Re: [PATCH v4] x86/xen: Use __pa_symbol instead of __pa on C visible symbols

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

On Fri, Nov 16, 2012 at 01:45:25PM -0800, Alexander Duyck wrote:
> This change updates a few of the functions to use __pa_symbol when
> translating C visible symbols instead of __pa.  By using __pa_symbol we are
> able to drop a few extra lines of code as don't have to test to see if the
> virtual pointer is a part of the kernel text or just standard virtual memory.
> 
> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
> Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
> ---
> 
> v4:  I have spun this patch off as a separate patch for v4 due to the fact that
>      this patch doesn't apply cleanly to Linus's tree.  As such I am
>      submitting it based off of the linux-next tree to be accepted in the Xen
>      tree since this patch can actually exist on its own without the need
>      for the other patches in the original __phys_addr performance series.

OK, let me stick it in my tree then.

> 
>  arch/x86/xen/mmu.c |   21 +++++++++++----------
>  1 files changed, 11 insertions(+), 10 deletions(-)
> 
> diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
> index 4a05b39..a63e5f9 100644
> --- a/arch/x86/xen/mmu.c
> +++ b/arch/x86/xen/mmu.c
> @@ -1486,7 +1486,8 @@ static int xen_pgd_alloc(struct mm_struct *mm)
>  
>  		if (user_pgd != NULL) {
>  			user_pgd[pgd_index(VSYSCALL_START)] =
> -				__pgd(__pa(level3_user_vsyscall) | _PAGE_TABLE);
> +				__pgd(__pa_symbol(level3_user_vsyscall) |
> +				      _PAGE_TABLE);
>  			ret = 0;
>  		}
>  
> @@ -1958,10 +1959,10 @@ void __init xen_setup_kernel_pagetable(pgd_t *pgd, unsigned long max_pfn)
>  	 * pgd.
>  	 */
>  	if (xen_feature(XENFEAT_writable_page_tables)) {
> -		native_write_cr3(__pa(init_level4_pgt));
> +		native_write_cr3(__pa_symbol(init_level4_pgt));
>  	} else {
>  		xen_mc_batch();
> -		__xen_write_cr3(true, __pa(init_level4_pgt));
> +		__xen_write_cr3(true, __pa_symbol(init_level4_pgt));
>  		xen_mc_issue(PARAVIRT_LAZY_CPU);
>  	}
>  	/* We can't that easily rip out L3 and L2, as the Xen pagetables are
> @@ -1984,10 +1985,10 @@ static RESERVE_BRK_ARRAY(pmd_t, swapper_kernel_pmd, PTRS_PER_PMD);
>  
>  static void __init xen_write_cr3_init(unsigned long cr3)
>  {
> -	unsigned long pfn = PFN_DOWN(__pa(swapper_pg_dir));
> +	unsigned long pfn = PFN_DOWN(__pa_symbol(swapper_pg_dir));
>  
> -	BUG_ON(read_cr3() != __pa(initial_page_table));
> -	BUG_ON(cr3 != __pa(swapper_pg_dir));
> +	BUG_ON(read_cr3() != __pa_symbol(initial_page_table));
> +	BUG_ON(cr3 != __pa_symbol(swapper_pg_dir));
>  
>  	/*
>  	 * We are switching to swapper_pg_dir for the first time (from
> @@ -2011,7 +2012,7 @@ static void __init xen_write_cr3_init(unsigned long cr3)
>  	pin_pagetable_pfn(MMUEXT_PIN_L3_TABLE, pfn);
>  
>  	pin_pagetable_pfn(MMUEXT_UNPIN_TABLE,
> -			  PFN_DOWN(__pa(initial_page_table)));
> +			  PFN_DOWN(__pa_symbol(initial_page_table)));
>  	set_page_prot(initial_page_table, PAGE_KERNEL);
>  	set_page_prot(initial_kernel_pmd, PAGE_KERNEL);
>  
> @@ -2036,7 +2037,7 @@ void __init xen_setup_kernel_pagetable(pgd_t *pgd, unsigned long max_pfn)
>  
>  	copy_page(initial_page_table, pgd);
>  	initial_page_table[KERNEL_PGD_BOUNDARY] =
> -		__pgd(__pa(initial_kernel_pmd) | _PAGE_PRESENT);
> +		__pgd(__pa_symbol(initial_kernel_pmd) | _PAGE_PRESENT);
>  
>  	set_page_prot(initial_kernel_pmd, PAGE_KERNEL_RO);
>  	set_page_prot(initial_page_table, PAGE_KERNEL_RO);
> @@ -2045,8 +2046,8 @@ void __init xen_setup_kernel_pagetable(pgd_t *pgd, unsigned long max_pfn)
>  	pin_pagetable_pfn(MMUEXT_UNPIN_TABLE, PFN_DOWN(__pa(pgd)));
>  
>  	pin_pagetable_pfn(MMUEXT_PIN_L3_TABLE,
> -			  PFN_DOWN(__pa(initial_page_table)));
> -	xen_write_cr3(__pa(initial_page_table));
> +			  PFN_DOWN(__pa_symbol(initial_page_table)));
> +	xen_write_cr3(__pa_symbol(initial_page_table));
>  
>  	memblock_reserve(__pa(xen_start_info->pt_base),
>  			 xen_start_info->nr_pt_frames * PAGE_SIZE);