linux-hardening - [PATCH] x86/mm/dump_pagetables: Add SLAB

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Date:   Fri, 15 Sep 2023 19:18:39 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Matteo Rizzo <matteorizzo@...gle.com>
Cc:     Kees Cook <keescook@...omium.org>, Jann Horn <jannh@...gle.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Andy Lutomirski <luto@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        x86@...nel.org, "H. Peter Anvin" <hpa@...or.com>,
        linux-kernel@...r.kernel.org, linux-hardening@...r.kernel.org
Subject: [PATCH] x86/mm/dump_pagetables: Add SLAB_VIRTUAL knowledge

Add the markings for the SLAB_VIRTUAL area.

Cc: Matteo Rizzo <matteorizzo@...gle.com>
Cc: Jann Horn <jannh@...gle.com>
Cc: Dave Hansen <dave.hansen@...ux.intel.com>
Cc: Andy Lutomirski <luto@...nel.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: Borislav Petkov <bp@...en8.de>
Cc: x86@...nel.org
Cc: "H. Peter Anvin" <hpa@...or.com>
Signed-off-by: Kees Cook <keescook@...omium.org>
---
This is on top of the SLAB_VIRTUAL series:
https://lore.kernel.org/all/20230915105933.495735-11-matteorizzo@google.com/

Feel free to collapse this into the x86 patch from the above series.

FYI, as expected, the kernel page table entries get way longer with
SLAB_VIRTUAL. :)

Without SLAB_VIRTUAL:

# wc -l /sys/kernel/debug/page_tables/kernel
1501 /sys/kernel/debug/page_tables/kernel

With SLAB_VIRTUAL:

# wc -l /sys/kernel/debug/page_tables/kernel
7549 /sys/kernel/debug/page_tables/kernel
---
 arch/x86/mm/dump_pagetables.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/x86/mm/dump_pagetables.c b/arch/x86/mm/dump_pagetables.c
index e1b599ecbbc2..b1fa68669e61 100644
--- a/arch/x86/mm/dump_pagetables.c
+++ b/arch/x86/mm/dump_pagetables.c
@@ -64,6 +64,9 @@ enum address_markers_idx {
 	KASAN_SHADOW_END_NR,
 #endif
 	CPU_ENTRY_AREA_NR,
+#ifdef CONFIG_SLAB_VIRTUAL
+	SLAB_AREA_NR,
+#endif
 #ifdef CONFIG_X86_ESPFIX64
 	ESPFIX_START_NR,
 #endif
@@ -95,6 +98,9 @@ static struct addr_marker address_markers[] = {
 	[LDT_NR]		= { 0UL,		"LDT remap" },
 #endif
 	[CPU_ENTRY_AREA_NR]	= { CPU_ENTRY_AREA_BASE,"CPU entry Area" },
+#ifdef CONFIG_SLAB_VIRTUAL
+	[SLAB_AREA_NR]		= { SLAB_BASE_ADDR,	"Slab Area" },
+#endif
 #ifdef CONFIG_X86_ESPFIX64
 	[ESPFIX_START_NR]	= { ESPFIX_BASE_ADDR,	"ESPfix Area", 16 },
 #endif
-- 
2.34.1