From cd65d69713349fc7b33fa9de2b32989b99c9fb39 Mon Sep 17 00:00:00 2001 From: Balbir Singh Date: Thu, 29 Jun 2017 03:04:08 +1000 Subject: 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 [mpe: Make the warning louder when we don't have MMU_FTR_KERNEL_RO] Signed-off-by: Michael Ellerman --- arch/powerpc/include/asm/book3s/64/hash.h | 3 +++ arch/powerpc/include/asm/book3s/64/radix.h | 4 ++++ arch/powerpc/mm/pgtable-hash64.c | 36 ++++++++++++++++++++++++++++++ arch/powerpc/mm/pgtable_64.c | 13 +++++++++++ 4 files changed, 56 insertions(+) (limited to 'arch/powerpc') 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 #include +#include #include +#include +#include +#include #include #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 -- cgit v1.2.3