linux-kernel - Re: [PATCH v2 03/13] mailbox: pcc: Drop unnecessary endianness conversion of pcc

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <f4142049-932e-2572-b199-6ba303b6d406@huawei.com>
Date: Tue, 11 Mar 2025 19:19:56 +0800
From: "lihuisong (C)" <lihuisong@...wei.com>
To: Sudeep Holla <sudeep.holla@....com>, <linux-acpi@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>
CC: Jassi Brar <jassisinghbrar@...il.com>, Adam Young
	<admiyo@...amperecomputing.com>, Robbie King <robbiek@...ghtlabs.com>
Subject: Re: [PATCH v2 03/13] mailbox: pcc: Drop unnecessary endianness
 conversion of pcc_hdr.flags


在 2025/3/6 0:38, Sudeep Holla 写道:
> The Sparse static checker flags a type mismatch warning related to
> endianness conversion:
>
>    |  warning: incorrect type in argument 1 (different base types)
>    |     expected restricted __le32 const [usertype] *p
>    |     got unsigned int *
>
> This is because an explicit endianness conversion (le32_to_cpu()) was
> applied unnecessarily to a pcc_hdr.flags field that is already in
> little-endian format.
>
> The PCC driver is only enabled on little-endian kernels due to its
> dependency on ACPI and EFI, making the explicit conversion unnecessary.
>
> The redundant conversion occurs in pcc_chan_check_and_ack() for the
> pcc_hdr.flags field. Drop this unnecessary endianness conversion of
> pcc_hdr.flags.
>
> Also drop the redundant PCC_ACK_FLAG_MASK definition and use the
> more appropriate and already defined PCC_CMD_COMPLETION_NOTIFY.
>
> Signed-off-by: Sudeep Holla <sudeep.holla@....com>
> ---
>   drivers/mailbox/pcc.c | 2 +-
>   include/acpi/pcc.h    | 1 -
>   2 files changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/drivers/mailbox/pcc.c b/drivers/mailbox/pcc.c
> index 4c582fa2b8bf4c9a9368dba8220f567555dba963..42dd405482e407cf90e66917a46fb8e350e0eeaf 100644
> --- a/drivers/mailbox/pcc.c
> +++ b/drivers/mailbox/pcc.c
> @@ -292,7 +292,7 @@ static void check_and_ack(struct pcc_chan_info *pchan, struct mbox_chan *chan)
>   	 *
>   	 * The PCC master subspace channel clears chan_in_use to free channel.
>   	 */
> -	if (le32_to_cpup(&pcc_hdr.flags) & PCC_ACK_FLAG_MASK)
> +	if (pcc_hdr.flags & PCC_CMD_COMPLETION_NOTIFY)
>   		pcc_send_data(chan, NULL);
>   	else
>   		pcc_chan_reg_read_modify_write(&pchan->cmd_update);
> diff --git a/include/acpi/pcc.h b/include/acpi/pcc.h
> index 699c1a37b8e7846362bae35477eb5736be15d79e..d1e506f041c5a80857d4a025fa3c1803746ba4b9 100644
> --- a/include/acpi/pcc.h
> +++ b/include/acpi/pcc.h
> @@ -32,7 +32,6 @@ struct pcc_mbox_chan {
>   #define PCC_CMD_COMPLETION_NOTIFY	BIT(0)
>   
>   #define MAX_PCC_SUBSPACES	256
> -#define PCC_ACK_FLAG_MASK	0x1
>   
>   #ifdef CONFIG_PCC
>   extern struct pcc_mbox_chan *
Acked-by: Huisong Li <lihuisong@...wei.com>
>