From 2ebe088b73a87c8fc70231b468c719337f258bf0 Mon Sep 17 00:00:00 2001 From: Ard Biesheuvel Date: Thu, 9 Mar 2017 21:52:03 +0100 Subject: [PATCH] arm64: mmu: apply strict permissions to .init.text and .init.data To avoid having mappings that are writable and executable at the same time, split the init region into a .init.text region that is mapped read-only, and a .init.data region that is mapped non-executable. This is possible now that the alternative patching occurs via the linear mapping, and the linear alias of the init region is always mapped writable (but never executable). Since the alternatives descriptions themselves are read-only data, move those into the .init.text region. Reviewed-by: Laura Abbott Reviewed-by: Mark Rutland Tested-by: Mark Rutland Signed-off-by: Ard Biesheuvel Signed-off-by: Catalin Marinas --- arch/arm64/include/asm/sections.h | 2 ++ arch/arm64/kernel/vmlinux.lds.S | 25 ++++++++++++++++--------- arch/arm64/mm/mmu.c | 12 ++++++++---- 3 files changed, 26 insertions(+), 13 deletions(-) diff --git a/arch/arm64/include/asm/sections.h b/arch/arm64/include/asm/sections.h index 4e7e7067afdb..941267caa39c 100644 --- a/arch/arm64/include/asm/sections.h +++ b/arch/arm64/include/asm/sections.h @@ -24,6 +24,8 @@ extern char __hibernate_exit_text_start[], __hibernate_exit_text_end[]; extern char __hyp_idmap_text_start[], __hyp_idmap_text_end[]; extern char __hyp_text_start[], __hyp_text_end[]; extern char __idmap_text_start[], __idmap_text_end[]; +extern char __initdata_begin[], __initdata_end[]; +extern char __inittext_begin[], __inittext_end[]; extern char __irqentry_text_start[], __irqentry_text_end[]; extern char __mmuoff_data_start[], __mmuoff_data_end[]; diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S index b8deffa9e1bf..2c93d259046c 100644 --- a/arch/arm64/kernel/vmlinux.lds.S +++ b/arch/arm64/kernel/vmlinux.lds.S @@ -143,12 +143,27 @@ SECTIONS . = ALIGN(SEGMENT_ALIGN); __init_begin = .; + __inittext_begin = .; INIT_TEXT_SECTION(8) .exit.text : { ARM_EXIT_KEEP(EXIT_TEXT) } + . = ALIGN(4); + .altinstructions : { + __alt_instructions = .; + *(.altinstructions) + __alt_instructions_end = .; + } + .altinstr_replacement : { + *(.altinstr_replacement) + } + + . = ALIGN(PAGE_SIZE); + __inittext_end = .; + __initdata_begin = .; + .init.data : { INIT_DATA INIT_SETUP(16) @@ -164,15 +179,6 @@ SECTIONS PERCPU_SECTION(L1_CACHE_BYTES) - . = ALIGN(4); - .altinstructions : { - __alt_instructions = .; - *(.altinstructions) - __alt_instructions_end = .; - } - .altinstr_replacement : { - *(.altinstr_replacement) - } .rela : ALIGN(8) { *(.rela .rela*) } @@ -181,6 +187,7 @@ SECTIONS __rela_size = SIZEOF(.rela); . = ALIGN(SEGMENT_ALIGN); + __initdata_end = .; __init_end = .; _data = .; diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c index 300e98e8cd63..75e21c33caff 100644 --- a/arch/arm64/mm/mmu.c +++ b/arch/arm64/mm/mmu.c @@ -459,7 +459,8 @@ early_param("rodata", parse_rodata); */ static void __init map_kernel(pgd_t *pgd) { - static struct vm_struct vmlinux_text, vmlinux_rodata, vmlinux_init, vmlinux_data; + static struct vm_struct vmlinux_text, vmlinux_rodata, vmlinux_inittext, + vmlinux_initdata, vmlinux_data; /* * External debuggers may need to write directly to the text @@ -469,9 +470,12 @@ static void __init map_kernel(pgd_t *pgd) pgprot_t text_prot = rodata_enabled ? PAGE_KERNEL_ROX : PAGE_KERNEL_EXEC; map_kernel_segment(pgd, _text, _etext, text_prot, &vmlinux_text); - map_kernel_segment(pgd, __start_rodata, __init_begin, PAGE_KERNEL, &vmlinux_rodata); - map_kernel_segment(pgd, __init_begin, __init_end, PAGE_KERNEL_EXEC, - &vmlinux_init); + map_kernel_segment(pgd, __start_rodata, __inittext_begin, PAGE_KERNEL, + &vmlinux_rodata); + map_kernel_segment(pgd, __inittext_begin, __inittext_end, text_prot, + &vmlinux_inittext); + map_kernel_segment(pgd, __initdata_begin, __initdata_end, PAGE_KERNEL, + &vmlinux_initdata); map_kernel_segment(pgd, _data, _end, PAGE_KERNEL, &vmlinux_data); if (!pgd_val(*pgd_offset_raw(pgd, FIXADDR_START))) {