From: Benjamin Berg <benjamin.b...@intel.com> The new version of the patchset uses execveat on a memfd instead of cloning twice to disable rseq. This should be much more robust going forward as it will also avoid issues with other new features like mseal.
This patchset fixes a few bugs, adds a new method of discovering the host task size and finally adds four level page table support. All of this means the userspace TASK_SIZE is much larger and in turns permits userspace applications that need a lot of virtual addresses to work fine. One such application is ASAN which uses a fixed address in memory that would otherwise not be addressable. v6: * Apply fixes pointed out by Tiwei Bie * Add temporary file fallback as memfd is not always supported v5: * Use execveat with memfd instead of double clone v4: * Do not use WNOHANG in wait for CLONE_VFORK v3: * Undo incorrect change in child wait loop v2: * Improved double clone logic using CLONE_VFORK * Kconfig fixes pointed out by Tiwei Bie Benjamin Berg (7): um: Add generic stub_syscall6 function um: Add generic stub_syscall1 function um: use execveat to create userspace MMs um: Fix stub_start address calculation um: Limit TASK_SIZE to the addressable range um: Discover host_task_size from envp um: Add 4 level page table support arch/um/Kconfig | 1 + arch/um/include/asm/page.h | 14 +- arch/um/include/asm/pgalloc.h | 11 +- arch/um/include/asm/pgtable-4level.h | 119 +++++++++++++++++ arch/um/include/asm/pgtable.h | 6 +- arch/um/include/shared/as-layout.h | 2 +- arch/um/include/shared/os.h | 2 +- arch/um/include/shared/skas/stub-data.h | 11 ++ arch/um/kernel/mem.c | 17 ++- arch/um/kernel/um_arch.c | 14 +- arch/um/os-Linux/main.c | 9 +- arch/um/os-Linux/skas/process.c | 171 ++++++++++++++++-------- arch/x86/um/.gitignore | 2 + arch/x86/um/Kconfig | 38 ++++-- arch/x86/um/Makefile | 32 ++++- arch/x86/um/os-Linux/task_size.c | 19 ++- arch/x86/um/shared/sysdep/stub_32.h | 22 +++ arch/x86/um/shared/sysdep/stub_64.h | 27 ++++ arch/x86/um/stub_elf.c | 86 ++++++++++++ arch/x86/um/stub_elf_embed.S | 11 ++ 20 files changed, 528 insertions(+), 86 deletions(-) create mode 100644 arch/um/include/asm/pgtable-4level.h create mode 100644 arch/x86/um/.gitignore create mode 100644 arch/x86/um/stub_elf.c create mode 100644 arch/x86/um/stub_elf_embed.S -- 2.45.2
