[PATCH v7 7/7] powerpc/32: use set_memory_attr()

[Christophe Leroy]

Le 01/04/2020 à 04:27, Russell Currey a écrit :
> On Tue, 2020-03-31 at 11:56 +0200, Christophe Leroy wrote:
>>
>> Le 31/03/2020 à 06:48, Russell Currey a écrit :
>>> From: Christophe Leroy <christophe.leroy at c-s.fr>
>>>
>>> Use set_memory_attr() instead of the PPC32 specific
>>> change_page_attr()
>>>
>>> change_page_attr() was checking that the address was not mapped by
>>> blocks and was handling highmem, but that's unneeded because the
>>> affected pages can't be in highmem and block mapping verification
>>> is already done by the callers.
>>>
>>> Signed-off-by: Christophe Leroy <christophe.leroy at c-s.fr>
>>> ---
>>>    arch/powerpc/mm/pgtable_32.c | 95 ++++---------------------------
>>> -----
>>>    1 file changed, 10 insertions(+), 85 deletions(-)
>>>
>>> diff --git a/arch/powerpc/mm/pgtable_32.c
>>> b/arch/powerpc/mm/pgtable_32.c
>>> index 5fb90edd865e..3d92eaf3ee2f 100644
>>> --- a/arch/powerpc/mm/pgtable_32.c
>>> +++ b/arch/powerpc/mm/pgtable_32.c
>>> @@ -23,6 +23,7 @@
>>>    #include <linux/highmem.h>
>>>    #include <linux/memblock.h>
>>>    #include <linux/slab.h>
>>> +#include <linux/set_memory.h>
>>>    
>>>    #include <asm/pgtable.h>
>>>    #include <asm/pgalloc.h>
>>> @@ -121,99 +122,20 @@ void __init mapin_ram(void)
>>>    	}
>>>    }
>>>    
>>> -/* Scan the real Linux page tables and return a PTE pointer for
>>> - * a virtual address in a context.
>>> - * Returns true (1) if PTE was found, zero otherwise.  The pointer
>>> to
>>> - * the PTE pointer is unmodified if PTE is not found.
>>> - */
>>> -static int
>>> -get_pteptr(struct mm_struct *mm, unsigned long addr, pte_t **ptep,
>>> pmd_t **pmdp)
>>
>> This will conflict, get_pteptr() is gone now, see
>> https://github.com/linuxppc/linux/commit/2efc7c085f05870eda6f29ac71eeb83f3bd54415
>>
>> Christophe
> 
> OK cool, so I can just drop that hunk?  Will try that and make sure it
> rebases on powerpc/next

Well, you still have to remove __change_page_attr_noflush() and 
change_page_attr(), everything else in this patch should still be the same.

Christophe

> 
> - Russell
> 
>>
>>
>>> -{
>>> -        pgd_t	*pgd;
>>> -	pud_t	*pud;
>>> -        pmd_t	*pmd;
>>> -        pte_t	*pte;
>>> -        int     retval = 0;
>>> -
>>> -        pgd = pgd_offset(mm, addr & PAGE_MASK);
>>> -        if (pgd) {
>>> -		pud = pud_offset(pgd, addr & PAGE_MASK);
>>> -		if (pud && pud_present(*pud)) {
>>> -			pmd = pmd_offset(pud, addr & PAGE_MASK);
>>> -			if (pmd_present(*pmd)) {
>>> -				pte = pte_offset_map(pmd, addr &
>>> PAGE_MASK);
>>> -				if (pte) {
>>> -					retval = 1;
>>> -					*ptep = pte;
>>> -					if (pmdp)
>>> -						*pmdp = pmd;
>>> -					/* XXX caller needs to do
>>> pte_unmap, yuck */
>>> -				}
>>> -			}
>>> -		}
>>> -        }
>>> -        return(retval);
>>> -}
>>> -
>>> -static int __change_page_attr_noflush(struct page *page, pgprot_t
>>> prot)
>>> -{
>>> -	pte_t *kpte;
>>> -	pmd_t *kpmd;
>>> -	unsigned long address;
>>> -
>>> -	BUG_ON(PageHighMem(page));
>>> -	address = (unsigned long)page_address(page);
>>> -
>>> -	if (v_block_mapped(address))
>>> -		return 0;
>>> -	if (!get_pteptr(&init_mm, address, &kpte, &kpmd))
>>> -		return -EINVAL;
>>> -	__set_pte_at(&init_mm, address, kpte, mk_pte(page, prot), 0);
>>> -	pte_unmap(kpte);
>>> -
>>> -	return 0;
>>> -}
>>> -
>>> -/*
>>> - * Change the page attributes of an page in the linear mapping.
>>> - *
>>> - * THIS DOES NOTHING WITH BAT MAPPINGS, DEBUG USE ONLY
>>> - */
>>> -static int change_page_attr(struct page *page, int numpages,
>>> pgprot_t prot)
>>> -{
>>> -	int i, err = 0;
>>> -	unsigned long flags;
>>> -	struct page *start = page;
>>> -
>>> -	local_irq_save(flags);
>>> -	for (i = 0; i < numpages; i++, page++) {
>>> -		err = __change_page_attr_noflush(page, prot);
>>> -		if (err)
>>> -			break;
>>> -	}
>>> -	wmb();
>>> -	local_irq_restore(flags);
>>> -	flush_tlb_kernel_range((unsigned long)page_address(start),
>>> -			       (unsigned long)page_address(page));
>>> -	return err;
>>> -}
>>> -
>>>    void mark_initmem_nx(void)
>>>    {
>>> -	struct page *page = virt_to_page(_sinittext);
>>>    	unsigned long numpages = PFN_UP((unsigned long)_einittext) -
>>>    				 PFN_DOWN((unsigned long)_sinittext);
>>>    
>>>    	if (v_block_mapped((unsigned long)_stext + 1))
>>>    		mmu_mark_initmem_nx();
>>>    	else
>>> -		change_page_attr(page, numpages, PAGE_KERNEL);
>>> +		set_memory_attr((unsigned long)_sinittext, numpages,
>>> PAGE_KERNEL);
>>>    }
>>>    
>>>    #ifdef CONFIG_STRICT_KERNEL_RWX
>>>    void mark_rodata_ro(void)
>>>    {
>>> -	struct page *page;
>>>    	unsigned long numpages;
>>>    
>>>    	if (v_block_mapped((unsigned long)_sinittext)) {
>>> @@ -222,20 +144,18 @@ void mark_rodata_ro(void)
>>>    		return;
>>>    	}
>>>    
>>> -	page = virt_to_page(_stext);
>>>    	numpages = PFN_UP((unsigned long)_etext) -
>>>    		   PFN_DOWN((unsigned long)_stext);
>>>    
>>> -	change_page_attr(page, numpages, PAGE_KERNEL_ROX);
>>> +	set_memory_attr((unsigned long)_stext, numpages,
>>> PAGE_KERNEL_ROX);
>>>    	/*
>>>    	 * mark .rodata as read only. Use __init_begin rather than
>>> __end_rodata
>>>    	 * to cover NOTES and EXCEPTION_TABLE.
>>>    	 */
>>> -	page = virt_to_page(__start_rodata);
>>>    	numpages = PFN_UP((unsigned long)__init_begin) -
>>>    		   PFN_DOWN((unsigned long)__start_rodata);
>>>    
>>> -	change_page_attr(page, numpages, PAGE_KERNEL_RO);
>>> +	set_memory_attr((unsigned long)__start_rodata, numpages,
>>> PAGE_KERNEL_RO);
>>>    
>>>    	// mark_initmem_nx() should have already run by now
>>>    	ptdump_check_wx();
>>> @@ -245,9 +165,14 @@ void mark_rodata_ro(void)
>>>    #ifdef CONFIG_DEBUG_PAGEALLOC
>>>    void __kernel_map_pages(struct page *page, int numpages, int
>>> enable)
>>>    {
>>> +	unsigned long addr = (unsigned long)page_address(page);
>>> +
>>>    	if (PageHighMem(page))
>>>    		return;
>>>    
>>> -	change_page_attr(page, numpages, enable ? PAGE_KERNEL :
>>> __pgprot(0));
>>> +	if (enable)
>>> +		set_memory_attr(addr, numpages, PAGE_KERNEL);
>>> +	else
>>> +		set_memory_attr(addr, numpages, __pgprot(0));
>>>    }
>>>    #endif /* CONFIG_DEBUG_PAGEALLOC */
>>>