Re: [Qemu-arm] [PATCH 4/7] target/arm: Make v7M exception entry stack push check MPU

[Peter Maydell]

On 30 January 2018 at 15:02, Peter Maydell <address@hidden> wrote:
> -static void v7m_push(CPUARMState *env, uint32_t val)
> +static bool v7m_stack_write(ARMCPU *cpu, uint32_t addr, uint32_t value,
> +                            ARMMMUIdx mmu_idx, bool ignfault)
>  {
> -    CPUState *cs = CPU(arm_env_get_cpu(env));
> +    CPUState *cs = CPU(cpu);
> +    CPUARMState *env = &cpu->env;
> +    MemTxAttrs attrs = {};
> +    MemTxResult txres;
> +    target_ulong page_size;
> +    hwaddr physaddr;
> +    int prot;
> +    ARMMMUFaultInfo fi;
> +    bool secure = mmu_idx & ARM_MMU_IDX_M_S;
> +    int exc;
> +    bool exc_secure;
>
> -    env->regs[13] -= 4;
> -    stl_phys(cs->as, env->regs[13], val);
> +    if (get_phys_addr(env, addr, MMU_DATA_STORE, mmu_idx, &physaddr,
> +                      &attrs, &prot, &page_size, &fi, NULL)) {
> +        /* MPU/SAU lookup failed */
> +        if (fi.type == ARMFault_QEMU_SFault) {
> +            qemu_log_mask(CPU_LOG_INT,
> +                          "...SecureFault with SFSR.AUVIOL during 
> stacking\n");
> +            env->v7m.sfsr |= R_V7M_SFSR_AUVIOL_MASK | 
> R_V7M_SFSR_SFARVALID_MASK;
> +            env->v7m.sfar = addr;
> +            exc = ARMV7M_EXCP_SECURE;
> +            exc_secure = true;

I noticed on Friday that this code isn't quite right -- it should be
   exc_secure = false;

This is because SecureFault is not banked, and for non-banked exceptions
we want to always pass false to armv7m_nvic_set_pending{,_derived}().
Otherwise that function will assert().

v7m_stack_read() in a later patch has the same bug.

thanks
-- PMM