lkml.org 
[lkml]   [2019]   [Sep]   [20]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [RFC patch 04/15] arm64/entry: Use generic syscall entry function
    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

    \
     
     \ /
      Last update: 2019-09-20 14:22    [W:4.962 / U:0.092 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site