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Diffstat (limited to 'arch/s390/boot/startup.c')
-rw-r--r--arch/s390/boot/startup.c27
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);