Date: Wed, 23 Aug 2017 14:45:25 -0500 Subject: Initial import of modified Linux 2.6.28 tree Original upstream URL: git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git | branch linux-2.6.28.y --- arch/mips/kernel/branch.c | 221 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 221 insertions(+) create mode 100644 arch/mips/kernel/branch.c (limited to 'arch/mips/kernel/branch.c') diff --git a/arch/mips/kernel/branch.c b/arch/mips/kernel/branch.c new file mode 100644 index 0000000..6b5df8b --- /dev/null +++ b/arch/mips/kernel/branch.c @@ -0,0 +1,221 @@ +/* + * 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 +#include +#include +#include +#include +#include +#include +#include +#include +#include + +/* + * Compute the return address and do emulate branch simulation, if required. + */ +int __compute_return_epc(struct pt_regs *regs) +{ + unsigned int __user *addr; + unsigned int bit, fcr31, dspcontrol; + 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; + } + + regs->regs[0] = 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); + 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); + 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); + 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); + 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; + 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); + 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); + 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); + 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); + 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); + 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); + else + epc += 8; + regs->cp0_epc = epc; + break; + } + break; + } + + return 0; + +unaligned: + printk("%s: unaligned epc - sending SIGBUS.\n", current->comm); + force_sig(SIGBUS, current); + return -EFAULT; + +sigill: + printk("%s: DSP branch but not DSP ASE - sending SIGBUS.\n", current->comm); + force_sig(SIGBUS, current); + return -EFAULT; +} -- cgit v1.1