// SPDX-License-Identifier: GPL-2.0 #include <linux/compiler.h> #include <linux/context_tracking.h> #include <linux/errno.h> #include <linux/nospec.h> #include <linux/ptrace.h> #include <linux/syscalls.h> #include <asm/daifflags.h> #include <asm/debug-monitors.h> #include <asm/fpsimd.h> #include <asm/syscall.h> #include <asm/thread_info.h> #include <asm/unistd.h> long compat_arm_syscall(struct pt_regs *regs, int scno); long sys_ni_syscall(void); static long do_ni_syscall(struct pt_regs *regs, int scno) { #ifdef CONFIG_COMPAT long ret; if (is_compat_task()) { ret = compat_arm_syscall(regs, scno); if (ret != -ENOSYS) return ret; } #endif return sys_ni_syscall(); } static long __invoke_syscall(struct pt_regs *regs, syscall_fn_t syscall_fn) { return syscall_fn(regs); } static void invoke_syscall(struct pt_regs *regs, unsigned int scno, unsigned int sc_nr, const syscall_fn_t syscall_table[]) { long ret; if (scno < sc_nr) { syscall_fn_t syscall_fn; syscall_fn = syscall_table[array_index_nospec(scno, sc_nr)]; ret = __invoke_syscall(regs, syscall_fn); } else { ret = do_ni_syscall(regs, scno); } regs->regs[0] = ret; } static inline bool has_syscall_work(unsigned long flags) { return unlikely(flags & _TIF_SYSCALL_WORK); } int syscall_trace_enter(struct pt_regs *regs); void syscall_trace_exit(struct pt_regs *regs); #ifdef CONFIG_ARM64_ERRATUM_1463225 DECLARE_PER_CPU(int, __in_cortex_a76_erratum_1463225_wa); static void cortex_a76_erratum_1463225_svc_handler(void) { u32 reg, val; if (!unlikely(test_thread_flag(TIF_SINGLESTEP))) return; if (!unlikely(this_cpu_has_cap(ARM64_WORKAROUND_1463225))) return; __this_cpu_write(__in_cortex_a76_erratum_1463225_wa, 1); reg = read_sysreg(mdscr_el1); val = reg | DBG_MDSCR_SS | DBG_MDSCR_KDE; write_sysreg(val, mdscr_el1); asm volatile("msr daifclr, #8"); isb(); /* We will have taken a single-step exception by this point */ write_sysreg(reg, mdscr_el1); __this_cpu_write(__in_cortex_a76_erratum_1463225_wa, 0); } #else static void cortex_a76_erratum_1463225_svc_handler(void) { } #endif /* CONFIG_ARM64_ERRATUM_1463225 */ static void el0_svc_common(struct pt_regs *regs, int scno, int sc_nr, const syscall_fn_t syscall_table[]) { unsigned long flags = current_thread_info()->flags; regs->orig_x0 = regs->regs[0]; regs->syscallno = scno; cortex_a76_erratum_1463225_svc_handler(); local_daif_restore(DAIF_PROCCTX); user_exit(); if (has_syscall_work(flags)) { /* set default errno for user-issued syscall(-1) */ if (scno == NO_SYSCALL) regs->regs[0] = -ENOSYS; scno = syscall_trace_enter(regs); if (scno == NO_SYSCALL) goto trace_exit; } invoke_syscall(regs, scno, sc_nr, syscall_table); /* * The tracing status may have changed under our feet, so we have to * check again. However, if we were tracing entry, then we always trace * exit regardless, as the old entry assembly did. */ if (!has_syscall_work(flags) && !IS_ENABLED(CONFIG_DEBUG_RSEQ)) { local_daif_mask(); flags = current_thread_info()->flags; if (!has_syscall_work(flags)) { /* * We're off to userspace, where interrupts are * always enabled after we restore the flags from * the SPSR. */ trace_hardirqs_on(); return; } local_daif_restore(DAIF_PROCCTX); } trace_exit: syscall_trace_exit(regs); } static inline void sve_user_discard(void) { if (!system_supports_sve()) return; clear_thread_flag(TIF_SVE); /* * task_fpsimd_load() won't be called to update CPACR_EL1 in * ret_to_user unless TIF_FOREIGN_FPSTATE is still set, which only * happens if a context switch or kernel_neon_begin() or context * modification (sigreturn, ptrace) intervenes. * So, ensure that CPACR_EL1 is already correct for the fast-path case. */ sve_user_disable(); } void do_el0_svc(struct pt_regs *regs) { sve_user_discard(); el0_svc_common(regs, regs->regs[8], __NR_syscalls, sys_call_table); } #ifdef CONFIG_COMPAT void do_el0_svc_compat(struct pt_regs *regs) { el0_svc_common(regs, regs->regs[7], __NR_compat_syscalls, compat_sys_call_table); } #endif