linux-kernel - Re: [PATCH] wifi: ath11k: fix remapped ce accessing issue on 64bit OS

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Message-ID: <22b0713e-49f2-482a-b145-e460b5632a7c@lwfinger.net>
Date: Wed, 1 May 2024 11:55:08 -0500
From: Larry Finger <Larry.Finger@...inger.net>
To: Ziyang Huang <hzyitc@...look.com>, kvalo@...nel.org
Cc: jjohnson@...nel.org, linux-wireless@...r.kernel.org,
 ath11k@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] wifi: ath11k: fix remapped ce accessing issue on 64bit OS

On 5/1/24 11:14 AM, Ziyang Huang wrote:
> On 64bit OS, when ab->mem_ce is lower than or 4G far away from ab->mem,
> u32 is not enough to store the offsets, which makes ath11k_ahb_read32()
> and ath11k_ahb_write32() access incorrect address and causes Data Abort
> Exception.
> 
> Let's use the high bits of offsets to decide where to access, which is
> similar as ath11k_pci_get_window_start() done. In the future, we can merge
> these functions for unified regs accessing.
> 
> Signed-off-by: Ziyang Huang <hzyitc@...look.com>
> ---
>   drivers/net/wireless/ath/ath11k/ahb.c | 34 ++++++++++++++++++++-------
>   drivers/net/wireless/ath/ath11k/hal.c | 17 +++++---------
>   drivers/net/wireless/ath/ath11k/hw.c  | 14 +++++------
>   drivers/net/wireless/ath/ath11k/hw.h  |  7 +++++-
>   4 files changed, 45 insertions(+), 27 deletions(-)
> 
> diff --git a/drivers/net/wireless/ath/ath11k/ahb.c b/drivers/net/wireless/ath/ath11k/ahb.c
> index 7c0a23517949..9e59b4de93a9 100644
> --- a/drivers/net/wireless/ath/ath11k/ahb.c
> +++ b/drivers/net/wireless/ath/ath11k/ahb.c
> @@ -198,12 +198,30 @@ static const struct ath11k_pci_ops ath11k_ahb_pci_ops_wcn6750 = {
>   
>   static inline u32 ath11k_ahb_read32(struct ath11k_base *ab, u32 offset)
>   {
> -	return ioread32(ab->mem + offset);
> +	switch (offset & ATH11K_REG_TYPE_MASK) {
> +	case ATH11K_REG_TYPE_NORMAL:
> +		return ioread32(ab->mem + FIELD_GET(ATH11K_REG_OFFSET_MASK, offset));
> +	case ATH11K_REG_TYPE_CE:
> +		return ioread32(ab->mem_ce + FIELD_GET(ATH11K_REG_OFFSET_MASK, offset));
> +	default:
> +		BUG();

Do you really want to crash the system here? A dev_warn() or something similar 
would log the situation. I suspect this case is never taken, but a system crash 
is not a good response if it is.

> +		return 0;
> +	}
>   }
>   
>   static inline void ath11k_ahb_write32(struct ath11k_base *ab, u32 offset, u32 value)
>   {
> -	iowrite32(value, ab->mem + offset);
> +	switch (offset & ATH11K_REG_TYPE_MASK) {
> +	case ATH11K_REG_TYPE_NORMAL:
> +		iowrite32(value, ab->mem + FIELD_GET(ATH11K_REG_OFFSET_MASK, offset));
> +		break;
> +	case ATH11K_REG_TYPE_CE:
> +		iowrite32(value, ab->mem_ce + FIELD_GET(ATH11K_REG_OFFSET_MASK, offset));
> +		break;
> +	default:
> +		BUG();

Ditto.

Larry