From 42d720d1731a9d7035c2812437c35e271ec4dd78 Mon Sep 17 00:00:00 2001 From: Nikolay Borisov Date: Mon, 12 May 2014 10:31:56 +0100 Subject: ARM: kexec: Make .text R/W in machine_kexec With the introduction of Kees Cook's patch to make the kernel .text read-only the existing method by which kexec works got broken since it directly pokes some values in the template code, which resides in the .text section. The current patch changes the way those values are inserted so that poking .text section occurs only in machine_kexec (e.g when we are about to nuke the old kernel and are beyond the point of return). This allows to use set_kernel_text_rw() to directly patch the values in the .text section. I had already sent a patch which achieved this but it was significantly more complicated, so this is a cleaner/straight-forward approach. Signed-off-by: Nikolay Borisov Acked-by: Will Deacon [kees: collapsed kexec_boot_atags (will.daecon)] [kees: for bisectability, moved set_kernel_text_rw() to RODATA patch] Signed-off-by: Kees Cook Acked-by: Nicolas Pitre --- arch/arm/kernel/machine_kexec.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) (limited to 'arch/arm/kernel/machine_kexec.c') diff --git a/arch/arm/kernel/machine_kexec.c b/arch/arm/kernel/machine_kexec.c index 8cf0996aa1a8..8f75250cbe30 100644 --- a/arch/arm/kernel/machine_kexec.c +++ b/arch/arm/kernel/machine_kexec.c @@ -29,6 +29,7 @@ extern unsigned long kexec_boot_atags; static atomic_t waiting_for_crash_ipi; +static unsigned long dt_mem; /* * Provide a dummy crash_notes definition while crash dump arrives to arm. * This prevents breakage of crash_notes attribute in kernel/ksysfs.c. @@ -64,7 +65,7 @@ int machine_kexec_prepare(struct kimage *image) return err; if (be32_to_cpu(header) == OF_DT_HEADER) - kexec_boot_atags = current_segment->mem; + dt_mem = current_segment->mem; } return 0; } @@ -166,9 +167,8 @@ void machine_kexec(struct kimage *image) kexec_start_address = image->start; kexec_indirection_page = page_list; kexec_mach_type = machine_arch_type; - if (!kexec_boot_atags) - kexec_boot_atags = image->start - KEXEC_ARM_ZIMAGE_OFFSET + KEXEC_ARM_ATAGS_OFFSET; - + kexec_boot_atags = dt_mem ?: image->start - KEXEC_ARM_ZIMAGE_OFFSET + + KEXEC_ARM_ATAGS_OFFSET; /* copy our kernel relocation code to the control code page */ reboot_entry = fncpy(reboot_code_buffer, -- cgit From 80d6b0c2eed2a504f6740cd1f5ea76dc50abfc4d Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Thu, 3 Apr 2014 13:29:50 -0700 Subject: ARM: mm: allow text and rodata sections to be read-only This introduces CONFIG_DEBUG_RODATA, making kernel text and rodata read-only. Additionally, this splits rodata from text so that rodata can also be NX, which may lead to wasted memory when aligning to SECTION_SIZE. The read-only areas are made writable during ftrace updates and kexec. Signed-off-by: Kees Cook Tested-by: Laura Abbott Acked-by: Nicolas Pitre --- arch/arm/kernel/machine_kexec.c | 1 + 1 file changed, 1 insertion(+) (limited to 'arch/arm/kernel/machine_kexec.c') diff --git a/arch/arm/kernel/machine_kexec.c b/arch/arm/kernel/machine_kexec.c index 8f75250cbe30..4423a565ef6f 100644 --- a/arch/arm/kernel/machine_kexec.c +++ b/arch/arm/kernel/machine_kexec.c @@ -164,6 +164,7 @@ void machine_kexec(struct kimage *image) reboot_code_buffer = page_address(image->control_code_page); /* Prepare parameters for reboot_code_buffer*/ + set_kernel_text_rw(); kexec_start_address = image->start; kexec_indirection_page = page_list; kexec_mach_type = machine_arch_type; -- cgit