[PATCH] riscv: change XIP's kernel_map.size to be size of the entire kernel

[PATCH] riscv: change XIP's kernel_map.size to be size of the entire kernel

[Nam Cao]

With XIP kernel, kernel_map.size is set to be only the size of data part of
the kernel. This is inconsistent with "normal" kernel, who sets it to be
the size of the entire kernel.

More importantly, XIP kernel fails to boot if CONFIG_DEBUG_VIRTUAL is
enabled, because there are checks on virtual addresses with the assumption
that kernel_map.size is the size of the entire kernel (these checks are in
arch/riscv/mm/physaddr.c).

Change XIP's kernel_map.size to be the size of the entire kernel.

Signed-off-by: Nam Cao <namcao@linutronix.de>
Cc: <stable@vger.kernel.org> # v6.1+
---
I wouldn't consider this inconsistency to be a bug. It only became a
a problem after kernel_map.size is used to check virtual addresses in
5f763b3b5960 ("riscv: Fix DEBUG_VIRTUAL false warnings"). So I will only
backport this to stable versions that contain this commit: v6.1+

 arch/riscv/mm/init.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
index c081e7d349b1..0c0562839899 100644
--- a/arch/riscv/mm/init.c
+++ b/arch/riscv/mm/init.c
@@ -903,7 +903,7 @@ static void __init create_kernel_page_table(pgd_t *pgdir,
 				   PMD_SIZE, PAGE_KERNEL_EXEC);
 
 	/* Map the data in RAM */
-	end_va = kernel_map.virt_addr + XIP_OFFSET + kernel_map.size;
+	end_va = kernel_map.virt_addr + kernel_map.size;
 	for (va = kernel_map.virt_addr + XIP_OFFSET; va < end_va; va += PMD_SIZE)
 		create_pgd_mapping(pgdir, va,
 				   kernel_map.phys_addr + (va - (kernel_map.virt_addr + XIP_OFFSET)),
@@ -1072,7 +1072,7 @@ asmlinkage void __init setup_vm(uintptr_t dtb_pa)
 
 	phys_ram_base = CONFIG_PHYS_RAM_BASE;
 	kernel_map.phys_addr = (uintptr_t)CONFIG_PHYS_RAM_BASE;
-	kernel_map.size = (uintptr_t)(&_end) - (uintptr_t)(&_sdata);
+	kernel_map.size = (uintptr_t)(&_end) - (uintptr_t)(&_start);
 
 	kernel_map.va_kernel_xip_pa_offset = kernel_map.virt_addr - kernel_map.xiprom;
 #else
-- 
2.39.2

Re: [PATCH] riscv: change XIP's kernel_map.size to be size of the entire kernel

[Alexandre Ghiti]

Hi Nam,

On 08/05/2024 21:19, Nam Cao wrote:
> With XIP kernel, kernel_map.size is set to be only the size of data part of
> the kernel. This is inconsistent with "normal" kernel, who sets it to be
> the size of the entire kernel.
>
> More importantly, XIP kernel fails to boot if CONFIG_DEBUG_VIRTUAL is
> enabled, because there are checks on virtual addresses with the assumption
> that kernel_map.size is the size of the entire kernel (these checks are in
> arch/riscv/mm/physaddr.c).
>
> Change XIP's kernel_map.size to be the size of the entire kernel.
>
> Signed-off-by: Nam Cao <namcao@linutronix.de>
> Cc: <stable@vger.kernel.org> # v6.1+
> ---
> I wouldn't consider this inconsistency to be a bug. It only became a
> a problem after kernel_map.size is used to check virtual addresses in
> 5f763b3b5960 ("riscv: Fix DEBUG_VIRTUAL false warnings"). So I will only
> backport this to stable versions that contain this commit: v6.1+
>
>   arch/riscv/mm/init.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
> index c081e7d349b1..0c0562839899 100644
> --- a/arch/riscv/mm/init.c
> +++ b/arch/riscv/mm/init.c
> @@ -903,7 +903,7 @@ static void __init create_kernel_page_table(pgd_t *pgdir,
>   				   PMD_SIZE, PAGE_KERNEL_EXEC);
>   
>   	/* Map the data in RAM */
> -	end_va = kernel_map.virt_addr + XIP_OFFSET + kernel_map.size;
> +	end_va = kernel_map.virt_addr + kernel_map.size;
>   	for (va = kernel_map.virt_addr + XIP_OFFSET; va < end_va; va += PMD_SIZE)
>   		create_pgd_mapping(pgdir, va,
>   				   kernel_map.phys_addr + (va - (kernel_map.virt_addr + XIP_OFFSET)),
> @@ -1072,7 +1072,7 @@ asmlinkage void __init setup_vm(uintptr_t dtb_pa)
>   
>   	phys_ram_base = CONFIG_PHYS_RAM_BASE;
>   	kernel_map.phys_addr = (uintptr_t)CONFIG_PHYS_RAM_BASE;
> -	kernel_map.size = (uintptr_t)(&_end) - (uintptr_t)(&_sdata);
> +	kernel_map.size = (uintptr_t)(&_end) - (uintptr_t)(&_start);
>   
>   	kernel_map.va_kernel_xip_pa_offset = kernel_map.virt_addr - kernel_map.xiprom;
>   #else


You can add:

Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com>

Thanks,

Alex

Re: [PATCH] riscv: change XIP's kernel_map.size to be size of the entire kernel

[patchwork-bot+linux-riscv]

Hello:

This patch was applied to riscv/linux.git (fixes)
by Palmer Dabbelt <palmer@rivosinc.com>:

On Wed,  8 May 2024 21:19:17 +0200 you wrote:
> With XIP kernel, kernel_map.size is set to be only the size of data part of
> the kernel. This is inconsistent with "normal" kernel, who sets it to be
> the size of the entire kernel.
> 
> More importantly, XIP kernel fails to boot if CONFIG_DEBUG_VIRTUAL is
> enabled, because there are checks on virtual addresses with the assumption
> that kernel_map.size is the size of the entire kernel (these checks are in
> arch/riscv/mm/physaddr.c).
> 
> [...]

Here is the summary with links:
  - riscv: change XIP's kernel_map.size to be size of the entire kernel
    https://git.kernel.org/riscv/c/57d76bc51fd8

You are awesome, thank you!
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