[RFC 5/8] powerpc/ptdump: Dump PXX level info for kernel_page_tables

Ritesh Harjani (IBM) ritesh.list at gmail.com
Sat Aug 30 13:51:44 AEST 2025


This patch adds PGD/PUD/PMD/PTE level information while dumping kernel
page tables. Before this patch it was hard to identify which entries
belongs to which page table level e.g.

~ # dmesg |grep -i radix
[0.000000] radix-mmu: Mapped 0x0000000000000000-0x0000000005400000 with 2.00 MiB pages (exec)
[0.000000] radix-mmu: Mapped 0x0000000005400000-0x0000000040000000 with 2.00 MiB pages
[0.000000] radix-mmu: Mapped 0x0000000040000000-0x0000000100000000 with 1.00 GiB pages
[0.000000] radix-mmu: Initializing Radix MMU

Before:
---[ Start of kernel VM ]---
0xc000000000000000-0xc000000003ffffff  XXX   64M   r      X   pte  valid  present  dirty  accessed
0xc000000004000000-0xc00000003fffffff  XXX  960M   r  w       pte  valid  present  dirty  accessed
0xc000000040000000-0xc0000000ffffffff  XXX    3G   r  w       pte  valid  present  dirty  accessed
...
---[ vmemmap start ]---
0xc00c000000000000-0xc00c0000003fffff  XXX    4M   r  w       pte  valid  present  dirty  accessed

After:
---[ Start of kernel VM ]---
0xc000000000000000-0xc000000003ffffff  XXX   64M PMD  r      X   pte  valid  present  dirty  accessed
0xc000000004000000-0xc00000003fffffff  XXX  960M PMD  r  w       pte  valid  present  dirty  accessed
0xc000000040000000-0xc0000000ffffffff  XXX    3G PUD  r  w       pte  valid  present  dirty  accessed
...
---[ vmemmap start ]---
0xc00c000000000000-0xc00c0000003fffff  XXX    4M PMD  r  w       pte  valid  present  dirty  accessed

Cc: Madhavan Srinivasan <maddy at linux.ibm.com>
Cc: Michael Ellerman <mpe at ellerman.id.au>
Cc: Nicholas Piggin <npiggin at gmail.com>
Cc: Christophe Leroy <christophe.leroy at csgroup.eu>
Cc: Paul Mackerras <paulus at ozlabs.org>
Cc: "Aneesh Kumar K.V" <aneesh.kumar at kernel.org>
Cc: Donet Tom <donettom at linux.ibm.com>
Cc: linuxppc-dev at lists.ozlabs.org
Signed-off-by: Ritesh Harjani (IBM) <ritesh.list at gmail.com>
---
 arch/powerpc/mm/ptdump/8xx.c      | 5 +++++
 arch/powerpc/mm/ptdump/book3s64.c | 5 +++++
 arch/powerpc/mm/ptdump/ptdump.c   | 1 +
 arch/powerpc/mm/ptdump/ptdump.h   | 1 +
 arch/powerpc/mm/ptdump/shared.c   | 5 +++++
 5 files changed, 17 insertions(+)

diff --git a/arch/powerpc/mm/ptdump/8xx.c b/arch/powerpc/mm/ptdump/8xx.c
index b5c79b11ea3c..1dc0f2438a73 100644
--- a/arch/powerpc/mm/ptdump/8xx.c
+++ b/arch/powerpc/mm/ptdump/8xx.c
@@ -71,18 +71,23 @@ static const struct flag_info flag_array[] = {

 struct pgtable_level pg_level[5] = {
 	{ /* pgd */
+		.name	= "PGD",
 		.flag	= flag_array,
 		.num	= ARRAY_SIZE(flag_array),
 	}, { /* p4d */
+		.name	= "P4D",
 		.flag	= flag_array,
 		.num	= ARRAY_SIZE(flag_array),
 	}, { /* pud */
+		.name	= "PUD",
 		.flag	= flag_array,
 		.num	= ARRAY_SIZE(flag_array),
 	}, { /* pmd */
+		.name	= "PMD",
 		.flag	= flag_array,
 		.num	= ARRAY_SIZE(flag_array),
 	}, { /* pte */
+		.name	= "PTX",
 		.flag	= flag_array,
 		.num	= ARRAY_SIZE(flag_array),
 	},
diff --git a/arch/powerpc/mm/ptdump/book3s64.c b/arch/powerpc/mm/ptdump/book3s64.c
index 5ad92d9dc5d1..79c9a8391042 100644
--- a/arch/powerpc/mm/ptdump/book3s64.c
+++ b/arch/powerpc/mm/ptdump/book3s64.c
@@ -104,18 +104,23 @@ static const struct flag_info flag_array[] = {

 struct pgtable_level pg_level[5] = {
 	{ /* pgd */
+		.name	= "PGD",
 		.flag	= flag_array,
 		.num	= ARRAY_SIZE(flag_array),
 	}, { /* p4d */
+		.name	= "P4D",
 		.flag	= flag_array,
 		.num	= ARRAY_SIZE(flag_array),
 	}, { /* pud */
+		.name	= "PUD",
 		.flag	= flag_array,
 		.num	= ARRAY_SIZE(flag_array),
 	}, { /* pmd */
+		.name	= "PMD",
 		.flag	= flag_array,
 		.num	= ARRAY_SIZE(flag_array),
 	}, { /* pte */
+		.name	= "PTE",
 		.flag	= flag_array,
 		.num	= ARRAY_SIZE(flag_array),
 	},
diff --git a/arch/powerpc/mm/ptdump/ptdump.c b/arch/powerpc/mm/ptdump/ptdump.c
index b2358d794855..0d499aebee72 100644
--- a/arch/powerpc/mm/ptdump/ptdump.c
+++ b/arch/powerpc/mm/ptdump/ptdump.c
@@ -178,6 +178,7 @@ static void dump_addr(struct pg_state *st, unsigned long addr)
 	pt_dump_seq_printf(st->seq, REG "-" REG " ", st->start_address, addr - 1);
 	pt_dump_seq_printf(st->seq, " " REG " ", st->start_pa);
 	pt_dump_size(st->seq, addr - st->start_address);
+	pt_dump_seq_printf(st->seq, "%s ", pg_level[st->level].name);
 }

 static void note_prot_wx(struct pg_state *st, unsigned long addr)
diff --git a/arch/powerpc/mm/ptdump/ptdump.h b/arch/powerpc/mm/ptdump/ptdump.h
index 154efae96ae0..88cf28c4138e 100644
--- a/arch/powerpc/mm/ptdump/ptdump.h
+++ b/arch/powerpc/mm/ptdump/ptdump.h
@@ -13,6 +13,7 @@ struct flag_info {

 struct pgtable_level {
 	const struct flag_info *flag;
+	char name[4];
 	size_t num;
 	u64 mask;
 };
diff --git a/arch/powerpc/mm/ptdump/shared.c b/arch/powerpc/mm/ptdump/shared.c
index 39c30c62b7ea..92d77f3e5155 100644
--- a/arch/powerpc/mm/ptdump/shared.c
+++ b/arch/powerpc/mm/ptdump/shared.c
@@ -69,18 +69,23 @@ static const struct flag_info flag_array[] = {

 struct pgtable_level pg_level[5] = {
 	{ /* pgd */
+		.name	= "PGD",
 		.flag	= flag_array,
 		.num	= ARRAY_SIZE(flag_array),
 	}, { /* p4d */
+		.name	= "P4D",
 		.flag	= flag_array,
 		.num	= ARRAY_SIZE(flag_array),
 	}, { /* pud */
+		.name	= "PUD",
 		.flag	= flag_array,
 		.num	= ARRAY_SIZE(flag_array),
 	}, { /* pmd */
+		.name	= "PMD",
 		.flag	= flag_array,
 		.num	= ARRAY_SIZE(flag_array),
 	}, { /* pte */
+		.name	= "PTE",
 		.flag	= flag_array,
 		.num	= ARRAY_SIZE(flag_array),
 	},
--
2.50.1



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