Eric W. Biederman 16cc1bc67d ptrace: Remove arch_ptrace_attach ... The last remaining implementation of arch_ptrace_attach is ia64's ptrace_attach_sync_user_rbs which was added at the end of 2007 in commit aa91a2e900 ("[IA64] Synchronize RBS on PTRACE_ATTACH"). Reading the comments and examining the code ptrace_attach_sync_user_rbs has the sole purpose of saving registers to the stack when ptrace_attach changes TASK_STOPPED to TASK_TRACED. In all other cases arch_ptrace_stop takes care of the register saving. In commit d79fdd6d96 ("ptrace: Clean transitions between TASK_STOPPED and TRACED") modified ptrace_attach to wake up the thread and enter ptrace_stop normally even when the thread starts out stopped. This makes ptrace_attach_sync_user_rbs completely unnecessary. So just remove it. I read through the code to verify that ptrace_attach_sync_user_rbs is unnecessary. What I found is that the code is quite dead. Reading ptrace_attach_sync_user_rbs it is easy to see that the it does nothing unless __state == TASK_STOPPED. Calling arch_ptrace_attach (aka ptrace_attach_sync_user_rbs) after ptrace_traceme it is easy to see that because we are talking about the current process the value of __state is TASK_RUNNING. Which means ptrace_attach_sync_user_rbs does nothing. The only other call of arch_ptrace_attach (aka ptrace_attach_sync_user_rbs) is after ptrace_attach. If the task is running (and PTRACE_SEIZE is not specified), a SIGSTOP is sent which results in do_signal_stop setting JOBCTL_TRAP_STOP on the target task (as it is ptraced) and the target task stopping in ptrace_stop with __state == TASK_TRACED. If the task was already stopped then ptrace_attach sets JOBCTL_TRAPPING and JOBCTL_TRAP_STOP, wakes it out of __TASK_STOPPED, and waits until the JOBCTL_TRAPPING_BIT is clear. At which point the task stops in ptrace_stop. In both cases there are a couple of funning excpetions such as if the traced task receiveds a SIGCONT, or is set a fatal signal. However in all of those cases the tracee never stops in __state TASK_STOPPED. Which is a long way of saying that ptrace_attach_sync_user_rbs is guaranteed never to do anything. Cc: linux-ia64@vger.kernel.org Tested-by: Kees Cook <keescook@chromium.org> Reviewed-by: Oleg Nesterov <oleg@redhat.com> Link: https://lkml.kernel.org/r/20220505182645.497868-4-ebiederm@xmission.com Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>		2022-05-11 14:33:54 -05:00
..
configs	arch: Remove references to CONFIG_NFSD_V3 in the default configs	2022-03-11 10:25:16 -05:00
hp/common	ia64/sba_iommu: return error code from sba_map_sg_attrs()	2021-08-09 17:13:05 +02:00
include	ptrace: Remove arch_ptrace_attach	2022-05-11 14:33:54 -05:00
kernel	ptrace: Remove arch_ptrace_attach	2022-05-11 14:33:54 -05:00
lib	Merge branch 'work.csum_and_copy' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs	2020-10-12 16:24:13 -07:00
mm	mm, memory_hotplug: drop arch_free_nodedata	2022-03-22 15:57:10 -07:00
pci	PCI/sysfs: Find shadow ROM before static attribute initialization	2022-01-26 10:41:21 -06:00
scripts	kbuild: remove PYTHON variable	2021-02-01 10:37:19 +09:00
uv	ia64: remove support for machvecs	2019-08-16 14:32:26 -07:00
install.sh
Kbuild	ia64: move core-y in arch/ia64/Makefile to arch/ia64/Kbuild	2021-09-03 08:17:20 +09:00
Kconfig	powerpc updates for 5.18	2022-03-25 09:39:36 -07:00
Kconfig.debug	ia64: don't do IA64_CMPXCHG_DEBUG without CONFIG_PRINTK	2021-10-04 10:45:58 +02:00
Makefile	kbuild: use more subdir- for visiting subdirectories while cleaning	2021-10-24 13:49:46 +09:00