diff options
Diffstat (limited to 'include/linux/entry-common.h')
| -rw-r--r-- | include/linux/entry-common.h | 397 |
1 files changed, 64 insertions, 333 deletions
diff --git a/include/linux/entry-common.h b/include/linux/entry-common.h index d95ab85f96ba..87efb38b7081 100644 --- a/include/linux/entry-common.h +++ b/include/linux/entry-common.h @@ -2,21 +2,15 @@ #ifndef __LINUX_ENTRYCOMMON_H #define __LINUX_ENTRYCOMMON_H -#include <linux/static_call_types.h> +#include <linux/irq-entry-common.h> +#include <linux/livepatch.h> #include <linux/ptrace.h> -#include <linux/syscalls.h> +#include <linux/resume_user_mode.h> #include <linux/seccomp.h> #include <linux/sched.h> #include <asm/entry-common.h> - -/* - * Define dummy _TIF work flags if not defined by the architecture or for - * disabled functionality. - */ -#ifndef _TIF_PATCH_PENDING -# define _TIF_PATCH_PENDING (0) -#endif +#include <asm/syscall.h> #ifndef _TIF_UPROBE # define _TIF_UPROBE (0) @@ -43,6 +37,7 @@ SYSCALL_WORK_SYSCALL_AUDIT | \ SYSCALL_WORK_SYSCALL_USER_DISPATCH | \ ARCH_SYSCALL_WORK_ENTER) + #define SYSCALL_WORK_EXIT (SYSCALL_WORK_SYSCALL_TRACEPOINT | \ SYSCALL_WORK_SYSCALL_TRACE | \ SYSCALL_WORK_SYSCALL_AUDIT | \ @@ -50,72 +45,7 @@ SYSCALL_WORK_SYSCALL_EXIT_TRAP | \ ARCH_SYSCALL_WORK_EXIT) -/* - * TIF flags handled in exit_to_user_mode_loop() - */ -#ifndef ARCH_EXIT_TO_USER_MODE_WORK -# define ARCH_EXIT_TO_USER_MODE_WORK (0) -#endif - -#define EXIT_TO_USER_MODE_WORK \ - (_TIF_SIGPENDING | _TIF_NOTIFY_RESUME | _TIF_UPROBE | \ - _TIF_NEED_RESCHED | _TIF_PATCH_PENDING | _TIF_NOTIFY_SIGNAL | \ - ARCH_EXIT_TO_USER_MODE_WORK) - -/** - * arch_enter_from_user_mode - Architecture specific sanity check for user mode regs - * @regs: Pointer to currents pt_regs - * - * Defaults to an empty implementation. Can be replaced by architecture - * specific code. - * - * Invoked from syscall_enter_from_user_mode() in the non-instrumentable - * section. Use __always_inline so the compiler cannot push it out of line - * and make it instrumentable. - */ -static __always_inline void arch_enter_from_user_mode(struct pt_regs *regs); - -#ifndef arch_enter_from_user_mode -static __always_inline void arch_enter_from_user_mode(struct pt_regs *regs) {} -#endif - -/** - * enter_from_user_mode - Establish state when coming from user mode - * - * Syscall/interrupt entry disables interrupts, but user mode is traced as - * interrupts enabled. Also with NO_HZ_FULL RCU might be idle. - * - * 1) Tell lockdep that interrupts are disabled - * 2) Invoke context tracking if enabled to reactivate RCU - * 3) Trace interrupts off state - * - * Invoked from architecture specific syscall entry code with interrupts - * disabled. The calling code has to be non-instrumentable. When the - * function returns all state is correct and interrupts are still - * disabled. The subsequent functions can be instrumented. - * - * This is invoked when there is architecture specific functionality to be - * done between establishing state and enabling interrupts. The caller must - * enable interrupts before invoking syscall_enter_from_user_mode_work(). - */ -void enter_from_user_mode(struct pt_regs *regs); - -/** - * syscall_enter_from_user_mode_prepare - Establish state and enable interrupts - * @regs: Pointer to currents pt_regs - * - * Invoked from architecture specific syscall entry code with interrupts - * disabled. The calling code has to be non-instrumentable. When the - * function returns all state is correct, interrupts are enabled and the - * subsequent functions can be instrumented. - * - * This handles lockdep, RCU (context tracking) and tracing state, i.e. - * the functionality provided by enter_from_user_mode(). - * - * This is invoked when there is extra architecture specific functionality - * to be done between establishing state and handling user mode entry work. - */ -void syscall_enter_from_user_mode_prepare(struct pt_regs *regs); +long syscall_trace_enter(struct pt_regs *regs, long syscall, unsigned long work); /** * syscall_enter_from_user_mode_work - Check and handle work before invoking @@ -124,8 +54,8 @@ void syscall_enter_from_user_mode_prepare(struct pt_regs *regs); * @syscall: The syscall number * * Invoked from architecture specific syscall entry code with interrupts - * enabled after invoking syscall_enter_from_user_mode_prepare() and extra - * architecture specific work. + * enabled after invoking enter_from_user_mode(), enabling interrupts and + * extra architecture specific work. * * Returns: The original or a modified syscall number * @@ -140,7 +70,15 @@ void syscall_enter_from_user_mode_prepare(struct pt_regs *regs); * ptrace_report_syscall_entry(), __secure_computing(), trace_sys_enter() * 2) Invocation of audit_syscall_entry() */ -long syscall_enter_from_user_mode_work(struct pt_regs *regs, long syscall); +static __always_inline long syscall_enter_from_user_mode_work(struct pt_regs *regs, long syscall) +{ + unsigned long work = READ_ONCE(current_thread_info()->syscall_work); + + if (work & SYSCALL_WORK_ENTER) + syscall = syscall_trace_enter(regs, syscall, work); + + return syscall; +} /** * syscall_enter_from_user_mode - Establish state and check and handle work @@ -153,130 +91,35 @@ long syscall_enter_from_user_mode_work(struct pt_regs *regs, long syscall); * function returns all state is correct, interrupts are enabled and the * subsequent functions can be instrumented. * - * This is combination of syscall_enter_from_user_mode_prepare() and - * syscall_enter_from_user_mode_work(). + * This is the combination of enter_from_user_mode() and + * syscall_enter_from_user_mode_work() to be used when there is no + * architecture specific work to be done between the two. * * Returns: The original or a modified syscall number. See * syscall_enter_from_user_mode_work() for further explanation. */ -long syscall_enter_from_user_mode(struct pt_regs *regs, long syscall); - -/** - * 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) +static __always_inline long syscall_enter_from_user_mode(struct pt_regs *regs, long syscall) { - local_irq_enable(); -} -#endif + long ret; -/** - * 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); + enter_from_user_mode(regs); -#ifndef local_irq_disable_exit_to_user -static inline void local_irq_disable_exit_to_user(void) -{ - local_irq_disable(); -} -#endif - -/** - * arch_exit_to_user_mode_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_user_mode_loop() with interrupt enabled - * - * Defaults to NOOP. Can be supplied by architecture specific code. - */ -static inline void arch_exit_to_user_mode_work(struct pt_regs *regs, - unsigned long ti_work); - -#ifndef arch_exit_to_user_mode_work -static inline void arch_exit_to_user_mode_work(struct pt_regs *regs, - unsigned long ti_work) -{ -} -#endif - -/** - * arch_exit_to_user_mode_prepare - 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_user_mode_prepare() with interrupt disabled as the last - * function before return. Defaults to NOOP. - */ -static inline void arch_exit_to_user_mode_prepare(struct pt_regs *regs, - unsigned long ti_work); + instrumentation_begin(); + local_irq_enable(); + ret = syscall_enter_from_user_mode_work(regs, syscall); + instrumentation_end(); -#ifndef arch_exit_to_user_mode_prepare -static inline void arch_exit_to_user_mode_prepare(struct pt_regs *regs, - unsigned long ti_work) -{ + return ret; } -#endif - -/** - * arch_exit_to_user_mode - Architecture specific final work before - * exit to user mode. - * - * Invoked from exit_to_user_mode() with interrupt disabled as the last - * function before return. Defaults to NOOP. - * - * This needs to be __always_inline because it is non-instrumentable code - * invoked after context tracking switched to user mode. - * - * An architecture implementation must not do anything complex, no locking - * etc. The main purpose is for speculation mitigations. - */ -static __always_inline void arch_exit_to_user_mode(void); - -#ifndef arch_exit_to_user_mode -static __always_inline void arch_exit_to_user_mode(void) { } -#endif /** - * arch_do_signal_or_restart - Architecture specific signal delivery function - * @regs: Pointer to currents pt_regs + * syscall_exit_work - Handle work before returning to user mode + * @regs: Pointer to current pt_regs + * @work: Current thread syscall work * - * Invoked from exit_to_user_mode_loop(). + * Do one-time syscall specific work. */ -void arch_do_signal_or_restart(struct pt_regs *regs); - -/** - * exit_to_user_mode - Fixup state when exiting to user mode - * - * Syscall/interrupt exit enables interrupts, but the kernel state is - * interrupts disabled when this is invoked. Also tell RCU about it. - * - * 1) Trace interrupts on state - * 2) Invoke context tracking if enabled to adjust RCU state - * 3) Invoke architecture specific last minute exit code, e.g. speculation - * mitigations, etc.: arch_exit_to_user_mode() - * 4) Tell lockdep that interrupts are enabled - * - * Invoked from architecture specific code when syscall_exit_to_user_mode() - * is not suitable as the last step before returning to userspace. Must be - * invoked with interrupts disabled and the caller must be - * non-instrumentable. - * The caller has to invoke syscall_exit_to_user_mode_work() before this. - */ -void exit_to_user_mode(void); +void syscall_exit_work(struct pt_regs *regs, unsigned long work); /** * syscall_exit_to_user_mode_work - Handle work before returning to user mode @@ -291,7 +134,30 @@ void exit_to_user_mode(void); * make the final state transitions. Interrupts must stay disabled between * return from this function and the invocation of exit_to_user_mode(). */ -void syscall_exit_to_user_mode_work(struct pt_regs *regs); +static __always_inline void syscall_exit_to_user_mode_work(struct pt_regs *regs) +{ + unsigned long work = READ_ONCE(current_thread_info()->syscall_work); + unsigned long nr = syscall_get_nr(current, regs); + + CT_WARN_ON(ct_state() != CT_STATE_KERNEL); + + if (IS_ENABLED(CONFIG_PROVE_LOCKING)) { + if (WARN(irqs_disabled(), "syscall %lu left IRQs disabled", nr)) + local_irq_enable(); + } + + rseq_debug_syscall_return(regs); + + /* + * Do one-time syscall specific work. If these work items are + * enabled, we want to run them exactly once per syscall exit with + * interrupts enabled. + */ + if (unlikely(work & SYSCALL_WORK_EXIT)) + syscall_exit_work(regs, work); + local_irq_disable_exit_to_user(); + syscall_exit_to_user_mode_prepare(regs); +} /** * syscall_exit_to_user_mode - Handle work before returning to user mode @@ -322,147 +188,12 @@ void syscall_exit_to_user_mode_work(struct pt_regs *regs); * exit_to_user_mode(). This function is preferred unless there is a * compelling architectural reason to use the separate functions. */ -void syscall_exit_to_user_mode(struct pt_regs *regs); - -/** - * irqentry_enter_from_user_mode - Establish state before invoking the irq handler - * @regs: Pointer to currents pt_regs - * - * Invoked from architecture specific entry code with interrupts disabled. - * Can only be called when the interrupt entry came from user mode. The - * calling code must be non-instrumentable. When the function returns all - * state is correct and the subsequent functions can be instrumented. - * - * The function establishes state (lockdep, RCU (context tracking), tracing) - */ -void irqentry_enter_from_user_mode(struct pt_regs *regs); - -/** - * irqentry_exit_to_user_mode - Interrupt exit work - * @regs: Pointer to current's pt_regs - * - * Invoked with interrupts disabled and fully valid regs. Returns with all - * work handled, interrupts disabled such that the caller can immediately - * switch to user mode. Called from architecture specific interrupt - * handling code. - * - * The call order is #2 and #3 as described in syscall_exit_to_user_mode(). - * Interrupt exit is not invoking #1 which is the syscall specific one time - * work. - */ -void irqentry_exit_to_user_mode(struct pt_regs *regs); - -#ifndef irqentry_state -/** - * struct irqentry_state - Opaque object for exception state storage - * @exit_rcu: Used exclusively in the irqentry_*() calls; signals whether the - * exit path has to invoke ct_irq_exit(). - * @lockdep: Used exclusively in the irqentry_nmi_*() calls; ensures that - * lockdep state is restored correctly on exit from nmi. - * - * This opaque object is filled in by the irqentry_*_enter() functions and - * must be passed back into the corresponding irqentry_*_exit() functions - * when the exception is complete. - * - * Callers of irqentry_*_[enter|exit]() must consider this structure opaque - * and all members private. Descriptions of the members are provided to aid in - * the maintenance of the irqentry_*() functions. - */ -typedef struct irqentry_state { - union { - bool exit_rcu; - bool lockdep; - }; -} irqentry_state_t; -#endif - -/** - * irqentry_enter - Handle state tracking on ordinary interrupt entries - * @regs: Pointer to pt_regs of interrupted context - * - * Invokes: - * - lockdep irqflag state tracking as low level ASM entry disabled - * interrupts. - * - * - Context tracking if the exception hit user mode. - * - * - The hardirq tracer to keep the state consistent as low level ASM - * entry disabled interrupts. - * - * As a precondition, this requires that the entry came from user mode, - * idle, or a kernel context in which RCU is watching. - * - * For kernel mode entries RCU handling is done conditional. If RCU is - * watching then the only RCU requirement is to check whether the tick has - * to be restarted. If RCU is not watching then ct_irq_enter() has to be - * invoked on entry and ct_irq_exit() on exit. - * - * Avoiding the ct_irq_enter/exit() calls is an optimization but also - * solves the problem of kernel mode pagefaults which can schedule, which - * is not possible after invoking ct_irq_enter() without undoing it. - * - * For user mode entries irqentry_enter_from_user_mode() is invoked to - * establish the proper context for NOHZ_FULL. Otherwise scheduling on exit - * would not be possible. - * - * Returns: An opaque object that must be passed to idtentry_exit() - */ -irqentry_state_t noinstr irqentry_enter(struct pt_regs *regs); - -/** - * irqentry_exit_cond_resched - Conditionally reschedule on return from interrupt - * - * Conditional reschedule with additional sanity checks. - */ -void raw_irqentry_exit_cond_resched(void); -#ifdef CONFIG_PREEMPT_DYNAMIC -#if defined(CONFIG_HAVE_PREEMPT_DYNAMIC_CALL) -#define irqentry_exit_cond_resched_dynamic_enabled raw_irqentry_exit_cond_resched -#define irqentry_exit_cond_resched_dynamic_disabled NULL -DECLARE_STATIC_CALL(irqentry_exit_cond_resched, raw_irqentry_exit_cond_resched); -#define irqentry_exit_cond_resched() static_call(irqentry_exit_cond_resched)() -#elif defined(CONFIG_HAVE_PREEMPT_DYNAMIC_KEY) -DECLARE_STATIC_KEY_TRUE(sk_dynamic_irqentry_exit_cond_resched); -void dynamic_irqentry_exit_cond_resched(void); -#define irqentry_exit_cond_resched() dynamic_irqentry_exit_cond_resched() -#endif -#else /* CONFIG_PREEMPT_DYNAMIC */ -#define irqentry_exit_cond_resched() raw_irqentry_exit_cond_resched() -#endif /* CONFIG_PREEMPT_DYNAMIC */ - -/** - * irqentry_exit - Handle return from exception that used irqentry_enter() - * @regs: Pointer to pt_regs (exception entry regs) - * @state: Return value from matching call to irqentry_enter() - * - * Depending on the return target (kernel/user) this runs the necessary - * preemption and work checks if possible and required and returns to - * the caller with interrupts disabled and no further work pending. - * - * This is the last action before returning to the low level ASM code which - * just needs to return to the appropriate context. - * - * Counterpart to irqentry_enter(). - */ -void noinstr irqentry_exit(struct pt_regs *regs, irqentry_state_t state); - -/** - * irqentry_nmi_enter - Handle NMI entry - * @regs: Pointer to currents pt_regs - * - * Similar to irqentry_enter() but taking care of the NMI constraints. - */ -irqentry_state_t noinstr irqentry_nmi_enter(struct pt_regs *regs); - -/** - * irqentry_nmi_exit - Handle return from NMI handling - * @regs: Pointer to pt_regs (NMI entry regs) - * @irq_state: Return value from matching call to irqentry_nmi_enter() - * - * Last action before returning to the low level assembly code. - * - * Counterpart to irqentry_nmi_enter(). - */ -void noinstr irqentry_nmi_exit(struct pt_regs *regs, irqentry_state_t irq_state); +static __always_inline void syscall_exit_to_user_mode(struct pt_regs *regs) +{ + instrumentation_begin(); + syscall_exit_to_user_mode_work(regs); + instrumentation_end(); + exit_to_user_mode(); +} #endif |