Changes since v3:
- fixed usage of 64-bit random mask for 32-bit mm->mmap_compat_base,
during introducing mmap_compat{_legacy,}_base
Changes since v2:
- don't distinguish native and compat tasks by TIF_ADDR32,
introduced mmap_compat{_legacy,}_base which allows to treat them
the same
- fixed kbuild errors
Changes since v1:
- Recalculate mmap_base instead of using max possible virtual address
for compat/native syscall. That will make policy for allocation the
same in 32-bit binaries and in 32-bit syscalls in 64-bit binaries.
I need this because sys_mmap() in restored 32-bit process shouldn't
hit the stack area.
- Fixed mmap() with MAP_32BIT flag in the same usecases
- used in_compat_syscall() helper rather TS_COMPAT check (Andy noticed)
- introduced find_top() helper as suggested by Andy to simplify code
- fixed test error-handeling: it checked the result of sys_mmap() with
MMAP_FAILED, which is not correct, as it calls raw syscall - now
checks return value to be aligned to PAGE_SIZE.
Description from v1 [2]:
A fix for bug in mmap() that I referenced in [1].
Also selftest for it.
I would like to mark the fix as for stable v4.9 kernel if it'll
be accepted, as I try to support compatible 32-bit C/R
after v4.9 and working compatible mmap() is really wanted there.
[1]: https://marc.info/?l=linux-kernel&m=148311451525315
[2]: https://marc.info/?l=linux-kernel&m=148415888707662
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxx>
Cc: x86@xxxxxxxxxx
Cc: linux-mm@xxxxxxxxx
Dmitry Safonov (5):
x86/mm: split arch_mmap_rnd() on compat/native versions
x86/mm: introduce mmap{,_legacy}_base
x86/mm: fix 32-bit mmap() for 64-bit ELF
x86/mm: check in_compat_syscall() instead TIF_ADDR32 for
mmap(MAP_32BIT)
selftests/x86: add test to check compat mmap() return addr
arch/Kconfig | 7 +
arch/x86/Kconfig | 1 +
arch/x86/include/asm/elf.h | 4 +-
arch/x86/include/asm/processor.h | 3 +-
arch/x86/kernel/sys_x86_64.c | 32 +++-
arch/x86/mm/mmap.c | 89 +++++++----
include/linux/mm_types.h | 5 +
tools/testing/selftests/x86/Makefile | 2 +-
tools/testing/selftests/x86/test_compat_mmap.c | 208 +++++++++++++++++++++++++
9 files changed, 311 insertions(+), 40 deletions(-)
create mode 100644 tools/testing/selftests/x86/test_compat_mmap.c
--
2.11.0
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