Commit f222ab83 authored by Christophe Leroy's avatar Christophe Leroy Committed by Michael Ellerman
Browse files

powerpc: Add set_memory_{p/np}() and remove set_memory_attr() 



set_memory_attr() was implemented by commit 4d1755b6 ("powerpc/mm:
implement set_memory_attr()") because the set_memory_xx() couldn't
be used at that time to modify memory "on the fly" as explained it
the commit.

But set_memory_attr() uses set_pte_at() which leads to warnings when
CONFIG_DEBUG_VM is selected, because set_pte_at() is unexpected for
updating existing page table entries.

The check could be bypassed by using __set_pte_at() instead,
as it was the case before commit c988cfd3 ("powerpc/32:
use set_memory_attr()") but since commit 9f7853d7 ("powerpc/mm:
Fix set_memory_*() against concurrent accesses") it is now possible
to use set_memory_xx() functions to update page table entries
"on the fly" because the update is now atomic.

For DEBUG_PAGEALLOC we need to clear and set back _PAGE_PRESENT.
Add set_memory_np() and set_memory_p() for that.

Replace all uses of set_memory_attr() by the relevant set_memory_xx()
and remove set_memory_attr().

Fixes: c988cfd3 ("powerpc/32: use set_memory_attr()")
Cc: stable@vger.kernel.org
Reported-by: default avatarMaxime Bizon <mbizon@freebox.fr>
Signed-off-by: default avatarChristophe Leroy <christophe.leroy@csgroup.eu>
Tested-by: default avatarMaxime Bizon <mbizon@freebox.fr>
Reviewed-by: default avatarRussell Currey <ruscur@russell.cc>
Depends-on: 9f7853d7 ("powerpc/mm: Fix set_memory_*() against concurrent accesses")
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/cda2b44b55c96f9ac69fa92e68c01084ec9495c5.1640344012.git.christophe.leroy@csgroup.eu
parent a4c182ec

arch/powerpc/include/asm/set_memory.h

+11 −1
Original line number Diff line number Diff line
@@ -6,6 +6,8 @@ 
#define SET_MEMORY_RW	1

#define SET_MEMORY_NX	2

#define SET_MEMORY_X	3

#define SET_MEMORY_NP	4	/* Set memory non present */

#define SET_MEMORY_P	5	/* Set memory present */



int change_memory_attr(unsigned long addr, int numpages, long action);
@@ -29,6 +31,14 @@ static inline int set_memory_x(unsigned long addr, int numpages) 
	return change_memory_attr(addr, numpages, SET_MEMORY_X);

}



int set_memory_attr(unsigned long addr, int numpages, pgprot_t prot);

static inline int set_memory_np(unsigned long addr, int numpages)

{

	return change_memory_attr(addr, numpages, SET_MEMORY_NP);

}



static inline int set_memory_p(unsigned long addr, int numpages)

{

	return change_memory_attr(addr, numpages, SET_MEMORY_P);

}



#endif

arch/powerpc/mm/pageattr.c

+6 −33
Original line number Diff line number Diff line
@@ -46,6 +46,12 @@ static int change_page_attr(pte_t *ptep, unsigned long addr, void *data) 
	case SET_MEMORY_X:

		pte_update_delta(ptep, addr, _PAGE_KERNEL_RO, _PAGE_KERNEL_ROX);

		break;

	case SET_MEMORY_NP:

		pte_update(&init_mm, addr, ptep, _PAGE_PRESENT, 0, 0);

		break;

	case SET_MEMORY_P:

		pte_update(&init_mm, addr, ptep, 0, _PAGE_PRESENT, 0);

		break;

	default:

		WARN_ON_ONCE(1);

		break;
@@ -90,36 +96,3 @@ int change_memory_attr(unsigned long addr, int numpages, long action) 
	return apply_to_existing_page_range(&init_mm, start, size,

					    change_page_attr, (void *)action);

}
 


/*

 * Set the attributes of a page:

 *

 * This function is used by PPC32 at the end of init to set final kernel memory

 * protection. It includes changing the maping of the page it is executing from

 * and data pages it is using.

 */

static int set_page_attr(pte_t *ptep, unsigned long addr, void *data)

{

	pgprot_t prot = __pgprot((unsigned long)data);



	spin_lock(&init_mm.page_table_lock);



	set_pte_at(&init_mm, addr, ptep, pte_modify(*ptep, prot));

	flush_tlb_kernel_range(addr, addr + PAGE_SIZE);



	spin_unlock(&init_mm.page_table_lock);



	return 0;

}



int set_memory_attr(unsigned long addr, int numpages, pgprot_t prot)

{

	unsigned long start = ALIGN_DOWN(addr, PAGE_SIZE);

	unsigned long sz = numpages * PAGE_SIZE;



	if (numpages <= 0)

		return 0;



	return apply_to_existing_page_range(&init_mm, start, sz, set_page_attr,

					    (void *)pgprot_val(prot));

}

arch/powerpc/mm/pgtable_32.c

+11 −13
Original line number Diff line number Diff line
@@ -135,10 +135,12 @@ void mark_initmem_nx(void) 
	unsigned long numpages = PFN_UP((unsigned long)_einittext) -

				 PFN_DOWN((unsigned long)_sinittext);



	if (v_block_mapped((unsigned long)_sinittext))

	if (v_block_mapped((unsigned long)_sinittext)) {

		mmu_mark_initmem_nx();

	else

		set_memory_attr((unsigned long)_sinittext, numpages, PAGE_KERNEL);

	} else {

		set_memory_nx((unsigned long)_sinittext, numpages);

		set_memory_rw((unsigned long)_sinittext, numpages);

	}

}



#ifdef CONFIG_STRICT_KERNEL_RWX
@@ -152,18 +154,14 @@ void mark_rodata_ro(void) 
		return;

	}



	numpages = PFN_UP((unsigned long)_etext) -

		   PFN_DOWN((unsigned long)_stext);



	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.

	 * mark .text and .rodata as read only. Use __init_begin rather than

	 * __end_rodata to cover NOTES and EXCEPTION_TABLE.

	 */

	numpages = PFN_UP((unsigned long)__init_begin) -

		   PFN_DOWN((unsigned long)__start_rodata);

		   PFN_DOWN((unsigned long)_stext);



	set_memory_attr((unsigned long)__start_rodata, numpages, PAGE_KERNEL_RO);

	set_memory_ro((unsigned long)_stext, numpages);



	// mark_initmem_nx() should have already run by now

	ptdump_check_wx();
@@ -179,8 +177,8 @@ void __kernel_map_pages(struct page *page, int numpages, int enable) 
		return;



	if (enable)

		set_memory_attr(addr, numpages, PAGE_KERNEL);

		set_memory_p(addr, numpages);

	else

		set_memory_attr(addr, numpages, __pgprot(0));

		set_memory_np(addr, numpages);

}

#endif /* CONFIG_DEBUG_PAGEALLOC */