| // 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 el0_svc_handler(struct pt_regs *regs) |
| { |
| sve_user_discard(); |
| el0_svc_common(regs, regs->regs[8], __NR_syscalls, sys_call_table); |
| } |
| |
| #ifdef CONFIG_COMPAT |
| void el0_svc_compat_handler(struct pt_regs *regs) |
| { |
| el0_svc_common(regs, regs->regs[7], __NR_compat_syscalls, |
| compat_sys_call_table); |
| } |
| #endif |