// SPDX-License-Identifier: GPL-2.0-or-later #include <linux/context_tracking.h> #include <linux/entry-common.h> #include <linux/err.h> #include <linux/compat.h> #include <linux/rseq.h> #include <linux/sched/debug.h> /* for show_regs */ #include <asm/kup.h> #include <asm/cputime.h> #include <asm/hw_irq.h> #include <asm/interrupt.h> #include <asm/kprobes.h> #include <asm/paca.h> #include <asm/ptrace.h> #include <asm/reg.h> #include <asm/signal.h> #include <asm/switch_to.h> #include <asm/syscall.h> #include <asm/time.h> #include <asm/tm.h> #include <asm/unistd.h> #if defined(CONFIG_PPC_ADV_DEBUG_REGS) && defined(CONFIG_PPC32) unsigned long global_dbcr0[NR_CPUS]; #endif #ifdef CONFIG_PPC_BOOK3S_64 DEFINE_STATIC_KEY_FALSE(interrupt_exit_not_reentrant); static inline bool exit_must_hard_disable(void) { return static_branch_unlikely(&interrupt_exit_not_reentrant); } #else static inline bool exit_must_hard_disable(void) { return true; } #endif /* * local irqs must be disabled. Returns false if the caller must re-enable * them, check for new work, and try again. * * This should be called with local irqs disabled, but if they were previously * enabled when the interrupt handler returns (indicating a process-context / * synchronous interrupt) then irqs_enabled should be true. * * restartable is true then EE/RI can be left on because interrupts are handled * with a restart sequence. */ static notrace __always_inline bool prep_irq_for_enabled_exit(bool restartable) { bool must_hard_disable = (exit_must_hard_disable() || !restartable); /* This must be done with RI=1 because tracing may touch vmaps */ trace_hardirqs_on(); if (must_hard_disable) __hard_EE_RI_disable(); #ifdef CONFIG_PPC64 /* This pattern matches prep_irq_for_idle */ if (unlikely(lazy_irq_pending_nocheck())) { if (must_hard_disable) { local_paca->irq_happened |= PACA_IRQ_HARD_DIS; __hard_RI_enable(); } trace_hardirqs_off(); return false; } #endif return true; } /* * This should be called after a syscall returns, with r3 the return value * from the syscall. If this function returns non-zero, the system call * exit assembly should additionally load all GPR registers and CTR and XER * from the interrupt frame. * * The function graph tracer can not trace the return side of this function, * because RI=0 and soft mask state is "unreconciled", so it is marked notrace. */ notrace unsigned long syscall_exit_prepare(unsigned long r3, struct pt_regs *regs, long scv) { unsigned long ti_flags; unsigned long ret = 0; bool is_not_scv = !IS_ENABLED(CONFIG_PPC_BOOK3S_64) || !scv; kuap_assert_locked(); regs->result = r3; /* Clear exit_flags so only flags set during this exit are visible */ current->thread_info.exit_flags = 0; ti_flags = read_thread_flags(); if (unlikely(r3 >= (unsigned long)-MAX_ERRNO) && is_not_scv) { if (likely(!(ti_flags & (_TIF_NOERROR | _TIF_RESTOREALL)))) { r3 = -r3; regs->ccr |= 0x10000000; /* Set SO bit in CR */ } } if (unlikely(ti_flags & _TIF_PERSYSCALL_MASK)) { if (ti_flags & _TIF_RESTOREALL) ret = _TIF_RESTOREALL; else regs->gpr[3] = r3; clear_bits(_TIF_PERSYSCALL_MASK, ¤t_thread_info()->flags); } else { regs->gpr[3] = r3; } if (unlikely(ti_flags & _TIF_SYSCALL_DOTRACE)) { ret |= _TIF_RESTOREALL; } syscall_exit_to_user_mode(regs); again: user_enter_irqoff(); if (!prep_irq_for_enabled_exit(true)) { user_exit_irqoff(); local_irq_enable(); local_irq_disable(); goto again; } /* Restore user access locks last */ kuap_user_restore(regs); ret |= current->thread_info.exit_flags; #ifdef CONFIG_PPC64 regs->exit_result = ret; #endif return ret; } #ifdef CONFIG_PPC64 notrace unsigned long syscall_exit_restart(unsigned long r3, struct pt_regs *regs) { unsigned long ret; /* * This is called when detecting a soft-pending interrupt as well as * an alternate-return interrupt. So we can't just have the alternate * return path clear SRR1[MSR] and set PACA_IRQ_HARD_DIS (unless * the soft-pending case were to fix things up as well). RI might be * disabled, in which case it gets re-enabled by __hard_irq_disable(). */ __hard_irq_disable(); local_paca->irq_happened |= PACA_IRQ_HARD_DIS; #ifdef CONFIG_PPC_BOOK3S_64 set_kuap(AMR_KUAP_BLOCKED); #endif again: user_enter_irqoff(); if (!prep_irq_for_enabled_exit(true)) { user_exit_irqoff(); local_irq_enable(); local_irq_disable(); goto again; } kuap_user_restore(regs); ret = current_thread_info()->exit_flags & _TIF_RESTOREALL; current_thread_info()->exit_flags &= ~_TIF_RESTOREALL; regs->exit_result |= ret; return ret; } #endif notrace unsigned long interrupt_exit_user_prepare(struct pt_regs *regs) { unsigned long ret; BUG_ON(regs_is_unrecoverable(regs)); BUG_ON(regs_irqs_disabled(regs)); /* * We don't need to restore AMR on the way back to userspace for KUAP. * AMR can only have been unlocked if we interrupted the kernel. */ kuap_assert_locked(); /* Clear exit_flags so only flags set during this exit are visible */ current_thread_info()->exit_flags = 0; local_irq_disable(); again: check_return_regs_valid(regs); user_enter_irqoff(); if (!prep_irq_for_enabled_exit(true)) { user_exit_irqoff(); local_irq_enable(); local_irq_disable(); goto again; } /* Restore user access locks last */ kuap_user_restore(regs); ret = current_thread_info()->exit_flags & _TIF_RESTOREALL; #ifdef CONFIG_PPC64 regs->exit_result = ret; #endif return ret; } void preempt_schedule_irq(void); notrace unsigned long interrupt_exit_kernel_prepare(struct pt_regs *regs) { unsigned long ret = 0; unsigned long kuap; bool stack_store = read_thread_flags() & _TIF_EMULATE_STACK_STORE; if (regs_is_unrecoverable(regs)) unrecoverable_exception(regs); /* * CT_WARN_ON comes here via program_check_exception, so avoid * recursion. * * Skip the assertion on PMIs on 64e to work around a problem caused * by NMI PMIs incorrectly taking this interrupt return path, it's * possible for this to hit after interrupt exit to user switches * context to user. See also the comment in the performance monitor * handler in exceptions-64e.S */ if (!IS_ENABLED(CONFIG_PPC_BOOK3E_64) && TRAP(regs) != INTERRUPT_PROGRAM && TRAP(regs) != INTERRUPT_PERFMON) CT_WARN_ON(ct_state() == CT_STATE_USER); kuap = kuap_get_and_assert_locked(); local_irq_disable(); if (!regs_irqs_disabled(regs)) { /* Returning to a kernel context with local irqs enabled. */ WARN_ON_ONCE(!(regs->msr & MSR_EE)); again: check_return_regs_valid(regs); /* * Stack store exit can't be restarted because the interrupt * stack frame might have been clobbered. */ if (!prep_irq_for_enabled_exit(unlikely(stack_store))) { /* * Replay pending soft-masked interrupts now. Don't * just local_irq_enabe(); local_irq_disable(); because * if we are returning from an asynchronous interrupt * here, another one might hit after irqs are enabled, * and it would exit via this same path allowing * another to fire, and so on unbounded. */ hard_irq_disable(); replay_soft_interrupts(); /* Took an interrupt, may have more exit work to do. */ goto again; } #ifdef CONFIG_PPC64 /* * An interrupt may clear MSR[EE] and set this concurrently, * but it will be marked pending and the exit will be retried. * This leaves a racy window where MSR[EE]=0 and HARD_DIS is * clear, until interrupt_exit_kernel_restart() calls * hard_irq_disable(), which will set HARD_DIS again. */ local_paca->irq_happened &= ~PACA_IRQ_HARD_DIS; } else { check_return_regs_valid(regs); if (unlikely(stack_store)) __hard_EE_RI_disable(); #else } else { __hard_EE_RI_disable(); #endif /* CONFIG_PPC64 */ } if (unlikely(stack_store)) { clear_bits(_TIF_EMULATE_STACK_STORE, ¤t_thread_info()->flags); ret = 1; } #ifdef CONFIG_PPC_TRANSACTIONAL_MEM local_paca->tm_scratch = regs->msr; #endif /* * 64s does not want to mfspr(SPRN_AMR) here, because this comes after * mtmsr, which would cause Read-After-Write stalls. Hence, take the * AMR value from the check above. */ kuap_kernel_restore(regs, kuap); return ret; } #ifdef CONFIG_PPC64 notrace unsigned long interrupt_exit_user_restart(struct pt_regs *regs) { __hard_irq_disable(); local_paca->irq_happened |= PACA_IRQ_HARD_DIS; #ifdef CONFIG_PPC_BOOK3S_64 set_kuap(AMR_KUAP_BLOCKED); #endif trace_hardirqs_off(); account_cpu_user_entry(); BUG_ON(!user_mode(regs)); regs->exit_result |= interrupt_exit_user_prepare(regs); return regs->exit_result; } /* * No real need to return a value here because the stack store case does not * get restarted. */ notrace unsigned long interrupt_exit_kernel_restart(struct pt_regs *regs) { __hard_irq_disable(); local_paca->irq_happened |= PACA_IRQ_HARD_DIS; #ifdef CONFIG_PPC_BOOK3S_64 set_kuap(AMR_KUAP_BLOCKED); #endif if (regs->softe == IRQS_ENABLED) trace_hardirqs_off(); BUG_ON(user_mode(regs)); return interrupt_exit_kernel_prepare(regs); } #endif
