uprobes/x86: Return error from uprobe syscall when not called from trampoline

Currently uprobe syscall handles all errors with forcing SIGILL to current
process. As suggested by Andrii it'd be helpful for uprobe syscall detection
to return error value for the !in_uprobe_trampoline check.

This way we could just call uprobe syscall and based on return value we will
find out if the kernel has it.

Suggested-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Oleg Nesterov <oleg@redhat.com>

diff --git a/arch/x86/kernel/uprobes.c b/arch/x86/kernel/uprobes.c
index 0a8c0a4a54233a389817a11dc5bdb723358faa95..845aeaf36b8d2fc3740255f421833369e7651cf2 100644 (file)
--- a/arch/x86/kernel/uprobes.c
+++ b/arch/x86/kernel/uprobes.c
@@ -810,7 +810,7 @@ SYSCALL_DEFINE0(uprobe)
 
        /* Allow execution only from uprobe trampolines. */
        if (!in_uprobe_trampoline(regs->ip))
-               goto sigill;
+               return -ENXIO;
 
        err = copy_from_user(&args, (void __user *)regs->sp, sizeof(args));
        if (err)