[PATCH v17 23/23] mm: ptdump: Reduce level numbers by 1 in note_page()

From: Steven Price <steven.price@arm.com>
To: Andrew Morton <akpm@linux-foundation.org>, linux-mm@kvack.org
Cc: "Steven Price" <steven.price@arm.com>,
	"Andy Lutomirski" <luto@kernel.org>,
	"Ard Biesheuvel" <ard.biesheuvel@linaro.org>,
	"Arnd Bergmann" <arnd@arndb.de>, "Borislav Petkov" <bp@alien8.de>,
	"Catalin Marinas" <catalin.marinas@arm.com>,
	"Dave Hansen" <dave.hansen@linux.intel.com>,
	"Ingo Molnar" <mingo@redhat.com>,
	"James Morse" <james.morse@arm.com>,
	"Jérôme Glisse" <jglisse@redhat.com>,
	"Peter Zijlstra" <peterz@infradead.org>,
	"Thomas Gleixner" <tglx@linutronix.de>,
	"Will Deacon" <will@kernel.org>,
	x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org,
	"Mark Rutland" <Mark.Rutland@arm.com>,
	"Liang, Kan" <kan.liang@linux.intel.com>
Subject: [PATCH v17 23/23] mm: ptdump: Reduce level numbers by 1 in note_page()
Date: Wed, 18 Dec 2019 16:24:02 +0000	[thread overview]
Message-ID: <20191218162402.45610-24-steven.price@arm.com> (raw)
In-Reply-To: <20191218162402.45610-1-steven.price@arm.com>

Rather than having to increment the 'depth' number by 1 in
ptdump_hole(), let's change the meaning of 'level' in note_page() since
that makes the code simplier.

Note that for x86, the level numbers were previously increased by 1 in
commit 45dcd2091363 ("x86/mm/dump_pagetables: Fix printout of p4d level")
and the comment "Bit 7 has a different meaning" was not updated, so this
change also makes the code match the comment again.

Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Steven Price <steven.price@arm.com>
---
 arch/arm64/mm/dump.c          |  6 +++---
 arch/x86/mm/dump_pagetables.c | 19 ++++++++++---------
 include/linux/ptdump.h        |  1 +
 mm/ptdump.c                   | 16 ++++++++--------
 4 files changed, 22 insertions(+), 20 deletions(-)

diff --git a/arch/arm64/mm/dump.c b/arch/arm64/mm/dump.c
index e5b6691c5bfc..ef4b3ca1e058 100644
--- a/arch/arm64/mm/dump.c
+++ b/arch/arm64/mm/dump.c
@@ -176,8 +176,7 @@ struct pg_level {
 };
 
 static struct pg_level pg_level[] = {
-	{
-	}, { /* pgd */
+	{ /* pgd */
 		.name	= "PGD",
 		.bits	= pte_bits,
 		.num	= ARRAY_SIZE(pte_bits),
@@ -257,7 +256,7 @@ static void note_page(struct ptdump_state *pt_st, unsigned long addr, int level,
 	if (level >= 0)
 		prot = val & pg_level[level].mask;
 
-	if (!st->level) {
+	if (st->level == -1) {
 		st->level = level;
 		st->current_prot = prot;
 		st->start_address = addr;
@@ -351,6 +350,7 @@ void ptdump_check_wx(void)
 			{ 0, NULL},
 			{ -1, NULL},
 		},
+		.level = -1,
 		.check_wx = true,
 		.ptdump = {
 			.note_page = note_page,
diff --git a/arch/x86/mm/dump_pagetables.c b/arch/x86/mm/dump_pagetables.c
index a0b8ffc927bb..411f6a758998 100644
--- a/arch/x86/mm/dump_pagetables.c
+++ b/arch/x86/mm/dump_pagetables.c
@@ -180,7 +180,7 @@ static struct addr_marker address_markers[] = {
 static void printk_prot(struct seq_file *m, pgprotval_t pr, int level, bool dmsg)
 {
 	static const char * const level_name[] =
-		{ "cr3", "pgd", "p4d", "pud", "pmd", "pte" };
+		{ "pgd", "p4d", "pud", "pmd", "pte" };
 
 	if (!(pr & _PAGE_PRESENT)) {
 		/* Not present */
@@ -204,12 +204,12 @@ static void printk_prot(struct seq_file *m, pgprotval_t pr, int level, bool dmsg
 			pt_dump_cont_printf(m, dmsg, "    ");
 
 		/* Bit 7 has a different meaning on level 3 vs 4 */
-		if (level <= 4 && pr & _PAGE_PSE)
+		if (level <= 3 && pr & _PAGE_PSE)
 			pt_dump_cont_printf(m, dmsg, "PSE ");
 		else
 			pt_dump_cont_printf(m, dmsg, "    ");
-		if ((level == 5 && pr & _PAGE_PAT) ||
-		    ((level == 4 || level == 3) && pr & _PAGE_PAT_LARGE))
+		if ((level == 4 && pr & _PAGE_PAT) ||
+		    ((level == 3 || level == 2) && pr & _PAGE_PAT_LARGE))
 			pt_dump_cont_printf(m, dmsg, "PAT ");
 		else
 			pt_dump_cont_printf(m, dmsg, "    ");
@@ -271,15 +271,15 @@ static void note_page(struct ptdump_state *pt_st, unsigned long addr, int level,
 
 	new_prot = val & PTE_FLAGS_MASK;
 
-	if (level > 1) {
-		new_eff = effective_prot(st->prot_levels[level - 2],
+	if (level > 0) {
+		new_eff = effective_prot(st->prot_levels[level - 1],
 					 new_prot);
 	} else {
 		new_eff = new_prot;
 	}
 
-	if (level > 0)
-		st->prot_levels[level - 1] = new_eff;
+	if (level >= 0)
+		st->prot_levels[level] = new_eff;
 
 	/*
 	 * If we have a "break" in the series, we need to flush the state that
@@ -289,7 +289,7 @@ static void note_page(struct ptdump_state *pt_st, unsigned long addr, int level,
 	cur = st->current_prot;
 	eff = st->effective_prot;
 
-	if (!st->level) {
+	if (st->level == -1) {
 		/* First entry */
 		st->current_prot = new_prot;
 		st->effective_prot = new_eff;
@@ -380,6 +380,7 @@ static void ptdump_walk_pgd_level_core(struct seq_file *m, pgd_t *pgd,
 			.note_page	= note_page,
 			.range		= ptdump_ranges
 		},
+		.level = -1,
 		.to_dmesg	= dmesg,
 		.check_wx	= checkwx,
 		.seq		= m
diff --git a/include/linux/ptdump.h b/include/linux/ptdump.h
index a0fb8dd2be97..b28f3f2acf90 100644
--- a/include/linux/ptdump.h
+++ b/include/linux/ptdump.h
@@ -11,6 +11,7 @@ struct ptdump_range {
 };
 
 struct ptdump_state {
+	/* level is 0:PGD to 4:PTE, or -1 if unknown */
 	void (*note_page)(struct ptdump_state *st, unsigned long addr,
 			  int level, unsigned long val);
 	const struct ptdump_range *range;
diff --git a/mm/ptdump.c b/mm/ptdump.c
index 868638b8e404..ad18a9839d6f 100644
--- a/mm/ptdump.c
+++ b/mm/ptdump.c
@@ -17,7 +17,7 @@ static inline int note_kasan_page_table(struct mm_walk *walk,
 {
 	struct ptdump_state *st = walk->private;
 
-	st->note_page(st, addr, 5, pte_val(kasan_early_shadow_pte[0]));
+	st->note_page(st, addr, 4, pte_val(kasan_early_shadow_pte[0]));
 
 	walk->action = ACTION_CONTINUE;
 
@@ -37,7 +37,7 @@ static int ptdump_pgd_entry(pgd_t *pgd, unsigned long addr,
 #endif
 
 	if (pgd_leaf(val))
-		st->note_page(st, addr, 1, pgd_val(val));
+		st->note_page(st, addr, 0, pgd_val(val));
 
 	return 0;
 }
@@ -54,7 +54,7 @@ static int ptdump_p4d_entry(p4d_t *p4d, unsigned long addr,
 #endif
 
 	if (p4d_leaf(val))
-		st->note_page(st, addr, 2, p4d_val(val));
+		st->note_page(st, addr, 1, p4d_val(val));
 
 	return 0;
 }
@@ -71,7 +71,7 @@ static int ptdump_pud_entry(pud_t *pud, unsigned long addr,
 #endif
 
 	if (pud_leaf(val))
-		st->note_page(st, addr, 3, pud_val(val));
+		st->note_page(st, addr, 2, pud_val(val));
 
 	return 0;
 }
@@ -88,7 +88,7 @@ static int ptdump_pmd_entry(pmd_t *pmd, unsigned long addr,
 #endif
 
 	if (pmd_leaf(val))
-		st->note_page(st, addr, 4, pmd_val(val));
+		st->note_page(st, addr, 3, pmd_val(val));
 
 	return 0;
 }
@@ -98,7 +98,7 @@ static int ptdump_pte_entry(pte_t *pte, unsigned long addr,
 {
 	struct ptdump_state *st = walk->private;
 
-	st->note_page(st, addr, 5, pte_val(READ_ONCE(*pte)));
+	st->note_page(st, addr, 4, pte_val(READ_ONCE(*pte)));
 
 	return 0;
 }
@@ -108,7 +108,7 @@ static int ptdump_hole(unsigned long addr, unsigned long next,
 {
 	struct ptdump_state *st = walk->private;
 
-	st->note_page(st, addr, depth + 1, 0);
+	st->note_page(st, addr, depth, 0);
 
 	return 0;
 }
@@ -135,5 +135,5 @@ void ptdump_walk_pgd(struct ptdump_state *st, struct mm_struct *mm)
 	up_read(&mm->mmap_sem);
 
 	/* Flush out the last page */
-	st->note_page(st, 0, 0, 0);
+	st->note_page(st, 0, -1, 0);
 }
-- 
2.20.1


