From: Nikolay Borisov <Nikolay.Borisov@xxxxxxx> 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 <Nikolay.Borisov@xxxxxxx> Acked-by: Will Deacon <will.deacon@xxxxxxx> [kees: collapsed kexec_boot_atags (will.daecon)] [kees: for bisectability, moved set_kernel_text_rw() to RODATA patch] Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx> --- arch/arm/kernel/machine_kexec.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) 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, -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
