Commit 5f9099d9 authored by Peter Maydell's avatar Peter Maydell Committed by Riku Voipio
Browse files

ARM: linux-user: Restore VFP state from ucontext on sigreturn 



Restore the VFP registers from the ucontext on return from a signal
handler in linux-user mode. This means that signal handlers cannot
accidentally corrupt the interrupted code's VFP state, and allows
them to deliberately modify the state via the ucontext structure.

Signed-off-by: default avatarPeter Maydell <peter.maydell@linaro.org>
Signed-off-by: default avatarRiku Voipio <riku.voipio@nokia.com>
parent 0d871bdb

linux-user/signal.c

+40 −0
Original line number Diff line number Diff line
@@ -1535,10 +1535,41 @@ badframe: 
	return 0;

}



static abi_ulong *restore_sigframe_v2_vfp(CPUState *env, abi_ulong *regspace)

{

    int i;

    abi_ulong magic, sz;

    uint32_t fpscr, fpexc;

    struct target_vfp_sigframe *vfpframe;

    vfpframe = (struct target_vfp_sigframe *)regspace;



    __get_user(magic, &vfpframe->magic);

    __get_user(sz, &vfpframe->size);

    if (magic != TARGET_VFP_MAGIC || sz != sizeof(*vfpframe)) {

        return 0;

    }

    for (i = 0; i < 32; i++) {

        __get_user(env->vfp.regs[i], &vfpframe->ufp.fpregs[i]);

    }

    __get_user(fpscr, &vfpframe->ufp.fpscr);

    vfp_set_fpscr(env, fpscr);

    __get_user(fpexc, &vfpframe->ufp_exc.fpexc);

    /* Sanitise FPEXC: ensure VFP is enabled, FPINST2 is invalid

     * and the exception flag is cleared

     */

    fpexc |= (1 << 30);

    fpexc &= ~((1 << 31) | (1 << 28));

    env->vfp.xregs[ARM_VFP_FPEXC] = fpexc;

    __get_user(env->vfp.xregs[ARM_VFP_FPINST], &vfpframe->ufp_exc.fpinst);

    __get_user(env->vfp.xregs[ARM_VFP_FPINST2], &vfpframe->ufp_exc.fpinst2);

    return (abi_ulong*)(vfpframe + 1);

}



static int do_sigframe_return_v2(CPUState *env, target_ulong frame_addr,

                                 struct target_ucontext_v2 *uc)

{

    sigset_t host_set;

    abi_ulong *regspace;



    target_to_host_sigset(&host_set, &uc->tuc_sigmask);

    sigprocmask(SIG_SETMASK, &host_set, NULL);
@@ -1546,6 +1577,15 @@ static int do_sigframe_return_v2(CPUState *env, target_ulong frame_addr, 
    if (restore_sigcontext(env, &uc->tuc_mcontext))

        return 1;



    /* Restore coprocessor signal frame */

    regspace = uc->tuc_regspace;

    if (arm_feature(env, ARM_FEATURE_VFP)) {

        regspace = restore_sigframe_v2_vfp(env, regspace);

        if (!regspace) {

            return 1;

        }

    }



    if (do_sigaltstack(frame_addr + offsetof(struct target_ucontext_v2, tuc_stack), 0, get_sp_from_cpustate(env)) == -EFAULT)

        return 1;