Messages in this thread |  | | From | Atish Patra <> | Date | Mon, 11 Jan 2021 11:20:03 -0800 | Subject | Re: [PATCH 2/4] RISC-V: Set current memblock limit |
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On Sun, Jan 10, 2021 at 7:59 PM Anup Patel <anup@brainfault.org> wrote: > > On Thu, Jan 7, 2021 at 2:57 PM Atish Patra <atish.patra@wdc.com> wrote: > > > > Currently, linux kernel can not use last 4k bytes of addressable space because > > IS_ERR_VALUE macro treats those as an error. This will be an issue for RV32 > > as any memblock allocator potentially allocate chunk of memory from the end > > of DRAM (2GB) leading bad address error even though the address was technically > > valid. > > > > Fix this issue by limiting the memblock if available memory spans the entire > > address space. > > > > Signed-off-by: Atish Patra <atish.patra@wdc.com> > > --- > > arch/riscv/mm/init.c | 16 ++++++++++++++-- > > 1 file changed, 14 insertions(+), 2 deletions(-) > > > > diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c > > index bf5379135e39..da53902ef0fc 100644 > > --- a/arch/riscv/mm/init.c > > +++ b/arch/riscv/mm/init.c > > @@ -157,9 +157,10 @@ static void __init setup_initrd(void) > > void __init setup_bootmem(void) > > { > > phys_addr_t mem_start = 0; > > - phys_addr_t start, end = 0; > > + phys_addr_t start, dram_end, end = 0; > > phys_addr_t vmlinux_end = __pa_symbol(&_end); > > phys_addr_t vmlinux_start = __pa_symbol(&_start); > > + phys_addr_t max_mapped_addr = __pa(PHYS_ADDR_MAX); > > Using PHYS_ADDR_MAX as the max virtual address does not look right. > > Better use __pa(~(ulong)0) here. Otherwise looks good to me. >
ok will change it. Thanks for the review.
> Reviewed-by: Anup Patel <anup@brainfault.org> > > > u64 i; > > > > /* Find the memory region containing the kernel */ > > @@ -181,7 +182,18 @@ void __init setup_bootmem(void) > > /* Reserve from the start of the kernel to the end of the kernel */ > > memblock_reserve(vmlinux_start, vmlinux_end - vmlinux_start); > > > > - max_pfn = PFN_DOWN(memblock_end_of_DRAM()); > > + dram_end = memblock_end_of_DRAM(); > > + > > + /* > > + * memblock allocator is not aware of the fact that last 4K bytes of > > + * the addressable memory can not be mapped because of IS_ERR_VALUE > > + * macro. Make sure that last 4k bytes are not usable by memblock > > + * if end of dram is equal to maximum addressable memory. > > + */ > > + if (max_mapped_addr == (dram_end - 1)) > > + memblock_set_current_limit(max_mapped_addr - 4096); > > + > > + max_pfn = PFN_DOWN(dram_end); > > max_low_pfn = max_pfn; > > dma32_phys_limit = min(4UL * SZ_1G, (unsigned long)PFN_PHYS(max_low_pfn)); > > set_max_mapnr(max_low_pfn); > > -- > > 2.25.1 > > > > > > _______________________________________________ > > linux-riscv mailing list > > linux-riscv@lists.infradead.org > > http://lists.infradead.org/mailman/listinfo/linux-riscv > > Regards, > Anup > > _______________________________________________ > linux-riscv mailing list > linux-riscv@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-riscv
-- Regards, Atish
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