diff options
Diffstat (limited to 'arch/powerpc/kernel/interrupt.c')
| -rw-r--r-- | arch/powerpc/kernel/interrupt.c | 505 |
1 files changed, 505 insertions, 0 deletions
diff --git a/arch/powerpc/kernel/interrupt.c b/arch/powerpc/kernel/interrupt.c new file mode 100644 index 000000000000..eca293794a1e --- /dev/null +++ b/arch/powerpc/kernel/interrupt.c @@ -0,0 +1,505 @@ +// SPDX-License-Identifier: GPL-2.0-or-later + +#include <linux/context_tracking.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; +} + +static notrace void booke_load_dbcr0(void) +{ +#ifdef CONFIG_PPC_ADV_DEBUG_REGS + unsigned long dbcr0 = current->thread.debug.dbcr0; + + if (likely(!(dbcr0 & DBCR0_IDM))) + return; + + /* + * Check to see if the dbcr0 register is set up to debug. + * Use the internal debug mode bit to do this. + */ + mtmsr(mfmsr() & ~MSR_DE); + if (IS_ENABLED(CONFIG_PPC32)) { + isync(); + global_dbcr0[smp_processor_id()] = mfspr(SPRN_DBCR0); + } + mtspr(SPRN_DBCR0, dbcr0); + mtspr(SPRN_DBSR, -1); +#endif +} + +static notrace void check_return_regs_valid(struct pt_regs *regs) +{ +#ifdef CONFIG_PPC_BOOK3S_64 + unsigned long trap, srr0, srr1; + static bool warned; + u8 *validp; + char *h; + + if (trap_is_scv(regs)) + return; + + trap = TRAP(regs); + // EE in HV mode sets HSRRs like 0xea0 + if (cpu_has_feature(CPU_FTR_HVMODE) && trap == INTERRUPT_EXTERNAL) + trap = 0xea0; + + switch (trap) { + case 0x980: + case INTERRUPT_H_DATA_STORAGE: + case 0xe20: + case 0xe40: + case INTERRUPT_HMI: + case 0xe80: + case 0xea0: + case INTERRUPT_H_FAC_UNAVAIL: + case 0x1200: + case 0x1500: + case 0x1600: + case 0x1800: + validp = &local_paca->hsrr_valid; + if (!READ_ONCE(*validp)) + return; + + srr0 = mfspr(SPRN_HSRR0); + srr1 = mfspr(SPRN_HSRR1); + h = "H"; + + break; + default: + validp = &local_paca->srr_valid; + if (!READ_ONCE(*validp)) + return; + + srr0 = mfspr(SPRN_SRR0); + srr1 = mfspr(SPRN_SRR1); + h = ""; + break; + } + + if (srr0 == regs->nip && srr1 == regs->msr) + return; + + /* + * A NMI / soft-NMI interrupt may have come in after we found + * srr_valid and before the SRRs are loaded. The interrupt then + * comes in and clobbers SRRs and clears srr_valid. Then we load + * the SRRs here and test them above and find they don't match. + * + * Test validity again after that, to catch such false positives. + * + * This test in general will have some window for false negatives + * and may not catch and fix all such cases if an NMI comes in + * later and clobbers SRRs without clearing srr_valid, but hopefully + * such things will get caught most of the time, statistically + * enough to be able to get a warning out. + */ + if (!READ_ONCE(*validp)) + return; + + if (!data_race(warned)) { + data_race(warned = true); + printk("%sSRR0 was: %lx should be: %lx\n", h, srr0, regs->nip); + printk("%sSRR1 was: %lx should be: %lx\n", h, srr1, regs->msr); + show_regs(regs); + } + + WRITE_ONCE(*validp, 0); /* fixup */ +#endif +} + +static notrace unsigned long +interrupt_exit_user_prepare_main(unsigned long ret, struct pt_regs *regs) +{ + unsigned long ti_flags; + +again: + ti_flags = read_thread_flags(); + while (unlikely(ti_flags & (_TIF_USER_WORK_MASK & ~_TIF_RESTORE_TM))) { + local_irq_enable(); + if (ti_flags & _TIF_NEED_RESCHED) { + schedule(); + } else { + /* + * SIGPENDING must restore signal handler function + * argument GPRs, and some non-volatiles (e.g., r1). + * Restore all for now. This could be made lighter. + */ + if (ti_flags & _TIF_SIGPENDING) + ret |= _TIF_RESTOREALL; + do_notify_resume(regs, ti_flags); + } + local_irq_disable(); + ti_flags = read_thread_flags(); + } + + if (IS_ENABLED(CONFIG_PPC_BOOK3S_64) && IS_ENABLED(CONFIG_PPC_FPU)) { + if (IS_ENABLED(CONFIG_PPC_TRANSACTIONAL_MEM) && + unlikely((ti_flags & _TIF_RESTORE_TM))) { + restore_tm_state(regs); + } else { + unsigned long mathflags = MSR_FP; + + if (cpu_has_feature(CPU_FTR_VSX)) + mathflags |= MSR_VEC | MSR_VSX; + else if (cpu_has_feature(CPU_FTR_ALTIVEC)) + mathflags |= MSR_VEC; + + /* + * If userspace MSR has all available FP bits set, + * then they are live and no need to restore. If not, + * it means the regs were given up and restore_math + * may decide to restore them (to avoid taking an FP + * fault). + */ + if ((regs->msr & mathflags) != mathflags) + restore_math(regs); + } + } + + 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; + } + +#ifdef CONFIG_PPC_TRANSACTIONAL_MEM + local_paca->tm_scratch = regs->msr; +#endif + + booke_load_dbcr0(); + + account_cpu_user_exit(); + + /* Restore user access locks last */ + kuap_user_restore(regs); + + return ret; +} + +/* + * 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; + + CT_WARN_ON(ct_state() == CONTEXT_USER); + + kuap_assert_locked(); + + regs->result = r3; + + /* Check whether the syscall is issued inside a restartable sequence */ + rseq_syscall(regs); + + 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)) { + do_syscall_trace_leave(regs); + ret |= _TIF_RESTOREALL; + } + + local_irq_disable(); + ret = interrupt_exit_user_prepare_main(ret, regs); + +#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) +{ + /* + * 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 + + trace_hardirqs_off(); + user_exit_irqoff(); + account_cpu_user_entry(); + + BUG_ON(!user_mode(regs)); + + regs->exit_result = interrupt_exit_user_prepare_main(regs->exit_result, regs); + + return regs->exit_result; +} +#endif + +notrace unsigned long interrupt_exit_user_prepare(struct pt_regs *regs) +{ + unsigned long ret; + + BUG_ON(regs_is_unrecoverable(regs)); + BUG_ON(arch_irq_disabled_regs(regs)); + CT_WARN_ON(ct_state() == CONTEXT_USER); + + /* + * 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(); + + local_irq_disable(); + + ret = interrupt_exit_user_prepare_main(0, regs); + +#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() == CONTEXT_USER); + + kuap = kuap_get_and_assert_locked(); + + local_irq_disable(); + + if (!arch_irq_disabled_regs(regs)) { + /* Returning to a kernel context with local irqs enabled. */ + WARN_ON_ONCE(!(regs->msr & MSR_EE)); +again: + if (IS_ENABLED(CONFIG_PREEMPT)) { + /* Return to preemptible kernel context */ + if (unlikely(read_thread_flags() & _TIF_NEED_RESCHED)) { + if (preempt_count() == 0) + preempt_schedule_irq(); + } + } + + 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(); +#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(); + user_exit_irqoff(); + 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 |