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powerpc/mm: Implement STRICT_KERNEL_RWX on PPC32

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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: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Christophe Leroy
2017-08-02 15:51:05 +02:00
committed by Michael Ellerman
parent 3184cc4b6f
commit 95902e6c88
4 changed files with 32 additions and 2 deletions
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6
arch/powerpc/mm/init_32.c
View File

@@ -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
}
/*

24
arch/powerpc/mm/pgtable_32.c
View File

@@ -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)
{