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riscv: Fix loading 64-bit NOMMU kernels past the start of RAM

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[ Upstream commit aea702dde7e9876fb00571a2602f25130847bf0f ]

commit 3335068f8721 ("riscv: Use PUD/P4D/PGD pages for the linear
mapping") added logic to allow using RAM below the kernel load address.
However, this does not work for NOMMU, where PAGE_OFFSET is fixed to the
kernel load address. Since that range of memory corresponds to PFNs
below ARCH_PFN_OFFSET, mm initialization runs off the beginning of
mem_map and corrupts adjacent kernel memory. Fix this by restoring the
previous behavior for NOMMU kernels.

Fixes: 3335068f8721 ("riscv: Use PUD/P4D/PGD pages for the linear mapping")
Signed-off-by: Samuel Holland <samuel.holland@sifive.com>
Link: https://lore.kernel.org/r/20240227003630.3634533-3-samuel.holland@sifive.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Samuel Holland 2024-02-26 16:34:47 -08:00 committed by Greg Kroah-Hartman
parent a0f0dbbb1b
commit b008e327fa
2 changed files with 2 additions and 2 deletions
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2
arch/riscv/include/asm/page.h
View File

@ -89,7 +89,7 @@ typedef struct page *pgtable_t;
#define PTE_FMT "%08lx"
#endif
#ifdef CONFIG_64BIT
#if defined(CONFIG_64BIT) && defined(CONFIG_MMU)
/*
* We override this value as its generic definition uses __pa too early in
* the boot process (before kernel_map.va_pa_offset is set).

2
arch/riscv/mm/init.c
View File

@ -230,7 +230,7 @@ static void __init setup_bootmem(void)
* In 64-bit, any use of __va/__pa before this point is wrong as we
* did not know the start of DRAM before.
*/
if (IS_ENABLED(CONFIG_64BIT))
if (IS_ENABLED(CONFIG_64BIT) && IS_ENABLED(CONFIG_MMU))
kernel_map.va_pa_offset = PAGE_OFFSET - phys_ram_base;
/*