[PATCH v3] lib: fix pointer of type 'void *' used in arithmetic

[Dong Du]

On Jan 13, 2022, at 7:05 PM, Jukka Laitinen jukka.laitinen at iki.fi wrote:

> Using "void *" in arithmetic causes errors with strict compiler settings:
> "error: pointer of type 'void *' used in arithmetic [-Werror=pointer-arith]"
> 
> Avoid these by calculating on "char *" where 1-byte data size is assumed.
> 
> Signed-off-by: Jukka Laitinen <jukkax at ssrc.tii.ae>

Hi Jukka,
   Thanks for the patch.
   It seems that there are still many pointer arithmetic cases are unhandled,
   especially for lib/utils, e.g., lib/utils/i2c/fdt_i2c_sifive.c, lib/utils/reset/fdt_reset_thead.c,
   lib/utils/serial/uart8250.c, etc.
   Any reasons for that?

   As a result, I can not successfully build with this patch when I enabled Werror=pointer-arith.
   
Regards,
Dong

> ---
> include/sbi/sbi_scratch.h       | 4 ++--
> lib/sbi/sbi_fifo.c              | 6 +++---
> lib/sbi/sbi_string.c            | 4 ++--
> lib/utils/irqchip/plic.c        | 8 ++++----
> lib/utils/timer/aclint_mtimer.c | 2 +-
> 5 files changed, 12 insertions(+), 12 deletions(-)
> 
> diff --git a/include/sbi/sbi_scratch.h b/include/sbi/sbi_scratch.h
> index 186a40c..0c27307 100644
> --- a/include/sbi/sbi_scratch.h
> +++ b/include/sbi/sbi_scratch.h
> @@ -104,11 +104,11 @@ unsigned long sbi_scratch_alloc_offset(unsigned long
> size);
> void sbi_scratch_free_offset(unsigned long offset);
> 
> /** Get pointer from offset in sbi_scratch */
> -#define sbi_scratch_offset_ptr(scratch, offset)	((void *)scratch + (offset))
> +#define sbi_scratch_offset_ptr(scratch, offset)	(void *)((char *)(scratch) +
> (offset))
> 
> /** Get pointer from offset in sbi_scratch for current HART */
> #define sbi_scratch_thishart_offset_ptr(offset)	\
> -	((void *)sbi_scratch_thishart_ptr() + (offset))
> +	(void *)((char *)sbi_scratch_thishart_ptr() + (offset))
> 
> /** HART id to scratch table */
> extern struct sbi_scratch *hartid_to_scratch_table[];
> diff --git a/lib/sbi/sbi_fifo.c b/lib/sbi/sbi_fifo.c
> index 589cc18..68d6039 100644
> --- a/lib/sbi/sbi_fifo.c
> +++ b/lib/sbi/sbi_fifo.c
> @@ -66,7 +66,7 @@ static inline void  __sbi_fifo_enqueue(struct sbi_fifo *fifo,
> void *data)
> 	if (head >= fifo->num_entries)
> 		head = head - fifo->num_entries;
> 
> -	sbi_memcpy(fifo->queue + head * fifo->entry_size, data, fifo->entry_size);
> +	sbi_memcpy((char *)fifo->queue + head * fifo->entry_size, data,
> fifo->entry_size);
> 
> 	fifo->avail++;
> }
> @@ -142,7 +142,7 @@ int sbi_fifo_inplace_update(struct sbi_fifo *fifo, void *in,
> 		index = fifo->tail + i;
> 		if (index >= fifo->num_entries)
> 			index -= fifo->num_entries;
> -		entry = (void *)fifo->queue + (u32)index * fifo->entry_size;
> +		entry = (char *)fifo->queue + (u32)index * fifo->entry_size;
> 		ret = fptr(in, entry);
> 
> 		if (ret == SBI_FIFO_SKIP || ret == SBI_FIFO_UPDATED) {
> @@ -184,7 +184,7 @@ int sbi_fifo_dequeue(struct sbi_fifo *fifo, void *data)
> 		return SBI_ENOENT;
> 	}
> 
> -	sbi_memcpy(data, fifo->queue + (u32)fifo->tail * fifo->entry_size,
> +	sbi_memcpy(data, (char *)fifo->queue + (u32)fifo->tail * fifo->entry_size,
> 	       fifo->entry_size);
> 
> 	fifo->avail--;
> diff --git a/lib/sbi/sbi_string.c b/lib/sbi/sbi_string.c
> index c87bce9..c163f31 100644
> --- a/lib/sbi/sbi_string.c
> +++ b/lib/sbi/sbi_string.c
> @@ -149,8 +149,8 @@ void *sbi_memmove(void *dest, const void *src, size_t count)
> 			count--;
> 		}
> 	} else {
> -		temp1 = dest + count - 1;
> -		temp2 = src + count - 1;
> +		temp1 = (char *)dest + count - 1;
> +		temp2 = (char *)src + count - 1;
> 
> 		while (count > 0) {
> 			*temp1-- = *temp2--;
> diff --git a/lib/utils/irqchip/plic.c b/lib/utils/irqchip/plic.c
> index 7665c62..0f58f3e 100644
> --- a/lib/utils/irqchip/plic.c
> +++ b/lib/utils/irqchip/plic.c
> @@ -23,7 +23,7 @@
> 
> static void plic_set_priority(struct plic_data *plic, u32 source, u32 val)
> {
> -	volatile void *plic_priority = (void *)plic->addr +
> +	volatile void *plic_priority = (char *)plic->addr +
> 			PLIC_PRIORITY_BASE + 4 * source;
> 	writel(val, plic_priority);
> }
> @@ -35,19 +35,19 @@ void plic_set_thresh(struct plic_data *plic, u32 cntxid, u32
> val)
> 	if (!plic)
> 		return;
> 
> -	plic_thresh = (void *)plic->addr +
> +	plic_thresh = (char *)plic->addr +
> 		      PLIC_CONTEXT_BASE + PLIC_CONTEXT_STRIDE * cntxid;
> 	writel(val, plic_thresh);
> }
> 
> void plic_set_ie(struct plic_data *plic, u32 cntxid, u32 word_index, u32 val)
> {
> -	volatile void *plic_ie;
> +	volatile char *plic_ie;
> 
> 	if (!plic)
> 		return;
> 
> -	plic_ie = (void *)plic->addr +
> +	plic_ie = (char *)plic->addr +
> 		   PLIC_ENABLE_BASE + PLIC_ENABLE_STRIDE * cntxid;
> 	writel(val, plic_ie + word_index * 4);
> }
> diff --git a/lib/utils/timer/aclint_mtimer.c b/lib/utils/timer/aclint_mtimer.c
> index 62e87f7..2532b63 100644
> --- a/lib/utils/timer/aclint_mtimer.c
> +++ b/lib/utils/timer/aclint_mtimer.c
> @@ -47,7 +47,7 @@ static u64 mtimer_time_rd32(volatile u64 *addr)
> static void mtimer_time_wr32(bool timecmp, u64 value, volatile u64 *addr)
> {
> 	writel_relaxed((timecmp) ? -1U : 0U, (void *)(addr));
> -	writel_relaxed((u32)(value >> 32), (void *)(addr) + 0x04);
> +	writel_relaxed((u32)(value >> 32), (char *)(addr) + 0x04);
> 	writel_relaxed((u32)value, (void *)(addr));
> }
> 
> --
> 2.25.1
> 
> 
> --
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