From: Samuel Holland samuel.holland@sifive.com
[ Upstream commit 2c0391b29b27f315c1b4c29ffde66f50b29fab99 ]
NOMMU kernels currently cannot access memory below the kernel link address. Remove this restriction by setting PAGE_OFFSET to the actual start of RAM, as determined from the devicetree. The kernel link address must be a constant, so keep using CONFIG_PAGE_OFFSET for that purpose.
Signed-off-by: Samuel Holland samuel.holland@sifive.com Reviewed-by: Jesse Taube mr.bossman075@gmail.com Link: https://lore.kernel.org/r/20241026171441.3047904-3-samuel.holland@sifive.com Signed-off-by: Palmer Dabbelt palmer@rivosinc.com Signed-off-by: Sasha Levin sashal@kernel.org --- arch/riscv/include/asm/page.h | 12 ++++-------- arch/riscv/include/asm/pgtable.h | 2 +- 2 files changed, 5 insertions(+), 9 deletions(-)
diff --git a/arch/riscv/include/asm/page.h b/arch/riscv/include/asm/page.h index 125f5ecd95652..6409fd78ae6fa 100644 --- a/arch/riscv/include/asm/page.h +++ b/arch/riscv/include/asm/page.h @@ -24,12 +24,9 @@ * When not using MMU this corresponds to the first free page in * physical memory (aligned on a page boundary). */ -#ifdef CONFIG_64BIT #ifdef CONFIG_MMU +#ifdef CONFIG_64BIT #define PAGE_OFFSET kernel_map.page_offset -#else -#define PAGE_OFFSET _AC(CONFIG_PAGE_OFFSET, UL) -#endif /* * By default, CONFIG_PAGE_OFFSET value corresponds to SV57 address space so * define the PAGE_OFFSET value for SV48 and SV39. @@ -39,6 +36,9 @@ #else #define PAGE_OFFSET _AC(CONFIG_PAGE_OFFSET, UL) #endif /* CONFIG_64BIT */ +#else +#define PAGE_OFFSET ((unsigned long)phys_ram_base) +#endif /* CONFIG_MMU */
#ifndef __ASSEMBLY__
@@ -95,11 +95,7 @@ typedef struct page *pgtable_t; #define MIN_MEMBLOCK_ADDR 0 #endif
-#ifdef CONFIG_MMU #define ARCH_PFN_OFFSET (PFN_DOWN((unsigned long)phys_ram_base)) -#else -#define ARCH_PFN_OFFSET (PAGE_OFFSET >> PAGE_SHIFT) -#endif /* CONFIG_MMU */
struct kernel_mapping { unsigned long page_offset; diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h index 050fdc49b5ad7..eb7b25ef556ec 100644 --- a/arch/riscv/include/asm/pgtable.h +++ b/arch/riscv/include/asm/pgtable.h @@ -12,7 +12,7 @@ #include <asm/pgtable-bits.h>
#ifndef CONFIG_MMU -#define KERNEL_LINK_ADDR PAGE_OFFSET +#define KERNEL_LINK_ADDR _AC(CONFIG_PAGE_OFFSET, UL) #define KERN_VIRT_SIZE (UL(-1)) #else