Re: [PATCH v2] mtd: rawnand: meson: check buffer length
From: Arseniy Krasnov
Date: Fri Jun 09 2023 - 07:00:31 EST
On 09.06.2023 10:59, Liang Yang wrote:
> Hi Miquel,
>
> On 2023/6/8 21:21, Miquel Raynal wrote:
>> [ EXTERNAL EMAIL ]
>>
>> Hi Liang,
>>
>> liang.yang@xxxxxxxxxxx wrote on Thu, 8 Jun 2023 20:37:14 +0800:
>>
>>> Hi Arseniy and Miquel,
>>>
>>> On 2023/6/8 15:12, Liang Yang wrote:
>>>> Hi Miquel,
>>>>
>>>> On 2023/6/8 14:54, Miquel Raynal wrote:
>>>>> [ EXTERNAL EMAIL ]
>>>>>
>>>>> Hi Liang,
>>>>>
>>>>> liang.yang@xxxxxxxxxxx wrote on Thu, 8 Jun 2023 14:42:53 +0800:
>>>>>
>>>>>> Hi Arseniy,
>>>>>>
>>>>>> On 2023/6/8 5:17, Arseniy Krasnov wrote:
>>>>>>> [ EXTERNAL EMAIL ]
>>>>>>>
>>>>>>> Hi again Miquel, Liang!
>>>>>>>
>>>>>>> What do You think about this patch?
>>>>>>>
>>>>>>> Thanks, Arseniy
>>>>>>>
>>>>>>> On 06.06.2023 19:29, Arseniy Krasnov wrote:
>>>>>>>> Sorry, here is changelog:
>>>>>>>> v1 -> v2:
>>>>>>>> * Move checks from 'switch/case' which executes commands in >>>>> 'meson_nfc_exec_op()' to a special
>>>>>>>> separated function 'meson_nfc_check_op()' which is called >>>>> before commands processing.
>>>>>>>>
>>>>>>>> On 06.06.2023 13:16, Arseniy Krasnov wrote:
>>>>>>>>> Meson NAND controller has limited buffer length, so check it before
>>>>>>>>> command execution to avoid length trim. Also check MTD write size on
>>>>>>>>> chip attach.
>>>>>>>>>
>>>>>>>>> Signed-off-by: Arseniy Krasnov <AVKrasnov@xxxxxxxxxxxxxx>
>>>>>>>>> ---
>>>>>>>>> drivers/mtd/nand/raw/meson_nand.c | 47 >>>>>> +++++++++++++++++++++++++++----
>>>>>>>>> 1 file changed, 42 insertions(+), 5 deletions(-)
>>>>>>>>>
>>>>>>>>> diff --git a/drivers/mtd/nand/raw/meson_nand.c >>>>>> b/drivers/mtd/nand/raw/meson_nand.c
>>>>>>>>> index 23a73268421b..db6b18753071 100644
>>>>>>>>> --- a/drivers/mtd/nand/raw/meson_nand.c
>>>>>>>>> +++ b/drivers/mtd/nand/raw/meson_nand.c
>>>>>>>>> @@ -111,6 +111,8 @@
>>>>>>>>>
>>>>>>>>> #define PER_INFO_BYTE 8
>>>>>>>>>
>>>>>>>>> +#define NFC_CMD_RAW_LEN GENMASK(13, 0)
>>>>>>>>> +
>>>>>>>>> struct meson_nfc_nand_chip {
>>>>>>>>> struct list_head node;
>>>>>>>>> struct nand_chip nand;
>>>>>>>>> @@ -284,7 +286,7 @@ static void meson_nfc_cmd_access(struct >>>>>> nand_chip *nand, int raw, bool dir,
>>>>>>>>>
>>>>>>>>> if (raw) {
>>>>>>>>> len = mtd->writesize + mtd->oobsize;
>>>>>>>>> - cmd = (len & GENMASK(13, 0)) | scrambler | DMA_DIR(dir);
>>>>>>>>> + cmd = len | scrambler | DMA_DIR(dir);
>>>>>>>>> writel(cmd, nfc->reg_base + NFC_REG_CMD);
>>>>>>
>>>>>> I think we could keep "& GENMASK(13, 0)". it is better here to >>> indicate how many bits of length in this command and don't destory >>> the command once we don't check the "len" outside of this function. >>> or the code "if (len > NFC_CMD_RAW_LEN)" is better to put inside >>> this function nearly. Thanks.
>>>>>
>>>>> It depends who calls this helper. If only used inside >> exec_op,write_page_raw() and read_page_raw() also call >> meson_nfc_cmd_access(), > but i don't find where constrain the "len".
>>>
>>> Is the helper "meson_nfc_check_op()" needed by exec_op() after the constraint in attach_chip()? the length passed in exec_op() seems smaller than "mtd->writesize + mtd->oobsize" now.
>>
>> exec_op() is primarily dedicated to performing side commands than page
>> accesses, typically the parameter page is X bytes, you might want to
>> read it 3 times, depending on the capabilities of the controller, you
>> might need to split the operation or not, so the core checks what are
>> the controller capabilities before doing the operation. So yes, the
>> check_op() thing is necessary.
>
> ok, i get it. thanks
>
> @Arseniy I have no other questions about this patch.
Got it!
Thanks, Arseniy
>>
>>>
>>> @Arseniy if it does need, I think the same constraint is needed by
>>> "meson_nfc_cmd_access()"
>>>
>>>>
>>>>> it's not useful. If used outside, then if you want to clarify
>>>>> things you may want to use:
>>>>>
>>>>> #define NFC_CMD_OP_LEN(cmd) FIELD_PREP(GENMASK(13, 0), (cmd))
>>>>>
>>>>> This is by far my favorite construction. Could apply to many other
>>>>> fields, like DMA_DIR, scrambler, etc.
>>>
>>> @Miquel, FIELD_PREP() is better, but i have no idea whether we should add FIELD_PREP() in this patch, or keep the previous code.
>>>
>>>>>
>>>>>>>>> return;
>>>>>>>>> }
>>>>>>>>> @@ -573,7 +575,7 @@ static int meson_nfc_read_buf(struct nand_chip >>>>>> *nand, u8 *buf, int len)
>>>>>>>>> if (ret)
>>>>>>>>> goto out;
>>>>>>>>>
>>>>>>>>> - cmd = NFC_CMD_N2M | (len & GENMASK(13, 0));
>>>>>>>>> + cmd = NFC_CMD_N2M | len;
>>>>>>>>> writel(cmd, nfc->reg_base + NFC_REG_CMD);
>>>>>>>>>
>>>>>>>>> meson_nfc_drain_cmd(nfc);
>>>>>>>>> @@ -597,7 +599,7 @@ static int meson_nfc_write_buf(struct >>>>>> nand_chip *nand, u8 *buf, int len)
>>>>>>>>> if (ret)
>>>>>>>>> return ret;
>>>>>>>>>
>>>>>>>>> - cmd = NFC_CMD_M2N | (len & GENMASK(13, 0));
>>>>>>>>> + cmd = NFC_CMD_M2N | len;
>>>>>>>>> writel(cmd, nfc->reg_base + NFC_REG_CMD);
>>>>>>>>>
>>>>>>>>> meson_nfc_drain_cmd(nfc);
>>>>>>>>> @@ -1007,6 +1009,31 @@ meson_nand_op_put_dma_safe_output_buf(const >>>>>> struct nand_op_instr *instr,
>>>>>>>>> kfree(buf);
>>>>>>>>> }
>>>>>>>>>
>>>>>>>>> +static int meson_nfc_check_op(struct nand_chip *chip,
>>>>>>>>> + const struct nand_operation *op)
>>>>>>>>> +{
>>>>>>>>> + int op_id;
>>>>>>>>> +
>>>>>>>>> + for (op_id = 0; op_id < op->ninstrs; op_id++) {
>>>>>>>>> + const struct nand_op_instr *instr;
>>>>>>>>> +
>>>>>>>>> + instr = &op->instrs[op_id];
>>>>>>>>> +
>>>>>>>>> + switch (instr->type) {
>>>>>>>>> + case NAND_OP_DATA_IN_INSTR:
>>>>>>>>> + case NAND_OP_DATA_OUT_INSTR:
>>>>>>>>> + if (instr->ctx.data.len > NFC_CMD_RAW_LEN)
>>>>>>>>> + return -ENOTSUPP;
>>>>>>>>> +
>>>>>>>>> + break;
>>>>>>>>> + default:
>>>>>>>>> + break;
>>>>>>>>> + }
>>>>>>>>> + }
>>>>>>>>> +
>>>>>>>>> + return 0;
>>>>>>>>> +}
>>>>>>>>> +
>>>>>>>>> static int meson_nfc_exec_op(struct nand_chip *nand,
>>>>>>>>> const struct nand_operation *op, bool >>>>>> check_only)
>>>>>>>>> {
>>>>>>>>> @@ -1015,10 +1042,12 @@ static int meson_nfc_exec_op(struct >>>>>> nand_chip *nand,
>>>>>>>>> const struct nand_op_instr *instr = NULL;
>>>>>>>>> void *buf;
>>>>>>>>> u32 op_id, delay_idle, cmd;
>>>>>>>>> + int err;
>>>>>>>>> int i;
>>>>>>>>>
>>>>>>>>> - if (check_only)
>>>>>>>>> - return 0;
>>>>>>>>> + err = meson_nfc_check_op(nand, op);
>>>>>>>>> + if (err || check_only)
>>>>>>>>> + return err;
>>>>>>>>>
>>>>>>>>> meson_nfc_select_chip(nand, op->cs);
>>>>>>>>> for (op_id = 0; op_id < op->ninstrs; op_id++) {
>>>>>>>>> @@ -1293,6 +1322,7 @@ static int meson_nand_attach_chip(struct >>>>>> nand_chip *nand)
>>>>>>>>> struct meson_nfc_nand_chip *meson_chip = to_meson_nand(nand);
>>>>>>>>> struct mtd_info *mtd = nand_to_mtd(nand);
>>>>>>>>> int nsectors = mtd->writesize / 1024;
>>>>>>>>> + int raw_writesize;
>>>>>>>>> int ret;
>>>>>>>>>
>>>>>>>>> if (!mtd->name) {
>>>>>>>>> @@ -1304,6 +1334,13 @@ static int meson_nand_attach_chip(struct >>>>>> nand_chip *nand)
>>>>>>>>> return -ENOMEM;
>>>>>>>>> }
>>>>>>>>>
>>>>>>>>> + raw_writesize = mtd->writesize + mtd->oobsize;
>>>>>>>>> + if (raw_writesize > NFC_CMD_RAW_LEN) {
>>>>>>>>> + dev_err(nfc->dev, "too big write size in raw mode: %d >>>>>> > %ld\n",
>>>>>>>>> + raw_writesize, NFC_CMD_RAW_LEN);
>>>>>>>>> + return -EINVAL;
>>>>>>>>> + }
>>>>>>>>> +
>>>>>>>>> if (nand->bbt_options & NAND_BBT_USE_FLASH)
>>>>>>>>> nand->bbt_options |= NAND_BBT_NO_OOB;
>>>>>>>>>
>>>>>
>>>>>
>>>>> Thanks,
>>>>> Miquèl
>>
>>
>> Thanks,
>> Miquèl