This is a note to let you know that I've just added the patch titled
riscv: Fix loading 64-bit NOMMU kernels past the start of RAM
to the 6.8-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
riscv-fix-loading-64-bit-nommu-kernels-past-the-star.patch
and it can be found in the queue-6.8 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit a95520097e1d9b281b9584f79993862fa512911b
Author: Samuel Holland <samuel.holland@xxxxxxxxxx>
Date: Mon Feb 26 16:34:47 2024 -0800
riscv: Fix loading 64-bit NOMMU kernels past the start of RAM
[ 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@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20240227003630.3634533-3-samuel.holland@xxxxxxxxxx
Signed-off-by: Palmer Dabbelt <palmer@xxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/arch/riscv/include/asm/page.h b/arch/riscv/include/asm/page.h
index 57e887bfa34cb..94b3d6930fc37 100644
--- a/arch/riscv/include/asm/page.h
+++ b/arch/riscv/include/asm/page.h
@@ -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).
diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
index fa34cf55037bd..0c00efc75643a 100644
--- a/arch/riscv/mm/init.c
+++ b/arch/riscv/mm/init.c
@@ -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;
/*
