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

set_memory_attr() was implemented by commit 4d1755b6a762 ("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 c988cfd38e48 ("powerpc/32:
use set_memory_attr()") but since commit 9f7853d7609d ("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: c988cfd38e48 ("powerpc/32: use set_memory_attr()")
Cc: stable@vger.kernel.org
Reported-by: Maxime Bizon <mbizon@freebox.fr>
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Tested-by: Maxime Bizon <mbizon@freebox.fr>
Reviewed-by: Russell Currey <ruscur@russell.cc>
Depends-on: 9f7853d7609d ("powerpc/mm: Fix set_memory_*() against concurrent accesses")
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/cda2b44b55c96f9ac69fa92e68c01084ec9495c5.1640344012.git.christophe.leroy@csgroup.eu

1 files changed, 11 insertions, 13 deletions

diff --git a/arch/powerpc/mm/pgtable_32.c b/arch/powerpc/mm/pgtable_32.c
index 906e4e4328b2..f71ededdc02a 100644
--- a/arch/powerpc/mm/pgtable_32.c
+++ b/arch/powerpc/mm/pgtable_32.c
@@ -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 */