Thomas Gleixner a9f3a74a29 entry: Provide generic syscall exit function ... Like syscall entry all architectures have similar and pointlessly different code to handle pending work before returning from a syscall to user space. 1) One-time syscall exit work: - rseq syscall exit - audit - syscall tracing - tracehook (single stepping) 2) Preparatory work - Exit to user mode loop (common TIF handling). - Architecture specific one time work arch_exit_to_user_mode_prepare() - Address limit and lockdep checks 3) Final transition (lockdep, tracing, context tracking, RCU). Invokes arch_exit_to_user_mode() to handle e.g. speculation mitigations Provide a generic version based on the x86 code which has all the RCU and instrumentation protections right. Provide a variant for interrupt return to user mode as well which shares the above #2 and #3 work items. After syscall_exit_to_user_mode() and irqentry_exit_to_user_mode() the architecture code just has to return to user space. The code after returning from these functions must not be instrumented. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Kees Cook <keescook@chromium.org> Link: https://lkml.kernel.org/r/20200722220519.613977173@linutronix.de		2020-07-24 14:59:03 +02:00
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common.c	entry: Provide generic syscall exit function	2020-07-24 14:59:03 +02:00