No it doesn't mean that.
But the following code will make the size TARGET_PAGE_SIZE - (page offset)
if the address is not aligned.
pmp_size = -(address | TARGET_PAGE_MASK)
On Fri, Oct 11, 2019, 7:37 PM Jonathan Behrens <finte...@gmail.com> wrote:
> How do you know that the access won't straddle a page boundary? Is there a
> guarantee somewhere that size=0 means that the access is naturally aligned?
>
> Jonathan
>
>
> On Fri, Oct 11, 2019 at 7:14 PM Dayeol Lee <day...@berkeley.edu> wrote:
>
>> riscv_cpu_tlb_fill() uses the `size` parameter to check PMP violation
>> using pmp_hart_has_privs().
>> However, if the size is unknown (=0), the ending address will be
>> `addr - 1` as it is `addr + size - 1` in `pmp_hart_has_privs()`.
>> This always causes a false PMP violation on the starting address of the
>> range, as `addr - 1` is not in the range.
>>
>> In order to fix, we just assume that all bytes from addr to the end of
>> the page will be accessed if the size is unknown.
>>
>> Signed-off-by: Dayeol Lee <day...@berkeley.edu>
>> Reviewed-by: Richard Henderson <richard.hender...@linaro.org>
>> ---
>> target/riscv/cpu_helper.c | 13 ++++++++++++-
>> 1 file changed, 12 insertions(+), 1 deletion(-)
>>
>> diff --git a/target/riscv/cpu_helper.c b/target/riscv/cpu_helper.c
>> index e32b6126af..7d9a22b601 100644
>> --- a/target/riscv/cpu_helper.c
>> +++ b/target/riscv/cpu_helper.c
>> @@ -441,6 +441,7 @@ bool riscv_cpu_tlb_fill(CPUState *cs, vaddr address,
>> int size,
>> CPURISCVState *env = &cpu->env;
>> hwaddr pa = 0;
>> int prot;
>> + int pmp_size = 0;
>> bool pmp_violation = false;
>> int ret = TRANSLATE_FAIL;
>> int mode = mmu_idx;
>> @@ -460,9 +461,19 @@ bool riscv_cpu_tlb_fill(CPUState *cs, vaddr address,
>> int size,
>> "%s address=%" VADDR_PRIx " ret %d physical "
>> TARGET_FMT_plx
>> " prot %d\n", __func__, address, ret, pa, prot);
>>
>> + /*
>> + * if size is unknown (0), assume that all bytes
>> + * from addr to the end of the page will be accessed.
>> + */
>> + if (size == 0) {
>> + pmp_size = -(address | TARGET_PAGE_MASK);
>> + } else {
>> + pmp_size = size;
>> + }
>> +
>> if (riscv_feature(env, RISCV_FEATURE_PMP) &&
>> (ret == TRANSLATE_SUCCESS) &&
>> - !pmp_hart_has_privs(env, pa, size, 1 << access_type, mode)) {
>> + !pmp_hart_has_privs(env, pa, pmp_size, 1 << access_type, mode)) {
>> ret = TRANSLATE_PMP_FAIL;
>> }
>> if (ret == TRANSLATE_PMP_FAIL) {
>> --
>> 2.20.1
>>
>>
>>
