On Tue, Aug 20, 2019 at 12:58:49PM +0200, Christophe Leroy wrote: > Le 20/08/2019 à 12:06, Peter Zijlstra a écrit : > > On Mon, Aug 19, 2019 at 04:41:11PM -0700, Kees Cook wrote: > > > > > diff --git a/include/asm-generic/bug.h b/include/asm-generic/bug.h > > > index 588dd59a5b72..da471fcc5487 100644 > > > --- a/include/asm-generic/bug.h > > > +++ b/include/asm-generic/bug.h > > > @@ -10,6 +10,7 @@ > > > #define BUGFLAG_WARNING (1 << 0) > > > #define BUGFLAG_ONCE (1 << 1) > > > #define BUGFLAG_DONE (1 << 2) > > > +#define BUGFLAG_PRINTK (1 << 3) > > > #define BUGFLAG_TAINT(taint) ((taint) << 8) > > > #define BUG_GET_TAINT(bug) ((bug)->flags >> 8) > > > #endif > > > > > diff --git a/lib/bug.c b/lib/bug.c > > > index 1077366f496b..6c22e8a6f9de 100644 > > > --- a/lib/bug.c > > > +++ b/lib/bug.c > > > @@ -181,6 +181,15 @@ enum bug_trap_type report_bug(unsigned long bugaddr, struct pt_regs *regs) > > > } > > > } > > > + /* > > > + * BUG() and WARN_ON() families don't print a custom debug message > > > + * before triggering the exception handler, so we must add the > > > + * "cut here" line now. WARN() issues its own "cut here" before the > > > + * extra debugging message it writes before triggering the handler. > > > + */ > > > + if ((bug->flags & BUGFLAG_PRINTK) == 0) > > > + printk(KERN_DEFAULT CUT_HERE); > > > > I'm not loving that BUGFLAG_PRINTK name, BUGFLAG_CUT_HERE makes more > > sense to me. That's fine -- easy rename. :) > Actually it would be BUGFLAG_NO_CUT_HERE then, otherwise all arches not > using the generic macros will have to add the flag to get the "cut here" > line. I am testing for the lack of the flag (so that only the CONFIG_GENERIC_BUG with __WARN_FLAGS case needs to set it). I was thinking of the flag to mean "this reporting flow has already issued cut-here". It sounds like it would be more logical to have it named BUGFLAG_NO_CUT_HERE to mean "do not issue a cut-here; it has already happened"? I will update the patch. Thanks! -- Kees Cook
