parisc: fix map_pages() to actually populate upper directory

PATCH In review Mike Rapoport 3 participants 4 messages Jan 8, 2020 – Jan 11, 2020 PA-RISC architecture

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Mike Rapoport

author

2020-01-08 12:59 UTC #0 lore raw

PATCH 1/1 parisc: fix map_pages() to actually populate upper directory

From: Mike Rapoport <[email protected]>

The commit d96885e277b5 ("parisc: use pgtable-nopXd instead of 4level-fixup") converted PA-RISC to use folded page tables, but it missed the conversion of pgd_populate() to pud_populate() in maps_pages() function. This caused the upper page table directory to remain empty and the system would crash as a result.

Using pud_populate() that actually populates the page table instead of dummy pgd_populate() fixes the issue.

Fixes d96885e277b5 ("parisc: use pgtable-nopXd instead of 4level-fixup")

Reported-by Meelis Roos <[email protected]>

Reported-by Jeroen Roovers <[email protected]>

Reported-by Mikulas Patocka <[email protected]>

Tested-by Jeroen Roovers <[email protected]>

Tested-by Mikulas Patocka <[email protected]>

Signed-off-by Mike Rapoport <[email protected]>

---
 arch/parisc/mm/init.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

arch/parisc/mm/init.c +1 -1

index ddca8287d43b..354cf060b67f 100644
@@ -401,7 +401,7 @@ static void __init map_pages(unsigned long start_vaddr,
 			pmd = (pmd_t *) __pa(pmd);
 		}
 
-		pgd_populate(NULL, pg_dir, __va(pmd));
+		pud_populate(NULL, (pud_t *)pg_dir, __va(pmd));
 #endif
 		pg_dir++;

Signature · 1 line

2.24.0

Helge Deller

maintainer

2020-01-09 06:51 UTC #1 lore raw

Quoted 14 lines

The commit d96885e277b5 ("parisc: use pgtable-nopXd instead of 4level-fixup") converted PA-RISC to use folded page tables, but it missed the conversion of pgd_populate() to pud_populate() in maps_pages() function. This caused the upper page table directory to remain empty and the system would crash as a result.
Using pud_populate() that actually populates the page table instead of dummy pgd_populate() fixes the issue.
...
arch/parisc/mm/init.c +0 -0
index ddca8287d43b..354cf060b67f 100644

arch/parisc/mm/init.c static void __init map_pages(unsigned long start_vaddr, · line 405

Quoted 6 lines

arch/parisc/mm/init.c +1 -1

@@ -401,7 +401,7 @@ static void __init map_pages(unsigned long start_vaddr,
 			pmd = (pmd_t *) __pa(pmd);
 		}
 
-		pgd_populate(NULL, pg_dir, __va(pmd));
+		pud_populate(NULL, (pud_t *)pg_dir, __va(pmd));
 #endif

Wouldn't the untested patch below be more clean?

Helge

arch/parisc/mm/init.c +5 -1

index ddca8287d43b..73de58f31f5f 100644
@@ -387,6 +387,8 @@ static void __init map_pages(unsigned long start_vaddr,
 #if PTRS_PER_PMD == 1
 		pmd = (pmd_t *)__pa(pg_dir);
 #else
+		p4d_t *p4d;
+		pud_t *pud;
 		pmd = (pmd_t *)pgd_address(*pg_dir);
 
 		/*

@@ -401,7 +403,9 @@ static void __init map_pages(unsigned long start_vaddr,
 			pmd = (pmd_t *) __pa(pmd);
 		}
 
-		pgd_populate(NULL, pg_dir, __va(pmd));
+		p4d = p4d_offset(pg_dir, vaddr);
+		pud = pud_offset(p4d, vaddr);
+		pud_populate(NULL, pud, __va(pmd));
 #endif
 		pg_dir++;

Mike Rapoport

2020-01-09 08:45 UTC #2 lore raw

Hi,

Quoted 39 lines · Helge Deller

Quoted 14 lines
The commit d96885e277b5 ("parisc: use pgtable-nopXd instead of 4level-fixup") converted PA-RISC to use folded page tables, but it missed the conversion of pgd_populate() to pud_populate() in maps_pages() function. This caused the upper page table directory to remain empty and the system would crash as a result.
Using pud_populate() that actually populates the page table instead of dummy pgd_populate() fixes the issue.
...
arch/parisc/mm/init.c +0 -0
index ddca8287d43b..354cf060b67f 100644
arch/parisc/mm/init.c static void __init map_pages(unsigned long start_vaddr, · line 405
Quoted 6 lines
arch/parisc/mm/init.c +1 -1
@@ -401,7 +401,7 @@ static void __init map_pages(unsigned long start_vaddr,
 			pmd = (pmd_t *) __pa(pmd);
 		}
 
-		pgd_populate(NULL, pg_dir, __va(pmd));
+		pud_populate(NULL, (pud_t *)pg_dir, __va(pmd));
 #endif
Wouldn't the untested patch below be more clean?
Helge
arch/parisc/mm/init.c +2 -0
index ddca8287d43b..73de58f31f5f 100644
@@ -387,6 +387,8 @@ static void __init map_pages(unsigned long start_vaddr,
 #if PTRS_PER_PMD == 1
 		pmd = (pmd_t *)__pa(pg_dir);
 #else
+		p4d_t *p4d;
+		pud_t *pud;
 		pmd = (pmd_t *)pgd_address(*pg_dir);
 
 		/*

arch/parisc/mm/init.c static void __init map_pages(unsigned long start_vaddr, · line 410

Quoted 9 lines

arch/parisc/mm/init.c +3 -1

@@ -401,7 +403,9 @@ static void __init map_pages(unsigned long start_vaddr,
 			pmd = (pmd_t *) __pa(pmd);
 		}
 
-		pgd_populate(NULL, pg_dir, __va(pmd));
+		p4d = p4d_offset(pg_dir, vaddr);
+		pud = pud_offset(p4d, vaddr);
+		pud_populate(NULL, pud, __va(pmd));
 #endif
 		pg_dir++;

I've tried to keep the changes to minimum :) Otherwise I'd go with something even more surgical:

arch/parisc/mm/init.c +11 ~~-34~~

index 354cf060b67f..94baa4382c29 100644
@@ -351,7 +351,6 @@ static void __init map_pages(unsigned long start_vaddr,
 			     unsigned long start_paddr, unsigned long size,
 			     pgprot_t pgprot, int force)
 {
-	pgd_t *pg_dir;
 	pmd_t *pmd;
 	pte_t *pg_table;
 	unsigned long end_paddr;

@@ -372,8 +371,6 @@ static void __init map_pages(unsigned long start_vaddr,
 
 	end_paddr = start_paddr + size;
 
-	pg_dir = pgd_offset_k(start_vaddr);
-
 #if PTRS_PER_PMD == 1
 	start_pmd = 0;
 #else

@@ -384,50 +381,30 @@ static void __init map_pages(unsigned long start_vaddr,
 	address = start_paddr;
 	vaddr = start_vaddr;
 	while (address < end_paddr) {
-#if PTRS_PER_PMD == 1
-		pmd = (pmd_t *)__pa(pg_dir);
-#else
-		pmd = (pmd_t *)pgd_address(*pg_dir);
+		pgd_t *pgd = pgd_offset_k(vaddr);
+		p4d_t *p4d = p4d_offset(pgd, vaddr);
+		pud_t *pud = pud_offset(p4d, vaddr);
 
-		/*
-		 * pmd is physical at this point
-		 */
-
-		if (!pmd) {
+#if CONFIG_PGTABLE_LEVELS == 3
+		if (pud_none(*pud)) {
 			pmd = memblock_alloc(PAGE_SIZE << PMD_ORDER,
 					     PAGE_SIZE << PMD_ORDER);
 			if (!pmd)
 				panic("pmd allocation failed.\n");
-			pmd = (pmd_t *) __pa(pmd);
+			pud_populate(NULL, pud, pmd);
 		}
-
-		pud_populate(NULL, (pud_t *)pg_dir, __va(pmd));
 #endif
-		pg_dir++;
 
-		/* now change pmd to kernel virtual addresses */
-
-		pmd = (pmd_t *)__va(pmd) + start_pmd;
+		pmd = pmd_offset(pud, vaddr);
 		for (tmp1 = start_pmd; tmp1 < PTRS_PER_PMD; tmp1++, pmd++) {
-
-			/*
-			 * pg_table is physical at this point
-			 */
-
-			pg_table = (pte_t *)pmd_address(*pmd);
-			if (!pg_table) {
-				pg_table = memblock_alloc(PAGE_SIZE,
-							  PAGE_SIZE);
+			if (pmd_none(*pmd)) {
+				pg_table = memblock_alloc(PAGE_SIZE, PAGE_SIZE);
 				if (!pg_table)
 					panic("page table allocation failed\n");
-				pg_table = (pte_t *) __pa(pg_table);
+				pmd_populate_kernel(NULL, pmd, pg_table);
 			}
 
-			pmd_populate_kernel(NULL, pmd, __va(pg_table));
-
-			/* now change pg_table to kernel virtual addresses */
-
-			pg_table = (pte_t *) __va(pg_table) + start_pte;
+			pg_table = pte_offset_kernel(pmd, vaddr);
 			for (tmp2 = start_pte; tmp2 < PTRS_PER_PTE; tmp2++, pg_table++) {
 				pte_t pte;
 				pgprot_t prot;

Signature · 2 lines

Sincerely yours,
Mike.

Helge Deller

maintainer

2020-01-11 15:54 UTC #3 lore raw

Quoted 45 lines · Mike Rapoport

Hi,
Quoted 42 lines · Helge Deller
Quoted 14 lines
The commit d96885e277b5 ("parisc: use pgtable-nopXd instead of 4level-fixup") converted PA-RISC to use folded page tables, but it missed the conversion of pgd_populate() to pud_populate() in maps_pages() function. This caused the upper page table directory to remain empty and the system would crash as a result.
Using pud_populate() that actually populates the page table instead of dummy pgd_populate() fixes the issue.
...
arch/parisc/mm/init.c +0 -0
index ddca8287d43b..354cf060b67f 100644
arch/parisc/mm/init.c static void __init map_pages(unsigned long start_vaddr, · line 405
Quoted 6 lines
arch/parisc/mm/init.c +1 -1
@@ -401,7 +401,7 @@ static void __init map_pages(unsigned long start_vaddr,
 			pmd = (pmd_t *) __pa(pmd);
 		}
 
-		pgd_populate(NULL, pg_dir, __va(pmd));
+		pud_populate(NULL, (pud_t *)pg_dir, __va(pmd));
 #endif
Wouldn't the untested patch below be more clean?
Helge
arch/parisc/mm/init.c +2 -0
index ddca8287d43b..73de58f31f5f 100644
@@ -387,6 +387,8 @@ static void __init map_pages(unsigned long start_vaddr,
 #if PTRS_PER_PMD == 1
 		pmd = (pmd_t *)__pa(pg_dir);
 #else
+		p4d_t *p4d;
+		pud_t *pud;
 		pmd = (pmd_t *)pgd_address(*pg_dir);
 
 		/*
@@ -401,7 +403,9 @@ static void __init map_pages(unsigned long start_vaddr,
 			pmd = (pmd_t *) __pa(pmd);
 		}
 

Quoted 9 lines

arch/parisc/mm/init.c static void __init map_pages(unsigned long start_vaddr, · line 410
Quoted 6 lines
arch/parisc/mm/init.c +3 -1
-		pgd_populate(NULL, pg_dir, __va(pmd));
+		p4d = p4d_offset(pg_dir, vaddr);
+		pud = pud_offset(p4d, vaddr);
+		pud_populate(NULL, pud, __va(pmd));
 #endif
 		pg_dir++;
I've tried to keep the changes to minimum :) Otherwise I'd go with something even more surgical:

Ok, then let's use the small fix for v5.5, and the bigger one for v5.6. I'll push the small fixup to Linux through the parisc tree shortly.

Would you mind resending the full cleanup patch for v5.6 later again ?

Thanks!!
Helge

Quoted 86 lines

arch/parisc/mm/init.c +11 ~~-34~~

index 354cf060b67f..94baa4382c29 100644
@@ -351,7 +351,6 @@ static void __init map_pages(unsigned long start_vaddr,
 			     unsigned long start_paddr, unsigned long size,
 			     pgprot_t pgprot, int force)
 {
-	pgd_t *pg_dir;
 	pmd_t *pmd;
 	pte_t *pg_table;
 	unsigned long end_paddr;

@@ -372,8 +371,6 @@ static void __init map_pages(unsigned long start_vaddr,
 
 	end_paddr = start_paddr + size;
 
-	pg_dir = pgd_offset_k(start_vaddr);
-
 #if PTRS_PER_PMD == 1
 	start_pmd = 0;
 #else

@@ -384,50 +381,30 @@ static void __init map_pages(unsigned long start_vaddr,
 	address = start_paddr;
 	vaddr = start_vaddr;
 	while (address < end_paddr) {
-#if PTRS_PER_PMD == 1
-		pmd = (pmd_t *)__pa(pg_dir);
-#else
-		pmd = (pmd_t *)pgd_address(*pg_dir);
+		pgd_t *pgd = pgd_offset_k(vaddr);
+		p4d_t *p4d = p4d_offset(pgd, vaddr);
+		pud_t *pud = pud_offset(p4d, vaddr);
 
-		/*
-		 * pmd is physical at this point
-		 */
-
-		if (!pmd) {
+#if CONFIG_PGTABLE_LEVELS == 3
+		if (pud_none(*pud)) {
 			pmd = memblock_alloc(PAGE_SIZE << PMD_ORDER,
 					     PAGE_SIZE << PMD_ORDER);
 			if (!pmd)
 				panic("pmd allocation failed.\n");
-			pmd = (pmd_t *) __pa(pmd);
+			pud_populate(NULL, pud, pmd);
 		}
-
-		pud_populate(NULL, (pud_t *)pg_dir, __va(pmd));
 #endif
-		pg_dir++;
 
-		/* now change pmd to kernel virtual addresses */
-
-		pmd = (pmd_t *)__va(pmd) + start_pmd;
+		pmd = pmd_offset(pud, vaddr);
 		for (tmp1 = start_pmd; tmp1 < PTRS_PER_PMD; tmp1++, pmd++) {
-
-			/*
-			 * pg_table is physical at this point
-			 */
-
-			pg_table = (pte_t *)pmd_address(*pmd);
-			if (!pg_table) {
-				pg_table = memblock_alloc(PAGE_SIZE,
-							  PAGE_SIZE);
+			if (pmd_none(*pmd)) {
+				pg_table = memblock_alloc(PAGE_SIZE, PAGE_SIZE);
 				if (!pg_table)
 					panic("page table allocation failed\n");
-				pg_table = (pte_t *) __pa(pg_table);
+				pmd_populate_kernel(NULL, pmd, pg_table);
 			}
 
-			pmd_populate_kernel(NULL, pmd, __va(pg_table));
-
-			/* now change pg_table to kernel virtual addresses */
-
-			pg_table = (pte_t *) __va(pg_table) + start_pte;
+			pg_table = pte_offset_kernel(pmd, vaddr);
 			for (tmp2 = start_pte; tmp2 < PTRS_PER_PTE; tmp2++, pg_table++) {
 				pte_t pte;
 				pgprot_t prot;