From 836a24183273e9db1c092246bd8e306b297d9917 Mon Sep 17 00:00:00 2001 From: Rob Herring Date: Wed, 2 Jul 2014 02:01:15 -0500 Subject: ARM: expand fixmap region to 3MB With commit a05e54c103b0 ("ARM: 8031/2: change fixmap mapping region to support 32 CPUs"), the fixmap region was expanded to 2MB, but it precluded any other uses of the fixmap region. In order to support other uses the fixmap region needs to be expanded beyond 2MB. Fortunately, the adjacent 1MB range 0xffe00000-0xfff00000 is availabe. Remove fixmap_page_table ptr and lookup the page table via the virtual address so that the fixmap region can span more that one pmd. The 2nd pmd is already created since it is shared with the vector page. Signed-off-by: Rob Herring [kees: fixed CONFIG_DEBUG_HIGHMEM get_fixmap() calls] [kees: moved pte allocation outside of CONFIG_HIGHMEM] Signed-off-by: Kees Cook Acked-by: Nicolas Pitre --- arch/arm/mm/mmu.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'arch/arm/mm/mmu.c') diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c index 8348ed6b2efe..7fa0966cd15f 100644 --- a/arch/arm/mm/mmu.c +++ b/arch/arm/mm/mmu.c @@ -1326,10 +1326,10 @@ static void __init kmap_init(void) #ifdef CONFIG_HIGHMEM pkmap_page_table = early_pte_alloc(pmd_off_k(PKMAP_BASE), PKMAP_BASE, _PAGE_KERNEL_TABLE); - - fixmap_page_table = early_pte_alloc(pmd_off_k(FIXADDR_START), - FIXADDR_START, _PAGE_KERNEL_TABLE); #endif + + early_pte_alloc(pmd_off_k(FIXADDR_START), FIXADDR_START, + _PAGE_KERNEL_TABLE); } static void __init map_lowmem(void) -- cgit v1.2.3 From 99b4ac9afce4129323b5b4c7002a942a9489914c Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Fri, 4 Apr 2014 23:27:49 +0200 Subject: arm: fixmap: implement __set_fixmap() This is used from set_fixmap() and clear_fixmap() via asm-generic/fixmap.h. Also makes sure that the fixmap allocation fits into the expected range. Based on patch by Rabin Vincent. Signed-off-by: Kees Cook Cc: Rabin Vincent Acked-by: Nicolas Pitre --- arch/arm/include/asm/fixmap.h | 2 ++ arch/arm/mm/mmu.c | 24 ++++++++++++++++++++++++ 2 files changed, 26 insertions(+) (limited to 'arch/arm/mm/mmu.c') diff --git a/arch/arm/include/asm/fixmap.h b/arch/arm/include/asm/fixmap.h index d984ca69ce19..714606f70425 100644 --- a/arch/arm/include/asm/fixmap.h +++ b/arch/arm/include/asm/fixmap.h @@ -14,6 +14,8 @@ enum fixed_addresses { __end_of_fixed_addresses }; +void __set_fixmap(enum fixed_addresses idx, phys_addr_t phys, pgprot_t prot); + #include #endif diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c index 7fa0966cd15f..bdf5c94f7c36 100644 --- a/arch/arm/mm/mmu.c +++ b/arch/arm/mm/mmu.c @@ -22,6 +22,7 @@ #include #include #include +#include #include #include #include @@ -392,6 +393,29 @@ SET_MEMORY_FN(rw, pte_set_rw) SET_MEMORY_FN(x, pte_set_x) SET_MEMORY_FN(nx, pte_set_nx) +/* + * To avoid TLB flush broadcasts, this uses local_flush_tlb_kernel_range(). + * As a result, this can only be called with preemption disabled, as under + * stop_machine(). + */ +void __set_fixmap(enum fixed_addresses idx, phys_addr_t phys, pgprot_t prot) +{ + unsigned long vaddr = __fix_to_virt(idx); + pte_t *pte = pte_offset_kernel(pmd_off_k(vaddr), vaddr); + + /* Make sure fixmap region does not exceed available allocation. */ + BUILD_BUG_ON(FIXADDR_START + (__end_of_fixed_addresses * PAGE_SIZE) > + FIXADDR_END); + BUG_ON(idx >= __end_of_fixed_addresses); + + if (pgprot_val(prot)) + set_pte_at(NULL, vaddr, pte, + pfn_pte(phys >> PAGE_SHIFT, prot)); + else + pte_clear(NULL, vaddr, pte); + local_flush_tlb_kernel_range(vaddr, vaddr + PAGE_SIZE); +} + /* * Adjust the PMD section entries according to the CPU in use. */ -- cgit v1.2.3 From 1e6b48116a95046ec51f3d40f83aff8b006674d7 Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Thu, 3 Apr 2014 17:28:11 -0700 Subject: ARM: mm: allow non-text sections to be non-executable Adds CONFIG_ARM_KERNMEM_PERMS to separate the kernel memory regions into section-sized areas that can have different permisions. Performs the NX permission changes during free_initmem, so that init memory can be reclaimed. This uses section size instead of PMD size to reduce memory lost to padding on non-LPAE systems. Based on work by Brad Spengler, Larry Bassel, and Laura Abbott. Signed-off-by: Kees Cook Tested-by: Laura Abbott Acked-by: Nicolas Pitre --- arch/arm/kernel/vmlinux.lds.S | 16 +++++++ arch/arm/mm/Kconfig | 9 ++++ arch/arm/mm/init.c | 101 +++++++++++++++++++++++++++++++++++++++++- arch/arm/mm/mmu.c | 9 +++- 4 files changed, 133 insertions(+), 2 deletions(-) (limited to 'arch/arm/mm/mmu.c') diff --git a/arch/arm/kernel/vmlinux.lds.S b/arch/arm/kernel/vmlinux.lds.S index 6f57cb94367f..18fd68a295ea 100644 --- a/arch/arm/kernel/vmlinux.lds.S +++ b/arch/arm/kernel/vmlinux.lds.S @@ -8,6 +8,9 @@ #include #include #include +#ifdef CONFIG_ARM_KERNMEM_PERMS +#include +#endif #define PROC_INFO \ . = ALIGN(4); \ @@ -90,6 +93,11 @@ SECTIONS _text = .; HEAD_TEXT } + +#ifdef CONFIG_ARM_KERNMEM_PERMS + . = ALIGN(1< #include #include +#include #include #include @@ -615,7 +616,99 @@ void __init mem_init(void) } } -void free_initmem(void) +#ifdef CONFIG_ARM_KERNMEM_PERMS +struct section_perm { + unsigned long start; + unsigned long end; + pmdval_t mask; + pmdval_t prot; +}; + +struct section_perm nx_perms[] = { + /* Make pages tables, etc before _stext RW (set NX). */ + { + .start = PAGE_OFFSET, + .end = (unsigned long)_stext, + .mask = ~PMD_SECT_XN, + .prot = PMD_SECT_XN, + }, + /* Make init RW (set NX). */ + { + .start = (unsigned long)__init_begin, + .end = (unsigned long)_sdata, + .mask = ~PMD_SECT_XN, + .prot = PMD_SECT_XN, + }, +}; + +/* + * Updates section permissions only for the current mm (sections are + * copied into each mm). During startup, this is the init_mm. Is only + * safe to be called with preemption disabled, as under stop_machine(). + */ +static inline void section_update(unsigned long addr, pmdval_t mask, + pmdval_t prot) +{ + struct mm_struct *mm; + pmd_t *pmd; + + mm = current->active_mm; + pmd = pmd_offset(pud_offset(pgd_offset(mm, addr), addr), addr); + +#ifdef CONFIG_ARM_LPAE + pmd[0] = __pmd((pmd_val(pmd[0]) & mask) | prot); +#else + if (addr & SECTION_SIZE) + pmd[1] = __pmd((pmd_val(pmd[1]) & mask) | prot); + else + pmd[0] = __pmd((pmd_val(pmd[0]) & mask) | prot); +#endif + flush_pmd_entry(pmd); + local_flush_tlb_kernel_range(addr, addr + SECTION_SIZE); +} + +/* Make sure extended page tables are in use. */ +static inline bool arch_has_strict_perms(void) +{ + if (cpu_architecture() < CPU_ARCH_ARMv6) + return false; + + return !!(get_cr() & CR_XP); +} + +#define set_section_perms(perms, field) { \ + size_t i; \ + unsigned long addr; \ + \ + if (!arch_has_strict_perms()) \ + return; \ + \ + for (i = 0; i < ARRAY_SIZE(perms); i++) { \ + if (!IS_ALIGNED(perms[i].start, SECTION_SIZE) || \ + !IS_ALIGNED(perms[i].end, SECTION_SIZE)) { \ + pr_err("BUG: section %lx-%lx not aligned to %lx\n", \ + perms[i].start, perms[i].end, \ + SECTION_SIZE); \ + continue; \ + } \ + \ + for (addr = perms[i].start; \ + addr < perms[i].end; \ + addr += SECTION_SIZE) \ + section_update(addr, perms[i].mask, \ + perms[i].field); \ + } \ +} + +static inline void fix_kernmem_perms(void) +{ + set_section_perms(nx_perms, prot); +} +#else +static inline void fix_kernmem_perms(void) { } +#endif /* CONFIG_ARM_KERNMEM_PERMS */ + +void free_tcmmem(void) { #ifdef CONFIG_HAVE_TCM extern char __tcm_start, __tcm_end; @@ -623,6 +716,12 @@ void free_initmem(void) poison_init_mem(&__tcm_start, &__tcm_end - &__tcm_start); free_reserved_area(&__tcm_start, &__tcm_end, -1, "TCM link"); #endif +} + +void free_initmem(void) +{ + fix_kernmem_perms(); + free_tcmmem(); poison_init_mem(__init_begin, __init_end - __init_begin); if (!machine_is_integrator() && !machine_is_cintegrator()) diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c index bdf5c94f7c36..1c52c8e94372 100644 --- a/arch/arm/mm/mmu.c +++ b/arch/arm/mm/mmu.c @@ -1373,12 +1373,19 @@ static void __init map_lowmem(void) if (start >= end) break; - if (end < kernel_x_start || start >= kernel_x_end) { + if (end < kernel_x_start) { map.pfn = __phys_to_pfn(start); map.virtual = __phys_to_virt(start); map.length = end - start; map.type = MT_MEMORY_RWX; + create_mapping(&map); + } else if (start >= kernel_x_end) { + map.pfn = __phys_to_pfn(start); + map.virtual = __phys_to_virt(start); + map.length = end - start; + map.type = MT_MEMORY_RW; + create_mapping(&map); } else { /* This better cover the entire kernel */ -- cgit v1.2.3