Re: [PATCH] PCI: rcar-gen4: Fix type of type parameter in rcar_gen4_pcie_ep_raise_irq()

[Bjorn Helgaas <helgaas@kernel.org>]

On Tue, Oct 17, 2023 at 11:41:58AM -0700, Nathan Chancellor wrote:
> With clang's kernel control flow integrity (kCFI, CONFIG_CFI_CLANG),
> indirect call targets are validated against the expected function
> pointer prototype to make sure the call target is valid to help mitigate
> ROP attacks. If they are not identical, there is a failure at run time,
> which manifests as either a kernel panic or thread getting killed. A
> warning in clang aims to catch these at compile time, which reveals:
> 
>   drivers/pci/controller/dwc/pcie-rcar-gen4.c:403:15: error: incompatible function pointer types initializing 'int (*)(struct dw_pcie_ep *, u8, enum pci_epc_irq_type, u16)' (aka 'int (*)(struct dw_pcie_ep *, unsigned char, enum pci_epc_irq_type, unsigned sort)') with an expression of type 'int (struct dw_pcie_ep *, u8, unsigned int, u16)' (aka 'int (struct dw_pcie_ep *, unsigned char, unsigned int, unsigned short)') [-Werror,-Wincompatible-function-pointer-types-strict]
>     403 |         .raise_irq = rcar_gen4_pcie_ep_raise_irq,
>         |                      ^~~~~~~~~~~~~~~~~~~~~~~~~~~
>   1 error generated.
> 
> '->raise_irq()' in 'struct dw_pcie_ep_ops' expects a type parameter of
> type 'enum pci_epc_irq_type', not 'unsigned int'. Adjust the type to
> match and use the proper enum values in the switch. The underlying value
> of both the enum and the macro is the same, so there is no functional
> change while clearing up the warning and avoiding a CFI failure at run
> time.
> 
> Fixes: 32b83c68d634 ("PCI: rcar-gen4: Add endpoint mode support")
> Signed-off-by: Nathan Chancellor <nathan@kernel.org>

Thanks, Nathan.

Yoshihiro, can you fold this in on the next rev of your rcar-gen4
series?

I dropped the rcar-gen4 branch for today since it broke Marek's system
(Samsung Exynos5433-based TM2e board), so when we fix that we should
be able to fold in this fix at the same time.

> ---
>  drivers/pci/controller/dwc/pcie-rcar-gen4.c | 7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/pci/controller/dwc/pcie-rcar-gen4.c b/drivers/pci/controller/dwc/pcie-rcar-gen4.c
> index 619262d32f4e..0c0f5c257b14 100644
> --- a/drivers/pci/controller/dwc/pcie-rcar-gen4.c
> +++ b/drivers/pci/controller/dwc/pcie-rcar-gen4.c
> @@ -353,14 +353,15 @@ static void rcar_gen4_pcie_ep_deinit(struct dw_pcie_ep *ep)
>  }
>  
>  static int rcar_gen4_pcie_ep_raise_irq(struct dw_pcie_ep *ep, u8 func_no,
> -				       unsigned int type, u16 interrupt_num)
> +				       enum pci_epc_irq_type type,
> +				       u16 interrupt_num)
>  {
>  	struct dw_pcie *dw = to_dw_pcie_from_ep(ep);
>  
>  	switch (type) {
> -	case PCI_IRQ_LEGACY:
> +	case PCI_EPC_IRQ_LEGACY:
>  		return dw_pcie_ep_raise_legacy_irq(ep, func_no);
> -	case PCI_IRQ_MSI:
> +	case PCI_EPC_IRQ_MSI:
>  		return dw_pcie_ep_raise_msi_irq(ep, func_no, interrupt_num);
>  	default:
>  		dev_err(dw->dev, "Unknown IRQ type\n");
> 
> ---
> base-commit: de45624e69e14ccd6b4b2886155578bb218925de
> change-id: 20231017-pcie-rcar-wifpts-6c65df6f8c8b
> 
> Best regards,
> -- 
> Nathan Chancellor <nathan@kernel.org>
>