From: Xu Lu luxu.kernel@bytedance.com

[ Upstream commit f754f27e98f88428aaf6be6e00f5cbce97f62d4b ]

In sparse vmemmap model, the virtual address of vmemmap is calculated as: ((struct page *)VMEMMAP_START - (phys_ram_base >> PAGE_SHIFT)). And the struct page's va can be calculated with an offset: (vmemmap + (pfn)).

However, when initializing struct pages, kernel actually starts from the first page from the same section that phys_ram_base belongs to. If the first page's physical address is not (phys_ram_base >> PAGE_SHIFT), then we get an va below VMEMMAP_START when calculating va for it's struct page.

For example, if phys_ram_base starts from 0x82000000 with pfn 0x82000, the first page in the same section is actually pfn 0x80000. During init_unavailable_range(), we will initialize struct page for pfn 0x80000 with virtual address ((struct page *)VMEMMAP_START - 0x2000), which is below VMEMMAP_START as well as PCI_IO_END.

This commit fixes this bug by introducing a new variable 'vmemmap_start_pfn' which is aligned with memory section size and using it to calculate vmemmap address instead of phys_ram_base.

Fixes: a11dd49dcb93 ("riscv: Sparse-Memory/vmemmap out-of-bounds fix") Signed-off-by: Xu Lu luxu.kernel@bytedance.com Reviewed-by: Alexandre Ghiti alexghiti@rivosinc.com Tested-by: Björn Töpel bjorn@rivosinc.com Reviewed-by: Björn Töpel bjorn@rivosinc.com Link: https://lore.kernel.org/r/20241209122617.53341-1-luxu.kernel@bytedance.com Signed-off-by: Palmer Dabbelt palmer@rivosinc.com Signed-off-by: Zhaoyang Li lizy04@hust.edu.cn --- arch/riscv/include/asm/page.h | 1 + arch/riscv/include/asm/pgtable.h | 2 +- arch/riscv/mm/init.c | 17 ++++++++++++++++- 3 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/arch/riscv/include/asm/page.h b/arch/riscv/include/asm/page.h index 86048c60f700..fd861ac47a89 100644 --- a/arch/riscv/include/asm/page.h +++ b/arch/riscv/include/asm/page.h @@ -115,6 +115,7 @@ struct kernel_mapping {

extern struct kernel_mapping kernel_map; extern phys_addr_t phys_ram_base; +extern unsigned long vmemmap_start_pfn;

#define is_kernel_mapping(x) \ ((x) >= kernel_map.virt_addr && (x) < (kernel_map.virt_addr + kernel_map.size)) diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h index 7d1688f850c3..bb19a643c5c2 100644 --- a/arch/riscv/include/asm/pgtable.h +++ b/arch/riscv/include/asm/pgtable.h @@ -79,7 +79,7 @@ * Define vmemmap for pfn_to_page & page_to_pfn calls. Needed if kernel * is configured with CONFIG_SPARSEMEM_VMEMMAP enabled. */ -#define vmemmap ((struct page *)VMEMMAP_START - (phys_ram_base >> PAGE_SHIFT)) +#define vmemmap ((struct page *)VMEMMAP_START - vmemmap_start_pfn)

#define PCI_IO_SIZE SZ_16M #define PCI_IO_END VMEMMAP_START diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c index ba2210b553f9..72b3462babbf 100644 --- a/arch/riscv/mm/init.c +++ b/arch/riscv/mm/init.c @@ -22,6 +22,7 @@ #include <linux/hugetlb.h>

#include <asm/fixmap.h> +#include <asm/sparsemem.h> #include <asm/tlbflush.h> #include <asm/sections.h> #include <asm/soc.h> @@ -52,6 +53,13 @@ EXPORT_SYMBOL(pgtable_l5_enabled); phys_addr_t phys_ram_base __ro_after_init; EXPORT_SYMBOL(phys_ram_base);

+#ifdef CONFIG_SPARSEMEM_VMEMMAP +#define VMEMMAP_ADDR_ALIGN (1ULL << SECTION_SIZE_BITS) + +unsigned long vmemmap_start_pfn __ro_after_init; +EXPORT_SYMBOL(vmemmap_start_pfn); +#endif + unsigned long empty_zero_page[PAGE_SIZE / sizeof(unsigned long)] __page_aligned_bss; EXPORT_SYMBOL(empty_zero_page); @@ -210,8 +218,12 @@ static void __init setup_bootmem(void) memblock_reserve(vmlinux_start, vmlinux_end - vmlinux_start);

phys_ram_end = memblock_end_of_DRAM(); - if (!IS_ENABLED(CONFIG_XIP_KERNEL)) + if (!IS_ENABLED(CONFIG_XIP_KERNEL)) { phys_ram_base = memblock_start_of_DRAM(); +#ifdef CONFIG_SPARSEMEM_VMEMMAP + vmemmap_start_pfn = round_down(phys_ram_base, VMEMMAP_ADDR_ALIGN) >> PAGE_SHIFT; +#endif +} /* * Reserve physical address space that would be mapped to virtual * addresses greater than (void *)(-PAGE_SIZE) because: @@ -946,6 +958,9 @@ asmlinkage void __init setup_vm(uintptr_t dtb_pa) kernel_map.xiprom_sz = (uintptr_t)(&_exiprom) - (uintptr_t)(&_xiprom);

phys_ram_base = CONFIG_PHYS_RAM_BASE; +#ifdef CONFIG_SPARSEMEM_VMEMMAP + vmemmap_start_pfn = round_down(phys_ram_base, VMEMMAP_ADDR_ALIGN) >> PAGE_SHIFT; +#endif kernel_map.phys_addr = (uintptr_t)CONFIG_PHYS_RAM_BASE; kernel_map.size = (uintptr_t)(&_end) - (uintptr_t)(&_start);