On Thu, Sep 19, 2019 at 05:03:18PM +0200, Thomas Gleixner wrote:
> #ifdef CONFIG_ARM64_ERRATUM_1463225
> @@ -97,19 +97,16 @@ static void el0_svc_common(struct pt_reg
>
> regs->orig_x0 = regs->regs[0];
> regs->syscallno = scno;
> + /* Set default error number */
> + regs->regs[0] = -ENOSYS;
I think this corrupts the first argument of all valid syscalls.
SC_ARM64_REGS_TO_ARGS uses regs[0] instead of orig_x0. ptrace should be
fine since it calls syscall_get_arguments() which uses orig_x0.
We could change the SC_ARM64_REGS_TO_ARGS macro though (in theory there
shouldn't be any performance hit as it's already cached).
>
> 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;
> - }
> + scno = syscall_enter_from_usermode(regs, scno);
> + if (scno == NO_SYSCALL)
> + goto trace_exit;
>
> invoke_syscall(regs, scno, sc_nr, syscall_table);
--
Catalin
