linux-dev/arch/s390/kernel/signal.c, branch linus/master

Merge tag 'ptrace-cleanups-for-v5.18' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace

2022-03-29T00:29:53Z

Pull ptrace cleanups from Eric Biederman: "This set of changes removes tracehook.h, moves modification of all of the ptrace fields inside of siglock to remove races, adds a missing permission check to ptrace.c The removal of tracehook.h is quite significant as it has been a major source of confusion in recent years. Much of that confusion was around task_work and TIF_NOTIFY_SIGNAL (which I have now decoupled making the semantics clearer). For people who don't know tracehook.h is a vestiage of an attempt to implement uprobes like functionality that was never fully merged, and was later superseeded by uprobes when uprobes was merged. For many years now we have been removing what tracehook functionaly a little bit at a time. To the point where anything left in tracehook.h was some weird strange thing that was difficult to understand" * tag 'ptrace-cleanups-for-v5.18' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: ptrace: Remove duplicated include in ptrace.c ptrace: Check PTRACE_O_SUSPEND_SECCOMP permission on PTRACE_SEIZE ptrace: Return the signal to continue with from ptrace_stop ptrace: Move setting/clearing ptrace_message into ptrace_stop tracehook: Remove tracehook.h resume_user_mode: Move to resume_user_mode.h resume_user_mode: Remove #ifdef TIF_NOTIFY_RESUME in set_notify_resume signal: Move set_notify_signal and clear_notify_signal into sched/signal.h task_work: Decouple TIF_NOTIFY_SIGNAL and task_work task_work: Call tracehook_notify_signal from get_signal on all architectures task_work: Introduce task_work_pending task_work: Remove unnecessary include from posix_timers.h ptrace: Remove tracehook_signal_handler ptrace: Remove arch_syscall_{enter,exit}_tracehook ptrace: Create ptrace_report_syscall_{entry,exit} in ptrace.h ptrace/arm: Rename tracehook_report_syscall report_syscall ptrace: Move ptrace_report_syscall into ptrace.h

tracehook: Remove tracehook.h

2022-03-10T22:51:51Z

Now that all of the definitions have moved out of tracehook.h into ptrace.h, sched/signal.h, resume_user_mode.h there is nothing left in tracehook.h so remove it. Update the few files that were depending upon tracehook.h to bring in definitions to use the headers they need directly. Reviewed-by: Kees Cook Link: https://lkml.kernel.org/r/20220309162454.123006-13-ebiederm@xmission.com Signed-off-by: "Eric W. Biederman"

task_work: Call tracehook_notify_signal from get_signal on all architectures

2022-03-10T22:51:36Z

Always handle TIF_NOTIFY_SIGNAL in get_signal. With commit 35d0b389f3b2 ("task_work: unconditionally run task_work from get_signal()") always calling task_work_run all of the work of tracehook_notify_signal is already happening except clearing TIF_NOTIFY_SIGNAL. Factor clear_notify_signal out of tracehook_notify_signal and use it in get_signal so that get_signal only needs one call of task_work_run. To keep the semantics in sync update xfer_to_guest_mode_work (which does not call get_signal) to call tracehook_notify_signal if either _TIF_SIGPENDING or _TIF_NOTIFY_SIGNAL. Reviewed-by: Kees Cook Link: https://lkml.kernel.org/r/20220309162454.123006-8-ebiederm@xmission.com Signed-off-by: "Eric W. Biederman"

s390/signal: fix typo in comments

2022-03-07T23:33:01Z

Signed-off-by: Heiko Carstens Signed-off-by: Vasily Gorbik

s390: remove do_signal() prototype and do_notify_resume() function

2021-08-25T09:03:34Z

Both are no longer used since the conversion to generic entry, therefore remove them. Fixes: 56e62a737028 ("s390: convert to generic entry") Signed-off-by: Sven Schnelle Reviewed-by: Heiko Carstens Signed-off-by: Heiko Carstens

s390/signal: switch to using vdso for sigreturn and syscall restart

2021-07-08T20:09:47Z

with generic entry, there's a bug when it comes to restarting of signals. The failing sequence is: a) a signal is coming in, and no handler is registered, so the lower part of arch_do_signal_or_restart() in arch/s390/kernel/signal.c sets PIF_SYSCALL_RESTART. b) a second signal gets pending while the kernel is still in the exit loop, and for that one, a handler exists. c) The first part of arch_do_signal_or_restart() is called. That part calls handle_signal(), which sets up stack + registers for handling the signal. d) __do_syscall() in arch/s390/kernel/syscall.c checks for PIF_SYSCALL_RESTART right before leaving to userspace. If it is set, it restart's the syscall. However, the registers are already setup for handling a signal from c). The syscall is now restarted with the wrong arguments. Change the code to: - use vdso for syscall_restart() instead of PIF_SYSCALL_RESTART because we cannot rewind and go back to userspace on s390 because the system call number might be encoded in the svc instruction. - for all other syscalls we rewind the PSW and return to userspace. Cc: # v5.12+ d57778feb987: s390/vdso: always enable vdso Cc: # v5.12+ 686341f2548b: s390/vdso64: add sigreturn,rt_sigreturn and restart_syscall Cc: # v5.12+ 43e1f76b0b69: s390/vdso: rename VDSO64_LBASE to VDSO_LBASE Cc: # v5.12+ 779df2248739: s390/vdso: add minimal compat vdso Cc: # v5.12+ Signed-off-by: Sven Schnelle Reviewed-by: Heiko Carstens Signed-off-by: Vasily Gorbik

s390: fix system call restart with multiple signals

2021-06-21T09:19:18Z

glibc complained with "The futex facility returned an unexpected error code.". It turned out that the futex syscall returned -ERESTARTSYS because a signal is pending. arch_do_signal_or_restart() restored the syscall parameters (nameley regs->gprs[2]) and set PIF_SYSCALL_RESTART. When another signal is made pending later in the exit loop arch_do_signal_or_restart() is called again. This function clears PIF_SYSCALL_RESTART and checks the return code which is set in regs->gprs[2]. However, regs->gprs[2] was restored in the previous run and no longer contains -ERESTARTSYS, so PIF_SYSCALL_RESTART isn't set again and the syscall is skipped. Fix this by not clearing PIF_SYSCALL_RESTART - it is already cleared in __do_syscall() when the syscall is restarted. Reported-by: Bjoern Walk Signed-off-by: Sven Schnelle Reviewed-by: Heiko Carstens Fixes: 56e62a737028 ("s390: convert to generic entry") Cc: # 5.12 Signed-off-by: Vasily Gorbik

s390: add missing include to arch/s390/kernel/signal.c

2021-01-27T12:00:47Z

This fixes the following warning: CHECK linux/arch/s390/kernel/signal.c linux/arch/s390/kernel/signal.c:465:6: warning: symbol 'arch_do_signal_or_restart' was not declared. Should it be static? Signed-off-by: Sven Schnelle Signed-off-by: Vasily Gorbik

s390: convert to generic entry

2021-01-19T11:29:26Z

This patch converts s390 to use the generic entry infrastructure from kernel/entry/*. There are a few special things on s390: - PIF_PER_TRAP is moved to TIF_PER_TRAP as the generic code doesn't know about our PIF flags in exit_to_user_mode_loop(). - The old code had several ways to restart syscalls: a) PIF_SYSCALL_RESTART, which was only set during execve to force a restart after upgrading a process (usually qemu-kvm) to pgste page table extensions. b) PIF_SYSCALL, which is set by do_signal() to indicate that the current syscall should be restarted. This is changed so that do_signal() now also uses PIF_SYSCALL_RESTART. Continuing to use PIF_SYSCALL doesn't work with the generic code, and changing it to PIF_SYSCALL_RESTART makes PIF_SYSCALL and PIF_SYSCALL_RESTART more unique. - On s390 calling sys_sigreturn or sys_rt_sigreturn is implemented by executing a svc instruction on the process stack which causes a fault. While handling that fault the fault code sets PIF_SYSCALL to hand over processing to the syscall code on exit to usermode. The patch introduces PIF_SYSCALL_RET_SET, which is set if ptrace sets a return value for a syscall. The s390x ptrace ABI uses r2 both for the syscall number and return value, so ptrace cannot set the syscall number + return value at the same time. The flag makes handling that a bit easier. do_syscall() will just skip executing the syscall if PIF_SYSCALL_RET_SET is set. CONFIG_DEBUG_ASCE was removd in favour of the generic CONFIG_DEBUG_ENTRY. CR1/7/13 will be checked both on kernel entry and exit to contain the correct asces. Signed-off-by: Sven Schnelle Signed-off-by: Vasily Gorbik

s390: add support for TIF_NOTIFY_SIGNAL

2020-11-09T15:16:55Z

Wire up TIF_NOTIFY_SIGNAL handling for s390. Cc: linux-s390@vger.kernel.org Acked-by: Heiko Carstens Acked-by: Sven Schnelle Signed-off-by: Jens Axboe