[PATCH v2 1/2] arm64: don't make early_*map() calls post paging_init()

[msalter@redhat.com (Mark Salter)]

On Tue, 2015-01-06 at 13:41 +0000, Leif Lindholm wrote:
> arm64 early_ioremap/iounmap/memremap/memunmap are not supported beyond
> the call to paging_init(), but arm64_enter_virtual_mode() (an early
> initcall) makes one call to unmap the UEFI memory map.
> 
> Rearrange the code to unmap this region before paging_init(), and then
> pull back the remapping of the EFI memory map to the second part of
> UEFI initialisation - efi_idmap_init() - renaming that function as
> efi_memmap_init(), which better describes what it now does.

> Signed-off-by: Leif Lindholm <leif.lindholm@linaro.org>
> Fixes: f84d02755f5a ("arm64: add EFI runtime services")
> ---
>  arch/arm64/include/asm/efi.h |  4 ++--
>  arch/arm64/kernel/efi.c      | 27 ++++++++++++++-------------
>  arch/arm64/kernel/setup.c    |  2 +-
>  3 files changed, 17 insertions(+), 16 deletions(-)
> 
> diff --git a/arch/arm64/include/asm/efi.h b/arch/arm64/include/asm/efi.h
> index a34fd3b..92f4d44 100644
> --- a/arch/arm64/include/asm/efi.h
> +++ b/arch/arm64/include/asm/efi.h
> @@ -6,10 +6,10 @@
>  
>  #ifdef CONFIG_EFI
>  extern void efi_init(void);
> -extern void efi_idmap_init(void);
> +extern void efi_memmap_init(void);
>  #else
>  #define efi_init()
> -#define efi_idmap_init()
> +#define efi_memmap_init()
>  #endif
>  
>  #define efi_call_virt(f, ...)						\
> diff --git a/arch/arm64/kernel/efi.c b/arch/arm64/kernel/efi.c
> index 6fac253..e311066 100644
> --- a/arch/arm64/kernel/efi.c
> +++ b/arch/arm64/kernel/efi.c
> @@ -313,17 +313,26 @@ void __init efi_init(void)
>  	memmap.desc_size = params.desc_size;
>  	memmap.desc_version = params.desc_ver;
>  
> -	if (uefi_init() < 0)
> -		return;
> +	if (uefi_init() >= 0)
> +		reserve_regions();
>  
> -	reserve_regions();
> +	early_memunmap(memmap.map, params.mmap_size);
>  }
>  
> -void __init efi_idmap_init(void)
> +void __init efi_memmap_init(void)
>  {
> +	u64 mapsize;
> +
>  	if (!efi_enabled(EFI_BOOT))
>  		return;
>  
> +	/* replace early memmap mapping with permanent mapping */
> +	mapsize = memmap.map_end - memmap.map;
> +	memmap.map = (__force void *)ioremap_cache((phys_addr_t)memmap.phys_map,
> +						   mapsize);

ioremap_cache() could potententially fail here if the phys_map address
doesn't have a valid pfn (not in the kernel linear ram mapping) because
some of the underlying vm support hasn't been initialized yet.

Since this is a mapping which we need during early boot and beyond, why
not just create a fixed mapping for it similar to what we do for the
early console (see FIX_EARLYCON_MEM_BASE)? 

> +	memmap.map_end = memmap.map + mapsize;
> +	efi.memmap = &memmap;
> +
>  	/* boot time idmap_pg_dir is incomplete, so fill in missing parts */
>  	efi_setup_idmap();
>  }
> @@ -379,23 +388,15 @@ static int __init arm64_enter_virtual_mode(void)
>  		return -1;
>  	}
>  
> -	mapsize = memmap.map_end - memmap.map;
> -	early_memunmap(memmap.map, mapsize);
> -
>  	if (efi_runtime_disabled()) {
>  		pr_info("EFI runtime services will be disabled.\n");
>  		return -1;
>  	}
>  
>  	pr_info("Remapping and enabling EFI services.\n");
> -	/* replace early memmap mapping with permanent mapping */
> -	memmap.map = (__force void *)ioremap_cache((phys_addr_t)memmap.phys_map,
> -						   mapsize);
> -	memmap.map_end = memmap.map + mapsize;
> -
> -	efi.memmap = &memmap;
>  
>  	/* Map the runtime regions */
> +	mapsize = memmap.map_end - memmap.map;
>  	virtmap = kmalloc(mapsize, GFP_KERNEL);
>  	if (!virtmap) {
>  		pr_err("Failed to allocate EFI virtual memmap\n");
> diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
> index b809911..ebf7820 100644
> --- a/arch/arm64/kernel/setup.c
> +++ b/arch/arm64/kernel/setup.c
> @@ -401,7 +401,7 @@ void __init setup_arch(char **cmdline_p)
>  	paging_init();
>  	request_standard_resources();
>  
> -	efi_idmap_init();
> +	efi_memmap_init();
>  
>  	unflatten_device_tree();
>