diff options
Diffstat (limited to 'arch/s390/boot/startup.c')
| -rw-r--r-- | arch/s390/boot/startup.c | 27 |
1 files changed, 24 insertions, 3 deletions
diff --git a/arch/s390/boot/startup.c b/arch/s390/boot/startup.c index 182aac6a0f77..48ef5fe5c08a 100644 --- a/arch/s390/boot/startup.c +++ b/arch/s390/boot/startup.c @@ -384,7 +384,7 @@ static void fixup_vmlinux_info(void) void startup_kernel(void) { unsigned long kernel_size = vmlinux.image_size + vmlinux.bss_size; - unsigned long nokaslr_offset_phys = mem_safe_offset(); + unsigned long nokaslr_offset_phys, kaslr_large_page_offset; unsigned long amode31_lma = 0; unsigned long max_physmem_end; unsigned long asce_limit; @@ -393,6 +393,12 @@ void startup_kernel(void) fixup_vmlinux_info(); setup_lpp(); + + /* + * Non-randomized kernel physical start address must be _SEGMENT_SIZE + * aligned (see blow). + */ + nokaslr_offset_phys = ALIGN(mem_safe_offset(), _SEGMENT_SIZE); safe_addr = PAGE_ALIGN(nokaslr_offset_phys + kernel_size); /* @@ -425,10 +431,25 @@ void startup_kernel(void) save_ipl_cert_comp_list(); rescue_initrd(safe_addr, ident_map_size); - if (kaslr_enabled()) - __kaslr_offset_phys = randomize_within_range(kernel_size, THREAD_SIZE, 0, ident_map_size); + /* + * __kaslr_offset_phys must be _SEGMENT_SIZE aligned, so the lower + * 20 bits (the offset within a large page) are zero. Copy the last + * 20 bits of __kaslr_offset, which is THREAD_SIZE aligned, to + * __kaslr_offset_phys. + * + * With this the last 20 bits of __kaslr_offset_phys and __kaslr_offset + * are identical, which is required to allow for large mappings of the + * kernel image. + */ + kaslr_large_page_offset = __kaslr_offset & ~_SEGMENT_MASK; + if (kaslr_enabled()) { + unsigned long end = ident_map_size - kaslr_large_page_offset; + + __kaslr_offset_phys = randomize_within_range(kernel_size, _SEGMENT_SIZE, 0, end); + } if (!__kaslr_offset_phys) __kaslr_offset_phys = nokaslr_offset_phys; + __kaslr_offset_phys |= kaslr_large_page_offset; kaslr_adjust_vmlinux_info(__kaslr_offset_phys); physmem_reserve(RR_VMLINUX, __kaslr_offset_phys, kernel_size); deploy_kernel((void *)__kaslr_offset_phys); |