From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) (using TLSv1.2 with cipher ADH-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4124g80wf3zF356 for ; Fri, 8 Jun 2018 11:33:24 +1000 (AEST) Received: from ozlabs.org (bilbo.ozlabs.org [203.11.71.1]) by bilbo.ozlabs.org (Postfix) with ESMTP id 4124g75t5Rz8t0F for ; Fri, 8 Jun 2018 11:33:23 +1000 (AEST) Received: from mail-pl0-x242.google.com (mail-pl0-x242.google.com [IPv6:2607:f8b0:400e:c01::242]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 4124g71jlTz9s1b for ; Fri, 8 Jun 2018 11:33:23 +1000 (AEST) Received: by mail-pl0-x242.google.com with SMTP id i5-v6so7250187plt.2 for ; Thu, 07 Jun 2018 18:33:23 -0700 (PDT) Date: Fri, 8 Jun 2018 11:33:14 +1000 From: Nicholas Piggin To: Mahesh J Salgaonkar Cc: linuxppc-dev , stable@vger.kernel.org, "Aneesh Kumar K.V" , Michael Ellerman , Laurent Dufour Subject: Re: [v3 PATCH 2/5] powerpc/pseries: Fix endainness while restoring of r3 in MCE handler. Message-ID: <20180608113314.02fca098@roar.ozlabs.ibm.com> In-Reply-To: <152839249913.25118.1191250274945665204.stgit@jupiter.in.ibm.com> References: <152839244928.25118.15100234720683911223.stgit@jupiter.in.ibm.com> <152839249913.25118.1191250274945665204.stgit@jupiter.in.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Thu, 07 Jun 2018 22:58:33 +0530 Mahesh J Salgaonkar wrote: > From: Mahesh Salgaonkar > > During Machine Check interrupt on pseries platform, register r3 points > RTAS extended event log passed by hypervisor. Since hypervisor uses r3 > to pass pointer to rtas log, it stores the original r3 value at the > start of the memory (first 8 bytes) pointed by r3. Since hypervisor > stores this info and rtas log is in BE format, linux should make > sure to restore r3 value in correct endian format. > > Without this patch when MCE handler, after recovery, returns to code that > that caused the MCE may end up with Data SLB access interrupt for invalid > address followed by kernel panic or hang. > > [ 62.878965] Severe Machine check interrupt [Recovered] > [ 62.878968] NIP [d00000000ca301b8]: init_module+0x1b8/0x338 [bork_kernel] > [ 62.878969] Initiator: CPU > [ 62.878970] Error type: SLB [Multihit] > [ 62.878971] Effective address: d00000000ca70000 > cpu 0xa: Vector: 380 (Data SLB Access) at [c0000000fc7775b0] > pc: c0000000009694c0: vsnprintf+0x80/0x480 > lr: c0000000009698e0: vscnprintf+0x20/0x60 > sp: c0000000fc777830 > msr: 8000000002009033 > dar: a803a30c000000d0 > current = 0xc00000000bc9ef00 > paca = 0xc00000001eca5c00 softe: 3 irq_happened: 0x01 > pid = 8860, comm = insmod > [c0000000fc7778b0] c0000000009698e0 vscnprintf+0x20/0x60 > [c0000000fc7778e0] c00000000016b6c4 vprintk_emit+0xb4/0x4b0 > [c0000000fc777960] c00000000016d40c vprintk_func+0x5c/0xd0 > [c0000000fc777980] c00000000016cbb4 printk+0x38/0x4c > [c0000000fc7779a0] d00000000ca301c0 init_module+0x1c0/0x338 [bork_kernel] > [c0000000fc777a40] c00000000000d9c4 do_one_initcall+0x54/0x230 > [c0000000fc777b00] c0000000001b3b74 do_init_module+0x8c/0x248 > [c0000000fc777b90] c0000000001b2478 load_module+0x12b8/0x15b0 > [c0000000fc777d30] c0000000001b29e8 sys_finit_module+0xa8/0x110 > [c0000000fc777e30] c00000000000b204 system_call+0x58/0x6c > --- Exception: c00 (System Call) at 00007fff8bda0644 > SP (7fffdfbfe980) is in userspace > > This patch fixes this issue. LGTM Reviewed-by: Nicholas Piggin > > Fixes: a08a53ea4c97 ("powerpc/le: Enable RTAS events support") > Cc: stable@vger.kernel.org > Signed-off-by: Mahesh Salgaonkar > --- > arch/powerpc/platforms/pseries/ras.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/powerpc/platforms/pseries/ras.c b/arch/powerpc/platforms/pseries/ras.c > index 5e1ef9150182..2edc673be137 100644 > --- a/arch/powerpc/platforms/pseries/ras.c > +++ b/arch/powerpc/platforms/pseries/ras.c > @@ -360,7 +360,7 @@ static struct rtas_error_log *fwnmi_get_errinfo(struct pt_regs *regs) > } > > savep = __va(regs->gpr[3]); > - regs->gpr[3] = savep[0]; /* restore original r3 */ > + regs->gpr[3] = be64_to_cpu(savep[0]); /* restore original r3 */ > > /* If it isn't an extended log we can use the per cpu 64bit buffer */ > h = (struct rtas_error_log *)&savep[1]; >