cpu/stm32/periph/usbdev: fix alignment issues #17154
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Make sure in `_usbdev_new_ep()` that `usbdev_ep_t::buf` is always aligned to 4 bytes. With this in mind, add intermediate casts to `uintptr_t` before casting `usbdev_ep_t::buf` to `uint32_t *` to silence `-Wcast-align`, as we now manually enforced correct alignment.
maribu
commented
Nov 12, 2021
| @@ -513,6 +523,7 @@ static usbdev_ep_t *_usbdev_new_ep(usbdev_t *dev, usb_ep_type_t type, | |||
| ep->dev = dev; | |||
| ep->len = buf_len; | |||
| usbdev->occupied += buf_len; | |||
| usbdev->occupied = _round_up_to_multiple_of_four(usbdev->occupied); | |||
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@bergzand an alternative here would be adding
assert((buf_len & 3) == 0);Would that make more sense?
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I'm fine with the current solution
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Contribution description
Make sure in
_usbdev_new_ep()thatusbdev_ep_t::bufis always aligned to 4 bytes. With this in mind, add intermediate casts touintptr_tbefore castingusbdev_ep_t::buftouint32_t *to silence-Wcast-align, as we now manually enforced correct alignment.Testing procedure
Everything should still work as before, but unaligned memory access should now prevented. (That is, no crash on architectures that do not support them.)
Issues/PRs references
Split out of #14955