From: Yann Sionneau <ysionneau@kalray.eu>
To: Ahmad Fatoum <a.fatoum@pengutronix.de>, barebox@lists.infradead.org
Subject: Re: [PATCH] mci: fix wrong sd/mmc/emmc card size computation for arch where char is signed
Date: Mon, 14 Sep 2020 18:03:15 +0200 [thread overview]
Message-ID: <2b8c02e5-6366-f9fa-780e-c726a041d95d@kalray.eu> (raw)
In-Reply-To: <4a5bc850-9785-0db5-350a-7ae6d5b22cd6@pengutronix.de>
Woops, forgot about the Signed-off-by. Sorry!
On 9/14/20 5:51 PM, Ahmad Fatoum wrote:
> Hello Yann,
>
> On 9/14/20 5:27 PM, Yann Sionneau wrote:
>> char type can be either signed or unsigned according to C standard.
>> If your arch has signed char, this kind of computation will end up wrong
>> because of sign extension:
>>
>> https://git.pengutronix.de/cgit/barebox/tree/drivers/mci/mci-core.c#n869
>>
>> mci->capacity = mci->ext_csd[EXT_CSD_SEC_COUNT] << 0 |
>> mci->ext_csd[EXT_CSD_SEC_COUNT + 1] << 8 |
>> mci->ext_csd[EXT_CSD_SEC_COUNT + 2] << 16 |
>> mci->ext_csd[EXT_CSD_SEC_COUNT + 3] << 24;
> Good catch! I wondered why this wasn't noticed before,
> so I looked at the OSELAS.Toolchain`s we have on our build
> server. Only x86 and MIPS have signed chars by default.
>
> On x86, we usually do EFI, so barebox mci-core is not involved
> and MIPS apparently doesn't have any MCI drivers yet.
>
> (Of course, you can compile do -fsigned-char or compile
> your own toolchain with a different default, but I guess
> not many do that)
>
> Thanks for fixing it.
>
>> Turning the ext_csd field into u8 * fixes the issue.
> Your Signed-off-by is required.
> Please check https://developercertificate.org/
>
>> ---
>> include/mci.h | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/include/mci.h b/include/mci.h
>> index 96547fb39..f6d845440 100644
>> --- a/include/mci.h
>> +++ b/include/mci.h
>> @@ -456,7 +456,7 @@ struct mci {
>> uint64_t capacity; /**< Card's data capacity in bytes */
>> int ready_for_use; /** true if already probed */
>> int dsr_imp; /**< DSR implementation state from CSD */
>> - char *ext_csd;
>> + u8 *ext_csd;
>> int probe;
>> struct param_d *param_boot;
>> int bootpart;
>>
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next prev parent reply other threads:[~2020-09-14 16:03 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-14 15:27 Yann Sionneau
2020-09-14 15:51 ` Ahmad Fatoum
2020-09-14 16:03 ` Yann Sionneau [this message]
2020-09-14 16:02 Yann Sionneau
2020-09-15 7:33 ` Sascha Hauer
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