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SubjectRe: [PATCH] x86/calgary: fix bitcast type warnings
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On 3/30/2019 3:15 AM, Jann Horn wrote:
> On Fri, Mar 29, 2019 at 9:19 AM Mukesh Ojha <mojha@codeaurora.org> wrote:
>> On 3/29/2019 4:29 AM, Jann Horn wrote:
>>> The sparse checker attempts to ensure that all conversions between
>>> fixed-endianness numbers and numbers with native endianness are explicit.
>>> However, the calgary code reads and writes big-endian numbers from/to IO
>>> memory using {read,write}{l,q}(), which return native-endian numbers.
>>>
>>> This could be addressed by putting __force casts all over the place, but
>>> that would kind of defeat the point of the warning. Instead, create new
>>> helpers {read,write}{l,q}_be() for big-endian IO that convert from/to
>>> native endianness.
>>>
>>> Most of this patch is a straightforward conversion; the following parts
>>> aren't just mechanical replacement:
>>>
>>> - ->tar_val is now a native-endian number instead of big-endian
>>> - calioc2_handle_quirks() did `cpu_to_be32(readl(target))` when it
>>> intended to do `be32_to_cpu(readl(target))` (but that has no actual
>>> effects outside of type warnings)
>>>
>>> This gets rid of 108 lines of sparse warnings.
>>>
>>> Signed-off-by: Jann Horn <jannh@google.com>
>>> ---
>>> compile-tested only
>>>
>>> arch/x86/kernel/pci-calgary_64.c | 108 ++++++++++++++++++-------------
>>> 1 file changed, 64 insertions(+), 44 deletions(-)
>>>
>>> diff --git a/arch/x86/kernel/pci-calgary_64.c b/arch/x86/kernel/pci-calgary_64.c
>>> index c70720f61a34..36cd66d940fb 100644
>>> --- a/arch/x86/kernel/pci-calgary_64.c
>>> +++ b/arch/x86/kernel/pci-calgary_64.c
>>> @@ -534,6 +534,26 @@ static inline int is_cal_pci_dev(unsigned short device)
>>> return (is_calgary(device) || is_calioc2(device));
>>> }
>>
>> Can the existing api's not be used here like iowrite64be/ioread64be/ or
>> similar variant in "include/asm-generic/io.h"
> Given what Logan said, I think it probably makes sense to keep the patch as-is?

Sure go ahead, will have a look at this patch one more time.



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