Started from discussion [1], where was noted that currently a couple of architectures support mremap() for vdso/sigpage, but not munmap(). If an application maps something on the ex-place of vdso/sigpage, later after processing signal it will land there (good luck!) Patches set is based on linux-next (next-20201106) and it depends on changes in x86/cleanups (those reclaim TIF_IA32/TIF_X32) and also on my changes in akpm (fixing several mremap() issues). Logically, the patches set divides on: - patch 1: cleanup for patches in x86/cleanups - patches 2-11: cleanups for arch_setup_additional_pages() - patches 12-13: x86 signal changes for unmapped vdso - patches 14-19: provide generic user_landing in mm_struct In the end, besides cleanups, it's now more predictable what happens for applications with unmapped vdso on architectures those support .mremap() for vdso/sigpage. I'm aware of only one user that unmaps vdso - Valgrind [2]. (there possibly are more, but this one is "special", it unmaps vdso, but not vvar, which confuses CRIU [Checkpoint Restore In Userspace], that's why I'm aware of it) Patches as a .git branch: https://github.com/0x7f454c46/linux/tree/setup_additional_pages [1]: https://lore.kernel.org/linux-arch/CAJwJo6ZANqYkSHbQ+3b+Fi_VT80MtrzEV5yreQAWx-L8j8x2zA@xxxxxxxxxxxxxx/ [2]: https://github.com/checkpoint-restore/criu/issues/488 Cc: Alexander Viro <viro@xxxxxxxxxxxxxxxxxx> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Cc: Andy Lutomirski <luto@xxxxxxxxxx> Cc: Arnd Bergmann <arnd@xxxxxxxx> Cc: Borislav Petkov <bp@xxxxxxxxx> Cc: Catalin Marinas <catalin.marinas@xxxxxxx> Cc: Christophe Leroy <christophe.leroy@xxxxxxxxxx> Cc: Guo Ren <guoren@xxxxxxxxxx> Cc: "H. Peter Anvin" <hpa@xxxxxxxxx> Cc: Ingo Molnar <mingo@xxxxxxxxxx> Cc: Oleg Nesterov <oleg@xxxxxxxxxx> Cc: Russell King <linux@xxxxxxxxxxxxxxx> Cc: Thomas Bogendoerfer <tsbogend@xxxxxxxxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: Vincenzo Frascino <vincenzo.frascino@xxxxxxx> Cc: Will Deacon <will@xxxxxxxxxx> Cc: x86@xxxxxxxxxx Dmitry Safonov (19): x86/elf: Check in_x32_syscall() in compat_arch_setup_additional_pages() elf: Move arch_setup_additional_pages() to generic elf.h arm64: Use in_compat_task() in arch_setup_additional_pages() x86: Remove compat_arch_setup_additional_pages() elf: Remove compat_arch_setup_additional_pages() elf/vdso: Reuse arch_setup_additional_pages() parameters elf: Use sysinfo_ehdr in ARCH_DLINFO() arm/vdso: Remove vdso pointer from mm->context s390/vdso: Remove vdso_base pointer from mm->context sparc/vdso: Remove vdso pointer from mm->context mm/mmap: Make vm_special_mapping::mremap return void x86/signal: Land on &frame->retcode when vdso isn't mapped x86/signal: Check if vdso_image_32 is mapped before trying to land on it mm: Add user_landing in mm_struct x86/vdso: Migrate to user_landing arm/vdso: Migrate to user_landing arm64/vdso: Migrate compat signals to user_landing arm64/vdso: Migrate native signals to user_landing mips/vdso: Migrate to user_landing arch/alpha/include/asm/elf.h | 2 +- arch/arm/Kconfig | 2 + arch/arm/include/asm/elf.h | 10 +--- arch/arm/include/asm/mmu.h | 3 - arch/arm/include/asm/vdso.h | 6 +- arch/arm/kernel/process.c | 14 +---- arch/arm/kernel/signal.c | 6 +- arch/arm/kernel/vdso.c | 20 ++----- arch/arm64/Kconfig | 2 + arch/arm64/include/asm/elf.h | 27 ++------- arch/arm64/kernel/signal.c | 10 +++- arch/arm64/kernel/signal32.c | 17 ++++-- arch/arm64/kernel/vdso.c | 47 ++++++--------- arch/csky/Kconfig | 1 + arch/csky/include/asm/elf.h | 4 -- arch/csky/kernel/vdso.c | 3 +- arch/hexagon/Kconfig | 1 + arch/hexagon/include/asm/elf.h | 6 -- arch/hexagon/kernel/vdso.c | 3 +- arch/ia64/include/asm/elf.h | 2 +- arch/mips/Kconfig | 2 + arch/mips/include/asm/elf.h | 10 +--- arch/mips/kernel/signal.c | 11 ++-- arch/mips/kernel/vdso.c | 5 +- arch/mips/vdso/genvdso.c | 9 --- arch/nds32/Kconfig | 1 + arch/nds32/include/asm/elf.h | 8 +-- arch/nds32/kernel/vdso.c | 3 +- arch/nios2/Kconfig | 1 + arch/nios2/include/asm/elf.h | 4 -- arch/nios2/mm/init.c | 2 +- arch/powerpc/Kconfig | 1 + arch/powerpc/include/asm/elf.h | 9 +-- arch/powerpc/kernel/vdso.c | 3 +- arch/riscv/Kconfig | 1 + arch/riscv/include/asm/elf.h | 10 +--- arch/riscv/kernel/vdso.c | 9 +-- arch/s390/Kconfig | 1 + arch/s390/include/asm/elf.h | 10 +--- arch/s390/include/asm/mmu.h | 1 - arch/s390/kernel/vdso.c | 13 +--- arch/sh/Kconfig | 1 + arch/sh/include/asm/elf.h | 16 ++--- arch/sh/kernel/vsyscall/vsyscall.c | 3 +- arch/sparc/Kconfig | 1 + arch/sparc/include/asm/elf_64.h | 11 +--- arch/sparc/include/asm/mmu_64.h | 1 - arch/sparc/vdso/vma.c | 18 +++--- arch/x86/Kconfig | 2 + arch/x86/entry/common.c | 8 ++- arch/x86/entry/vdso/vma.c | 72 ++++++++++++----------- arch/x86/ia32/ia32_signal.c | 18 +++--- arch/x86/include/asm/compat.h | 6 ++ arch/x86/include/asm/elf.h | 44 +++++--------- arch/x86/include/asm/mmu.h | 1 - arch/x86/include/asm/vdso.h | 4 ++ arch/x86/kernel/cpu/resctrl/pseudo_lock.c | 3 +- arch/x86/kernel/signal.c | 25 ++++---- arch/x86/um/asm/elf.h | 9 +-- arch/x86/um/vdso/vma.c | 2 +- fs/Kconfig.binfmt | 3 + fs/aio.c | 3 +- fs/binfmt_elf.c | 19 +++--- fs/binfmt_elf_fdpic.c | 17 +++--- fs/compat_binfmt_elf.c | 12 ---- include/linux/elf.h | 24 ++++++-- include/linux/mm.h | 3 +- include/linux/mm_types.h | 12 +++- mm/Kconfig | 3 + mm/mmap.c | 21 ++++++- mm/mremap.c | 2 +- 71 files changed, 308 insertions(+), 356 deletions(-) base-commit: c34f157421f6905e6b4a79a312e9175dce2bc607 -- 2.28.0
