linux-kernel - Re: [PATCH v2] PCI: endpoint: Cast the page number to phys_addr

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Date:   Tue, 15 Oct 2019 15:50:58 +0100
From:   Lorenzo Pieralisi <lorenzo.pieralisi@....com>
To:     Alan Mikhak <alan.mikhak@...ive.com>
Cc:     linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org,
        kishon@...com, bhelgaas@...gle.com, palmer@...ive.com,
        paul.walmsley@...ive.com
Subject: Re: [PATCH v2] PCI: endpoint: Cast the page number to phys_addr_t

On Wed, Oct 09, 2019 at 10:06:56AM -0700, Alan Mikhak wrote:
> From: Alan Mikhak <alan.mikhak@...ive.com>
> 
> Modify pci_epc_mem_alloc_addr() to cast the variable 'pageno'
> from type 'int' to 'phys_addr_t' before shifting left. This
> cast is needed to avoid treating bit 31 of 'pageno' as the
> sign bit which would otherwise get sign-extended to produce
> a negative value. When added to the base address of PCI memory
> space, the negative value would produce an invalid physical
> address which falls before the start of the PCI memory space.
> 
> Signed-off-by: Alan Mikhak <alan.mikhak@...ive.com>
> Acked-by: Kishon Vijay Abraham I <kishon@...com>
> ---
>  drivers/pci/endpoint/pci-epc-mem.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

Applied to pci/endpoint, thanks.

Lorenzo

> diff --git a/drivers/pci/endpoint/pci-epc-mem.c b/drivers/pci/endpoint/pci-epc-mem.c
> index 2bf8bd1f0563..d2b174ce15de 100644
> --- a/drivers/pci/endpoint/pci-epc-mem.c
> +++ b/drivers/pci/endpoint/pci-epc-mem.c
> @@ -134,7 +134,7 @@ void __iomem *pci_epc_mem_alloc_addr(struct pci_epc *epc,
>  	if (pageno < 0)
>  		return NULL;
>  
> -	*phys_addr = mem->phys_base + (pageno << page_shift);
> +	*phys_addr = mem->phys_base + ((phys_addr_t)pageno << page_shift);
>  	virt_addr = ioremap(*phys_addr, size);
>  	if (!virt_addr)
>  		bitmap_release_region(mem->bitmap, pageno, order);
> -- 
> 2.7.4
>