Hi Andrey, On Wed, Dec 2, 2020 at 8:11 AM Andrey Zhizhikin <andrey.zhizhikin@xxxxxxxxxxxxxxxxxxxx> wrote: > > ARMv7 Architecture Reference Manual [1] section A3.5.5 details Normal > memory type, together with cacheability attributes that could be applied > to memory regions defined as "Normal memory". > > Section B2.1.2 of the Architecture Reference Manual [1] also provides > details regarding the Memory attributes that could be assigned to > particular memory regions, which includes the descrption of cacheability > attributes and cache allocation hints. > > Memory type and cacheability attributes forms 2 separate definitions, > where cacheability attributes defines a mechanism of coherency control > rather than the type of memory itself. > > In other words: Normal memory type can be configured with several > combination of cacheability attributes, namely: > - Write-Through (WT) > - Write-Back (WB) followed by cache allocation hint: > - Write-Allocate > - No Write-Allocate (also known as Read-Allocate) > > Those types are mapped in the kernel to corresponding macros: > - Write-Through: L_PTE_MT_WRITETHROUGH > - Write-Back Write-Allocate: L_PTE_MT_WRITEALLOC > - Write-Back Read-Allocate: L_PTE_MT_WRITEBACK > > Current implementation of the op-tee driver takes in account only 2 last > memory region types, while performing a check if the memory block is > allocated as "Normal memory", leaving Write-Through allocations to be > not considered. > > Extend verification mechanism to include also Normal memory regios, > which are designated with Write-Through cacheability attributes. Are you trying to fix a real error with this or are you just trying to cover all cases? I suspect the latter since you'd likely have coherency problems with OP-TEE in Secure world if you used Write-Through instead. Correct me if I'm wrong, but "Write-Back Write-Allocate" and "Write-Back Read-Allocate" are both compatible with each other as the "Allocate" part is just a hint. Cheers, Jens > > Link: [1]: https://developer.arm.com/documentation/ddi0406/cd > Fixes: 853735e40424 ("optee: add writeback to valid memory type") > Cc: stable@xxxxxxxxxxxxxxx > Signed-off-by: Andrey Zhizhikin <andrey.zhizhikin@xxxxxxxxxxxxxxxxxxxx> > --- > drivers/tee/optee/call.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/tee/optee/call.c b/drivers/tee/optee/call.c > index c981757ba0d4..8da27d02a2d6 100644 > --- a/drivers/tee/optee/call.c > +++ b/drivers/tee/optee/call.c > @@ -535,7 +535,8 @@ static bool is_normal_memory(pgprot_t p) > { > #if defined(CONFIG_ARM) > return (((pgprot_val(p) & L_PTE_MT_MASK) == L_PTE_MT_WRITEALLOC) || > - ((pgprot_val(p) & L_PTE_MT_MASK) == L_PTE_MT_WRITEBACK)); > + ((pgprot_val(p) & L_PTE_MT_MASK) == L_PTE_MT_WRITEBACK) || > + ((pgprot_val(p) & L_PTE_MT_MASK) == L_PTE_MT_WRITETHROUGH)); > #elif defined(CONFIG_ARM64) > return (pgprot_val(p) & PTE_ATTRINDX_MASK) == PTE_ATTRINDX(MT_NORMAL); > #else > -- > 2.17.1 >
