Unverified Commit aea702dd authored by Samuel Holland's avatar Samuel Holland Committed by Palmer Dabbelt
Browse files

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



commit 3335068f ("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: 3335068f ("riscv: Use PUD/P4D/PGD pages for the linear mapping")
Signed-off-by: default avatarSamuel Holland <samuel.holland@sifive.com>
Link: https://lore.kernel.org/r/20240227003630.3634533-3-samuel.holland@sifive.com


Signed-off-by: default avatarPalmer Dabbelt <palmer@rivosinc.com>
parent 6065e736

arch/riscv/include/asm/page.h

+1 −1
Original line number Diff line number Diff line
@@ -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).

arch/riscv/mm/init.c

+1 −1
Original line number Diff line number Diff line
@@ -232,7 +232,7 @@ 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;



	/*