target/arm/translate-vfp.inc.c

/*
 *  ARM translation: AArch32 VFP instructions
 *
 *  Copyright (c) 2003 Fabrice Bellard
 *  Copyright (c) 2005-2007 CodeSourcery
 *  Copyright (c) 2007 OpenedHand, Ltd.
 *  Copyright (c) 2019 Linaro, Ltd.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, see <http://www.gnu.org/licenses/>.
 */

/*
 * This file is intended to be included from translate.c; it uses
 * some macros and definitions provided by that file.
 * It might be possible to convert it to a standalone .c file eventually.
 */

/* Include the generated VFP decoder */
#include "decode-vfp.inc.c"
#include "decode-vfp-uncond.inc.c"

/*
 * Check that VFP access is enabled. If it is, do the necessary
 * M-profile lazy-FP handling and then return true.
 * If not, emit code to generate an appropriate exception and
 * return false.
 * The ignore_vfp_enabled argument specifies that we should ignore
 * whether VFP is enabled via FPEXC[EN]: this should be true for FMXR/FMRX
 * accesses to FPSID, FPEXC, MVFR0, MVFR1, MVFR2, and false for all other insns.
 */
static bool full_vfp_access_check(DisasContext *s, bool ignore_vfp_enabled)
{
    if (s->fp_excp_el) {
        if (arm_dc_feature(s, ARM_FEATURE_M)) {
            gen_exception_insn(s, 4, EXCP_NOCP, syn_uncategorized(),
                               s->fp_excp_el);
        } else {
            gen_exception_insn(s, 4, EXCP_UDEF,
                               syn_fp_access_trap(1, 0xe, false),
                               s->fp_excp_el);
        }
        return false;
    }

    if (!s->vfp_enabled && !ignore_vfp_enabled) {
        assert(!arm_dc_feature(s, ARM_FEATURE_M));
        gen_exception_insn(s, 4, EXCP_UDEF, syn_uncategorized(),
                           default_exception_el(s));
        return false;
    }

    if (arm_dc_feature(s, ARM_FEATURE_M)) {
        /* Handle M-profile lazy FP state mechanics */

        /* Trigger lazy-state preservation if necessary */
        if (s->v7m_lspact) {
            /*
             * Lazy state saving affects external memory and also the NVIC,
             * so we must mark it as an IO operation for icount.
             */
            if (tb_cflags(s->base.tb) & CF_USE_ICOUNT) {
                gen_io_start();
            }
            gen_helper_v7m_preserve_fp_state(cpu_env);
            if (tb_cflags(s->base.tb) & CF_USE_ICOUNT) {
                gen_io_end();
            }
            /*
             * If the preserve_fp_state helper doesn't throw an exception
             * then it will clear LSPACT; we don't need to repeat this for
             * any further FP insns in this TB.
             */
            s->v7m_lspact = false;
        }

        /* Update ownership of FP context: set FPCCR.S to match current state */
        if (s->v8m_fpccr_s_wrong) {
            TCGv_i32 tmp;

            tmp = load_cpu_field(v7m.fpccr[M_REG_S]);
            if (s->v8m_secure) {
                tcg_gen_ori_i32(tmp, tmp, R_V7M_FPCCR_S_MASK);
            } else {
                tcg_gen_andi_i32(tmp, tmp, ~R_V7M_FPCCR_S_MASK);
            }
            store_cpu_field(tmp, v7m.fpccr[M_REG_S]);
            /* Don't need to do this for any further FP insns in this TB */
            s->v8m_fpccr_s_wrong = false;
        }

        if (s->v7m_new_fp_ctxt_needed) {
            /*
             * Create new FP context by updating CONTROL.FPCA, CONTROL.SFPA
             * and the FPSCR.
             */
            TCGv_i32 control, fpscr;
            uint32_t bits = R_V7M_CONTROL_FPCA_MASK;

            fpscr = load_cpu_field(v7m.fpdscr[s->v8m_secure]);
            gen_helper_vfp_set_fpscr(cpu_env, fpscr);
            tcg_temp_free_i32(fpscr);
            /*
             * We don't need to arrange to end the TB, because the only
             * parts of FPSCR which we cache in the TB flags are the VECLEN
             * and VECSTRIDE, and those don't exist for M-profile.
             */

            if (s->v8m_secure) {
                bits |= R_V7M_CONTROL_SFPA_MASK;
            }
            control = load_cpu_field(v7m.control[M_REG_S]);
            tcg_gen_ori_i32(control, control, bits);
            store_cpu_field(control, v7m.control[M_REG_S]);
            /* Don't need to do this for any further FP insns in this TB */
            s->v7m_new_fp_ctxt_needed = false;
        }
    }

    return true;
}

/*
 * The most usual kind of VFP access check, for everything except
 * FMXR/FMRX to the always-available special registers.
 */
static bool vfp_access_check(DisasContext *s)
{
    return full_vfp_access_check(s, false);
}