From 6ca055322da8fe25ff9ac50db6f3b7b59b6f961c Mon Sep 17 00:00:00 2001
From: Christophe Leroy <christophe.leroy@csgroup.eu>
Date: Mon, 29 Jun 2020 11:15:26 +0000
Subject: [PATCH] powerpc/32s: Use dedicated segment for modules with
STRICT_KERNEL_RWX
When STRICT_KERNEL_RWX is set, we want to set NX bit on vmalloc
segments. But modules require exec.
Use a dedicated segment for modules. There is not much space
above kernel, and we don't waste vmalloc space to do alignment.
Therefore, we take the segment before PAGE_OFFSET for modules.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/eb8faba9148b6cf17c696ba776b4e8ee2f6313bf.1593428200.git.christophe.leroy@csgroup.eu
---
arch/powerpc/Kconfig | 1 +
arch/powerpc/include/asm/book3s/32/pgtable.h | 15 +++++----------
arch/powerpc/mm/ptdump/ptdump.c | 8 ++++++++
3 files changed, 14 insertions(+), 10 deletions(-)
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index a751edacf4bc0..8c7656cc10eb6 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -1213,6 +1213,7 @@ config TASK_SIZE_BOOL
config TASK_SIZE
hex "Size of user task space" if TASK_SIZE_BOOL
default "0x80000000" if PPC_8xx
+ default "0xb0000000" if PPC_BOOK3S_32 && STRICT_KERNEL_RWX
default "0xc0000000"
endmenu
diff --git a/arch/powerpc/include/asm/book3s/32/pgtable.h b/arch/powerpc/include/asm/book3s/32/pgtable.h
index 224912432821f..36443cda8dcf2 100644
--- a/arch/powerpc/include/asm/book3s/32/pgtable.h
+++ b/arch/powerpc/include/asm/book3s/32/pgtable.h
@@ -184,17 +184,7 @@ int map_kernel_page(unsigned long va, phys_addr_t pa, pgprot_t prot);
*/
#define VMALLOC_OFFSET (0x1000000) /* 16M */
-/*
- * With CONFIG_STRICT_KERNEL_RWX, kernel segments are set NX. But when modules
- * are used, NX cannot be set on VMALLOC space. So vmalloc VM space and linear
- * memory shall not share segments.
- */
-#if defined(CONFIG_STRICT_KERNEL_RWX) && defined(CONFIG_MODULES)
-#define VMALLOC_START ((ALIGN((long)high_memory, 256L << 20) + VMALLOC_OFFSET) & \
- ~(VMALLOC_OFFSET - 1))
-#else
#define VMALLOC_START ((((long)high_memory + VMALLOC_OFFSET) & ~(VMALLOC_OFFSET-1)))
-#endif
#ifdef CONFIG_KASAN_VMALLOC
#define VMALLOC_END ALIGN_DOWN(ioremap_bot, PAGE_SIZE << KASAN_SHADOW_SCALE_SHIFT)
@@ -202,6 +192,11 @@ int map_kernel_page(unsigned long va, phys_addr_t pa, pgprot_t prot);
#define VMALLOC_END ioremap_bot
#endif
+#ifdef CONFIG_STRICT_KERNEL_RWX
+#define MODULES_END ALIGN_DOWN(PAGE_OFFSET, SZ_256M)
+#define MODULES_VADDR (MODULES_END - SZ_256M)
+#endif
+
#ifndef __ASSEMBLY__
#include <linux/sched.h>
#include <linux/threads.h>
diff --git a/arch/powerpc/mm/ptdump/ptdump.c b/arch/powerpc/mm/ptdump/ptdump.c
index 9d942136c7bee..b2ed1ca4f2545 100644
--- a/arch/powerpc/mm/ptdump/ptdump.c
+++ b/arch/powerpc/mm/ptdump/ptdump.c
@@ -74,6 +74,10 @@ struct addr_marker {
static struct addr_marker address_markers[] = {
{ 0, "Start of kernel VM" },
+#ifdef MODULES_VADDR
+ { 0, "modules start" },
+ { 0, "modules end" },
+#endif
{ 0, "vmalloc() Area" },
{ 0, "vmalloc() End" },
#ifdef CONFIG_PPC64
@@ -352,6 +356,10 @@ static void populate_markers(void)
address_markers[i++].start_address = PAGE_OFFSET;
#else
address_markers[i++].start_address = TASK_SIZE;
+#endif
+#ifdef MODULES_VADDR
+ address_markers[i++].start_address = MODULES_VADDR;
+ address_markers[i++].start_address = MODULES_END;
#endif
address_markers[i++].start_address = VMALLOC_START;
address_markers[i++].start_address = VMALLOC_END;
--
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