xref: /qemu/bsd-user/arm/target_arch_thread.h (revision ec11dc41eec5142b4776db1296972c6323ba5847)

/*
 *  arm thread support
 *
 *  Copyright (c) 2013 Stacey D. Son
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, see <http://www.gnu.org/licenses/>.
 */

#ifndef TARGET_ARCH_THREAD_H
#define TARGET_ARCH_THREAD_H

/* Compare to arm/arm/vm_machdep.c cpu_set_upcall_kse() */
static inline void target_thread_set_upcall(CPUARMState *env, abi_ulong entry,
    abi_ulong arg, abi_ulong stack_base, abi_ulong stack_size)
{
    abi_ulong sp;

    /*
     * Make sure the stack is properly aligned.
     * arm/include/param.h (STACKLIGN() macro)
     */
    sp = (u_int)(stack_base + stack_size) & ~0x7;

    /* sp = stack base */
    env->regs[13] = sp;
    /* pc = start function entry */
    env->regs[15] = entry & 0xfffffffe;
    /* r0 = arg */
    env->regs[0] = arg;
    env->spsr = ARM_CPU_MODE_USR;
    /*
     * Thumb mode is encoded by the low bit in the entry point (since ARM can't
     * execute at odd addresses). When it's set, set the Thumb bit (T) in the
     * CPSR.
     */
    cpsr_write(env, (entry & 1) * CPSR_T, CPSR_T, CPSRWriteByInstr);
}

static inline void target_thread_init(struct target_pt_regs *regs,
        struct image_info *infop)
{
    abi_long stack = infop->start_stack;
    memset(regs, 0, sizeof(*regs));
    regs->ARM_cpsr = ARM_CPU_MODE_USR;
    /*
     * Thumb mode is encoded by the low bit in the entry point (since ARM can't
     * execute at odd addresses). When it's set, set the Thumb bit (T) in the
     * CPSR.
     */
    if (infop->entry & 1) {
        regs->ARM_cpsr |= CPSR_T;
    }
    regs->ARM_pc = infop->entry & 0xfffffffe;
    regs->ARM_sp = stack;
    regs->ARM_lr = infop->entry & 0xfffffffe;
    /*
     * FreeBSD kernel passes the ps_strings pointer in r0. This is used by some
     * programs to set status messages that we see in ps. bsd-user doesn't
     * support that functionality, so it's ignored. When set to 0, FreeBSD's csu
     * code ignores it. For the static case, r1 and r2 are effectively ignored
     * by the csu __startup() routine. For the dynamic case, rtld saves r0 but
     * generates r1 and r2 and passes them into the csu _startup.
     *
     * r0 ps_strings 0 passed since ps arg setting not supported
     * r1 obj_main   ignored by _start(), so 0 passed
     * r2 cleanup    generated by rtld or ignored by _start(), so 0 passed
     */
}

#endif /* TARGET_ARCH_THREAD_H */