From: Keith Busch <kbusch@kernel•org>
To: Hans Zhang <18255117159@163•com>
Cc: "Gerd Bayer" <gbayer@linux•ibm.com>,
"Manivannan Sadhasivam" <mani@kernel•org>,
"Hans Zhang" <hans.zhang@cixtech•com>,
"Arnd Bergmann" <arnd@kernel•org>,
"Bjorn Helgaas" <helgaas@kernel•org>,
bhelgaas@google•com, "Alexander Gordeev" <agordeev@linux•ibm.com>,
"Christian Borntraeger" <borntraeger@linux•ibm.com>,
"Ilpo Järvinen" <ilpo.jarvinen@linux•intel.com>,
jingoohan1@gmail•com,
"Krzysztof Wilczy´nski" <kwilczynski@kernel•org>,
linux-kernel@vger•kernel.org, linux-s390@vger•kernel.org,
linux-next <linux-next@vger•kernel.org>,
linux-pci@vger•kernel.org,
"Lorenzo Pieralisi" <lpieralisi@kernel•org>,
"Rob Herring" <robh@kernel•org>,
"Niklas Schnelle" <schnelle@linux•ibm.com>,
geert@linux-m68k•org
Subject: Re: [PATCH] PCI: Fix endianness issues in pci_bus_read_config()
Date: Fri, 1 Aug 2025 12:08:58 -0600 [thread overview]
Message-ID: <aI0CupiFvyOvgNQY@kbusch-mbp> (raw)
In-Reply-To: <659b8389-16a7-423b-a231-5489c7cc0da9@163.com>
On Sat, Aug 02, 2025 at 12:54:27AM +0800, Hans Zhang wrote:
> As I mentioned in my reply to Mani's email, the data ultimately read here is
> also a forced type conversion.
>
> #define PCI_OP_READ(size, type, len) \
> int noinline pci_bus_read_config_##size \
> (struct pci_bus *bus, unsigned int devfn, int pos, type *value) \
> { \
> unsigned long flags; \
> u32 data = 0; \
> int res; \
> \
> if (PCI_##size##_BAD) \
> return PCIBIOS_BAD_REGISTER_NUMBER; \
> \
> pci_lock_config(flags); \
> res = bus->ops->read(bus, devfn, pos, len, &data); \
> if (res) \
> PCI_SET_ERROR_RESPONSE(value); \
> else \
> *value = (type)data; \
> pci_unlock_config(flags); \
> \
> return res; \
> }
>
> And this function. Could it be that I misunderstood something?
The above macro retains the caller's type for "value". If the caller
passes a "u8 *", the value is deferenced as a u8.
The function below promotes everything to a u32 pointer and deferences
it as such regardless of what type the user passed in.
> int pci_generic_config_read(struct pci_bus *bus, unsigned int devfn,
> int where, int size, u32 *val)
> {
> void __iomem *addr;
>
> addr = bus->ops->map_bus(bus, devfn, where);
> if (!addr)
> return PCIBIOS_DEVICE_NOT_FOUND;
>
> if (size == 1)
> *val = readb(addr);
> else if (size == 2)
> *val = readw(addr);
> else
> *val = readl(addr);
>
> return PCIBIOS_SUCCESSFUL;
> }
next prev parent reply other threads:[~2025-08-01 18:09 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20250716231121.GA2564572@bhelgaas>
2025-07-31 7:32 ` [REGRESSION] next/master: suspect endianness issue in common PCI capability search macro Gerd Bayer
2025-07-31 17:38 ` [PATCH] PCI: Fix endianness issues in pci_bus_read_config() Gerd Bayer
2025-07-31 18:39 ` Bjorn Helgaas
2025-07-31 19:01 ` Arnd Bergmann
2025-08-01 8:18 ` Manivannan Sadhasivam
2025-08-01 9:25 ` Hans Zhang
2025-08-01 9:47 ` Manivannan Sadhasivam
2025-08-01 10:06 ` Hans Zhang
2025-08-01 10:54 ` Manivannan Sadhasivam
2025-08-01 11:30 ` Gerd Bayer
2025-08-01 16:54 ` Hans Zhang
2025-08-01 18:08 ` Keith Busch [this message]
2025-08-02 15:23 ` Hans Zhang
2025-08-02 15:40 ` Arnd Bergmann
2025-08-04 3:06 ` Hans Zhang
2025-08-04 8:03 ` Arnd Bergmann
2025-08-04 8:25 ` Hans Zhang
2025-08-04 10:09 ` Gerd Bayer
2025-08-12 14:44 ` Hans Zhang
2025-08-13 7:47 ` Niklas Schnelle
2025-08-13 7:50 ` Hans Zhang
2025-08-04 14:33 ` Bjorn Helgaas
2025-08-04 15:04 ` Hans Zhang
2025-08-01 16:47 ` Hans Zhang
2025-07-31 18:53 ` Lukas Wunner
2025-08-01 7:52 ` Geert Uytterhoeven
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