diff --git a/arch/powerpc/kernel/Makefile b/arch/powerpc/kernel/Makefile index de954fe106c5..0963d39464c8 100644 --- a/arch/powerpc/kernel/Makefile +++ b/arch/powerpc/kernel/Makefile @@ -62,7 +62,7 @@ obj-y := cputable.o syscalls.o \ udbg.o misc.o io.o misc_$(BITS).o \ of_platform.o prom_parse.o firmware.o \ hw_breakpoint_constraints.o interrupt.o \ - kdebugfs.o stacktrace.o + kdebugfs.o stacktrace.o syscall.o obj-y += ptrace/ obj-$(CONFIG_PPC64) += setup_64.o irq_64.o\ paca.o nvram_64.o note.o diff --git a/arch/powerpc/kernel/interrupt.c b/arch/powerpc/kernel/interrupt.c index 784ea3289c84..0e75cb03244a 100644 --- a/arch/powerpc/kernel/interrupt.c +++ b/arch/powerpc/kernel/interrupt.c @@ -24,8 +24,6 @@ unsigned long global_dbcr0[NR_CPUS]; #endif -typedef long (*syscall_fn)(long, long, long, long, long, long); - #ifdef CONFIG_PPC_BOOK3S_64 DEFINE_STATIC_KEY_FALSE(interrupt_exit_not_reentrant); static inline bool exit_must_hard_disable(void) @@ -73,165 +71,6 @@ static notrace __always_inline bool prep_irq_for_enabled_exit(bool restartable) return true; } -/* Has to run notrace because it is entered not completely "reconciled" */ -notrace long system_call_exception(long r3, long r4, long r5, - long r6, long r7, long r8, - unsigned long r0, struct pt_regs *regs) -{ - syscall_fn f; - - kuap_lock(); - - regs->orig_gpr3 = r3; - - if (IS_ENABLED(CONFIG_PPC_IRQ_SOFT_MASK_DEBUG)) - BUG_ON(irq_soft_mask_return() != IRQS_ALL_DISABLED); - - trace_hardirqs_off(); /* finish reconciling */ - - CT_WARN_ON(ct_state() == CONTEXT_KERNEL); - user_exit_irqoff(); - - BUG_ON(regs_is_unrecoverable(regs)); - BUG_ON(!(regs->msr & MSR_PR)); - BUG_ON(arch_irq_disabled_regs(regs)); - -#ifdef CONFIG_PPC_PKEY - if (mmu_has_feature(MMU_FTR_PKEY)) { - unsigned long amr, iamr; - bool flush_needed = false; - /* - * When entering from userspace we mostly have the AMR/IAMR - * different from kernel default values. Hence don't compare. - */ - amr = mfspr(SPRN_AMR); - iamr = mfspr(SPRN_IAMR); - regs->amr = amr; - regs->iamr = iamr; - if (mmu_has_feature(MMU_FTR_BOOK3S_KUAP)) { - mtspr(SPRN_AMR, AMR_KUAP_BLOCKED); - flush_needed = true; - } - if (mmu_has_feature(MMU_FTR_BOOK3S_KUEP)) { - mtspr(SPRN_IAMR, AMR_KUEP_BLOCKED); - flush_needed = true; - } - if (flush_needed) - isync(); - } else -#endif - kuap_assert_locked(); - - booke_restore_dbcr0(); - - account_cpu_user_entry(); - - account_stolen_time(); - - /* - * This is not required for the syscall exit path, but makes the - * stack frame look nicer. If this was initialised in the first stack - * frame, or if the unwinder was taught the first stack frame always - * returns to user with IRQS_ENABLED, this store could be avoided! - */ - irq_soft_mask_regs_set_state(regs, IRQS_ENABLED); - - /* - * If system call is called with TM active, set _TIF_RESTOREALL to - * prevent RFSCV being used to return to userspace, because POWER9 - * TM implementation has problems with this instruction returning to - * transactional state. Final register values are not relevant because - * the transaction will be aborted upon return anyway. Or in the case - * of unsupported_scv SIGILL fault, the return state does not much - * matter because it's an edge case. - */ - if (IS_ENABLED(CONFIG_PPC_TRANSACTIONAL_MEM) && - unlikely(MSR_TM_TRANSACTIONAL(regs->msr))) - set_bits(_TIF_RESTOREALL, ¤t_thread_info()->flags); - - /* - * If the system call was made with a transaction active, doom it and - * return without performing the system call. Unless it was an - * unsupported scv vector, in which case it's treated like an illegal - * instruction. - */ -#ifdef CONFIG_PPC_TRANSACTIONAL_MEM - if (unlikely(MSR_TM_TRANSACTIONAL(regs->msr)) && - !trap_is_unsupported_scv(regs)) { - /* Enable TM in the kernel, and disable EE (for scv) */ - hard_irq_disable(); - mtmsr(mfmsr() | MSR_TM); - - /* tabort, this dooms the transaction, nothing else */ - asm volatile(".long 0x7c00071d | ((%0) << 16)" - :: "r"(TM_CAUSE_SYSCALL|TM_CAUSE_PERSISTENT)); - - /* - * Userspace will never see the return value. Execution will - * resume after the tbegin. of the aborted transaction with the - * checkpointed register state. A context switch could occur - * or signal delivered to the process before resuming the - * doomed transaction context, but that should all be handled - * as expected. - */ - return -ENOSYS; - } -#endif // CONFIG_PPC_TRANSACTIONAL_MEM - - local_irq_enable(); - - if (unlikely(read_thread_flags() & _TIF_SYSCALL_DOTRACE)) { - if (unlikely(trap_is_unsupported_scv(regs))) { - /* Unsupported scv vector */ - _exception(SIGILL, regs, ILL_ILLOPC, regs->nip); - return regs->gpr[3]; - } - /* - * We use the return value of do_syscall_trace_enter() as the - * syscall number. If the syscall was rejected for any reason - * do_syscall_trace_enter() returns an invalid syscall number - * and the test against NR_syscalls will fail and the return - * value to be used is in regs->gpr[3]. - */ - r0 = do_syscall_trace_enter(regs); - if (unlikely(r0 >= NR_syscalls)) - return regs->gpr[3]; - r3 = regs->gpr[3]; - r4 = regs->gpr[4]; - r5 = regs->gpr[5]; - r6 = regs->gpr[6]; - r7 = regs->gpr[7]; - r8 = regs->gpr[8]; - - } else if (unlikely(r0 >= NR_syscalls)) { - if (unlikely(trap_is_unsupported_scv(regs))) { - /* Unsupported scv vector */ - _exception(SIGILL, regs, ILL_ILLOPC, regs->nip); - return regs->gpr[3]; - } - return -ENOSYS; - } - - /* May be faster to do array_index_nospec? */ - barrier_nospec(); - - if (unlikely(is_compat_task())) { - f = (void *)compat_sys_call_table[r0]; - - r3 &= 0x00000000ffffffffULL; - r4 &= 0x00000000ffffffffULL; - r5 &= 0x00000000ffffffffULL; - r6 &= 0x00000000ffffffffULL; - r7 &= 0x00000000ffffffffULL; - r8 &= 0x00000000ffffffffULL; - - } else { - f = (void *)sys_call_table[r0]; - } - - return f(r3, r4, r5, r6, r7, r8); -} - static notrace void booke_load_dbcr0(void) { #ifdef CONFIG_PPC_ADV_DEBUG_REGS diff --git a/arch/powerpc/kernel/syscall.c b/arch/powerpc/kernel/syscall.c new file mode 100644 index 000000000000..4d5689eeaf25 --- /dev/null +++ b/arch/powerpc/kernel/syscall.c @@ -0,0 +1,173 @@ +// SPDX-License-Identifier: GPL-2.0-or-later + +#include +#include + +#include +#include +#include +#include +#include +#include + + +typedef long (*syscall_fn)(long, long, long, long, long, long); + +/* Has to run notrace because it is entered not completely "reconciled" */ +notrace long system_call_exception(long r3, long r4, long r5, + long r6, long r7, long r8, + unsigned long r0, struct pt_regs *regs) +{ + syscall_fn f; + + kuap_lock(); + + regs->orig_gpr3 = r3; + + if (IS_ENABLED(CONFIG_PPC_IRQ_SOFT_MASK_DEBUG)) + BUG_ON(irq_soft_mask_return() != IRQS_ALL_DISABLED); + + trace_hardirqs_off(); /* finish reconciling */ + + CT_WARN_ON(ct_state() == CONTEXT_KERNEL); + user_exit_irqoff(); + + BUG_ON(regs_is_unrecoverable(regs)); + BUG_ON(!(regs->msr & MSR_PR)); + BUG_ON(arch_irq_disabled_regs(regs)); + +#ifdef CONFIG_PPC_PKEY + if (mmu_has_feature(MMU_FTR_PKEY)) { + unsigned long amr, iamr; + bool flush_needed = false; + /* + * When entering from userspace we mostly have the AMR/IAMR + * different from kernel default values. Hence don't compare. + */ + amr = mfspr(SPRN_AMR); + iamr = mfspr(SPRN_IAMR); + regs->amr = amr; + regs->iamr = iamr; + if (mmu_has_feature(MMU_FTR_BOOK3S_KUAP)) { + mtspr(SPRN_AMR, AMR_KUAP_BLOCKED); + flush_needed = true; + } + if (mmu_has_feature(MMU_FTR_BOOK3S_KUEP)) { + mtspr(SPRN_IAMR, AMR_KUEP_BLOCKED); + flush_needed = true; + } + if (flush_needed) + isync(); + } else +#endif + kuap_assert_locked(); + + booke_restore_dbcr0(); + + account_cpu_user_entry(); + + account_stolen_time(); + + /* + * This is not required for the syscall exit path, but makes the + * stack frame look nicer. If this was initialised in the first stack + * frame, or if the unwinder was taught the first stack frame always + * returns to user with IRQS_ENABLED, this store could be avoided! + */ + irq_soft_mask_regs_set_state(regs, IRQS_ENABLED); + + /* + * If system call is called with TM active, set _TIF_RESTOREALL to + * prevent RFSCV being used to return to userspace, because POWER9 + * TM implementation has problems with this instruction returning to + * transactional state. Final register values are not relevant because + * the transaction will be aborted upon return anyway. Or in the case + * of unsupported_scv SIGILL fault, the return state does not much + * matter because it's an edge case. + */ + if (IS_ENABLED(CONFIG_PPC_TRANSACTIONAL_MEM) && + unlikely(MSR_TM_TRANSACTIONAL(regs->msr))) + set_bits(_TIF_RESTOREALL, ¤t_thread_info()->flags); + + /* + * If the system call was made with a transaction active, doom it and + * return without performing the system call. Unless it was an + * unsupported scv vector, in which case it's treated like an illegal + * instruction. + */ +#ifdef CONFIG_PPC_TRANSACTIONAL_MEM + if (unlikely(MSR_TM_TRANSACTIONAL(regs->msr)) && + !trap_is_unsupported_scv(regs)) { + /* Enable TM in the kernel, and disable EE (for scv) */ + hard_irq_disable(); + mtmsr(mfmsr() | MSR_TM); + + /* tabort, this dooms the transaction, nothing else */ + asm volatile(".long 0x7c00071d | ((%0) << 16)" + :: "r"(TM_CAUSE_SYSCALL|TM_CAUSE_PERSISTENT)); + + /* + * Userspace will never see the return value. Execution will + * resume after the tbegin. of the aborted transaction with the + * checkpointed register state. A context switch could occur + * or signal delivered to the process before resuming the + * doomed transaction context, but that should all be handled + * as expected. + */ + return -ENOSYS; + } +#endif // CONFIG_PPC_TRANSACTIONAL_MEM + + local_irq_enable(); + + if (unlikely(read_thread_flags() & _TIF_SYSCALL_DOTRACE)) { + if (unlikely(trap_is_unsupported_scv(regs))) { + /* Unsupported scv vector */ + _exception(SIGILL, regs, ILL_ILLOPC, regs->nip); + return regs->gpr[3]; + } + /* + * We use the return value of do_syscall_trace_enter() as the + * syscall number. If the syscall was rejected for any reason + * do_syscall_trace_enter() returns an invalid syscall number + * and the test against NR_syscalls will fail and the return + * value to be used is in regs->gpr[3]. + */ + r0 = do_syscall_trace_enter(regs); + if (unlikely(r0 >= NR_syscalls)) + return regs->gpr[3]; + r3 = regs->gpr[3]; + r4 = regs->gpr[4]; + r5 = regs->gpr[5]; + r6 = regs->gpr[6]; + r7 = regs->gpr[7]; + r8 = regs->gpr[8]; + + } else if (unlikely(r0 >= NR_syscalls)) { + if (unlikely(trap_is_unsupported_scv(regs))) { + /* Unsupported scv vector */ + _exception(SIGILL, regs, ILL_ILLOPC, regs->nip); + return regs->gpr[3]; + } + return -ENOSYS; + } + + /* May be faster to do array_index_nospec? */ + barrier_nospec(); + + if (unlikely(is_compat_task())) { + f = (void *)compat_sys_call_table[r0]; + + r3 &= 0x00000000ffffffffULL; + r4 &= 0x00000000ffffffffULL; + r5 &= 0x00000000ffffffffULL; + r6 &= 0x00000000ffffffffULL; + r7 &= 0x00000000ffffffffULL; + r8 &= 0x00000000ffffffffULL; + + } else { + f = (void *)sys_call_table[r0]; + } + + return f(r3, r4, r5, r6, r7, r8); +}