From: Vasily Gorbik gor@linux.ibm.com
commit 9a39abb7c9aab50eec4ac4421e9ee7f3de013d24 upstream.
Initial KASAN shadow memory range was picked to preserve original kernel modules area position. With protected execution support, which might impose addressing limitation on vmalloc area and hence affect modules area position, current fixed KASAN shadow memory range is only making kernel memory layout setup more complex. So move it to the very end of available virtual space and simplify calculations.
At the same time return to previous kernel address space split. In particular commit 0c4f2623b957 ("s390: setup kernel memory layout early") introduced precise identity map size calculation and keeping vmemmap left most starting from a fresh region table entry. This didn't take into account additional mapping region requirement for potential DCSS mapping above available physical memory. So go back to virtual space split between 1:1 mapping & vmemmap array once vmalloc area size is subtracted.
Cc: stable@vger.kernel.org Fixes: 0c4f2623b957 ("s390: setup kernel memory layout early") Reported-by: Gerald Schaefer gerald.schaefer@linux.ibm.com Reviewed-by: Heiko Carstens hca@linux.ibm.com Reviewed-by: Alexander Gordeev agordeev@linux.ibm.com Signed-off-by: Vasily Gorbik gor@linux.ibm.com Signed-off-by: Heiko Carstens hca@linux.ibm.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/s390/Kconfig | 2 - arch/s390/boot/startup.c | 88 ++++++++++++++++------------------------------- 2 files changed, 32 insertions(+), 58 deletions(-)
--- a/arch/s390/Kconfig +++ b/arch/s390/Kconfig @@ -47,7 +47,7 @@ config ARCH_SUPPORTS_UPROBES config KASAN_SHADOW_OFFSET hex depends on KASAN - default 0x18000000000000 + default 0x1C000000000000
config S390 def_bool y --- a/arch/s390/boot/startup.c +++ b/arch/s390/boot/startup.c @@ -148,82 +148,56 @@ static void setup_ident_map_size(unsigne
static void setup_kernel_memory_layout(void) { - bool vmalloc_size_verified = false; - unsigned long vmemmap_off; - unsigned long vspace_left; + unsigned long vmemmap_start; unsigned long rte_size; unsigned long pages; - unsigned long vmax;
pages = ident_map_size / PAGE_SIZE; /* vmemmap contains a multiple of PAGES_PER_SECTION struct pages */ vmemmap_size = SECTION_ALIGN_UP(pages) * sizeof(struct page);
/* choose kernel address space layout: 4 or 3 levels. */ - vmemmap_off = round_up(ident_map_size, _REGION3_SIZE); + vmemmap_start = round_up(ident_map_size, _REGION3_SIZE); if (IS_ENABLED(CONFIG_KASAN) || vmalloc_size > _REGION2_SIZE || - vmemmap_off + vmemmap_size + vmalloc_size + MODULES_LEN > _REGION2_SIZE) - vmax = _REGION1_SIZE; - else - vmax = _REGION2_SIZE; - - /* keep vmemmap_off aligned to a top level region table entry */ - rte_size = vmax == _REGION1_SIZE ? _REGION2_SIZE : _REGION3_SIZE; - MODULES_END = vmax; - if (is_prot_virt_host()) { - /* - * forcing modules and vmalloc area under the ultravisor - * secure storage limit, so that any vmalloc allocation - * we do could be used to back secure guest storage. - */ - adjust_to_uv_max(&MODULES_END); - } - -#ifdef CONFIG_KASAN - if (MODULES_END < vmax) { - /* force vmalloc and modules below kasan shadow */ - MODULES_END = min(MODULES_END, KASAN_SHADOW_START); + vmemmap_start + vmemmap_size + vmalloc_size + MODULES_LEN > + _REGION2_SIZE) { + MODULES_END = _REGION1_SIZE; + rte_size = _REGION2_SIZE; } else { - /* - * leave vmalloc and modules above kasan shadow but make - * sure they don't overlap with it - */ - vmalloc_size = min(vmalloc_size, vmax - KASAN_SHADOW_END - MODULES_LEN); - vmalloc_size_verified = true; - vspace_left = KASAN_SHADOW_START; + MODULES_END = _REGION2_SIZE; + rte_size = _REGION3_SIZE; } + /* + * forcing modules and vmalloc area under the ultravisor + * secure storage limit, so that any vmalloc allocation + * we do could be used to back secure guest storage. + */ + adjust_to_uv_max(&MODULES_END); +#ifdef CONFIG_KASAN + /* force vmalloc and modules below kasan shadow */ + MODULES_END = min(MODULES_END, KASAN_SHADOW_START); #endif MODULES_VADDR = MODULES_END - MODULES_LEN; VMALLOC_END = MODULES_VADDR;
- if (vmalloc_size_verified) { - VMALLOC_START = VMALLOC_END - vmalloc_size; - } else { - vmemmap_off = round_up(ident_map_size, rte_size); - - if (vmemmap_off + vmemmap_size > VMALLOC_END || - vmalloc_size > VMALLOC_END - vmemmap_off - vmemmap_size) { - /* - * allow vmalloc area to occupy up to 1/2 of - * the rest virtual space left. - */ - vmalloc_size = min(vmalloc_size, VMALLOC_END / 2); - } - VMALLOC_START = VMALLOC_END - vmalloc_size; - vspace_left = VMALLOC_START; - } + /* allow vmalloc area to occupy up to about 1/2 of the rest virtual space left */ + vmalloc_size = min(vmalloc_size, round_down(VMALLOC_END / 2, _REGION3_SIZE)); + VMALLOC_START = VMALLOC_END - vmalloc_size;
- pages = vspace_left / (PAGE_SIZE + sizeof(struct page)); + /* split remaining virtual space between 1:1 mapping & vmemmap array */ + pages = VMALLOC_START / (PAGE_SIZE + sizeof(struct page)); pages = SECTION_ALIGN_UP(pages); - vmemmap_off = round_up(vspace_left - pages * sizeof(struct page), rte_size); - /* keep vmemmap left most starting from a fresh region table entry */ - vmemmap_off = min(vmemmap_off, round_up(ident_map_size, rte_size)); - /* take care that identity map is lower then vmemmap */ - ident_map_size = min(ident_map_size, vmemmap_off); + /* keep vmemmap_start aligned to a top level region table entry */ + vmemmap_start = round_down(VMALLOC_START - pages * sizeof(struct page), rte_size); + /* vmemmap_start is the future VMEM_MAX_PHYS, make sure it is within MAX_PHYSMEM */ + vmemmap_start = min(vmemmap_start, 1UL << MAX_PHYSMEM_BITS); + /* make sure identity map doesn't overlay with vmemmap */ + ident_map_size = min(ident_map_size, vmemmap_start); vmemmap_size = SECTION_ALIGN_UP(ident_map_size / PAGE_SIZE) * sizeof(struct page); - VMALLOC_START = max(vmemmap_off + vmemmap_size, VMALLOC_START); - vmemmap = (struct page *)vmemmap_off; + /* make sure vmemmap doesn't overlay with vmalloc area */ + VMALLOC_START = max(vmemmap_start + vmemmap_size, VMALLOC_START); + vmemmap = (struct page *)vmemmap_start; }
/*