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Date: Tue, 25 Aug 2020 14:06:21 +0200 From: Christophe Leroy <christophe.leroy@...roup.eu> To: Ravi Bangoria <ravi.bangoria@...ux.ibm.com>, christophe.leroy@....fr Cc: mpe@...erman.id.au, mikey@...ling.org, paulus@...ba.org, naveen.n.rao@...ux.vnet.ibm.com, pedromfc@...ux.ibm.com, rogealve@...ux.ibm.com, jniethe5@...il.com, linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org Subject: Re: [PATCH v5 5/8] powerpc/watchpoint: Fix exception handling for CONFIG_HAVE_HW_BREAKPOINT=N Le 25/08/2020 à 13:07, Ravi Bangoria a écrit : > Hi Christophe, > >>> diff --git a/arch/powerpc/kernel/ptrace/ptrace-noadv.c >>> b/arch/powerpc/kernel/ptrace/ptrace-noadv.c >>> index 57a0ab822334..866597b407bc 100644 >>> --- a/arch/powerpc/kernel/ptrace/ptrace-noadv.c >>> +++ b/arch/powerpc/kernel/ptrace/ptrace-noadv.c >>> @@ -286,11 +286,16 @@ long ppc_del_hwdebug(struct task_struct *child, >>> long data) >>> } >>> return ret; >>> #else /* CONFIG_HAVE_HW_BREAKPOINT */ >>> + if (child->thread.hw_brk[data - 1].flags & HW_BRK_FLAG_DISABLED) >> >> I think child->thread.hw_brk[data - 1].flags & HW_BRK_FLAG_DISABLED >> should go around additionnal () > > Not sure I follow. Neither do I .... I thought that GCC would emit a warning for that, but in fact it only emit warnings for things like: if (flags & HW_BRK_FLAG_DISABLED == HW_BRK_FLAG_DISABLED) > >> >>> + goto del; >>> + >>> if (child->thread.hw_brk[data - 1].address == 0) >>> return -ENOENT; >> >> What about replacing the above if by: >> if (!(child->thread.hw_brk[data - 1].flags) & >> HW_BRK_FLAG_DISABLED) && >> child->thread.hw_brk[data - 1].address == 0) >> return -ENOENT; > okay.. that's more compact. > > But more importantly, what I wanted to know is whether > CONFIG_HAVE_HW_BREAKPOINT > is set or not in production/distro builds for 8xx. Because I see it's > not set in > 8xx defconfigs. Yes in our production configs with have CONFIG_PERF_EVENTS, that implies CONFIG_HAVE_HW_BREAKPOINT Christophe
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