kernel.git/arch/x86/include/asm/thread_info.h, branch linux-5.12.y

x86: Introduce restart_block->arch_data to remove TS_COMPAT_RESTART

2021-03-16T21:13:11Z

Save the current_thread_info()->status of X86 in the new restart_block->arch_data field so TS_COMPAT_RESTART can be removed again. Signed-off-by: Oleg Nesterov Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/r/20210201174716.GA17898@redhat.com

x86: Introduce TS_COMPAT_RESTART to fix get_nr_restart_syscall()

2021-03-16T21:13:11Z

The comment in get_nr_restart_syscall() says: * The problem is that we can get here when ptrace pokes * syscall-like values into regs even if we're not in a syscall * at all. Yes, but if not in a syscall then the status & (TS_COMPAT|TS_I386_REGS_POKED) check below can't really help: - TS_COMPAT can't be set - TS_I386_REGS_POKED is only set if regs->orig_ax was changed by 32bit debugger; and even in this case get_nr_restart_syscall() is only correct if the tracee is 32bit too. Suppose that a 64bit debugger plays with a 32bit tracee and * Tracee calls sleep(2) // TS_COMPAT is set * User interrupts the tracee by CTRL-C after 1 sec and does "(gdb) call func()" * gdb saves the regs by PTRACE_GETREGS * does PTRACE_SETREGS to set %rip='func' and %orig_rax=-1 * PTRACE_CONT // TS_COMPAT is cleared * func() hits int3. * Debugger catches SIGTRAP. * Restore original regs by PTRACE_SETREGS. * PTRACE_CONT get_nr_restart_syscall() wrongly returns __NR_restart_syscall==219, the tracee calls ia32_sys_call_table[219] == sys_madvise. Add the sticky TS_COMPAT_RESTART flag which survives after return to user mode. It's going to be removed in the next step again by storing the information in the restart block. As a further cleanup it might be possible to remove also TS_I386_REGS_POKED with that. Test-case: $ cvs -d :pserver:anoncvs:anoncvs@sourceware.org:/cvs/systemtap co ptrace-tests $ gcc -o erestartsys-trap-debuggee ptrace-tests/tests/erestartsys-trap-debuggee.c --m32 $ gcc -o erestartsys-trap-debugger ptrace-tests/tests/erestartsys-trap-debugger.c -lutil $ ./erestartsys-trap-debugger Unexpected: retval 1, errno 22 erestartsys-trap-debugger: ptrace-tests/tests/erestartsys-trap-debugger.c:421 Fixes: 609c19a385c8 ("x86/ptrace: Stop setting TS_COMPAT in ptrace code") Reported-by: Jan Kratochvil Signed-off-by: Oleg Nesterov Signed-off-by: Thomas Gleixner Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20210201174709.GA17895@redhat.com

x86: Move TS_COMPAT back to asm/thread_info.h

2021-03-16T21:13:11Z

Move TS_COMPAT back to asm/thread_info.h, close to TS_I386_REGS_POKED. It was moved to asm/processor.h by b9d989c7218a ("x86/asm: Move the thread_info::status field to thread_struct"), then later 37a8f7c38339 ("x86/asm: Move 'status' from thread_struct to thread_info") moved the 'status' field back but TS_COMPAT was forgotten. Preparatory patch to fix the COMPAT case for get_nr_restart_syscall() Fixes: 609c19a385c8 ("x86/ptrace: Stop setting TS_COMPAT in ptrace code") Signed-off-by: Oleg Nesterov Signed-off-by: Thomas Gleixner Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20210201174649.GA17880@redhat.com

x86: Reclaim unused x86 TI flags

2020-11-16T20:53:16Z

Reclaim TI flags that were migrated to syscall_work flags. Signed-off-by: Gabriel Krisman Bertazi Signed-off-by: Thomas Gleixner Reviewed-by: Andy Lutomirski Link: https://lore.kernel.org/r/20201116174206.2639648-11-krisman@collabora.com

x86: Expose syscall_work field in thread_info

2020-11-16T20:53:15Z

This field will be used by SYSCALL_WORK flags, migrated from TI flags. Signed-off-by: Gabriel Krisman Bertazi Signed-off-by: Thomas Gleixner Reviewed-by: Andy Lutomirski Link: https://lore.kernel.org/r/20201116174206.2639648-2-krisman@collabora.com

x86: Wire up TIF_NOTIFY_SIGNAL

2020-10-29T10:29:51Z

The generic entry code has support for TIF_NOTIFY_SIGNAL already. Just provide the TIF bit. [ tglx: Adopted to other TIF changes in x86 ] Signed-off-by: Jens Axboe Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/r/20201026203230.386348-4-axboe@kernel.dk

x86: Reclaim TIF_IA32 and TIF_X32

2020-10-26T12:46:47Z

Now that these flags are no longer used, reclaim those TIF bits. Signed-off-by: Gabriel Krisman Bertazi Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/r/20201004032536.1229030-11-krisman@collabora.com

x86: remove address space overrides using set_fs()

2020-09-09T02:21:36Z

Stop providing the possibility to override the address space using set_fs() now that there is no need for that any more. To properly handle the TASK_SIZE_MAX checking for 4 vs 5-level page tables on x86 a new alternative is introduced, which just like the one in entry_64.S has to use the hardcoded virtual address bits to escape the fact that TASK_SIZE_MAX isn't actually a constant when 5-level page tables are enabled. Signed-off-by: Christoph Hellwig Reviewed-by: Kees Cook Signed-off-by: Al Viro

x86/entry: Use generic syscall entry function

2020-07-24T13:04:59Z

Replace the syscall entry work handling with the generic version. Provide the necessary helper inlines to handle the real architecture specific parts, e.g. ptrace. Use a temporary define for idtentry_enter_user which will be cleaned up seperately. Signed-off-by: Thomas Gleixner Reviewed-by: Kees Cook Link: https://lkml.kernel.org/r/20200722220520.376213694@linutronix.de

Merge tag 'x86-splitlock-2020-03-30' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2020-03-31T02:35:52Z

Pull x86 splitlock updates from Thomas Gleixner: "Support for 'split lock' detection: Atomic operations (lock prefixed instructions) which span two cache lines have to acquire the global bus lock. This is at least 1k cycles slower than an atomic operation within a cache line and disrupts performance on other cores. Aside of performance disruption this is a unpriviledged form of DoS. Some newer CPUs have the capability to raise an #AC trap when such an operation is attempted. The detection is by default enabled in warning mode which will warn once when a user space application is caught. A command line option allows to disable the detection or to select fatal mode which will terminate offending applications with SIGBUS" * tag 'x86-splitlock-2020-03-30' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/split_lock: Avoid runtime reads of the TEST_CTRL MSR x86/split_lock: Rework the initialization flow of split lock detection x86/split_lock: Enable split lock detection by kernel