From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from co1outboundpool.messaging.microsoft.com (co1ehsobe002.messaging.microsoft.com [216.32.180.185]) (using TLSv1 with cipher AES128-SHA (128/128 bits)) (Client CN "mail.global.frontbridge.com", Issuer "MSIT Machine Auth CA 2" (not verified)) by ozlabs.org (Postfix) with ESMTPS id 64C9A2C008E for ; Sat, 19 Oct 2013 09:57:23 +1100 (EST) Message-ID: <1382137030.7979.914.camel@snotra.buserror.net> Subject: Re: [v5][PATCH 3/6] book3e/kgdb: update thread's dbcr0 From: Scott Wood To: Tiejun Chen Date: Fri, 18 Oct 2013 17:57:10 -0500 In-Reply-To: <1371724110-8250-4-git-send-email-tiejun.chen@windriver.com> References: <1371724110-8250-1-git-send-email-tiejun.chen@windriver.com> <1371724110-8250-4-git-send-email-tiejun.chen@windriver.com> Content-Type: text/plain; charset="UTF-8" MIME-Version: 1.0 Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Thu, 2013-06-20 at 18:28 +0800, Tiejun Chen wrote: > gdb always need to generate a single step properly to invoke > a kgdb state. But with lazy interrupt, book3e can't always > trigger a debug exception with a single step since the current > is blocked for handling those pending exception, then we miss > that expected dbcr configuration at last to generate a debug > exception. What do you mean by "the current is blocked"? Could you explain more clearly what lazy EE has to do with MSR_DE and DBCR0? > So here we also update thread's dbcr0 to make sure the current > can go back with that missed dbcr0 configuration. > > Signed-off-by: Tiejun Chen > --- > arch/powerpc/kernel/kgdb.c | 13 ++++++++++--- > 1 file changed, 10 insertions(+), 3 deletions(-) > > diff --git a/arch/powerpc/kernel/kgdb.c b/arch/powerpc/kernel/kgdb.c > index c1eef24..55409ac 100644 > --- a/arch/powerpc/kernel/kgdb.c > +++ b/arch/powerpc/kernel/kgdb.c > @@ -410,7 +410,7 @@ int kgdb_arch_handle_exception(int vector, int signo, int err_code, > struct pt_regs *linux_regs) > { > char *ptr = &remcom_in_buffer[1]; > - unsigned long addr; > + unsigned long addr, dbcr0; > > switch (remcom_in_buffer[0]) { > /* > @@ -427,8 +427,15 @@ int kgdb_arch_handle_exception(int vector, int signo, int err_code, > /* set the trace bit if we're stepping */ > if (remcom_in_buffer[0] == 's') { > #ifdef CONFIG_PPC_ADV_DEBUG_REGS > - mtspr(SPRN_DBCR0, > - mfspr(SPRN_DBCR0) | DBCR0_IC | DBCR0_IDM); > + dbcr0 = mfspr(SPRN_DBCR0) | DBCR0_IC | DBCR0_IDM; > + mtspr(SPRN_DBCR0, dbcr0); > +#ifdef CONFIG_PPC_BOOK3E_64 This could as well be "CONFIG_PPC64" -- CONFIG_PPC_ADV_DEBUG_REGS implies booke or 40x. Lazy EE is a CONFIG_PPC64 thing, not specifically CONFIG_PPC_BOOK3E_64. > + /* With lazy interrut we have to update thread dbcr0 here s/interrut/interrupts/ > + * to make sure we can set debug properly at last to invoke > + * kgdb again to work well. > + */ > + current->thread.dbcr0 = dbcr0; > +#endif > linux_regs->msr |= MSR_DE; > #else > linux_regs->msr |= MSR_SE; Hmm, what happens here if we enable KGDB on booke without CONFIG_PPC_ADV_DEBUG_REGS? Kconfig doesn't appear to prevent it. -Scott