[PATCH v2] arm64/mm: use lm_alias() with addresses passed to memblock_free()

[Rong Qianfeng]

Hi Joey,

在 2024/9/5 23:29, Joey Gouly 写道:
> [You don't often get email from joey.gouly at arm.com. Learn why this is important at https://aka.ms/LearnAboutSenderIdentification ]
>
> The pointer argument to memblock_free() needs to be a linear map address, but
> in mem_init() we pass __init_begin/__init_end, which is a kernel image address.
>
> This results in warnings when building with CONFIG_DEBUG_VIRTUAL=y:
>
>      virt_to_phys used for non-linear address: ffff800081270000 (set_reset_devices+0x0/0x10)
>      WARNING: CPU: 0 PID: 1 at arch/arm64/mm/physaddr.c:12 __virt_to_phys+0x54/0x70
>      Modules linked in:
>      CPU: 0 UID: 0 PID: 1 Comm: swapper/0 Not tainted 6.11.0-rc6-next-20240905 #5810 b1ebb0ad06653f35ce875413d5afad24668df3f3
>      Hardware name: FVP Base RevC (DT)
>      pstate: 2161402005 (nZCv daif +PAN -UAO -TCO +DIT -SSBS BTYPE=--)
>      pc : __virt_to_phys+0x54/0x70
>      lr : __virt_to_phys+0x54/0x70
>      sp : ffff80008169be20
>      ...
>      Call trace:
>       __virt_to_phys+0x54/0x70
>       memblock_free+0x18/0x30
>       free_initmem+0x3c/0x9c
>       kernel_init+0x30/0x1cc
>       ret_from_fork+0x10/0x20
>
> Fix this by having mem_init() convert the pointers via lm_alias().
>
> Fixes: 1db9716d4487 ("arm64/mm: Delete __init region from memblock.reserved")
> Signed-off-by: Joey Gouly <joey.gouly at arm.com>
> Suggested-by: Mark Rutland <mark.rutland at arm.com>
> Cc: Will Deacon <will at kernel.org>
> Cc: Catalin Marinas <catalin.marinas at arm.com>
> Cc: Rong Qianfeng <rongqianfeng at vivo.com>
> ---
>   arch/arm64/mm/init.c | 12 +++++++-----
>   1 file changed, 7 insertions(+), 5 deletions(-)
>
> diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
> index 0bde16aadc83..27a32ff15412 100644
> --- a/arch/arm64/mm/init.c
> +++ b/arch/arm64/mm/init.c
> @@ -411,14 +411,16 @@ void __init mem_init(void)
>
>   void free_initmem(void)
>   {
> -       unsigned long aligned_begin = ALIGN_DOWN((u64)__init_begin, PAGE_SIZE);
> -       unsigned long aligned_end = ALIGN((u64)__init_end, PAGE_SIZE);
> +       void *lm_init_begin = lm_alias(__init_begin);
> +       void *lm_init_end = lm_alias(__init_end);
> +
> +       WARN_ON(!IS_ALIGNED((unsigned long)lm_init_begin, PAGE_SIZE));
> +       WARN_ON(!IS_ALIGNED((unsigned long)lm_init_end, PAGE_SIZE));
>
>          /* Delete __init region from memblock.reserved. */
> -       memblock_free((void *)aligned_begin, aligned_end - aligned_begin);
> +       memblock_free(lm_init_begin, lm_init_end - lm_init_begin);
Thank you for discovering and fixing this hidden problem.  I will pay more
attention to it in the future. Thank you again.
>
> -       free_reserved_area(lm_alias(__init_begin),
> -                          lm_alias(__init_end),
> +       free_reserved_area(lm_init_begin, lm_init_end,
>                             POISON_FREE_INITMEM, "unused kernel");
>          /*
>           * Unmap the __init region but leave the VM area in place. This
> --
> 2.25.1
Best Regards,
Qianfeng