Messages in this thread Patch in this message | | | Date | Sat, 10 Jul 2010 15:48:49 +0200 | From | Sam Ravnborg <> | Subject | Re: [PATCH] tracing: properly align linker defined symbols |
| |
On Sat, Jul 10, 2010 at 07:34:05AM -0400, Steven Rostedt wrote: > On Sat, 2010-07-10 at 13:18 +0300, Zeev Tarantov wrote: > > On Sat, Jul 10, 2010 at 09:35, Sam Ravnborg <sam@ravnborg.org> wrote: > > > > +/* > > > + * Align to a 32 byte boundary equal to the > > > + * alignment gcc 4.5 uses for a struct > > > + */ > > > +#define STRUCT_ALIGN() . = ALIGN(32) > > > + > > What I'm nervous about is when gcc 4.8 decides to up the alignment to > 64. > > Maybe we should have both patches, just to be safe.
Another approach could be to just stop playing games with alignment and use the fact that __stop_syscalls_metadata point to next byte after last entry.
Something like the below untested patch.
But to fix the current regression I prefer the simpler patch that just fixup the aligment.
Sam
diff --git a/kernel/trace/trace_syscalls.c b/kernel/trace/trace_syscalls.c index 34e3580..50e9606 100644 --- a/kernel/trace/trace_syscalls.c +++ b/kernel/trace/trace_syscalls.c @@ -79,15 +79,19 @@ static struct syscall_metadata *find_syscall_meta(unsigned long syscall) stop = (struct syscall_metadata *)__stop_syscalls_metadata; kallsyms_lookup(syscall, NULL, NULL, NULL, str); - for ( ; start < stop; start++) { + /* + * start may point a few bytes before first entry + * stop points at first byte after last entry + */ + for (stop--; stop >= start; stop--) { /* * Only compare after the "sys" prefix. Archs that use * syscall wrappers may have syscalls symbols aliases prefixed * with "SyS" instead of "sys", leading to an unwanted * mismatch. */ - if (start->name && !strcmp(start->name + 3, str + 3)) - return start; + if (stop->name && !strcmp(stop->name + 3, str + 3)) + return stop; } return NULL; }
| |