linux/kernel/entry/Makefile

# SPDX-License-Identifier: GPL-2.0

# Prevent the noinstr section from being pestered by sanitizer and other goodies
# as long as these things cannot be disabled per function.
KASAN_SANITIZE := n
UBSAN_SANITIZE := n
KCOV_INSTRUMENT := n

CFLAGS_REMOVE_common.o	 = -fstack-protector -fstack-protector-strong
CFLAGS_common.o		+= -fno-stack-protector

obj-$(CONFIG_GENERIC_ENTRY) 		+= common.o
obj-$(CONFIG_KVM_XFER_TO_GUEST_WORK)	+= kvm.o
entry: Provide generic syscall entry functionality On syscall entry certain work needs to be done: - Establish state (lockdep, context tracking, tracing) - Conditional work (ptrace, seccomp, audit...) This code is needlessly duplicated and different in all architectures. Provide a generic version based on the x86 implementation which has all the RCU and instrumentation bits right. As interrupt/exception entry from user space needs parts of the same functionality, provide a function for this as well. syscall_enter_from_user_mode() and irqentry_enter_from_user_mode() must be called right after the low level ASM entry. The calling code must be non-instrumentable. After the functions returns state is correct and the subsequent functions can be instrumented. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Kees Cook <keescook@chromium.org> Link: https://lkml.kernel.org/r/20200722220519.513463269@linutronix.de 2020-07-22 21:59:56 +00:00			`# SPDX-License-Identifier: GPL-2.0`

			`# Prevent the noinstr section from being pestered by sanitizer and other goodies`
			`# as long as these things cannot be disabled per function.`
			`KASAN_SANITIZE := n`
			`UBSAN_SANITIZE := n`
			`KCOV_INSTRUMENT := n`

			`CFLAGS_REMOVE_common.o = -fstack-protector -fstack-protector-strong`
			`CFLAGS_common.o += -fno-stack-protector`

entry: Provide infrastructure for work before transitioning to guest mode Entering a guest is similar to exiting to user space. Pending work like handling signals, rescheduling, task work etc. needs to be handled before that. Provide generic infrastructure to avoid duplication of the same handling code all over the place. The transfer to guest mode handling is different from the exit to usermode handling, e.g. vs. rseq and live patching, so a separate function is used. The initial list of work items handled is: TIF_SIGPENDING, TIF_NEED_RESCHED, TIF_NOTIFY_RESUME Architecture specific TIF flags can be added via defines in the architecture specific include files. The calling convention is also different from the syscall/interrupt entry functions as KVM invokes this from the outer vcpu_run() loop with interrupts and preemption enabled. To prevent missing a pending work item it invokes a check for pending TIF work from interrupt disabled code right before transitioning to guest mode. The lockdep, RCU and tracing state handling is also done directly around the switch to and from guest mode. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lkml.kernel.org/r/20200722220519.833296398@linutronix.de 2020-07-22 21:59:59 +00:00			`obj-$(CONFIG_GENERIC_ENTRY) += common.o`
			`obj-$(CONFIG_KVM_XFER_TO_GUEST_WORK) += kvm.o`