linux-kernel - Re: [PATCH] x86: EFI runtime code mapping enhancement

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Date:	Fri, 15 Feb 2008 10:25:28 +0800
From:	"Huang, Ying" <ying.huang@...el.com>
To:	Ingo Molnar <mingo@...hat.com>
Cc:	ThomasGleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>, Andi Kleen <ak@...e.de>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] x86: EFI runtime code mapping enhancement

Hi, Ingo,

Please revert this patch. Because it does not work with 1GB pages.
Although the original implementation does not work with 1GB pages too,
it can be fixed easier than this one. I will compose a new patch to fix
the original implementation.

Best Regards,
Huang Ying

On Wed, 2008-02-13 at 17:22 +0800, Huang, Ying wrote:
> This patch enhances EFI runtime code memory mapping as following:
> 
> - Move __supported_pte_mask & _PAGE_NX checking before invoking
>   runtime_code_page_mkexec(). This makes it possible for compiler to
>   eliminate runtime_code_page_mkexec() on machine without NX support.
> 
> - Use set_memory_x/nx in early_mapping_set_exec(). This eliminates the
>   duplicated implementation.
> 
> This patch has been tested on Intel x86_64 platform with EFI64/32
> firmware.
> 
> Signed-off-by: Huang Ying <ying.huang@...el.com>
> 
> ---
>  arch/x86/kernel/efi.c    |    6 ++----
>  arch/x86/kernel/efi_64.c |   30 ++++++++++++------------------
>  2 files changed, 14 insertions(+), 22 deletions(-)
> 
> --- a/arch/x86/kernel/efi.c
> +++ b/arch/x86/kernel/efi.c
> @@ -384,9 +384,6 @@ static void __init runtime_code_page_mke
>  	efi_memory_desc_t *md;
>  	void *p;
>  
> -	if (!(__supported_pte_mask & _PAGE_NX))
> -		return;
> -
>  	/* Make EFI runtime service code area executable */
>  	for (p = memmap.map; p < memmap.map_end; p += memmap.desc_size) {
>  		md = p;
> @@ -476,7 +473,8 @@ void __init efi_enter_virtual_mode(void)
>  	efi.get_next_high_mono_count = virt_efi_get_next_high_mono_count;
>  	efi.reset_system = virt_efi_reset_system;
>  	efi.set_virtual_address_map = virt_efi_set_virtual_address_map;
> -	runtime_code_page_mkexec();
> +	if (__supported_pte_mask & _PAGE_NX)
> +		runtime_code_page_mkexec();
>  	early_iounmap(memmap.map, memmap.nr_map * memmap.desc_size);
>  	memmap.map = NULL;
>  }
> --- a/arch/x86/kernel/efi_64.c
> +++ b/arch/x86/kernel/efi_64.c
> @@ -35,6 +35,7 @@
>  #include <asm/tlbflush.h>
>  #include <asm/proto.h>
>  #include <asm/efi.h>
> +#include <asm/cacheflush.h>
>  
>  static pgd_t save_pgd __initdata;
>  static unsigned long efi_flags __initdata;
> @@ -43,22 +44,15 @@ static void __init early_mapping_set_exe
>  					  unsigned long end,
>  					  int executable)
>  {
> -	pte_t *kpte;
> -	unsigned int level;
> +	unsigned long num_pages;
>  
> -	while (start < end) {
> -		kpte = lookup_address((unsigned long)__va(start), &level);
> -		BUG_ON(!kpte);
> -		if (executable)
> -			set_pte(kpte, pte_mkexec(*kpte));
> -		else
> -			set_pte(kpte, __pte((pte_val(*kpte) | _PAGE_NX) & \
> -					    __supported_pte_mask));
> -		if (level == PG_LEVEL_4K)
> -			start = (start + PAGE_SIZE) & PAGE_MASK;
> -		else
> -			start = (start + PMD_SIZE) & PMD_MASK;
> -	}
> +	start &= PMD_MASK;
> +	end = (end + PMD_SIZE - 1) & PMD_MASK;
> +	num_pages = (end - start) >> PAGE_SHIFT;
> +	if (executable)
> +		set_memory_x((unsigned long)__va(start), num_pages);
> +	else
> +		set_memory_nx((unsigned long)__va(start), num_pages);
>  }
>  
>  static void __init early_runtime_code_mapping_set_exec(int executable)
> @@ -74,7 +68,7 @@ static void __init early_runtime_code_ma
>  		md = p;
>  		if (md->type == EFI_RUNTIME_SERVICES_CODE) {
>  			unsigned long end;
> -			end = md->phys_addr + (md->num_pages << PAGE_SHIFT);
> +			end = md->phys_addr + (md->num_pages << EFI_PAGE_SHIFT);
>  			early_mapping_set_exec(md->phys_addr, end, executable);
>  		}
>  	}
> @@ -84,8 +78,8 @@ void __init efi_call_phys_prelog(void)
>  {
>  	unsigned long vaddress;
>  
> -	local_irq_save(efi_flags);
>  	early_runtime_code_mapping_set_exec(1);
> +	local_irq_save(efi_flags);
>  	vaddress = (unsigned long)__va(0x0UL);
>  	save_pgd = *pgd_offset_k(0x0UL);
>  	set_pgd(pgd_offset_k(0x0UL), *pgd_offset_k(vaddress));
> @@ -98,9 +92,9 @@ void __init efi_call_phys_epilog(void)
>  	 * After the lock is released, the original page table is restored.
>  	 */
>  	set_pgd(pgd_offset_k(0x0UL), save_pgd);
> -	early_runtime_code_mapping_set_exec(0);
>  	__flush_tlb_all();
>  	local_irq_restore(efi_flags);
> +	early_runtime_code_mapping_set_exec(0);
>  }
>  
>  void __init efi_reserve_bootmem(void)
> 
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