On Tue, Sep 15, 2020 at 11:08:55PM +0800, Phil Chang wrote: > Allowing the DMA32 zone be configurable in ARM64 but at most 4Gb.
Please add more details why would you like to limit the DMA32 zone. > Signed-off-by: Alix Wu <[email protected]> > Signed-off-by: YJ Chiang <[email protected]> > Signed-off-by: Phil Chang <[email protected]> > --- > > .../admin-guide/kernel-parameters.txt | 3 ++ > arch/arm64/include/asm/memory.h | 2 + > arch/arm64/mm/init.c | 39 +++++++++++++++++-- > 3 files changed, 41 insertions(+), 3 deletions(-) > > diff --git a/Documentation/admin-guide/kernel-parameters.txt > b/Documentation/admin-guide/kernel-parameters.txt > index bdc1f33fd3d1..5be6259e9ba8 100644 > --- a/Documentation/admin-guide/kernel-parameters.txt > +++ b/Documentation/admin-guide/kernel-parameters.txt > @@ -980,6 +980,9 @@ > The filter can be disabled or changed to another > driver later using sysfs. > > + dma32_size=nn[MG] [KNL,BOOT,ARM64] > + Forces the DMA32 zone size of <nn> in MB. Most of the kernel parameters that deal with memory sizes allow either of [KMG] suffixes. > + > driver_async_probe= [KNL] > List of driver names to be probed asynchronously. > Format: <driver_name1>,<driver_name2>... > diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h > index afa722504bfd..710de08ae8ae 100644 > --- a/arch/arm64/include/asm/memory.h > +++ b/arch/arm64/include/asm/memory.h > @@ -175,6 +175,8 @@ extern u64 kimage_vaddr; > /* the offset between the kernel virtual and physical mappings */ > extern u64 kimage_voffset; > > +extern phys_addr_t dma32_zone_size; > + > static inline unsigned long kaslr_offset(void) > { > return kimage_vaddr - KIMAGE_VADDR; > diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c > index 481d22c32a2e..c8af53680d46 100644 > --- a/arch/arm64/mm/init.c > +++ b/arch/arm64/mm/init.c > @@ -60,6 +60,9 @@ EXPORT_SYMBOL(physvirt_offset); > struct page *vmemmap __ro_after_init; > EXPORT_SYMBOL(vmemmap); > > +phys_addr_t dma32_zone_size __ro_after_init; > +EXPORT_SYMBOL(dma32_zone_size); > + > /* > * We create both ZONE_DMA and ZONE_DMA32. ZONE_DMA covers the first 1G of > * memory as some devices, namely the Raspberry Pi 4, have peripherals with > @@ -242,6 +245,29 @@ static int __init early_mem(char *p) > } > early_param("mem", early_mem); > > +static int __init setup_dma32_zone(char *p) > +{ > + u64 size; > + > + if (!p) > + return -EINVAL; > + > + if (kstrtoull(p, 0, &size)) > + return -EINVAL; Better to use memparse() here. > + > + /* DMA32 zone size should never grater than 4G */ > + if (size > max_zone_phys(32) / SZ_1M) > + return -EINVAL; > + > + pr_notice("Setup dma32 zone size to %llu Mb\n", size); > + > + dma32_zone_size = size * SZ_1M; > + > + return 0; > +} > + > +early_param("dma32_size", setup_dma32_zone); > + > static int __init early_init_dt_scan_usablemem(unsigned long node, > const char *uname, int depth, void *data) > { > @@ -392,10 +418,17 @@ void __init arm64_memblock_init(void) > arm64_dma_phys_limit = max_zone_phys(ARM64_ZONE_DMA_BITS); > } > > - if (IS_ENABLED(CONFIG_ZONE_DMA32)) > - arm64_dma32_phys_limit = max_zone_phys(32); > - else > + if (IS_ENABLED(CONFIG_ZONE_DMA32)) { > + if (dma32_zone_size) { > + arm64_dma32_phys_limit = min(max_zone_phys(32), > + dma32_zone_size + memblock_start_of_DRAM()); > + } else { > + arm64_dma32_phys_limit = max_zone_phys(32); > + dma32_zone_size = arm64_dma32_phys_limit; > + } I think this calculations can be hidden in max_zone_phys(), e.g. diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c index 481d22c32a2e..be3fdfb35a56 100644 --- a/arch/arm64/mm/init.c +++ b/arch/arm64/mm/init.c @@ -189,7 +189,12 @@ static void __init reserve_elfcorehdr(void) static phys_addr_t __init max_zone_phys(unsigned int zone_bits) { phys_addr_t offset = memblock_start_of_DRAM() & GENMASK_ULL(63, zone_bits); - return min(offset + (1ULL << zone_bits), memblock_end_of_DRAM()); + phys_addr_t zone_size = (1ULL << zone_bits); + + if (IS_ENABLED(CONFIG_ZONE_DMA32) && zone_bits == 32 && dma32_zone_size) + zone_bits = min(zone_size,dma32_zone_size); + + return min(offset + zone_size, memblock_end_of_DRAM()); } static void __init zone_sizes_init(unsigned long min, unsigned long max) > + } else { > arm64_dma32_phys_limit = PHYS_MASK + 1; > + } > > reserve_crashkernel(); > > -- > 2.18.0 -- Sincerely yours, Mike.
