[PATCH v5 04/11] mm/mmap: Add IBT bitmap size to address space limit check
From: Yu-cheng Yu <hidden>
Date: 2018-10-11 15:22:08
Also in:
linux-api, linux-arch, 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 | 7 +++++++ mm/mmap.c | 19 ++++++++++++++++++- 2 files changed, 25 insertions(+), 1 deletion(-)
diff --git a/arch/x86/include/asm/mmu_context.h b/arch/x86/include/asm/mmu_context.h
index 8da7c999b7ee..9c726171e5c5 100644
--- a/arch/x86/include/asm/mmu_context.h
+++ b/arch/x86/include/asm/mmu_context.h@@ -341,4 +341,11 @@ 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) +{ + return current->thread.cet.ibt_bitmap_size; +} +#endif + #endif /* _ASM_X86_MMU_CONTEXT_H */
diff --git a/mm/mmap.c b/mm/mmap.c
index fa581ced3f56..62b3045af005 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c@@ -3231,13 +3231,30 @@ struct vm_area_struct *copy_vma(struct vm_area_struct **vmap, return NULL; } +#ifndef CONFIG_ARCH_HAS_AS_LIMIT +static inline int 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