diff options
Diffstat (limited to 'arch/s390/mm')
| -rw-r--r-- | arch/s390/mm/dump_pagetables.c | 14 | ||||
| -rw-r--r-- | arch/s390/mm/vmem.c | 10 |
2 files changed, 19 insertions, 5 deletions
diff --git a/arch/s390/mm/dump_pagetables.c b/arch/s390/mm/dump_pagetables.c index 0b0c8c284953..9f9af5298dd6 100644 --- a/arch/s390/mm/dump_pagetables.c +++ b/arch/s390/mm/dump_pagetables.c @@ -8,6 +8,7 @@ #include <linux/kasan.h> #include <asm/ptdump.h> #include <asm/kasan.h> +#include <asm/nospec-branch.h> #include <asm/sections.h> static unsigned long max_addr; @@ -116,8 +117,13 @@ static void note_prot_wx(struct pg_state *st, unsigned long addr) return; if (st->current_prot & _PAGE_NOEXEC) return; - /* The first lowcore page is currently still W+X. */ - if (addr == PAGE_SIZE) + /* + * The first lowcore page is W+X if spectre mitigations are using + * trampolines or the BEAR enhancements facility is not installed, + * in which case we have two lpswe instructions in lowcore that need + * to be executable. + */ + if (addr == PAGE_SIZE && (nospec_uses_trampoline() || !static_key_enabled(&cpu_has_bear))) return; WARN_ONCE(1, "s390/mm: Found insecure W+X mapping at address %pS\n", (void *)st->start_address); @@ -203,7 +209,9 @@ void ptdump_check_wx(void) if (st.wx_pages) pr_warn("Checked W+X mappings: FAILED, %lu W+X pages found\n", st.wx_pages); else - pr_info("Checked W+X mappings: passed, no unexpected W+X pages found\n"); + pr_info("Checked W+X mappings: passed, no %sW+X pages found\n", + (nospec_uses_trampoline() || !static_key_enabled(&cpu_has_bear)) ? + "unexpected " : ""); } #endif /* CONFIG_DEBUG_WX */ diff --git a/arch/s390/mm/vmem.c b/arch/s390/mm/vmem.c index 2b1c6d916cf9..7d9705eeb02f 100644 --- a/arch/s390/mm/vmem.c +++ b/arch/s390/mm/vmem.c @@ -13,6 +13,7 @@ #include <linux/hugetlb.h> #include <linux/slab.h> #include <asm/cacheflush.h> +#include <asm/nospec-branch.h> #include <asm/pgalloc.h> #include <asm/setup.h> #include <asm/tlbflush.h> @@ -584,8 +585,13 @@ void __init vmem_map_init(void) __set_memory(__stext_amode31, (__etext_amode31 - __stext_amode31) >> PAGE_SHIFT, SET_MEMORY_RO | SET_MEMORY_X); - /* we need lowcore executable for our LPSWE instructions */ - set_memory_x(0, 1); + if (nospec_uses_trampoline() || !static_key_enabled(&cpu_has_bear)) { + /* + * Lowcore must be executable for LPSWE + * and expoline trampoline branch instructions. + */ + set_memory_x(0, 1); + } pr_info("Write protected kernel read-only data: %luk\n", (unsigned long)(__end_rodata - _stext) >> 10); |