[PATCH 2/3] powerpc/ftrace: Simplify error checking when patching instructions

Christophe Leroy christophe.leroy at c-s.fr
Fri Apr 24 01:44:51 AEST 2020



Le 23/04/2020 à 17:09, Naveen N. Rao a écrit :
> Introduce a macro PATCH_INSN() to simplify instruction patching, and to
> make the error messages more uniform and useful:
> - print an error message that includes the original return value
> - print the function name and line numbers, so that the offending
>    location is clear
> - always return -EPERM, which ftrace_bug() expects for proper error
>    handling
> 
> Also eliminate use of patch_branch() since most such uses already call
> create_branch() for error checking before patching. Instead, use the
> return value from create_branch() with PATCH_INSN().

I have the same comment here as for patch 3, this kind of macro hides 
the return action and can be dangerous.

What about implementing a macro that takes an explicit label as third 
argument and jump to that label in case of error ? On the same model as 
unsafe_put_user() ?

Christophe


More information about the Linuxppc-dev mailing list