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[64.2.3.195]) by mx.google.com with ESMTPS id fh1sm3876984pac.1.2013.03.20.16.14.58 (version=TLSv1 cipher=RC4-SHA bits=128/128); Wed, 20 Mar 2013 16:14:59 -0700 (PDT) Message-ID: <514A42F2.4080501@gmail.com> Date: Wed, 20 Mar 2013 16:14:58 -0700 From: David Daney User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130110 Thunderbird/17.0.2 MIME-Version: 1.0 To: Huacai Chen , Ralf Baechle CC: linux-mips@linux-mips.org, linux-kernel@vger.kernel.org, Fuxin Zhang , Zhangjin Wu , Hongbing Hu Subject: Re: [PATCH V2 01/02] MIPS: Build uasm-generated code only once to avoid CPU Hotplug problem References: <1363524578-3765-1-git-send-email-chenhc@lemote.com> In-Reply-To: <1363524578-3765-1-git-send-email-chenhc@lemote.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-archive-position: 35924 X-ecartis-version: Ecartis v1.0.0 Sender: linux-mips-bounce@linux-mips.org Errors-to: linux-mips-bounce@linux-mips.org X-original-sender: ddaney.cavm@gmail.com Precedence: bulk List-help: List-unsubscribe: List-software: Ecartis version 1.0.0 List-Id: linux-mips X-List-ID: linux-mips List-subscribe: List-owner: List-post: List-archive: X-list: linux-mips Return-Path: On 03/17/2013 05:49 AM, Huacai Chen wrote: > This and the next patch resolve memory corruption problems while CPU > hotplug. Without these patches, memory corruption can triggered easily > as below: > > On a quad-core MIPS platform, use "spawn" of UnixBench-5.1.3 (http:// > code.google.com/p/byte-unixbench/) and a CPU hotplug script like this > (hotplug.sh): > while true; do > echo 0 >/sys/devices/system/cpu/cpu1/online > echo 0 >/sys/devices/system/cpu/cpu2/online > echo 0 >/sys/devices/system/cpu/cpu3/online > sleep 1 > echo 1 >/sys/devices/system/cpu/cpu1/online > echo 1 >/sys/devices/system/cpu/cpu2/online > echo 1 >/sys/devices/system/cpu/cpu3/online > sleep 1 > done > > Run "hotplug.sh" and then run "spawn 10000", spawn will get segfault > after a few minutes. > > This patch: > Currently, clear_page()/copy_page() are generated by Micro-assembler > dynamically. But they are unavailable until uasm_resolve_relocs() has > finished because jump labels are illegal before that. Since these > functions are shared by every CPU, we only call build_clear_page()/ > build_copy_page() only once at boot time. Without this patch, programs > will get random memory corruption (segmentation fault, bus error, etc.) > while CPU Hotplug (e.g. one CPU is using clear_page() while another is > generating it in cpu_cache_init()). > > For similar reasons we modify build_tlb_refill_handler()'s invocation. > > V2: > 1, Rework the code to make CPU#0 can be online/offline. > 2, Introduce cpu_has_local_ebase feature since some types of MIPS CPU > need a per-CPU tlb_refill_handler(). > > Signed-off-by: Huacai Chen > Signed-off-by: Hongbing Hu We were seeing the same crashes, this patch set seems to fix the problem. Acked-by: David Daney > --- > arch/mips/include/asm/cpu-features.h | 3 +++ > .../asm/mach-loongson/cpu-feature-overrides.h | 1 + > arch/mips/mm/page.c | 10 ++++++++++ > arch/mips/mm/tlbex.c | 10 ++++++++-- > 4 files changed, 22 insertions(+), 2 deletions(-) > > diff --git a/arch/mips/include/asm/cpu-features.h b/arch/mips/include/asm/cpu-features.h > index 1a57e8b..e5ec8fc 100644 > --- a/arch/mips/include/asm/cpu-features.h > +++ b/arch/mips/include/asm/cpu-features.h > @@ -113,6 +113,9 @@ > #ifndef cpu_has_pindexed_dcache > #define cpu_has_pindexed_dcache (cpu_data[0].dcache.flags & MIPS_CACHE_PINDEX) > #endif > +#ifndef cpu_has_local_ebase > +#define cpu_has_local_ebase 1 > +#endif > > /* > * I-Cache snoops remote store. This only matters on SMP. Some multiprocessors > diff --git a/arch/mips/include/asm/mach-loongson/cpu-feature-overrides.h b/arch/mips/include/asm/mach-loongson/cpu-feature-overrides.h > index 75fd8c0..c0f3ef4 100644 > --- a/arch/mips/include/asm/mach-loongson/cpu-feature-overrides.h > +++ b/arch/mips/include/asm/mach-loongson/cpu-feature-overrides.h > @@ -57,5 +57,6 @@ > #define cpu_has_vint 0 > #define cpu_has_vtag_icache 0 > #define cpu_has_watch 1 > +#define cpu_has_local_ebase 0 > > #endif /* __ASM_MACH_LOONGSON_CPU_FEATURE_OVERRIDES_H */ > diff --git a/arch/mips/mm/page.c b/arch/mips/mm/page.c > index a29fba5..4eb8dcf 100644 > --- a/arch/mips/mm/page.c > +++ b/arch/mips/mm/page.c > @@ -247,6 +247,11 @@ void __cpuinit build_clear_page(void) > struct uasm_label *l = labels; > struct uasm_reloc *r = relocs; > int i; > + static atomic_t run_once = ATOMIC_INIT(0); > + > + if (atomic_xchg(&run_once, 1)) { > + return; > + } > > memset(labels, 0, sizeof(labels)); > memset(relocs, 0, sizeof(relocs)); > @@ -389,6 +394,11 @@ void __cpuinit build_copy_page(void) > struct uasm_label *l = labels; > struct uasm_reloc *r = relocs; > int i; > + static atomic_t run_once = ATOMIC_INIT(0); > + > + if (atomic_xchg(&run_once, 1)) { > + return; > + } > > memset(labels, 0, sizeof(labels)); > memset(relocs, 0, sizeof(relocs)); > diff --git a/arch/mips/mm/tlbex.c b/arch/mips/mm/tlbex.c > index 820e661..6bc28b4 100644 > --- a/arch/mips/mm/tlbex.c > +++ b/arch/mips/mm/tlbex.c > @@ -2162,8 +2162,11 @@ void __cpuinit build_tlb_refill_handler(void) > case CPU_TX3922: > case CPU_TX3927: > #ifndef CONFIG_MIPS_PGD_C0_CONTEXT > - build_r3000_tlb_refill_handler(); > + if (cpu_has_local_ebase) > + build_r3000_tlb_refill_handler(); > if (!run_once) { > + if (!cpu_has_local_ebase) > + build_r3000_tlb_refill_handler(); > build_r3000_tlb_load_handler(); > build_r3000_tlb_store_handler(); > build_r3000_tlb_modify_handler(); > @@ -2192,9 +2195,12 @@ void __cpuinit build_tlb_refill_handler(void) > build_r4000_tlb_load_handler(); > build_r4000_tlb_store_handler(); > build_r4000_tlb_modify_handler(); > + if (!cpu_has_local_ebase) > + build_r4000_tlb_refill_handler(); > run_once++; > } > - build_r4000_tlb_refill_handler(); > + if (cpu_has_local_ebase) > + build_r4000_tlb_refill_handler(); > } > } > >