linux-kernel - Re: [PATCH v2 2/2] soc: mediatek: devapc: add devapc-mt6873 driver

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Date:   Thu, 25 Jun 2020 14:19:02 +0800
From:   Chun-Kuang Hu <chunkuang.hu@...nel.org>
To:     Neal Liu <neal.liu@...iatek.com>
Cc:     Rob Herring <robh+dt@...nel.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        devicetree@...r.kernel.org,
        wsd_upstream <wsd_upstream@...iatek.com>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        "moderated list:ARM/Mediatek SoC support" 
        <linux-mediatek@...ts.infradead.org>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v2 2/2] soc: mediatek: devapc: add devapc-mt6873 driver

Hi, Neal:

Neal Liu <neal.liu@...iatek.com> 於 2020年6月19日 週五 下午6:01寫道：
>
> MT6873 bus frabric provides TrustZone security support and data
> protection to prevent slaves from being accessed by unexpected
> masters.
> The security violations are logged and sent to the processor for
> further analysis or countermeasures.
>
> Any occurrence of security violation would raise an interrupt, and
> it will be handled by devapc-mt6873 driver. The violation
> information is printed in order to find the murderer.
>
> Signed-off-by: Neal Liu <neal.liu@...iatek.com>
> ---

[snip]

> +
> +/*
> + * sramrom_vio_handler - clean sramrom violation & print violation information
> + *                      for debugging.
> + */
> +static void sramrom_vio_handler(struct mtk_devapc_context *devapc_ctx)
> +{
> +       const struct mtk_sramrom_sec_vio_desc *sramrom_vios;
> +       struct mtk_devapc_vio_info *vio_info;
> +       struct arm_smccc_res res;
> +       size_t sramrom_vio_sta;
> +       int sramrom_vio;
> +       u32 rw;
> +
> +       sramrom_vios = devapc_ctx->soc->sramrom_sec_vios;
> +       vio_info = devapc_ctx->soc->vio_info;
> +
> +       arm_smccc_smc(MTK_SIP_KERNEL_CLR_SRAMROM_VIO,
> +                     0, 0, 0, 0, 0, 0, 0, &res);
> +

This irq handler call arm_smccc_smc() to get into TrustZone, why not
let the whole irq handler in TrustZone?

Regards,
Chun-Kuang.

> +       sramrom_vio = res.a0;
> +       sramrom_vio_sta = res.a1;
> +       vio_info->vio_addr = res.a2;
> +
> +       if (sramrom_vio == SRAM_VIOLATION)
> +               pr_info(PFX "SRAM violation is triggered\n");
> +       else if (sramrom_vio == ROM_VIOLATION)
> +               pr_info(PFX "ROM violation is triggered\n");
> +       else
> +               return;
> +
> +       vio_info->master_id = (sramrom_vio_sta & sramrom_vios->vio_id_mask)
> +                       >> sramrom_vios->vio_id_shift;
> +       vio_info->domain_id = (sramrom_vio_sta & sramrom_vios->vio_domain_mask)
> +                       >> sramrom_vios->vio_domain_shift;
> +       rw = (sramrom_vio_sta & sramrom_vios->vio_rw_mask) >>
> +                       sramrom_vios->vio_rw_shift;
> +
> +       if (rw)
> +               vio_info->write = 1;
> +       else
> +               vio_info->read = 1;
> +
> +       pr_info(PFX "%s: master_id:0x%x, domain_id:0x%x, rw:%s, vio_addr:0x%x\n",
> +               __func__, vio_info->master_id, vio_info->domain_id,
> +               rw ? "Write" : "Read", vio_info->vio_addr);
> +}
> +