In extioi_setirq() we try to operate on a bit array stored as an
array of uint32_t using the set_bit() and clear_bit() functions
by casting the pointer to 'unsigned long *'.
This has two problems:
 * the alignment of 'uint32_t' is less than that of 'unsigned long'
   so we pass an insufficiently aligned pointer, which is
   undefined behaviour
 * on big-endian hosts the 64-bit 'unsigned long' will have
   its two halves the wrong way around, and we will produce
   incorrect results

The undefined behaviour is shown by the clang undefined-behaviour
sanitizer when running the loongarch64-virt functional test:

/mnt/nvmedisk/linaro/qemu-from-laptop/qemu/include/qemu/bitops.h:41:5: runtime error: store to misaligned address 0x555559745d9c for type 'unsigned long', which requires 8 byte alignment
0x555559745d9c: note: pointer points here
  ff ff ff ff 00 00 00 00  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00
              ^
    #0 0x555556fb81c4 in set_bit /mnt/nvmedisk/linaro/qemu-from-laptop/qemu/include/qemu/bitops.h:41:9
    #1 0x555556fb81c4 in extioi_setirq /mnt/nvmedisk/linaro/qemu-from-laptop/qemu/build/clang/../../hw/intc/loongarch_extioi.c:65:9
    #2 0x555556fb6e90 in pch_pic_irq_handler /mnt/nvmedisk/linaro/qemu-from-laptop/qemu/build/clang/../../hw/intc/loongarch_pch_pic.c:75:5
    #3 0x555556710265 in serial_ioport_write /mnt/nvmedisk/linaro/qemu-from-laptop/qemu/build/clang/../../hw/char/serial.c

Fix these problems by using set_bit32() and clear_bit32(),
which work with bit arrays stored as an array of uint32_t.

Cc: qemu-stable@nongnu.org
Fixes: cbff2db1e92f8759 ("hw/intc: Add LoongArch extioi interrupt controller(EIOINTC)")
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
 hw/intc/loongarch_extioi.c | 11 +++--------
 1 file changed, 3 insertions(+), 8 deletions(-)

diff --git a/hw/intc/loongarch_extioi.c b/hw/intc/loongarch_extioi.c
index 02dc4e6db3b..97d1af5ccc2 100644
--- a/hw/intc/loongarch_extioi.c
+++ b/hw/intc/loongarch_extioi.c
@@ -57,14 +57,9 @@ static void extioi_setirq(void *opaque, int irq, int level)
     LoongArchExtIOI *s = LOONGARCH_EXTIOI(opaque);
     trace_loongarch_extioi_setirq(irq, level);
     if (level) {
-        /*
-         * s->isr should be used in vmstate structure,
-         * but it not support 'unsigned long',
-         * so we have to switch it.
-         */
-        set_bit(irq, (unsigned long *)s->isr);
+        set_bit32(irq, s->isr);
     } else {
-        clear_bit(irq, (unsigned long *)s->isr);
+        clear_bit32(irq, s->isr);
     }
     extioi_update_irq(s, irq, level);
 }
@@ -154,7 +149,7 @@ static inline void extioi_update_sw_coremap(LoongArchExtIOI *s, int irq,
             continue;
         }
 
-        if (notify && test_bit(irq + i, (unsigned long *)s->isr)) {
+        if (notify && test_bit32(irq + i, s->isr)) {
             /*
              * lower irq at old cpu and raise irq at new cpu
              */
-- 
2.34.1

On 2024/11/8 下午9:55, Peter Maydell wrote:
> In extioi_setirq() we try to operate on a bit array stored as an
> array of uint32_t using the set_bit() and clear_bit() functions
> by casting the pointer to 'unsigned long *'.
> This has two problems:
>   * the alignment of 'uint32_t' is less than that of 'unsigned long'
>     so we pass an insufficiently aligned pointer, which is
>     undefined behaviour
>   * on big-endian hosts the 64-bit 'unsigned long' will have
>     its two halves the wrong way around, and we will produce
>     incorrect results
> 
> The undefined behaviour is shown by the clang undefined-behaviour
> sanitizer when running the loongarch64-virt functional test:
> 
> /mnt/nvmedisk/linaro/qemu-from-laptop/qemu/include/qemu/bitops.h:41:5: runtime error: store to misaligned address 0x555559745d9c for type 'unsigned long', which requires 8 byte alignment
> 0x555559745d9c: note: pointer points here
>    ff ff ff ff 00 00 00 00  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00
>                ^
>      #0 0x555556fb81c4 in set_bit /mnt/nvmedisk/linaro/qemu-from-laptop/qemu/include/qemu/bitops.h:41:9
>      #1 0x555556fb81c4 in extioi_setirq /mnt/nvmedisk/linaro/qemu-from-laptop/qemu/build/clang/../../hw/intc/loongarch_extioi.c:65:9
>      #2 0x555556fb6e90 in pch_pic_irq_handler /mnt/nvmedisk/linaro/qemu-from-laptop/qemu/build/clang/../../hw/intc/loongarch_pch_pic.c:75:5
>      #3 0x555556710265 in serial_ioport_write /mnt/nvmedisk/linaro/qemu-from-laptop/qemu/build/clang/../../hw/char/serial.c
> 
> Fix these problems by using set_bit32() and clear_bit32(),
> which work with bit arrays stored as an array of uint32_t.
> 
> Cc: qemu-stable@nongnu.org
> Fixes: cbff2db1e92f8759 ("hw/intc: Add LoongArch extioi interrupt controller(EIOINTC)")
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
> ---
>   hw/intc/loongarch_extioi.c | 11 +++--------
>   1 file changed, 3 insertions(+), 8 deletions(-)
> 
> diff --git a/hw/intc/loongarch_extioi.c b/hw/intc/loongarch_extioi.c
> index 02dc4e6db3b..97d1af5ccc2 100644
> --- a/hw/intc/loongarch_extioi.c
> +++ b/hw/intc/loongarch_extioi.c
> @@ -57,14 +57,9 @@ static void extioi_setirq(void *opaque, int irq, int level)
>       LoongArchExtIOI *s = LOONGARCH_EXTIOI(opaque);
>       trace_loongarch_extioi_setirq(irq, level);
>       if (level) {
> -        /*
> -         * s->isr should be used in vmstate structure,
> -         * but it not support 'unsigned long',
> -         * so we have to switch it.
> -         */
> -        set_bit(irq, (unsigned long *)s->isr);
> +        set_bit32(irq, s->isr);
>       } else {
> -        clear_bit(irq, (unsigned long *)s->isr);
> +        clear_bit32(irq, s->isr);
>       }
>       extioi_update_irq(s, irq, level);
>   }
> @@ -154,7 +149,7 @@ static inline void extioi_update_sw_coremap(LoongArchExtIOI *s, int irq,
>               continue;
>           }
>   
> -        if (notify && test_bit(irq + i, (unsigned long *)s->isr)) {
> +        if (notify && test_bit32(irq + i, s->isr)) {
>               /*
>                * lower irq at old cpu and raise irq at new cpu
>                */
> 
Hi Peter,

Thanks for finding and fixing this issue, it looks good to me.

Reviewed-by: Bibo Mao <maobibo@loongson.cn>

Regards
Bibo Mao