[PATCH perf/core 1/3] uprobes/x86: Return error from uprobe syscall when not called from trampoline

[Jiri Olsa]

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 <and...@kernel.org>
Acked-by: Andrii Nakryiko <and...@kernel.org>
Signed-off-by: Jiri Olsa <jo...@kernel.org>
---
 arch/x86/kernel/uprobes.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/uprobes.c b/arch/x86/kernel/uprobes.c
index 0a8c0a4a5423..845aeaf36b8d 100644
--- 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)
-- 
2.51.0