Unverified Commit db6b84a3 authored by Alexandre Ghiti's avatar Alexandre Ghiti Committed by Palmer Dabbelt
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riscv: Make sure the kernel mapping does not overlap with IS_ERR_VALUE 



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: default avatarAlexandre Ghiti <alex@ghiti.fr>
Fixes: 2bfc6cd8 ("riscv: Move kernel mapping outside of linear mapping")
Signed-off-by: default avatarPalmer Dabbelt <palmerdabbelt@google.com>
parent c99127c4

arch/riscv/mm/init.c

+16 −2
Original line number Diff line number Diff line
@@ -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