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riscv: Make sure the kernel mapping does not overlap with IS_ERR_VALUE

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The check that is done in setup_bootmem currently only works for 32-bit
kernel since the kernel mapping has been moved outside of the linear
mapping for 64-bit kernel. So make sure that for 64-bit kernel, the kernel
mapping does not overlap with the last 4K of the addressable memory.

Signed-off-by: Alexandre Ghiti <alex@ghiti.fr>
Fixes: 2bfc6cd81b ("riscv: Move kernel mapping outside of linear mapping")
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
This commit is contained in:
Alexandre Ghiti 2021-06-29 11:13:48 +02:00 committed by Palmer Dabbelt
parent c99127c452
commit db6b84a368
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1 changed files with 16 additions and 2 deletions
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18
arch/riscv/mm/init.c
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@ -159,7 +159,7 @@ static void __init setup_bootmem(void)
{
phys_addr_t vmlinux_end = __pa_symbol(&_end);
phys_addr_t vmlinux_start = __pa_symbol(&_start);
phys_addr_t max_mapped_addr = __pa(~(ulong)0);
phys_addr_t __maybe_unused max_mapped_addr;
phys_addr_t dram_end;
#ifdef CONFIG_XIP_KERNEL
@ -183,14 +183,20 @@ static void __init setup_bootmem(void)
dram_end = memblock_end_of_DRAM();
#ifndef CONFIG_64BIT
/*
* 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 end of dram is equal to maximum addressable memory. For 64-bit
* kernel, this problem can't happen here as the end of the virtual
* address space is occupied by the kernel mapping then this check must
* be done in create_kernel_page_table.
*/
max_mapped_addr = __pa(~(ulong)0);
if (max_mapped_addr == (dram_end - 1))
memblock_set_current_limit(max_mapped_addr - 4096);
#endif
min_low_pfn = PFN_UP(memblock_start_of_DRAM());
max_low_pfn = max_pfn = PFN_DOWN(dram_end);
@ -578,6 +584,14 @@ asmlinkage void __init setup_vm(uintptr_t dtb_pa)
BUG_ON((PAGE_OFFSET % PGDIR_SIZE) != 0);
BUG_ON((kernel_map.phys_addr % map_size) != 0);
#ifdef CONFIG_64BIT
/*
* The last 4K bytes of the addressable memory can not be mapped because
* of IS_ERR_VALUE macro.
*/
BUG_ON((kernel_map.virt_addr + kernel_map.size) > ADDRESS_SPACE_END - SZ_4K);
#endif
pt_ops.alloc_pte = alloc_pte_early;
pt_ops.get_pte_virt = get_pte_virt_early;
#ifndef __PAGETABLE_PMD_FOLDED