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Commit cd65d697 authored by Balbir Singh's avatar Balbir Singh Committed by Michael Ellerman
Browse files

powerpc/mm/hash: Implement mark_rodata_ro() for hash 



With hash we update the bolted pte to mark it read-only. We rely
on the MMU_FTR_KERNEL_RO to generate the correct permissions
for read-only text. The radix implementation just prints a warning
in this implementation

Signed-off-by: default avatarBalbir Singh <bsingharora@gmail.com>
[mpe: Make the warning louder when we don't have MMU_FTR_KERNEL_RO]
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
parent d924cc3f

arch/powerpc/include/asm/book3s/64/hash.h

+3 −0
Original line number Diff line number Diff line
@@ -89,6 +89,9 @@ static inline int hash__pgd_bad(pgd_t pgd) 
{

	return (pgd_val(pgd) == 0);

}

#ifdef CONFIG_STRICT_KERNEL_RWX

extern void hash__mark_rodata_ro(void);

#endif



extern void hpte_need_flush(struct mm_struct *mm, unsigned long addr,

			    pte_t *ptep, unsigned long pte, int huge);

arch/powerpc/include/asm/book3s/64/radix.h

+4 −0
Original line number Diff line number Diff line
@@ -116,6 +116,10 @@ 
#define RADIX_PUD_TABLE_SIZE	(sizeof(pud_t) << RADIX_PUD_INDEX_SIZE)

#define RADIX_PGD_TABLE_SIZE	(sizeof(pgd_t) << RADIX_PGD_INDEX_SIZE)



#ifdef CONFIG_STRICT_KERNEL_RWX

extern void radix__mark_rodata_ro(void);

#endif



static inline unsigned long __radix_pte_update(pte_t *ptep, unsigned long clr,

					       unsigned long set)

{

arch/powerpc/mm/pgtable-hash64.c

+36 −0
Original line number Diff line number Diff line
@@ -11,8 +11,12 @@ 


#include <linux/sched.h>

#include <linux/mm_types.h>

#include <linux/mm.h>



#include <asm/pgalloc.h>

#include <asm/pgtable.h>

#include <asm/sections.h>

#include <asm/mmu.h>

#include <asm/tlb.h>



#include "mmu_decl.h"
@@ -419,3 +423,35 @@ int hash__has_transparent_hugepage(void) 
	return 1;

}

#endif /* CONFIG_TRANSPARENT_HUGEPAGE */



#ifdef CONFIG_STRICT_KERNEL_RWX

void hash__mark_rodata_ro(void)

{

	unsigned long start = (unsigned long)_stext;

	unsigned long end = (unsigned long)__init_begin;

	unsigned long idx;

	unsigned int step, shift;

	unsigned long newpp = PP_RXXX;



	shift = mmu_psize_defs[mmu_linear_psize].shift;

	step = 1 << shift;



	start = ((start + step - 1) >> shift) << shift;

	end = (end >> shift) << shift;



	pr_devel("marking ro start %lx, end %lx, step %x\n",

			start, end, step);



	if (start == end) {

		pr_warn("could not set rodata ro, relocate the start"

			" of the kernel to a 0x%x boundary\n", step);

		return;

	}



	for (idx = start; idx < end; idx += step)

		/* Not sure if we can do much with the return value */

		mmu_hash_ops.hpte_updateboltedpp(newpp, idx, mmu_linear_psize,

							mmu_kernel_ssize);



}

#endif

arch/powerpc/mm/pgtable_64.c

+13 −0
Original line number Diff line number Diff line
@@ -491,3 +491,16 @@ void mmu_partition_table_set_entry(unsigned int lpid, unsigned long dw0, 
}

EXPORT_SYMBOL_GPL(mmu_partition_table_set_entry);

#endif /* CONFIG_PPC_BOOK3S_64 */



#ifdef CONFIG_STRICT_KERNEL_RWX

void mark_rodata_ro(void)

{

	if (!mmu_has_feature(MMU_FTR_KERNEL_RO)) {

		pr_warn("Warning: Unable to mark rodata read only on this CPU.\n");

		return;

	}



	if (!radix_enabled())

		hash__mark_rodata_ro();

}

#endif