Commit 6ca05532 authored by Christophe Leroy's avatar Christophe Leroy Committed by Michael Ellerman
Browse files

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: default avatarChristophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/eb8faba9148b6cf17c696ba776b4e8ee2f6313bf.1593428200.git.christophe.leroy@csgroup.eu
parent f1a1f7a1

arch/powerpc/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -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

arch/powerpc/include/asm/book3s/32/pgtable.h

+5 −10
Original line number Diff line number Diff line
@@ -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>

arch/powerpc/mm/ptdump/ptdump.c

+8 −0
Original line number Diff line number Diff line
@@ -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;

CRA Git | Maintained and supported by SUSTech CRA and CCSE