2023-12-19 11:17:17

by Guo Ren

Subject: [PATCH] riscv: mm: Fixup compat mode boot failure

From: Guo Ren <[email protected]>

In COMPAT mode, the STACK_TOP is 0x80000000, but the TASK_SIZE is
0x7fff000. When the user stack is upon 0x7fff000, it will cause a user
segment fault. Sometimes, it would cause boot failure when the whole
rootfs is rv32.

Freeing unused kernel image (initmem) memory: 2236K
Run /sbin/init as init process
Starting init: /sbin/init exists but couldn't execute it (error -14)
Run /etc/init as init process
...

Fixes: add2cc6b6515 ("RISC-V: mm: Restrict address space for sv39,sv48,sv57")
Signed-off-by: Guo Ren <[email protected]>
Signed-off-by: Guo Ren <[email protected]>
---
arch/riscv/include/asm/pgtable.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
index ab00235b018f..d2ec5e6fa331 100644
--- a/arch/riscv/include/asm/pgtable.h
+++ b/arch/riscv/include/asm/pgtable.h
@@ -881,7 +881,7 @@ static inline pte_t pte_swp_clear_exclusive(pte_t pte)
#define TASK_SIZE_MIN (PGDIR_SIZE_L3 * PTRS_PER_PGD / 2)

#ifdef CONFIG_COMPAT
-#define TASK_SIZE_32 (_AC(0x80000000, UL) - PAGE_SIZE)
+#define TASK_SIZE_32 (UL(1) << (MMAP_VA_BITS - 1))
#define TASK_SIZE (test_thread_flag(TIF_32BIT) ? \
TASK_SIZE_32 : TASK_SIZE_64)
#else
--
2.40.1

2023-12-22 00:18:57

by Guo Ren

Subject: Re: [PATCH] riscv: mm: Fixup compat mode boot failure

On Tue, Dec 19, 2023 at 06:17:01AM -0500, [email protected] wrote:
> From: Guo Ren <[email protected]>
>
> In COMPAT mode, the STACK_TOP is 0x80000000, but the TASK_SIZE is
> 0x7fff000. When the user stack is upon 0x7fff000, it will cause a user
> segment fault. Sometimes, it would cause boot failure when the whole
> rootfs is rv32.
>
> Freeing unused kernel image (initmem) memory: 2236K
> Run /sbin/init as init process
> Starting init: /sbin/init exists but couldn't execute it (error -14)
> Run /etc/init as init process
> ...
>
> Fixes: add2cc6b6515 ("RISC-V: mm: Restrict address space for sv39,sv48,sv57")
> Signed-off-by: Guo Ren <[email protected]>
> Signed-off-by: Guo Ren <[email protected]>
Abandon this patch, and here is the v2:
https://lore.kernel.org/linux-riscv/[email protected]/


> ---
> arch/riscv/include/asm/pgtable.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
> index ab00235b018f..d2ec5e6fa331 100644
> --- a/arch/riscv/include/asm/pgtable.h
> +++ b/arch/riscv/include/asm/pgtable.h
> @@ -881,7 +881,7 @@ static inline pte_t pte_swp_clear_exclusive(pte_t pte)
> #define TASK_SIZE_MIN (PGDIR_SIZE_L3 * PTRS_PER_PGD / 2)
>
> #ifdef CONFIG_COMPAT
> -#define TASK_SIZE_32 (_AC(0x80000000, UL) - PAGE_SIZE)
> +#define TASK_SIZE_32 (UL(1) << (MMAP_VA_BITS - 1))
> #define TASK_SIZE (test_thread_flag(TIF_32BIT) ? \
> TASK_SIZE_32 : TASK_SIZE_64)
> #else
> --
> 2.40.1
>
>
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>