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 <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: "H. Peter Anvin" <[email protected]> Cc: Andy Lutomirski <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: [email protected] Cc: [email protected] Dmitry Safonov (5): x86/mm: split arch_mmap_rnd() on compat/native versions x86/mm: introduce mmap_{,legacy}_base x86/mm: fix native mmap() in compat bins and vice-versa x86/mm: for MAP_32BIT check in_compat_syscall() instead TIF_ADDR32 selftests/x86: add test to check compat mmap() return addr arch/x86/include/asm/elf.h | 14 +- arch/x86/include/asm/processor.h | 2 +- arch/x86/kernel/sys_x86_64.c | 48 +++++- arch/x86/mm/hugetlbpage.c | 2 +- arch/x86/mm/mmap.c | 56 ++++--- tools/testing/selftests/x86/Makefile | 2 +- tools/testing/selftests/x86/test_compat_mmap.c | 208 +++++++++++++++++++++++++ 7 files changed, 301 insertions(+), 31 deletions(-) create mode 100644 tools/testing/selftests/x86/test_compat_mmap.c -- 2.11.0
