On Tue, Nov 23, 2021 at 9:37 PM Alexandre Ghiti <alexandre.ghiti@xxxxxxxxxxxxx> wrote: > > On Tue, Nov 23, 2021 at 4:56 AM Anup Patel <anup@xxxxxxxxxxxxxx> wrote: > > > > +Alex > > > > On Tue, Nov 23, 2021 at 7:27 AM <guoren@xxxxxxxxxx> wrote: > > > > > > From: Guo Ren <guoren@xxxxxxxxxxxxxxxxx> > > > > > > The current RISC-V's mm layout is based on a 2MB offset and wasting > > > memory. Remove 2MB offset and map PAGE_OFFSET at start_of_DRAM. > > > Then we could reduce the memory reserved for opensbi in the next > > > patch. > > > > The real problem is that the generic kernel marks memory before > > __pa(PAGE_OFFSET) as reserved which is evident from the boot > > print "OF: fdt: Ignoring memory range 0x80000000 - 0x80200000". > > Agreed, memblock 'rejects' this region because MIN_MEMBLOCK_ADDR is > defined as __pa(PAGE_OFFSET) which points to 0x80200000. I have a > patch to enable the use of hugepages for the linear mapping [1] that > does just that, things are not that easy since then it breaks initrd > initialization which is an early caller of __va, I updated this > patchset a few months ago, I can push that soon @Guo Ren. Seems your patch makes the mapping of early_pg_dir & swapper_pg_dir different. early_pg_dir: 0x80200000 -> 0xffffffe000000000 swapper_pg_dir: 0x80000000 -> 0xffffffe000000000 It breaks the vmlinux.ld.S, doesn't it? > > [1] https://lkml.org/lkml/2020/6/3/696 > > > > > > > One simple way to re-claim the first 2MB of memory is by: > > 1) Not placing OpenSBI firmware at start of RAM and rather > > place it towards end/middle or RAM away from kernel and initrd > > 2) Load kernel at start of the RAM > > > > The point#1 is already supported by OpenSBI firmwares using > > position independent compilation. In fact, U-Boot SPL does > > not load OpenSBI firmware at the start of RAM. > > > > I would suggest Allwinner D1 to follow U-Boot SPL and have > > the booting stage before OpenSBI to load OpenSBI firmware > > somewhere else. > > > > Regards, > > Anup > > > > > > > > Signed-off-by: Guo Ren <guoren@xxxxxxxxxxxxxxxxx> > > > Cc: Palmer Dabbelt <palmer@xxxxxxxxxxx> > > > Cc: Anup Patel <anup.patel@xxxxxxx> > > > Cc: Atish Patra <atishp@xxxxxxxxxxxx> > > > --- > > > arch/riscv/include/asm/page.h | 8 ++++++++ > > > arch/riscv/kernel/head.S | 10 +++------- > > > arch/riscv/kernel/vmlinux.lds.S | 5 ++--- > > > arch/riscv/mm/init.c | 11 ++++++++--- > > > 4 files changed, 21 insertions(+), 13 deletions(-) > > > > > > diff --git a/arch/riscv/include/asm/page.h b/arch/riscv/include/asm/page.h > > > index b3e5ff0125fe..299147c78b4a 100644 > > > --- a/arch/riscv/include/asm/page.h > > > +++ b/arch/riscv/include/asm/page.h > > > @@ -16,6 +16,14 @@ > > > #define PAGE_SIZE (_AC(1, UL) << PAGE_SHIFT) > > > #define PAGE_MASK (~(PAGE_SIZE - 1)) > > > > > > +#if __riscv_xlen == 64 > > > +/* Image load offset(2MB) from start of RAM */ > > > +#define LOAD_OFFSET 0x200000 > > > +#else > > > +/* Image load offset(4MB) from start of RAM */ > > > +#define LOAD_OFFSET 0x400000 > > > +#endif > > > + > > > #ifdef CONFIG_64BIT > > > #define HUGE_MAX_HSTATE 2 > > > #else > > > diff --git a/arch/riscv/kernel/head.S b/arch/riscv/kernel/head.S > > > index f52f01ecbeea..a6ac892d2ccf 100644 > > > --- a/arch/riscv/kernel/head.S > > > +++ b/arch/riscv/kernel/head.S > > > @@ -61,13 +61,7 @@ ENTRY(_start) > > > /* Image load offset (0MB) from start of RAM for M-mode */ > > > .dword 0 > > > #else > > > -#if __riscv_xlen == 64 > > > - /* Image load offset(2MB) from start of RAM */ > > > - .dword 0x200000 > > > -#else > > > - /* Image load offset(4MB) from start of RAM */ > > > - .dword 0x400000 > > > -#endif > > > + .dword LOAD_OFFSET > > > #endif > > > /* Effective size of kernel image */ > > > .dword _end - _start > > > @@ -94,6 +88,8 @@ relocate: > > > la a1, kernel_map > > > XIP_FIXUP_OFFSET a1 > > > REG_L a1, KERNEL_MAP_VIRT_ADDR(a1) > > > + li a2, LOAD_OFFSET > > > + add a1, a1, a2 > > > la a2, _start > > > sub a1, a1, a2 > > > add ra, ra, a1 > > > diff --git a/arch/riscv/kernel/vmlinux.lds.S b/arch/riscv/kernel/vmlinux.lds.S > > > index 5104f3a871e3..75b7c72cd4bd 100644 > > > --- a/arch/riscv/kernel/vmlinux.lds.S > > > +++ b/arch/riscv/kernel/vmlinux.lds.S > > > @@ -11,10 +11,9 @@ > > > #else > > > > > > #include <asm/pgtable.h> > > > -#define LOAD_OFFSET KERNEL_LINK_ADDR > > > > > > -#include <asm/vmlinux.lds.h> > > > #include <asm/page.h> > > > +#include <asm/vmlinux.lds.h> > > > #include <asm/cache.h> > > > #include <asm/thread_info.h> > > > #include <asm/set_memory.h> > > > @@ -32,7 +31,7 @@ PECOFF_FILE_ALIGNMENT = 0x200; > > > SECTIONS > > > { > > > /* Beginning of code and text segment */ > > > - . = LOAD_OFFSET; > > > + . = LOAD_OFFSET + KERNEL_LINK_ADDR; > > > _start = .; > > > HEAD_TEXT_SECTION > > > . = ALIGN(PAGE_SIZE); > > > diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c > > > index 24b2b8044602..920e78f8c3e4 100644 > > > --- a/arch/riscv/mm/init.c > > > +++ b/arch/riscv/mm/init.c > > > @@ -221,6 +221,11 @@ static void __init setup_bootmem(void) > > > if (!IS_ENABLED(CONFIG_BUILTIN_DTB)) > > > memblock_reserve(dtb_early_pa, fdt_totalsize(dtb_early_va)); > > > > > > + /* > > > + * Reserve OpenSBI region and depends on PMP to deny accesses. > > > + */ > > > + memblock_reserve(__pa(PAGE_OFFSET), LOAD_OFFSET); > > > + > > > early_init_fdt_scan_reserved_mem(); > > > dma_contiguous_reserve(dma32_phys_limit); > > > if (IS_ENABLED(CONFIG_64BIT)) > > > @@ -604,7 +609,7 @@ asmlinkage void __init setup_vm(uintptr_t dtb_pa) > > > > > > kernel_map.va_kernel_xip_pa_offset = kernel_map.virt_addr - kernel_map.xiprom; > > > #else > > > - kernel_map.phys_addr = (uintptr_t)(&_start); > > > + kernel_map.phys_addr = (uintptr_t)(&_start) - LOAD_OFFSET; > > > kernel_map.size = (uintptr_t)(&_end) - kernel_map.phys_addr; > > > #endif > > > kernel_map.va_pa_offset = PAGE_OFFSET - kernel_map.phys_addr; > > > @@ -645,8 +650,8 @@ asmlinkage void __init setup_vm(uintptr_t dtb_pa) > > > create_pmd_mapping(trampoline_pmd, kernel_map.virt_addr, > > > kernel_map.xiprom, PMD_SIZE, PAGE_KERNEL_EXEC); > > > #else > > > - create_pmd_mapping(trampoline_pmd, kernel_map.virt_addr, > > > - kernel_map.phys_addr, PMD_SIZE, PAGE_KERNEL_EXEC); > > > + create_pmd_mapping(trampoline_pmd, kernel_map.virt_addr + LOAD_OFFSET, > > > + kernel_map.phys_addr + LOAD_OFFSET, PMD_SIZE, PAGE_KERNEL_EXEC); > > > #endif > > > #else > > > /* Setup trampoline PGD */ > > > -- > > > 2.25.1 > > > -- Best Regards Guo Ren ML: https://lore.kernel.org/linux-csky/
