Re: [PATCH v4 7/8] arm64/efi: remove free_boot_services() and friends

[Leif Lindholm <leif.lindholm-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>]

On Mon, Dec 22, 2014 at 10:59:03AM +0000, Ard Biesheuvel wrote:
> Now that we are calling SetVirtualAddressMap() from the stub, there is no
> need to reserve boot-only memory regions, which implies that there is also
> no reason to free them again later.
> 
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
> ---
>  arch/arm64/kernel/efi.c | 123 +-----------------------------------------------
>  1 file changed, 1 insertion(+), 122 deletions(-)
> 
> diff --git a/arch/arm64/kernel/efi.c b/arch/arm64/kernel/efi.c
> index 2ebe67ffb629..e969c5076713 100644
> --- a/arch/arm64/kernel/efi.c
> +++ b/arch/arm64/kernel/efi.c
> @@ -198,9 +198,7 @@ static __init void reserve_regions(void)
>  		if (is_normal_ram(md))
>  			early_init_dt_add_memory_arch(paddr, size);
>  
> -		if (is_reserve_region(md) ||
> -		    md->type == EFI_BOOT_SERVICES_CODE ||
> -		    md->type == EFI_BOOT_SERVICES_DATA) {
> +		if (is_reserve_region(md)) {
>  			memblock_reserve(paddr, size);
>  			if (uefi_debug)
>  				pr_cont("*");
> @@ -213,123 +211,6 @@ static __init void reserve_regions(void)
>  	set_bit(EFI_MEMMAP, &efi.flags);
>  }
>  
> -
> -static u64 __init free_one_region(u64 start, u64 end)
> -{
> -	u64 size = end - start;
> -
> -	if (uefi_debug)
> -		pr_info("  EFI freeing: 0x%012llx-0x%012llx\n",	start, end - 1);
> -
> -	free_bootmem_late(start, size);
> -	return size;
> -}
> -
> -static u64 __init free_region(u64 start, u64 end)
> -{
> -	u64 map_start, map_end, total = 0;
> -
> -	if (end <= start)
> -		return total;
> -
> -	map_start = (u64)memmap.phys_map;
> -	map_end = PAGE_ALIGN(map_start + (memmap.map_end - memmap.map));
> -	map_start &= PAGE_MASK;
> -
> -	if (start < map_end && end > map_start) {
> -		/* region overlaps UEFI memmap */
> -		if (start < map_start)
> -			total += free_one_region(start, map_start);
> -
> -		if (map_end < end)
> -			total += free_one_region(map_end, end);
> -	} else
> -		total += free_one_region(start, end);
> -
> -	return total;
> -}
> -
> -static void __init free_boot_services(void)
> -{
> -	u64 total_freed = 0;
> -	u64 keep_end, free_start, free_end;
> -	efi_memory_desc_t *md;
> -
> -	/*
> -	 * If kernel uses larger pages than UEFI, we have to be careful
> -	 * not to inadvertantly free memory we want to keep if there is
> -	 * overlap at the kernel page size alignment. We do not want to
> -	 * free is_reserve_region() memory nor the UEFI memmap itself.
> -	 *
> -	 * The memory map is sorted, so we keep track of the end of
> -	 * any previous region we want to keep, remember any region
> -	 * we want to free and defer freeing it until we encounter
> -	 * the next region we want to keep. This way, before freeing
> -	 * it, we can clip it as needed to avoid freeing memory we
> -	 * want to keep for UEFI.
> -	 */
> -
> -	keep_end = 0;
> -	free_start = 0;
> -
> -	for_each_efi_memory_desc(&memmap, md) {
> -		u64 paddr, npages, size;
> -
> -		if (is_reserve_region(md)) {
> -			/*
> -			 * We don't want to free any memory from this region.
> -			 */
> -			if (free_start) {
> -				/* adjust free_end then free region */
> -				if (free_end > md->phys_addr)
> -					free_end -= PAGE_SIZE;
> -				total_freed += free_region(free_start, free_end);
> -				free_start = 0;
> -			}
> -			keep_end = md->phys_addr + (md->num_pages << EFI_PAGE_SHIFT);
> -			continue;
> -		}
> -
> -		if (md->type != EFI_BOOT_SERVICES_CODE &&
> -		    md->type != EFI_BOOT_SERVICES_DATA) {
> -			/* no need to free this region */
> -			continue;
> -		}
> -
> -		/*
> -		 * We want to free memory from this region.
> -		 */
> -		paddr = md->phys_addr;
> -		npages = md->num_pages;
> -		memrange_efi_to_native(&paddr, &npages);
> -		size = npages << PAGE_SHIFT;
> -
> -		if (free_start) {
> -			if (paddr <= free_end)
> -				free_end = paddr + size;
> -			else {
> -				total_freed += free_region(free_start, free_end);
> -				free_start = paddr;
> -				free_end = paddr + size;
> -			}
> -		} else {
> -			free_start = paddr;
> -			free_end = paddr + size;
> -		}
> -		if (free_start < keep_end) {
> -			free_start += PAGE_SIZE;
> -			if (free_start >= free_end)
> -				free_start = 0;
> -		}
> -	}
> -	if (free_start)
> -		total_freed += free_region(free_start, free_end);
> -
> -	if (total_freed)
> -		pr_info("Freed 0x%llx bytes of EFI boot services memory",
> -			total_freed);
> -}
> -
>  void __init efi_init(void)
>  {
>  	struct efi_fdt_params params;
> @@ -396,8 +277,6 @@ static int __init arm64_enter_virtual_mode(void)
>  	}
>  	set_bit(EFI_SYSTEM_TABLES, &efi.flags);
>  
> -	free_boot_services();
> -
>  	if (!efi_enabled(EFI_VIRTMAP)) {
>  		pr_err("No UEFI virtual mapping was installed -- runtime services will not be available\n");
>  		return -1;
> -- 
> 1.8.3.2

Acked-by: Leif Lindholm <leif.lindholm-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>