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Date: Mon, 27 Nov 2017 16:55:05 +0000
From: Lorenzo Pieralisi <lorenzo.pieralisi@....com>
To: Niklas Cassel <niklas.cassel@...s.com>
Cc: Jingoo Han <jingoohan1@...il.com>,
Joao Pinto <Joao.Pinto@...opsys.com>,
Bjorn Helgaas <bhelgaas@...gle.com>, kishon@...com,
Niklas Cassel <niklass@...s.com>, linux-pci@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 1/3] PCI: designware-ep: Fix find_first_zero_bit()
usage
On Mon, Nov 27, 2017 at 04:49:53PM +0100, Niklas Cassel wrote:
> find_first_zero_bit()'s parameter 'size' is defined in bits,
> not in bytes.
>
> find_first_zero_bit() was called with size in bytes rather than bits,
> which thus defined a too low upper limit, causing
> dw_pcie_ep_inbound_atu() to assign iatu index #4 to both bar 4
> and bar 5, which made bar 5 overwrite the settings set by bar 4.
Same comments about past tense usage.
> Fix this by using bitmaps with a static upper limit (MAX_IATUS).
I think that given that we have the size from FW (num_ib/ob_windows),
you should allocate them dynamically (sorry for asking another respin).
> 256 was chosen since according to the databook, that is the
Nit: I think "datasheet" is more appropriate than "databook" here.
> maximum number of iATUs supported by the IP.
>
> Additionally, make sure that ep->num_ob_windows and ep->num_ib_windows,
> which are obtained from device tree, are less than the maximum number of
s/less/smaller
> iATUs (MAX_IATUS).
>
> Fixes: f8aed6ec624f ("PCI: dwc: designware: Add EP mode support")
> Signed-off-by: Niklas Cassel <niklas.cassel@...s.com>
> ---
> drivers/pci/dwc/pcie-designware-ep.c | 22 ++++++++++++++--------
> drivers/pci/dwc/pcie-designware.h | 7 +++++--
> 2 files changed, 19 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/pci/dwc/pcie-designware-ep.c b/drivers/pci/dwc/pcie-designware-ep.c
> index d53d5f168363..8b14e7db5487 100644
> --- a/drivers/pci/dwc/pcie-designware-ep.c
> +++ b/drivers/pci/dwc/pcie-designware-ep.c
> @@ -70,8 +70,7 @@ static int dw_pcie_ep_inbound_atu(struct dw_pcie_ep *ep, enum pci_barno bar,
> u32 free_win;
> struct dw_pcie *pci = to_dw_pcie_from_ep(ep);
>
> - free_win = find_first_zero_bit(&ep->ib_window_map,
> - sizeof(ep->ib_window_map));
> + free_win = find_first_zero_bit(ep->ib_window_map, ep->num_ib_windows);
> if (free_win >= ep->num_ib_windows) {
> dev_err(pci->dev, "no free inbound window\n");
> return -EINVAL;
> @@ -85,7 +84,7 @@ static int dw_pcie_ep_inbound_atu(struct dw_pcie_ep *ep, enum pci_barno bar,
> }
>
> ep->bar_to_atu[bar] = free_win;
> - set_bit(free_win, &ep->ib_window_map);
> + set_bit(free_win, ep->ib_window_map);
>
> return 0;
> }
> @@ -96,8 +95,7 @@ static int dw_pcie_ep_outbound_atu(struct dw_pcie_ep *ep, phys_addr_t phys_addr,
> u32 free_win;
> struct dw_pcie *pci = to_dw_pcie_from_ep(ep);
>
> - free_win = find_first_zero_bit(&ep->ob_window_map,
> - sizeof(ep->ob_window_map));
> + free_win = find_first_zero_bit(ep->ob_window_map, ep->num_ob_windows);
> if (free_win >= ep->num_ob_windows) {
> dev_err(pci->dev, "no free outbound window\n");
> return -EINVAL;
> @@ -106,7 +104,7 @@ static int dw_pcie_ep_outbound_atu(struct dw_pcie_ep *ep, phys_addr_t phys_addr,
> dw_pcie_prog_outbound_atu(pci, free_win, PCIE_ATU_TYPE_MEM,
> phys_addr, pci_addr, size);
>
> - set_bit(free_win, &ep->ob_window_map);
> + set_bit(free_win, ep->ob_window_map);
> ep->outbound_addr[free_win] = phys_addr;
>
> return 0;
> @@ -121,7 +119,7 @@ static void dw_pcie_ep_clear_bar(struct pci_epc *epc, enum pci_barno bar)
> dw_pcie_ep_reset_bar(pci, bar);
>
> dw_pcie_disable_atu(pci, atu_index, DW_PCIE_REGION_INBOUND);
> - clear_bit(atu_index, &ep->ib_window_map);
> + clear_bit(atu_index, ep->ib_window_map);
> }
>
> static int dw_pcie_ep_set_bar(struct pci_epc *epc, enum pci_barno bar,
> @@ -175,7 +173,7 @@ static void dw_pcie_ep_unmap_addr(struct pci_epc *epc, phys_addr_t addr)
> return;
>
> dw_pcie_disable_atu(pci, atu_index, DW_PCIE_REGION_OUTBOUND);
> - clear_bit(atu_index, &ep->ob_window_map);
> + clear_bit(atu_index, ep->ob_window_map);
> }
>
> static int dw_pcie_ep_map_addr(struct pci_epc *epc, phys_addr_t addr,
> @@ -298,12 +296,20 @@ int dw_pcie_ep_init(struct dw_pcie_ep *ep)
> dev_err(dev, "unable to read *num-ib-windows* property\n");
> return ret;
> }
> + if (ep->num_ib_windows > MAX_IATUS) {
> + dev_err(dev, "invalid *num-ib-windows*\n");
> + return -EINVAL;
> + }
>
> ret = of_property_read_u32(np, "num-ob-windows", &ep->num_ob_windows);
> if (ret < 0) {
> dev_err(dev, "unable to read *num-ob-windows* property\n");
> return ret;
> }
> + if (ep->num_ob_windows > MAX_IATUS) {
> + dev_err(dev, "invalid *num-ob-windows*\n");
> + return -EINVAL;
> + }
>
> addr = devm_kzalloc(dev, sizeof(phys_addr_t) * ep->num_ob_windows,
> GFP_KERNEL);
> diff --git a/drivers/pci/dwc/pcie-designware.h b/drivers/pci/dwc/pcie-designware.h
> index e5d9d77b778e..189f45264c2a 100644
> --- a/drivers/pci/dwc/pcie-designware.h
> +++ b/drivers/pci/dwc/pcie-designware.h
> @@ -113,6 +113,9 @@
> #define MAX_MSI_IRQS 32
> #define MAX_MSI_CTRLS (MAX_MSI_IRQS / 32)
>
> +/* Maximum number of inbound/outbound iATUs */
> +#define MAX_IATUS 256
> +
> struct pcie_port;
> struct dw_pcie;
> struct dw_pcie_ep;
> @@ -192,8 +195,8 @@ struct dw_pcie_ep {
> size_t page_size;
> u8 bar_to_atu[6];
> phys_addr_t *outbound_addr;
> - unsigned long ib_window_map;
> - unsigned long ob_window_map;
> + DECLARE_BITMAP(ib_window_map, MAX_IATUS);
> + DECLARE_BITMAP(ob_window_map, MAX_IATUS);
Only comment I have on the patch is, make the bitmap dynamic ie allocate
them using eg:
ib_window_map = kzalloc(BITS_TO_LONG(num_ib_windows) * sizeof(long),
GFP_KERNEL);
it is a common pattern in the kernel. I just do not like preallocating
static arrays if we know the real size.
It is correct to check the number of ib/ob windows parsed from DT
against MAX_IATUS, since that's a HW limitation therefore a FW (DT)
bug if they are exceeded.
find_first_zero_bit() should use num_ib/ob_windows as size parameter
(ie current patch is correct).
Thanks,
Lorenzo
> u32 num_ib_windows;
> u32 num_ob_windows;
> };
> --
> 2.14.2
>
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