From: Thomas Gleixner <tglx@linutronix.de>
To: LKML <linux-kernel@vger.kernel.org>
Cc: x86@kernel.org, Peter Zijlstra <peterz@infradead.org>,
Andy Lutomirski <luto@kernel.org>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Marc Zyngier <maz@kernel.org>,
Paolo Bonzini <pbonzini@redhat.com>,
kvm@vger.kernel.org, linux-arch@vger.kernel.org
Subject: [RFC patch 09/15] entry: Provide generic exit to usermode functionality
Date: Thu, 19 Sep 2019 17:03:23 +0200 [thread overview]
Message-ID: <20190919150809.340471236@linutronix.de> (raw)
In-Reply-To: 20190919150314.054351477@linutronix.de
Provide a generic facility to handle the exit to usermode work. That's
aimed to replace the pointlessly different copies in each architecture.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
include/linux/entry-common.h | 105 +++++++++++++++++++++++++++++++++++++++++++
kernel/entry/common.c | 88 ++++++++++++++++++++++++++++++++++++
2 files changed, 193 insertions(+)
--- a/include/linux/entry-common.h
+++ b/include/linux/entry-common.h
@@ -34,6 +34,30 @@
# define _TIF_AUDIT (0)
#endif
+#ifndef _TIF_UPROBE
+# define _TIF_UPROBE (0)
+#endif
+
+#ifndef _TIF_PATCH_PENDING
+# define _TIF_PATCH_PENDING (0)
+#endif
+
+#ifndef _TIF_NOTIFY_RESUME
+# define _TIF_NOTIFY_RESUME (0)
+#endif
+
+/*
+ * TIF flags handled in exit_to_usermode()
+ */
+#ifndef ARCH_EXIT_TO_USERMODE_WORK
+# define ARCH_EXIT_TO_USERMODE_WORK (0)
+#endif
+
+#define EXIT_TO_USERMODE_WORK \
+ (_TIF_SIGPENDING | _TIF_NOTIFY_RESUME | _TIF_UPROBE | \
+ _TIF_NEED_RESCHED | _TIF_PATCH_PENDING | \
+ ARCH_EXIT_TO_USERMODE_WORK)
+
/*
* TIF flags handled in syscall_enter_from_usermode()
*/
@@ -58,6 +82,87 @@
_TIF_SYSCALL_TRACEPOINT | ARCH_SYSCALL_EXIT_WORK)
/**
+ * local_irq_enable_exit_to_user - Exit to user variant of local_irq_enable()
+ * @ti_work: Cached TIF flags gathered with interrupts disabled
+ *
+ * Defaults to local_irq_enable(). Can be supplied by architecture specific
+ * code.
+ */
+static inline void local_irq_enable_exit_to_user(unsigned long ti_work);
+
+#ifndef local_irq_enable_exit_to_user
+static inline void local_irq_enable_exit_to_user(unsigned long ti_work)
+{
+ local_irq_enable();
+}
+#endif
+
+/**
+ * local_irq_disable_exit_to_user - Exit to user variant of local_irq_disable()
+ *
+ * Defaults to local_irq_disable(). Can be supplied by architecture specific
+ * code.
+ */
+static inline void local_irq_disable_exit_to_user(void);
+
+#ifndef local_irq_disable_exit_to_user
+static inline void local_irq_disable_exit_to_user(void)
+{
+ local_irq_disable();
+}
+#endif
+
+/**
+ * arch_exit_to_usermode_work - Architecture specific TIF work for
+ * exit to user mode.
+ * @regs: Pointer to currents pt_regs
+ * @ti_work: Cached TIF flags gathered with interrupts disabled
+ *
+ * Invoked from exit_to_usermode() with interrupt disabled
+ *
+ * Defaults to NOOP. Can be supplied by architecture specific code.
+ */
+static inline void arch_exit_to_usermode_work(struct pt_regs *regs,
+ unsigned long ti_work);
+
+#ifndef arch_exit_to_usermode_work
+static inline void arch_exit_to_usermode_work(struct pt_regs *regs,
+ unsigned long ti_work)
+{
+}
+#endif
+
+/**
+ * arch_exit_to_usermode - Architecture specific preparation for
+ * exit to user mode.
+ * @regs: Pointer to currents pt_regs
+ * @ti_work: Cached TIF flags gathered with interrupts disabled
+ *
+ * Invoked from exit_to_usermode() with interrupt disabled as the last
+ * function before return.
+ */
+static inline void arch_exit_to_usermode(struct pt_regs *regs,
+ unsigned long ti_work);
+
+#ifndef arch_exit_to_usermode
+static inline void arch_exit_to_usermode(struct pt_regs *regs,
+ unsigned long ti_work)
+{
+}
+#endif
+
+/* Common exit to usermode function to handle TIF work */
+asmlinkage __visible void exit_to_usermode(struct pt_regs *regs);
+
+/**
+ * arch_do_signal - Architecture specific signal delivery function
+ * @regs: Pointer to currents pt_regs
+ *
+ * Invoked from exit_to_usermode()
+ */
+void arch_do_signal(struct pt_regs *regs);
+
+/**
* arch_syscall_enter_tracehook - Wrapper around tracehook_report_syscall_entry()
*
* Defaults to tracehook_report_syscall_entry(). Can be replaced by
--- a/kernel/entry/common.c
+++ b/kernel/entry/common.c
@@ -2,10 +2,90 @@
#include <linux/context_tracking.h>
#include <linux/entry-common.h>
+#include <linux/livepatch.h>
+#include <linux/uprobes.h>
#define CREATE_TRACE_POINTS
#include <trace/events/syscalls.h>
+static unsigned long core_exit_to_usermode_work(struct pt_regs *regs,
+ unsigned long ti_work)
+{
+ /*
+ * Before returning to user space ensure that all pending work
+ * items have been completed.
+ */
+ while (ti_work & EXIT_TO_USERMODE_WORK) {
+
+ local_irq_enable_exit_to_user(ti_work);
+
+ if (ti_work & _TIF_NEED_RESCHED)
+ schedule();
+
+ if (ti_work & _TIF_UPROBE)
+ uprobe_notify_resume(regs);
+
+ if (ti_work & _TIF_PATCH_PENDING)
+ klp_update_patch_state(current);
+
+ if (ti_work & _TIF_SIGPENDING)
+ arch_do_signal(regs);
+
+ if (ti_work & _TIF_NOTIFY_RESUME) {
+ clear_thread_flag(TIF_NOTIFY_RESUME);
+ tracehook_notify_resume(regs);
+ rseq_handle_notify_resume(NULL, regs);
+ }
+
+ /* Architecture specific TIF work */
+ arch_exit_to_usermode_work(regs, ti_work);
+
+ /*
+ * Disable interrupts and reevaluate the work flags as they
+ * might have changed while interrupts and preemption was
+ * enabled above.
+ */
+ local_irq_disable_exit_to_user();
+ ti_work = READ_ONCE(current_thread_info()->flags);
+ }
+ /*
+ * Was checked in exit_to_usermode_work() already, but the above
+ * loop might have wreckaged it.
+ */
+ addr_limit_user_check();
+ return ti_work;
+}
+
+static void do_exit_to_usermode(struct pt_regs *regs)
+{
+ unsigned long ti_work = READ_ONCE(current_thread_info()->flags);
+
+ lockdep_sys_exit();
+
+ addr_limit_user_check();
+
+ if (unlikely(ti_work & EXIT_TO_USERMODE_WORK))
+ ti_work = core_exit_to_usermode_work(regs, ti_work);
+
+ arch_exit_to_usermode(regs, ti_work);
+ /* Return to userspace right after this which turns on interrupts */
+ trace_hardirqs_on();
+}
+
+/**
+ * exit_to_usermode - Check and handle pending work which needs to be
+ * handled before returning to user mode
+ * @regs: Pointer to currents pt_regs
+ *
+ * Called and returns with interrupts disabled
+ */
+asmlinkage __visible void exit_to_usermode(struct pt_regs *regs)
+{
+ trace_hardirqs_off();
+ lockdep_assert_irqs_disabled();
+ do_exit_to_usermode(regs);
+}
+
long core_syscall_enter_from_usermode(struct pt_regs *regs, long syscall)
{
unsigned long ti_work = READ_ONCE(current_thread_info()->flags);
@@ -85,4 +165,12 @@ void syscall_exit_to_usermode(struct pt_
ti_work = READ_ONCE(current_thread_info()->flags);
if (unlikely(ti_work & SYSCALL_EXIT_WORK))
syscall_exit_work(regs, retval, ti_work);
+
+#ifdef ARCH_EXIT_TO_USER_FROM_SYSCALL_EXIT
+ /*
+ * Disable interrupts and handle the regular exit to user mode work
+ */
+ local_irq_disable_exit_to_user();
+ do_exit_to_usermode(regs);
+#endif
}
next prev parent reply other threads:[~2019-09-19 15:10 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-19 15:03 [RFC patch 00/15] entry: Provide generic implementation for host and guest entry/exit work Thomas Gleixner
2019-09-19 15:03 ` [RFC patch 01/15] entry: Provide generic syscall entry functionality Thomas Gleixner
2019-09-20 23:38 ` Andy Lutomirski
2019-10-20 11:49 ` Thomas Gleixner
2019-09-23 9:05 ` Mike Rapoport
2019-09-19 15:03 ` [RFC patch 02/15] x86/entry: Remove _TIF_NOHZ from _TIF_WORK_SYSCALL_ENTRY Thomas Gleixner
2019-09-20 23:39 ` Andy Lutomirski
2019-09-23 20:43 ` Thomas Gleixner
2019-09-19 15:03 ` [RFC patch 03/15] x86/entry: Use generic syscall entry function Thomas Gleixner
2019-09-20 23:41 ` Andy Lutomirski
2019-09-23 8:31 ` Peter Zijlstra
2019-09-23 8:40 ` Thomas Gleixner
2019-09-19 15:03 ` [RFC patch 04/15] arm64/entry: " Thomas Gleixner
2019-09-20 12:21 ` Catalin Marinas
2019-09-19 15:03 ` [RFC patch 05/15] entry: Provide generic syscall exit function Thomas Gleixner
2019-09-19 15:03 ` [RFC patch 06/15] x86/entry: Use generic syscall exit functionality Thomas Gleixner
2019-09-19 15:03 ` [RFC patch 07/15] arm64/syscall: Remove obscure flag check Thomas Gleixner
2019-09-20 14:29 ` Catalin Marinas
2019-09-19 15:03 ` [RFC patch 08/15] arm64/syscall: Use generic syscall exit functionality Thomas Gleixner
2019-09-19 15:03 ` Thomas Gleixner [this message]
2019-09-23 8:30 ` [RFC patch 09/15] entry: Provide generic exit to usermode functionality Peter Zijlstra
2019-09-19 15:03 ` [RFC patch 10/15] x86/entry: Move irq tracing to C code Thomas Gleixner
2019-09-23 8:47 ` Peter Zijlstra
2019-09-23 10:27 ` Thomas Gleixner
2019-09-23 11:49 ` Peter Zijlstra
2019-09-23 11:55 ` Peter Zijlstra
2019-09-23 12:10 ` Peter Zijlstra
2019-09-23 17:24 ` Andy Lutomirski
2019-09-26 2:59 ` Josh Poimboeuf
2019-09-19 15:03 ` [RFC patch 11/15] x86/entry: Use generic exit to usermode Thomas Gleixner
2019-09-19 15:03 ` [RFC patch 12/15] arm64/entry: " Thomas Gleixner
2019-09-19 15:03 ` [RFC patch 13/15] arm64/entry: Move FPU restore out of exit_to_usermode() loop Thomas Gleixner
2019-09-19 15:03 ` [RFC patch 14/15] workpending: Provide infrastructure for work before entering a guest Thomas Gleixner
2019-09-19 15:40 ` Paolo Bonzini
2019-09-20 11:48 ` Thomas Gleixner
2019-09-23 18:17 ` Andy Lutomirski
2019-09-26 11:35 ` Miroslav Benes
2019-09-19 15:03 ` [RFC patch 15/15] x86/kvm: Use GENERIC_EXIT_WORKPENDING Thomas Gleixner
2019-09-19 15:40 ` Paolo Bonzini
2019-09-20 15:12 ` [RFC patch 00/15] entry: Provide generic implementation for host and guest entry/exit work Mark Rutland
2019-09-23 20:50 ` Thomas Gleixner
2019-09-23 18:18 ` Andy Lutomirski
2019-09-24 6:50 ` Christian Borntraeger
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