[RFC PATCH v2 23/27] mm/mmap: Add IBT bitmap size to address space limit check
From: Yu-cheng Yu <hidden>
Date: 2018-07-10 22:31:46
Also in:
linux-arch, linux-doc, linux-mm, lkml
Subsystem:
generic include/asm header files, memory management, memory mapping, the rest, x86 architecture (32-bit and 64-bit) · Maintainers:
Arnd Bergmann, 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/uapi/asm/resource.h | 5 +++++ include/uapi/asm-generic/resource.h | 3 +++ mm/mmap.c | 12 +++++++++++- 3 files changed, 19 insertions(+), 1 deletion(-)
diff --git a/arch/x86/include/uapi/asm/resource.h b/arch/x86/include/uapi/asm/resource.h
index 04bc4db8921b..0741b2a6101a 100644
--- a/arch/x86/include/uapi/asm/resource.h
+++ b/arch/x86/include/uapi/asm/resource.h@@ -1 +1,6 @@ +/* SPDX-License-Identifier: GPL-2.0+ WITH Linux-syscall-note */ +#ifdef CONFIG_X86_INTEL_CET +#define rlimit_as_extra() current->thread.cet.ibt_bitmap_size +#endif + #include <asm-generic/resource.h>
diff --git a/include/uapi/asm-generic/resource.h b/include/uapi/asm-generic/resource.h
index f12db7a0da64..8a7608a09700 100644
--- a/include/uapi/asm-generic/resource.h
+++ b/include/uapi/asm-generic/resource.h@@ -58,5 +58,8 @@ # define RLIM_INFINITY (~0UL) #endif +#ifndef rlimit_as_extra +#define rlimit_as_extra() 0 +#endif #endif /* _UAPI_ASM_GENERIC_RESOURCE_H */
diff --git a/mm/mmap.c b/mm/mmap.c
index d1eb87ef4b1a..fad41b291ae1 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c@@ -3242,7 +3242,17 @@ struct vm_area_struct *copy_vma(struct vm_area_struct **vmap, */ 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 + rlimit_as_extra(); + + /* 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