[PATCH v7 05/14] mm/mmap: Add IBT bitmap size to address space limit check
From: Yu-cheng Yu <hidden>
Date: 2019-06-06 20:19:07
Also in:
linux-arch, linux-doc, linux-mm, lkml
Subsystem:
memory management, memory mapping, the rest, x86 architecture (32-bit and 64-bit) · Maintainers:
Andrew Morton, Liam R. Howlett, Lorenzo Stoakes, Linus Torvalds, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen
The indirect branch tracking legacy bitmap takes a large address space. This causes may_expand_vm() failure on the address limit check. For a IBT-enabled task, add the bitmap size to the address limit. Signed-off-by: Yu-cheng Yu <redacted> --- arch/x86/include/asm/mmu_context.h | 10 ++++++++++ mm/mmap.c | 19 ++++++++++++++++++- 2 files changed, 28 insertions(+), 1 deletion(-)
diff --git a/arch/x86/include/asm/mmu_context.h b/arch/x86/include/asm/mmu_context.h
index a9a768529540..2499f6490428 100644
--- a/arch/x86/include/asm/mmu_context.h
+++ b/arch/x86/include/asm/mmu_context.h@@ -360,6 +360,16 @@ static inline unsigned long __get_current_cr3_fast(void) return cr3; } +#ifdef CONFIG_X86_INTEL_BRANCH_TRACKING_USER +static inline unsigned long arch_as_limit(void) +{ + if (current->thread.cet.ibt_enabled) + return current->thread.cet.ibt_bitmap_size; + else + return 0; +} +#endif + typedef struct { struct mm_struct *mm; } temp_mm_state_t;
diff --git a/mm/mmap.c b/mm/mmap.c
index 3b643ace2c49..a0d6fb559518 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c@@ -3283,13 +3283,30 @@ struct vm_area_struct *copy_vma(struct vm_area_struct **vmap, return NULL; } +#ifndef CONFIG_ARCH_HAS_AS_LIMIT +static inline unsigned long arch_as_limit(void) +{ + return 0; +} +#endif + /* * Return true if the calling process may expand its vm space by the passed * number of pages */ bool may_expand_vm(struct mm_struct *mm, vm_flags_t flags, unsigned long npages) { - if (mm->total_vm + npages > rlimit(RLIMIT_AS) >> PAGE_SHIFT) + unsigned long as_limit = rlimit(RLIMIT_AS); + unsigned long as_limit_plus = as_limit + arch_as_limit(); + + /* as_limit_plus overflowed */ + if (as_limit_plus < as_limit) + as_limit_plus = RLIM_INFINITY; + + if (as_limit_plus > as_limit) + as_limit = as_limit_plus; + + if (mm->total_vm + npages > as_limit >> PAGE_SHIFT) return false; if (is_data_mapping(flags) &&
--
2.17.1