There are a few remaining cases where we *do* want to use `as`, because we specifically want to strip the data that does not fit into the destination type. Comment these uses to clear confusion about the intent.
Acked-by: Danilo Krummrich <[email protected]> Signed-off-by: Alexandre Courbot <[email protected]> --- drivers/gpu/nova-core/falcon.rs | 4 ++++ drivers/gpu/nova-core/fb/hal/ga100.rs | 4 ++++ drivers/gpu/nova-core/firmware/fwsec.rs | 2 ++ 3 files changed, 10 insertions(+) diff --git a/drivers/gpu/nova-core/falcon.rs b/drivers/gpu/nova-core/falcon.rs index a44df1ac8873..7f6c7091c9c3 100644 --- a/drivers/gpu/nova-core/falcon.rs +++ b/drivers/gpu/nova-core/falcon.rs @@ -479,9 +479,13 @@ fn dma_wr<F: FalconFirmware<Target = E>>( // Set up the base source DMA address. regs::NV_PFALCON_FALCON_DMATRFBASE::default() + // CAST: `as u32` is used on purpose since we do want to strip the upper bits, which + // will be written to `NV_PFALCON_FALCON_DMATRFBASE1`. .set_base((dma_start >> 8) as u32) .write(bar, &E::ID); regs::NV_PFALCON_FALCON_DMATRFBASE1::default() + // CAST: `as u16` is used on purpose since the remaining bits are guaranteed to fit + // within a `u16`. .set_base((dma_start >> 40) as u16) .write(bar, &E::ID); diff --git a/drivers/gpu/nova-core/fb/hal/ga100.rs b/drivers/gpu/nova-core/fb/hal/ga100.rs index 871c42bf033a..b9389fa382e5 100644 --- a/drivers/gpu/nova-core/fb/hal/ga100.rs +++ b/drivers/gpu/nova-core/fb/hal/ga100.rs @@ -18,9 +18,13 @@ pub(super) fn read_sysmem_flush_page_ga100(bar: &Bar0) -> u64 { pub(super) fn write_sysmem_flush_page_ga100(bar: &Bar0, addr: u64) { regs::NV_PFB_NISO_FLUSH_SYSMEM_ADDR_HI::default() + // CAST: `as u32` is used on purpose since the remaining bits are guaranteed to fit within + // a `u32`. .set_adr_63_40((addr >> FLUSH_SYSMEM_ADDR_SHIFT_HI) as u32) .write(bar); regs::NV_PFB_NISO_FLUSH_SYSMEM_ADDR::default() + // CAST: `as u32` is used on purpose since we want to strip the upper bits that have been + // written to `NV_PFB_NISO_FLUSH_SYSMEM_ADDR_HI`. .set_adr_39_08((addr >> FLUSH_SYSMEM_ADDR_SHIFT) as u32) .write(bar); } diff --git a/drivers/gpu/nova-core/firmware/fwsec.rs b/drivers/gpu/nova-core/firmware/fwsec.rs index ed82e74ccdc9..ecef4cc78942 100644 --- a/drivers/gpu/nova-core/firmware/fwsec.rs +++ b/drivers/gpu/nova-core/firmware/fwsec.rs @@ -161,6 +161,7 @@ unsafe fn transmute<'a, 'b, T: Sized + FromBytes>( if offset + size_of::<T>() > fw.size() { return Err(EINVAL); } + // CAST: `usize` has the same size as pointers. if (fw.start_ptr() as usize + offset) % align_of::<T>() != 0 { return Err(EINVAL); } @@ -184,6 +185,7 @@ unsafe fn transmute_mut<'a, 'b, T: Sized + FromBytes>( if offset + size_of::<T>() > fw.size() { return Err(EINVAL); } + // CAST: `usize` has the same size as pointers. if (fw.start_ptr_mut() as usize + offset) % align_of::<T>() != 0 { return Err(EINVAL); } -- 2.51.0
