Re: [PATCH] EDAC/altera: Silence an endian warning

[Thor Thayer <thor.thayer@linux.intel.com>]

Hi Dan,

On 6/24/19 8:47 AM, Dan Carpenter wrote:
> Smatch complains that we're casting a u32 pointer to unsigned long.
> 
>      drivers/edac/altera_edac.c:1878 altr_edac_a10_irq_handler()
>      warn: passing casted pointer '&irq_status' to 'find_first_bit()'
> 
> This code wouldn't work on a 64 bit big endian system because we would
> read past the end of &irq_status.
> 
> Fixes: 13ab8448d2c9 ("EDAC, altera: Add ECC Manager IRQ controller support")
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> ---
> Static analysis obviously and I don't know this subsystem at all.
> Probably we're never going to run this on a 64 bit big endian system...
> Feel free to ignore this if you want.
> 
>   drivers/edac/altera_edac.c | 4 +++-
>   1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/edac/altera_edac.c b/drivers/edac/altera_edac.c
> index c2e693e34d43..bf024ec0116c 100644
> --- a/drivers/edac/altera_edac.c
> +++ b/drivers/edac/altera_edac.c
> @@ -1866,6 +1866,7 @@ static void altr_edac_a10_irq_handler(struct irq_desc *desc)
>   	struct altr_arria10_edac *edac = irq_desc_get_handler_data(desc);
>   	struct irq_chip *chip = irq_desc_get_chip(desc);
>   	int irq = irq_desc_get_irq(desc);
> +	unsigned long bits;
>   
>   	dberr = (irq == edac->db_irq) ? 1 : 0;
>   	sm_offset = dberr ? A10_SYSMGR_ECC_INTSTAT_DERR_OFST :
> @@ -1875,7 +1876,8 @@ static void altr_edac_a10_irq_handler(struct irq_desc *desc)
>   
>   	regmap_read(edac->ecc_mgr_map, sm_offset, &irq_status);
>   
> -	for_each_set_bit(bit, (unsigned long *)&irq_status, 32) {
> +	bits = irq_status;
> +	for_each_set_bit(bit, &bits, 32) {
>   		irq = irq_linear_revmap(edac->domain, dberr * 32 + bit);
>   		if (irq)
>   			generic_handle_irq(irq);
> 
You are correct that we shouldn't use this on a 64 bit machine but this 
is a good fix. Thank you!

Reviewed-by: Thor Thayer <thor.thayer@linux.intel.com>