1 // SPDX-License-Identifier: GPL-2.0
3 #include <linux/compiler.h>
4 #include <linux/context_tracking.h>
5 #include <linux/errno.h>
6 #include <linux/nospec.h>
7 #include <linux/ptrace.h>
8 #include <linux/syscalls.h>
10 #include <asm/daifflags.h>
11 #include <asm/fpsimd.h>
12 #include <asm/syscall.h>
13 #include <asm/thread_info.h>
14 #include <asm/unistd.h>
16 long compat_arm_syscall(struct pt_regs *regs, int scno);
17 long sys_ni_syscall(void);
19 static long do_ni_syscall(struct pt_regs *regs, int scno)
23 if (is_compat_task()) {
24 ret = compat_arm_syscall(regs, scno);
30 return sys_ni_syscall();
33 static long __invoke_syscall(struct pt_regs *regs, syscall_fn_t syscall_fn)
35 return syscall_fn(regs);
38 static void invoke_syscall(struct pt_regs *regs, unsigned int scno,
40 const syscall_fn_t syscall_table[])
45 syscall_fn_t syscall_fn;
46 syscall_fn = syscall_table[array_index_nospec(scno, sc_nr)];
47 ret = __invoke_syscall(regs, syscall_fn);
49 ret = do_ni_syscall(regs, scno);
55 static inline bool has_syscall_work(unsigned long flags)
57 return unlikely(flags & _TIF_SYSCALL_WORK);
60 int syscall_trace_enter(struct pt_regs *regs);
61 void syscall_trace_exit(struct pt_regs *regs);
63 static void el0_svc_common(struct pt_regs *regs, int scno, int sc_nr,
64 const syscall_fn_t syscall_table[])
66 unsigned long flags = current_thread_info()->flags;
68 regs->orig_x0 = regs->regs[0];
69 regs->syscallno = scno;
71 local_daif_restore(DAIF_PROCCTX);
74 if (has_syscall_work(flags)) {
75 /* set default errno for user-issued syscall(-1) */
76 if (scno == NO_SYSCALL)
77 regs->regs[0] = -ENOSYS;
78 scno = syscall_trace_enter(regs);
79 if (scno == NO_SYSCALL)
83 invoke_syscall(regs, scno, sc_nr, syscall_table);
86 * The tracing status may have changed under our feet, so we have to
87 * check again. However, if we were tracing entry, then we always trace
88 * exit regardless, as the old entry assembly did.
90 if (!has_syscall_work(flags) && !IS_ENABLED(CONFIG_DEBUG_RSEQ)) {
92 flags = current_thread_info()->flags;
93 if (!has_syscall_work(flags)) {
95 * We're off to userspace, where interrupts are
96 * always enabled after we restore the flags from
102 local_daif_restore(DAIF_PROCCTX);
106 syscall_trace_exit(regs);
109 static inline void sve_user_discard(void)
111 if (!system_supports_sve())
114 clear_thread_flag(TIF_SVE);
117 * task_fpsimd_load() won't be called to update CPACR_EL1 in
118 * ret_to_user unless TIF_FOREIGN_FPSTATE is still set, which only
119 * happens if a context switch or kernel_neon_begin() or context
120 * modification (sigreturn, ptrace) intervenes.
121 * So, ensure that CPACR_EL1 is already correct for the fast-path case.
126 asmlinkage void el0_svc_handler(struct pt_regs *regs)
129 el0_svc_common(regs, regs->regs[8], __NR_syscalls, sys_call_table);
133 asmlinkage void el0_svc_compat_handler(struct pt_regs *regs)
135 el0_svc_common(regs, regs->regs[7], __NR_compat_syscalls,
136 compat_sys_call_table);