Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 95902e6c authored by Christophe Leroy's avatar Christophe Leroy Committed by Michael Ellerman
Browse files

powerpc/mm: Implement STRICT_KERNEL_RWX on PPC32 



This patch implements STRICT_KERNEL_RWX on PPC32.

As for CONFIG_DEBUG_PAGEALLOC, it deactivates BAT and LTLB mappings
in order to allow page protection setup at the level of each page.

As BAT/LTLB mappings are deactivated, there might be a performance
impact.

Signed-off-by: default avatarChristophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
parent 3184cc4b

arch/powerpc/Kconfig

+1 −1
Original line number Diff line number Diff line
@@ -176,7 +176,7 @@ config PPC 
	select HAVE_ARCH_MMAP_RND_COMPAT_BITS	if COMPAT

	select HAVE_ARCH_SECCOMP_FILTER

	select HAVE_ARCH_TRACEHOOK

	select ARCH_HAS_STRICT_KERNEL_RWX	if (PPC_BOOK3S_64 && !RELOCATABLE && !HIBERNATION)

	select ARCH_HAS_STRICT_KERNEL_RWX	if ((PPC_BOOK3S_64 || PPC32) && !RELOCATABLE && !HIBERNATION)

	select ARCH_OPTIONAL_KERNEL_RWX		if ARCH_HAS_STRICT_KERNEL_RWX

	select HAVE_CBPF_JIT			if !PPC64

	select HAVE_CONTEXT_TRACKING		if PPC64

arch/powerpc/kernel/vmlinux.lds.S

+1 −1
Original line number Diff line number Diff line
@@ -8,7 +8,7 @@ 
#include <asm/cache.h>

#include <asm/thread_info.h>



#ifdef CONFIG_STRICT_KERNEL_RWX

#if defined(CONFIG_STRICT_KERNEL_RWX) && !defined(CONFIG_PPC32)

#define STRICT_ALIGN_SIZE	(1 << 24)

#else

#define STRICT_ALIGN_SIZE	PAGE_SIZE

arch/powerpc/mm/init_32.c

+6 −0
Original line number Diff line number Diff line
@@ -113,6 +113,12 @@ void __init MMU_setup(void) 
		__map_without_bats = 1;

		__map_without_ltlbs = 1;

	}

#ifdef CONFIG_STRICT_KERNEL_RWX

	if (rodata_enabled) {

		__map_without_bats = 1;

		__map_without_ltlbs = 1;

	}

#endif

}



/*

arch/powerpc/mm/pgtable_32.c

+24 −0
Original line number Diff line number Diff line
@@ -34,6 +34,7 @@ 
#include <asm/fixmap.h>

#include <asm/io.h>

#include <asm/setup.h>

#include <asm/sections.h>



#include "mmu_decl.h"
@@ -375,6 +376,29 @@ void mark_initmem_nx(void) 
	change_page_attr(page, numpages, PAGE_KERNEL);

}



#ifdef CONFIG_STRICT_KERNEL_RWX

void mark_rodata_ro(void)

{

	struct page *page;

	unsigned long numpages;



	page = virt_to_page(_stext);

	numpages = PFN_UP((unsigned long)_etext) -

		   PFN_DOWN((unsigned long)_stext);



	change_page_attr(page, numpages, PAGE_KERNEL_ROX);

	/*

	 * mark .rodata as read only. Use __init_begin rather than __end_rodata

	 * to cover NOTES and EXCEPTION_TABLE.

	 */

	page = virt_to_page(__start_rodata);

	numpages = PFN_UP((unsigned long)__init_begin) -

		   PFN_DOWN((unsigned long)__start_rodata);



	change_page_attr(page, numpages, PAGE_KERNEL_RO);

}

#endif



#ifdef CONFIG_DEBUG_PAGEALLOC

void __kernel_map_pages(struct page *page, int numpages, int enable)

{