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authorBalbir Singh <bsingharora@gmail.com>2017-06-29 03:04:08 +1000
committerMichael Ellerman <mpe@ellerman.id.au>2017-07-04 11:35:16 +1000
commitcd65d69713349fc7b33fa9de2b32989b99c9fb39 (patch)
tree31d67b092228886108a0339c6953064c01b2a3b0 /arch/powerpc
parentd924cc3feda9c2bea8164930899f367ce249cbbf (diff)
downloadlinux-cd65d69713349fc7b33fa9de2b32989b99c9fb39.tar.bz2
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: Balbir Singh <bsingharora@gmail.com> [mpe: Make the warning louder when we don't have MMU_FTR_KERNEL_RO] Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Diffstat (limited to 'arch/powerpc')
-rw-r--r--arch/powerpc/include/asm/book3s/64/hash.h3
-rw-r--r--arch/powerpc/include/asm/book3s/64/radix.h4
-rw-r--r--arch/powerpc/mm/pgtable-hash64.c36
-rw-r--r--arch/powerpc/mm/pgtable_64.c13
4 files changed, 56 insertions, 0 deletions
diff --git a/arch/powerpc/include/asm/book3s/64/hash.h b/arch/powerpc/include/asm/book3s/64/hash.h
index 4e957b027fe0..0ce513f2926f 100644
--- a/arch/powerpc/include/asm/book3s/64/hash.h
+++ b/arch/powerpc/include/asm/book3s/64/hash.h
@@ -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);
diff --git a/arch/powerpc/include/asm/book3s/64/radix.h b/arch/powerpc/include/asm/book3s/64/radix.h
index ba43754e96d2..487709ff6875 100644
--- a/arch/powerpc/include/asm/book3s/64/radix.h
+++ b/arch/powerpc/include/asm/book3s/64/radix.h
@@ -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)
{
diff --git a/arch/powerpc/mm/pgtable-hash64.c b/arch/powerpc/mm/pgtable-hash64.c
index a0facee58811..188b4107584d 100644
--- a/arch/powerpc/mm/pgtable-hash64.c
+++ b/arch/powerpc/mm/pgtable-hash64.c
@@ -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
diff --git a/arch/powerpc/mm/pgtable_64.c b/arch/powerpc/mm/pgtable_64.c
index bce0ed50789c..fc2e6def2eb7 100644
--- a/arch/powerpc/mm/pgtable_64.c
+++ b/arch/powerpc/mm/pgtable_64.c
@@ -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