diff options
Diffstat (limited to 'include/linux/entry-common.h')
| -rw-r--r-- | include/linux/entry-common.h | 346 |
1 files changed, 268 insertions, 78 deletions
diff --git a/include/linux/entry-common.h b/include/linux/entry-common.h index 474f29638d2c..f94f3fdf15fc 100644 --- a/include/linux/entry-common.h +++ b/include/linux/entry-common.h @@ -2,33 +2,24 @@ #ifndef __LINUX_ENTRYCOMMON_H #define __LINUX_ENTRYCOMMON_H -#include <linux/tracehook.h> +#include <linux/static_call_types.h> +#include <linux/ptrace.h> #include <linux/syscalls.h> #include <linux/seccomp.h> #include <linux/sched.h> +#include <linux/context_tracking.h> +#include <linux/livepatch.h> +#include <linux/resume_user_mode.h> +#include <linux/tick.h> +#include <linux/kmsan.h> #include <asm/entry-common.h> +#include <asm/syscall.h> /* * Define dummy _TIF work flags if not defined by the architecture or for * disabled functionality. */ -#ifndef _TIF_SYSCALL_EMU -# define _TIF_SYSCALL_EMU (0) -#endif - -#ifndef _TIF_SYSCALL_TRACEPOINT -# define _TIF_SYSCALL_TRACEPOINT (0) -#endif - -#ifndef _TIF_SECCOMP -# define _TIF_SECCOMP (0) -#endif - -#ifndef _TIF_SYSCALL_AUDIT -# define _TIF_SYSCALL_AUDIT (0) -#endif - #ifndef _TIF_PATCH_PENDING # define _TIF_PATCH_PENDING (0) #endif @@ -38,27 +29,32 @@ #endif /* - * TIF flags handled in syscall_enter_from_user_mode() + * SYSCALL_WORK flags handled in syscall_enter_from_user_mode() */ -#ifndef ARCH_SYSCALL_ENTER_WORK -# define ARCH_SYSCALL_ENTER_WORK (0) +#ifndef ARCH_SYSCALL_WORK_ENTER +# define ARCH_SYSCALL_WORK_ENTER (0) #endif -#define SYSCALL_ENTER_WORK \ - (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | _TIF_SECCOMP | \ - _TIF_SYSCALL_TRACEPOINT | _TIF_SYSCALL_EMU | \ - ARCH_SYSCALL_ENTER_WORK) - /* - * TIF flags handled in syscall_exit_to_user_mode() + * SYSCALL_WORK flags handled in syscall_exit_to_user_mode() */ -#ifndef ARCH_SYSCALL_EXIT_WORK -# define ARCH_SYSCALL_EXIT_WORK (0) +#ifndef ARCH_SYSCALL_WORK_EXIT +# define ARCH_SYSCALL_WORK_EXIT (0) #endif -#define SYSCALL_EXIT_WORK \ - (_TIF_SYSCALL_TRACE | _TIF_SYSCALL_AUDIT | \ - _TIF_SYSCALL_TRACEPOINT | ARCH_SYSCALL_EXIT_WORK) +#define SYSCALL_WORK_ENTER (SYSCALL_WORK_SECCOMP | \ + SYSCALL_WORK_SYSCALL_TRACEPOINT | \ + SYSCALL_WORK_SYSCALL_TRACE | \ + SYSCALL_WORK_SYSCALL_EMU | \ + 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 | \ + SYSCALL_WORK_SYSCALL_USER_DISPATCH | \ + SYSCALL_WORK_SYSCALL_EXIT_TRAP | \ + ARCH_SYSCALL_WORK_EXIT) /* * TIF flags handled in exit_to_user_mode_loop() @@ -69,11 +65,12 @@ #define EXIT_TO_USER_MODE_WORK \ (_TIF_SIGPENDING | _TIF_NOTIFY_RESUME | _TIF_UPROBE | \ - _TIF_NEED_RESCHED | _TIF_PATCH_PENDING | \ + _TIF_NEED_RESCHED | _TIF_NEED_RESCHED_LAZY | \ + _TIF_PATCH_PENDING | _TIF_NOTIFY_SIGNAL | \ ARCH_EXIT_TO_USER_MODE_WORK) /** - * arch_check_user_regs - Architecture specific sanity check for user mode regs + * 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 @@ -83,31 +80,44 @@ * section. Use __always_inline so the compiler cannot push it out of line * and make it instrumentable. */ -static __always_inline void arch_check_user_regs(struct pt_regs *regs); +static __always_inline void arch_enter_from_user_mode(struct pt_regs *regs); -#ifndef arch_check_user_regs -static __always_inline void arch_check_user_regs(struct pt_regs *regs) {} +#ifndef arch_enter_from_user_mode +static __always_inline void arch_enter_from_user_mode(struct pt_regs *regs) {} #endif /** - * arch_syscall_enter_tracehook - Wrapper around tracehook_report_syscall_entry() - * @regs: Pointer to currents pt_regs + * 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. * - * Returns: 0 on success or an error code to skip the syscall. + * 1) Tell lockdep that interrupts are disabled + * 2) Invoke context tracking if enabled to reactivate RCU + * 3) Trace interrupts off state * - * Defaults to tracehook_report_syscall_entry(). Can be replaced by - * architecture specific code. + * 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. * - * Invoked from syscall_enter_from_user_mode() + * 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(). */ -static inline __must_check int arch_syscall_enter_tracehook(struct pt_regs *regs); - -#ifndef arch_syscall_enter_tracehook -static inline __must_check int arch_syscall_enter_tracehook(struct pt_regs *regs) +static __always_inline void enter_from_user_mode(struct pt_regs *regs) { - return tracehook_report_syscall_entry(regs); + arch_enter_from_user_mode(regs); + lockdep_hardirqs_off(CALLER_ADDR0); + + CT_WARN_ON(__ct_state() != CT_STATE_USER); + user_exit_irqoff(); + + instrumentation_begin(); + kmsan_unpoison_entry_regs(regs); + trace_hardirqs_off_finish(); + instrumentation_end(); } -#endif /** * syscall_enter_from_user_mode_prepare - Establish state and enable interrupts @@ -118,13 +128,17 @@ static inline __must_check int arch_syscall_enter_tracehook(struct pt_regs *regs * 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. + * 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 * a syscall @@ -144,11 +158,19 @@ void syscall_enter_from_user_mode_prepare(struct pt_regs *regs); * * It handles the following work items: * - * 1) TIF flag dependent invocations of arch_syscall_enter_tracehook(), - * __secure_computing(), trace_sys_enter() + * 1) syscall_work flag dependent invocations of + * 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 @@ -167,7 +189,19 @@ long syscall_enter_from_user_mode_work(struct pt_regs *regs, long syscall); * 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); +static __always_inline long syscall_enter_from_user_mode(struct pt_regs *regs, long syscall) +{ + long ret; + + enter_from_user_mode(regs); + + instrumentation_begin(); + local_irq_enable(); + ret = syscall_enter_from_user_mode_work(regs, syscall); + instrumentation_end(); + + return ret; +} /** * local_irq_enable_exit_to_user - Exit to user variant of local_irq_enable() @@ -259,31 +293,126 @@ static __always_inline void arch_exit_to_user_mode(void) { } #endif /** - * arch_do_signal - Architecture specific signal delivery function + * arch_do_signal_or_restart - Architecture specific signal delivery function * @regs: Pointer to currents pt_regs * * Invoked from exit_to_user_mode_loop(). */ -void arch_do_signal(struct pt_regs *regs); +void arch_do_signal_or_restart(struct pt_regs *regs); + +/** + * exit_to_user_mode_loop - do any pending work before leaving to user space + */ +unsigned long exit_to_user_mode_loop(struct pt_regs *regs, + unsigned long ti_work); + +/** + * exit_to_user_mode_prepare - call exit_to_user_mode_loop() if required + * @regs: Pointer to pt_regs on entry stack + * + * 1) check that interrupts are disabled + * 2) call tick_nohz_user_enter_prepare() + * 3) call exit_to_user_mode_loop() if any flags from + * EXIT_TO_USER_MODE_WORK are set + * 4) check that interrupts are still disabled + */ +static __always_inline void exit_to_user_mode_prepare(struct pt_regs *regs) +{ + unsigned long ti_work; + + lockdep_assert_irqs_disabled(); + + /* Flush pending rcuog wakeup before the last need_resched() check */ + tick_nohz_user_enter_prepare(); + + ti_work = read_thread_flags(); + if (unlikely(ti_work & EXIT_TO_USER_MODE_WORK)) + ti_work = exit_to_user_mode_loop(regs, ti_work); + + arch_exit_to_user_mode_prepare(regs, ti_work); + + /* Ensure that kernel state is sane for a return to userspace */ + kmap_assert_nomap(); + lockdep_assert_irqs_disabled(); + lockdep_sys_exit(); +} /** - * arch_syscall_exit_tracehook - Wrapper around tracehook_report_syscall_exit() + * 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. + */ +static __always_inline void exit_to_user_mode(void) +{ + instrumentation_begin(); + trace_hardirqs_on_prepare(); + lockdep_hardirqs_on_prepare(); + instrumentation_end(); + + user_enter_irqoff(); + arch_exit_to_user_mode(); + lockdep_hardirqs_on(CALLER_ADDR0); +} + +/** + * syscall_exit_work - Handle work before returning to user mode + * @regs: Pointer to current pt_regs + * @work: Current thread syscall work + * + * Do one-time syscall specific work. + */ +void syscall_exit_work(struct pt_regs *regs, unsigned long work); + +/** + * syscall_exit_to_user_mode_work - Handle work before returning to user mode * @regs: Pointer to currents pt_regs - * @step: Indicator for single step * - * Defaults to tracehook_report_syscall_exit(). Can be replaced by - * architecture specific code. + * Same as step 1 and 2 of syscall_exit_to_user_mode() but without calling + * exit_to_user_mode() to perform the final transition to user mode. * - * Invoked from syscall_exit_to_user_mode() + * Calling convention is the same as for syscall_exit_to_user_mode() and it + * returns with all work handled and interrupts disabled. The caller must + * invoke exit_to_user_mode() before actually switching to user mode to + * make the final state transitions. Interrupts must stay disabled between + * return from this function and the invocation of exit_to_user_mode(). */ -static inline void arch_syscall_exit_tracehook(struct pt_regs *regs, bool step); - -#ifndef arch_syscall_exit_tracehook -static inline void arch_syscall_exit_tracehook(struct pt_regs *regs, bool step) +static __always_inline void syscall_exit_to_user_mode_work(struct pt_regs *regs) { - tracehook_report_syscall_exit(regs, step); + 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_syscall(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(); + exit_to_user_mode_prepare(regs); } -#endif /** * syscall_exit_to_user_mode - Handle work before returning to user mode @@ -299,7 +428,7 @@ static inline void arch_syscall_exit_tracehook(struct pt_regs *regs, bool step) * - rseq syscall exit * - audit * - syscall tracing - * - tracehook (single stepping) + * - ptrace (single stepping) * * 2) Preparatory work * - Exit to user mode loop (common TIF handling). Invokes @@ -307,10 +436,20 @@ static inline void arch_syscall_exit_tracehook(struct pt_regs *regs, bool step) * - 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 + * 3) Final transition (lockdep, tracing, context tracking, RCU), i.e. the + * functionality in exit_to_user_mode(). + * + * This is a combination of syscall_exit_to_user_mode_work() (1,2) and + * 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); +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(); +} /** * irqentry_enter_from_user_mode - Establish state before invoking the irq handler @@ -329,7 +468,7 @@ 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 disbled and fully valid regs. Returns with all + * 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. @@ -341,8 +480,26 @@ void irqentry_enter_from_user_mode(struct pt_regs *regs); 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 { - bool exit_rcu; + union { + bool exit_rcu; + bool lockdep; + }; } irqentry_state_t; #endif @@ -364,12 +521,12 @@ typedef struct irqentry_state { * * 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 rcu_irq_enter() has to be - * invoked on entry and rcu_irq_exit() on exit. + * 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 rcu_irq_enter/exit() calls is an optimization but also + * 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 rcu_irq_enter() without undoing it. + * 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 @@ -384,7 +541,21 @@ irqentry_state_t noinstr irqentry_enter(struct pt_regs *regs); * * Conditional reschedule with additional sanity checks. */ -void irqentry_exit_cond_resched(void); +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() @@ -392,7 +563,7 @@ void irqentry_exit_cond_resched(void); * @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 reguired and returns to + * 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 @@ -402,4 +573,23 @@ void irqentry_exit_cond_resched(void); */ 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); + #endif |