On Wed, May 16, 2018 at 11:55 PM, Sascha Hauer <s.hauer@xxxxxxxxxxxxxx> wrote:
> On Wed, May 16, 2018 at 01:00:17PM -0700, Andrey Smirnov wrote:
>> Seeing
>>
>> create_sections(ttb, 0, PAGE_SIZE, ...);
>>
>> as the code the creates initial flat 4 GiB mapping is a bit less
>> intuitive then
>>
>> create_sections(ttb, 0, SZ_4G, ...);
>>
>> so, for the sake of clarification, convert create_sections() to accept
>> size in bytes and do bytes -> MiB converstion as a part of the
>> function.
>>
>> NOTE: To keep all of the arguments of create_sections() 32-bit:
>>
>> - Move all of the real code into a helper function accepting first
>> and last addresses of the region (e.g passing 0 and U32_MAX
>> means all 4GiB of address space)
>>
>> - Convert create_section() into a macro that does necessary size
>> -> last addres conversion under the hood to preserve original API
>>
>> Signed-off-by: Andrey Smirnov <andrew.smirnov@xxxxxxxxx>
>> ---
>> arch/arm/cpu/mmu-early.c | 4 ++--
>> arch/arm/cpu/mmu.c | 4 ++--
>> arch/arm/cpu/mmu.h | 22 ++++++++++++++++------
>> 3 files changed, 20 insertions(+), 10 deletions(-)
>>
>> diff --git a/arch/arm/cpu/mmu-early.c b/arch/arm/cpu/mmu-early.c
>> index 70ece0d2f..136b33c3a 100644
>> --- a/arch/arm/cpu/mmu-early.c
>> +++ b/arch/arm/cpu/mmu-early.c
>> @@ -16,7 +16,7 @@ static void map_cachable(unsigned long start, unsigned long size)
>> start = ALIGN_DOWN(start, SZ_1M);
>> size = ALIGN(size, SZ_1M);
>>
>> - create_sections(ttb, start, size >> 20, PMD_SECT_AP_WRITE |
>> + create_sections(ttb, start, size, PMD_SECT_AP_WRITE |
>> PMD_SECT_AP_READ | PMD_TYPE_SECT | PMD_SECT_WB);
>> }
>>
>> @@ -30,7 +30,7 @@ void mmu_early_enable(unsigned long membase, unsigned long memsize,
>> set_ttbr(ttb);
>> set_domain(DOMAIN_MANAGER);
>>
>> - create_sections(ttb, 0, 4096, PMD_SECT_AP_WRITE |
>> + create_sections(ttb, 0, SZ_4G, PMD_SECT_AP_WRITE |
>> PMD_SECT_AP_READ | PMD_TYPE_SECT);
>>
>> map_cachable(membase, memsize);
>> diff --git a/arch/arm/cpu/mmu.c b/arch/arm/cpu/mmu.c
>> index 0c367e47c..f02c99f65 100644
>> --- a/arch/arm/cpu/mmu.c
>> +++ b/arch/arm/cpu/mmu.c
>> @@ -460,7 +460,7 @@ static int mmu_init(void)
>> set_domain(DOMAIN_MANAGER);
>>
>> /* create a flat mapping using 1MiB sections */
>> - create_sections(ttb, 0, PAGE_SIZE, PMD_SECT_AP_WRITE | PMD_SECT_AP_READ |
>> + create_sections(ttb, 0, SZ_4G, PMD_SECT_AP_WRITE | PMD_SECT_AP_READ |
>> PMD_TYPE_SECT);
>> __mmu_cache_flush();
>>
>> @@ -472,7 +472,7 @@ static int mmu_init(void)
>> * below
>> */
>> for_each_memory_bank(bank) {
>> - create_sections(ttb, bank->start, bank->size >> 20,
>> + create_sections(ttb, bank->start, bank->size,
>> PMD_SECT_DEF_CACHED);
>> __mmu_cache_flush();
>> }
>> diff --git a/arch/arm/cpu/mmu.h b/arch/arm/cpu/mmu.h
>> index d71cd7e38..52689359a 100644
>> --- a/arch/arm/cpu/mmu.h
>> +++ b/arch/arm/cpu/mmu.h
>> @@ -27,16 +27,26 @@ static inline void set_domain(unsigned val)
>> }
>>
>> static inline void
>> -create_sections(uint32_t *ttb, unsigned long addr,
>> - int size_m, unsigned int flags)
>> +__create_sections(uint32_t *ttb, unsigned long first,
>> + unsigned long last, unsigned int flags)
>> {
>> - unsigned long ttb_start = addr >> 20;
>> - unsigned long ttb_end = ttb_start + size_m;
>> - unsigned int i;
>> + unsigned long ttb_start = first >> 20;
>> + unsigned long ttb_end = (last >> 20) + 1;
>> + unsigned int i, addr;
>>
>> - for (i = ttb_start; i < ttb_end; i++, addr += SZ_1M)
>> + for (i = ttb_start, addr = first; i < ttb_end; i++, addr += SZ_1M)
>> ttb[i] = addr | flags;
>> }
>>
>> +#define create_sections(ttb, addr, size, flags) \
>> + ({ \
>> + typeof(addr) __addr = addr; \
>> + typeof(size) __size = size; \
>> + /* Check for overflow */ \
>> + BUG_ON(__addr > ULONG_MAX - __size + 1); \
>> + __create_sections(ttb, __addr, __addr + (size) - 1, \
>> + flags); \
>> + })
>
> Why do you preserve the original API of create_sections()? I would just
> change it. We have only a few callers and they are easy to change.
>
Mostly because it keeps "addr + size - 1" arithmetic in one place
instead of spreading it to every caller. If you'd rather have that
instead of the macro above, I can change that in v3.
Thanks,
Andrey Smirnov
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