[PATCHv3 2/4] arm64/crashdump: unify routine to get page_offset

[Simon Horman]

On Tue, Dec 28, 2021 at 09:26:57PM +0800, Pingfan Liu wrote:
> There are two funcs to get page_offset:
>   get_kernel_page_offset()
>   get_page_offset()
> 
> Since get_kernel_page_offset() does not observe the kernel formula, and
> remove it. Unify them in order to introduce 52-bits VA kernel more
> easily in the coming patch.
> 
> Signed-off-by: Pingfan Liu <piliu at redhat.com>
> Cc: Kairui Song <kasong at tencent.com>
> Cc: Simon Horman <horms at verge.net.au>
> Cc: Philipp Rudo <prudo at redhat.com>
> To: kexec at lists.infradead.org
> ---
>  kexec/arch/arm64/crashdump-arm64.c | 23 +----------------------
>  kexec/arch/arm64/kexec-arm64.c     |  8 ++++----
>  kexec/arch/arm64/kexec-arm64.h     |  1 +
>  3 files changed, 6 insertions(+), 26 deletions(-)
> 
> diff --git a/kexec/arch/arm64/crashdump-arm64.c b/kexec/arch/arm64/crashdump-arm64.c
> index a02019a..0a8d44c 100644
> --- a/kexec/arch/arm64/crashdump-arm64.c
> +++ b/kexec/arch/arm64/crashdump-arm64.c
> @@ -46,27 +46,6 @@ static struct crash_elf_info elf_info = {
>  	.machine	= EM_AARCH64,
>  };
>  
> -/*
> - * Note: The returned value is correct only if !CONFIG_RANDOMIZE_BASE.
> - */
> -static uint64_t get_kernel_page_offset(void)
> -{
> -	int i;
> -
> -	if (elf_info.kern_vaddr_start == UINT64_MAX)
> -		return UINT64_MAX;
> -
> -	/* Current max virtual memory range is 48-bits. */
> -	for (i = 48; i > 0; i--)
> -		if (!(elf_info.kern_vaddr_start & (1UL << i)))
> -			break;
> -
> -	if (i <= 0)
> -		return UINT64_MAX;
> -	else
> -		return UINT64_MAX << i;
> -}
> -
>  /*
>   * iomem_range_callback() - callback called for each iomem region
>   * @data: not used
> @@ -198,7 +177,7 @@ int load_crashdump_segments(struct kexec_info *info)
>  	if (err)
>  		return EFAILED;
>  
> -	elf_info.page_offset = get_kernel_page_offset();
> +	get_page_offset(&elf_info.page_offset);
>  	dbgprintf("%s: page_offset:   %016llx\n", __func__,
>  			elf_info.page_offset);
>  
> diff --git a/kexec/arch/arm64/kexec-arm64.c b/kexec/arch/arm64/kexec-arm64.c
> index 7373fa3..037e51c 100644
> --- a/kexec/arch/arm64/kexec-arm64.c
> +++ b/kexec/arch/arm64/kexec-arm64.c
> @@ -909,7 +909,7 @@ static int get_va_bits(void)
>   * get_page_offset - Helper for getting PAGE_OFFSET
>   */
>  
> -static int get_page_offset(void)
> +int get_page_offset(unsigned long *page_offset)
>  {
>  	int ret;
>  
> @@ -917,8 +917,8 @@ static int get_page_offset(void)
>  	if (ret < 0)
>  		return ret;
>  
> -	page_offset = (0xffffffffffffffffUL) << (va_bits - 1);
> -	dbgprintf("page_offset : %lx\n", page_offset);
> +	*page_offset = (0xffffffffffffffffUL) << (va_bits - 1);

As this line is being updated, perhaps we could also make use of
UINT64_MAX or ULONG_MAX here.

> +	dbgprintf("page_offset : %lx\n", *page_offset);
>  
>  	return 0;
>  }
> @@ -954,7 +954,7 @@ int get_phys_base_from_pt_load(long *phys_offset)
>  	unsigned long long phys_start;
>  	unsigned long long virt_start;
>  
> -	ret = get_page_offset();
> +	ret = get_page_offset(&page_offset);
>  	if (ret < 0)
>  		return ret;
>  
> diff --git a/kexec/arch/arm64/kexec-arm64.h b/kexec/arch/arm64/kexec-arm64.h
> index 1844b67..ed99d9d 100644
> --- a/kexec/arch/arm64/kexec-arm64.h
> +++ b/kexec/arch/arm64/kexec-arm64.h
> @@ -69,6 +69,7 @@ extern struct arm64_mem arm64_mem;
>  
>  uint64_t get_phys_offset(void);
>  uint64_t get_vp_offset(void);
> +int get_page_offset(unsigned long *offset);
>  
>  static inline void reset_vp_offset(void)
>  {
> -- 
> 2.31.1
>