Messages in this thread | | | From | Anup Patel <> | Date | Thu, 28 Mar 2019 11:58:56 +0530 | Subject | Re: [PATCH 3/7] RISC-V: Rework kernel's virtual address space mapping |
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On Thu, Mar 28, 2019 at 11:09 AM Palmer Dabbelt <palmer@sifive.com> wrote: > > On Wed, 27 Mar 2019 14:36:39 PDT (-0700), logang@deltatee.com wrote: > > The motivation for this is to support P2P transactions. P2P requires > > having struct pages for IO memory which means the linear mapping must > > be able to cover all of the IO regions. Unfortunately with Sv39 we are > > not able to cover all the IO regions available on existing hardware, > > but we can do better than what we currently do (which only cover's > > physical memory). > > > > To this end, we restructure the kernel's virtual address space region. > > We position the vmemmap at the beginning of the region (based on how > > many virtual address bits we have) and the VMALLOC region comes > > immediately after. The linear mapping then takes up the remaining space. > > PAGE_OFFSET will need to be within the linear mapping but may not be > > the start of the mapping seeing many machines don't have RAM at address > > zero and we may still want to access lower addresses through the > > linear mapping. > > > > With these changes, on a 64-bit system the virtual memory map (with > > sparsemem enabled) will be: > > > > 32-bit: > > > > 00000000 - 7fffffff user space, different per mm (2G) > > 80000000 - 81ffffff virtual memory map (32MB) > > 82000000 - bfffffff vmalloc/ioremap space (1GB - 32MB) > > c0000000 - ffffffff direct mapping of all phys. memory (1GB) > > > > 64-bit, Sv39: > > > > 0000000000000000 - 0000003fffffffff user space, different per mm (256GB) > > hole caused by [38:63] sign extension > > ffffffc000000000 - ffffffc0ffffffff virtual memory map (4GB) > > ffffffc100000000 - ffffffd0ffffffff vmalloc/ioremap spac (64GB) > > ffffffd100000000 - ffffffffffffffff linear mapping of phys. space (188GB) > > > > On the Sifive hardware this allows us to provide struct pages for > > the lower I/O TileLink address ranges, the 32-bit and 34-bit DRAM areas > > and 172GB of 240GB of the high I/O TileLink region. Once we progress to > > Sv48 we should be able to cover all the available memory regions.. > > > > For the MAXPHYSMEM_2GB case, the physical memory must be in the highest > > 2GB of address space, so we cannot cover the any of the I/O regions > > that are higher than it but we do cover the lower I/O TileLink range. > > IIRC there was another patch floating around to fix an issue with overlapping > regions in the 32-bit port, did you also fix that issue? It's somewhere in my > email queue...
That was a patch I submitted to fix overlapping FIXMAP and VMALLOC regions.
This patch does not consider FIXMAP region.
I suggest we introduce asm/memory.h where we have all critical defines related to virtual memory layout. Also, this header should have detailed comments about virtual memory layout.
> > > Signed-off-by: Logan Gunthorpe <logang@deltatee.com> > > Cc: Palmer Dabbelt <palmer@sifive.com> > > Cc: Albert Ou <aou@eecs.berkeley.edu> > > Cc: Antony Pavlov <antonynpavlov@gmail.com> > > Cc: "Stefan O'Rear" <sorear2@gmail.com> > > Cc: Anup Patel <anup.patel@wdc.com> > > --- > > arch/riscv/Kconfig | 2 +- > > arch/riscv/include/asm/page.h | 2 -- > > arch/riscv/include/asm/pgtable.h | 27 ++++++++++++++++++--------- > > 3 files changed, 19 insertions(+), 12 deletions(-) > > > > diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig > > index 76fc340ae38e..d21e6a12e8b6 100644 > > --- a/arch/riscv/Kconfig > > +++ b/arch/riscv/Kconfig > > @@ -71,7 +71,7 @@ config PAGE_OFFSET > > hex > > default 0xC0000000 if 32BIT && MAXPHYSMEM_2GB > > default 0xffffffff80000000 if 64BIT && MAXPHYSMEM_2GB > > - default 0xffffffe000000000 if 64BIT && MAXPHYSMEM_128GB > > + default 0xffffffd200000000 if 64BIT && MAXPHYSMEM_128GB > > > > config ARCH_FLATMEM_ENABLE > > def_bool y > > diff --git a/arch/riscv/include/asm/page.h b/arch/riscv/include/asm/page.h > > index 2a546a52f02a..fa0b8058a246 100644 > > --- a/arch/riscv/include/asm/page.h > > +++ b/arch/riscv/include/asm/page.h > > @@ -31,8 +31,6 @@ > > */ > > #define PAGE_OFFSET _AC(CONFIG_PAGE_OFFSET, UL) > > > > -#define KERN_VIRT_SIZE (-PAGE_OFFSET) > > - > > #ifndef __ASSEMBLY__ > > > > #define PAGE_UP(addr) (((addr)+((PAGE_SIZE)-1))&(~((PAGE_SIZE)-1))) > > diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h > > index 5a9fea00ba09..2a5070540996 100644 > > --- a/arch/riscv/include/asm/pgtable.h > > +++ b/arch/riscv/include/asm/pgtable.h > > @@ -89,22 +89,31 @@ extern pgd_t swapper_pg_dir[]; > > #define __S110 PAGE_SHARED_EXEC > > #define __S111 PAGE_SHARED_EXEC > > > > -#define VMALLOC_SIZE (KERN_VIRT_SIZE >> 1) > > -#define VMALLOC_END (PAGE_OFFSET - 1) > > -#define VMALLOC_START (PAGE_OFFSET - VMALLOC_SIZE) > > +#define KERN_SPACE_START (-1UL << (CONFIG_VA_BITS - 1)) > > > > /* > > * Roughly size the vmemmap space to be large enough to fit enough > > * struct pages to map half the virtual address space. Then > > * position vmemmap directly below the VMALLOC region. > > */ > > -#define VMEMMAP_SHIFT \ > > - (CONFIG_VA_BITS - PAGE_SHIFT - 1 + STRUCT_PAGE_MAX_SHIFT) > > -#define VMEMMAP_SIZE (1UL << VMEMMAP_SHIFT) > > -#define VMEMMAP_END (VMALLOC_START - 1) > > -#define VMEMMAP_START (VMALLOC_START - VMEMMAP_SIZE) > > - > > +#ifdef CONFIG_SPARSEMEM > > +#define VMEMMAP_SIZE (UL(1) << (CONFIG_VA_BITS - PAGE_SHIFT - 1 + \ > > + STRUCT_PAGE_MAX_SHIFT)) > > +#define VMEMMAP_START (KERN_SPACE_START) > > +#define VMEMMAP_END (VMEMMAP_START + VMEMMAP_SIZE - 1) > > #define vmemmap ((struct page *)VMEMMAP_START) > > +#else > > +#define VMEMMAP_END KERN_SPACE_START > > +#endif > > + > > +#ifdef CONFIG_32BIT > > +#define VMALLOC_SIZE ((1UL << 30) - VMEMMAP_SIZE) > > +#else > > +#define VMALLOC_SIZE (64UL << 30) > > +#endif > > + > > +#define VMALLOC_START (VMEMMAP_END + 1) > > +#define VMALLOC_END (VMALLOC_START + VMALLOC_SIZE - 1) > > > > /* > > * ZERO_PAGE is a global shared page that is always zero,
Regards, Anup
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